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Valenčič T, Ansdell P, Brownstein CG, Spillane PM, Holobar A, Škarabot J. Motor unit discharge rate modulation during isometric contractions to failure is intensity- and modality-dependent. J Physiol 2024; 602:2287-2314. [PMID: 38619366 DOI: 10.1113/jp286143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 03/25/2024] [Indexed: 04/16/2024] Open
Abstract
The physiological mechanisms determining the progressive decline in the maximal muscle torque production capacity during isometric contractions to task failure are known to depend on task demands. Task-specificity of the associated adjustments in motor unit discharge rate (MUDR), however, remains unclear. This study examined MUDR adjustments during different submaximal isometric knee extension tasks to failure. Participants performed a sustained and an intermittent task at 20% and 50% of maximal voluntary torque (MVT), respectively (Experiment 1). High-density surface EMG signals were recorded from vastus lateralis (VL) and medialis (VM) and decomposed into individual MU discharge timings, with the identified MUs tracked from recruitment to task failure. MUDR was quantified and normalised to intervals of 10% of contraction time (CT). MUDR of both muscles exhibited distinct modulation patterns in each task. During the 20% MVT sustained task, MUDR decreased until ∼50% CT, after which it gradually returned to baseline. Conversely, during the 50% MVT intermittent task, MUDR remained stable until ∼40-50% CT, after which it started to continually increase until task failure. To explore the effect of contraction intensity on the observed patterns, VL and VM MUDR was quantified during sustained contractions at 30% and 50% MVT (Experiment 2). During the 30% MVT sustained task, MUDR remained stable until ∼80-90% CT in both muscles, after which it continually increased until task failure. During the 50% MVT sustained task the increase in MUDR occurred earlier, after ∼70-80% CT. Our results suggest that adjustments in MUDR during submaximal isometric contractions to failure are contraction modality- and intensity-dependent. KEY POINTS: During prolonged muscle contractions a constant motor output can be maintained by recruitment of additional motor units and adjustments in their discharge rate. Whilst contraction-induced decrements in neuromuscular function are known to depend on task demands, task-specificity of motor unit discharge behaviour adjustments is still unclear. In this study, we tracked and compared discharge activity of several concurrently active motor units in the vastii muscles during different submaximal isometric knee extension tasks to failure, including intermittent vs. sustained contraction modalities performed in the same intensity domain (Experiment 1), and two sustained contractions performed at different intensities (Experiment 2). During each task, motor units modulated their discharge rate in a distinct, biphasic manner, with the modulation pattern depending on contraction intensity and modality. These results provide insight into motoneuronal adjustments during contraction tasks posing different demands on the neuromuscular system.
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Affiliation(s)
- Tamara Valenčič
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
| | - Paul Ansdell
- Department of Sport, Exercise and Rehabilitation, Northumbria University, Newcastle upon Tyne, UK
| | - Callum G Brownstein
- School of Biomedical, Nutritional and Sport Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Padraig M Spillane
- Department of Sport, Exercise and Rehabilitation, Northumbria University, Newcastle upon Tyne, UK
| | - Aleš Holobar
- Faculty of Electrical Engineering and Computer Science, University of Maribor, Maribor, Slovenia
| | - Jakob Škarabot
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
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Ducrocq GP, Anselmi L, Ruiz-Velasco V, Kaufman MP. Lactate and hydrogen ions play a predominant role in evoking the exercise pressor reflex during ischaemic contractions but not during freely perfused contractions. J Physiol 2024. [PMID: 38685758 DOI: 10.1113/jp286488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Accepted: 04/04/2024] [Indexed: 05/02/2024] Open
Abstract
We investigated the role played by lactate and hydrogen in evoking the exercise pressor reflex (EPR) in decerebrated rats whose hindlimb muscles were either freely perfused or ischaemic. Production of lactate and hydrogen by the contracting hindlimb muscles was manipulated by knocking out the myophosphorylase gene (pygm). In knockout rats (pygm-/-; n = 13) or wild-type rats (pygm+/+; n = 13), the EPR was evoked by isometrically contracting the triceps surae muscles. Blood pressure, tension, blood flow, renal sympathetic nerve activity and blood lactate concentrations were measured. Intramuscular metabolites and pH changes induced by the contractions were quantified by 31P-magnetic resonance spectroscopy (n = 5). In a subset of pygm-/- rats (n = 5), contractions were evoked with prior infusion of lactate (pH 6.0) in an attempt to restore the effect of lactate and hydrogen ions. Contraction of freely perfused muscles increased blood lactate and decreased muscle pH in pygm+/+ rats only. Despite these differences, the reflex pressor and sympathetic responses to freely perfused contraction did not differ between groups (P = 0.992). During ischaemia, contraction increased muscle lactate and hydrogen ion production in pygm+/+ rats (P < 0.0134), whereas it had no effect in pygm-/- rats (P > 0.783). Likewise, ischaemia exaggerated the reflex pressor, and sympathetic responses to contraction in pygm+/+ but not in pygm-/- rats. This exaggeration was restored when a solution of lactate (pH 6.0) was infused prior to the contraction in pygm-/- rats. We conclude that lactate and hydrogen accumulation in contracting myocytes play a key role in evoking the metabolic component of the EPR during ischaemic but not during freely perfused contractions. KEY POINTS: Conflicting results exist about the role played by lactate and hydrogen ions in evoking the exercise pressor reflex. Using CRISP-Cas9, we rendered the myophosphorylase gene non-functional to block the production of lactate and hydrogen ions. The exercise pressor reflex was evoked in decerebrated rats by statically contracting the triceps surae muscles with or without muscle ischaemia. Static contraction elevated the concentration of lactate and hydrogen ions in pygm+/+ but not in pygm-/- rats. Despite these differences, the exercise pressor reflex was not different between groups. Acute muscle ischaemia exaggerated the concentration of lactate and hydrogen ions in pygm+/+ but not in pygm-/- rats. Likewise, acute muscle ischaemia exaggerated the exercise pressor reflex in pygm+/+ but not in pygm-/- rats. We conclude that lactate and hydrogen play a key role in evoking the exercise pressor reflex during ischaemic but not during freely perfused contractions.
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Affiliation(s)
- Guillaume P Ducrocq
- Heart and Vascular Institute, Penn State College of Medicine, Hershey, Pennsylvania, USA
- Mitochondrial, Oxidative Stress and Muscular Protection Laboratory (UR3072), Faculty of Medicine, University of Strasbourg, Strasbourg, France
| | - Laura Anselmi
- Heart and Vascular Institute, Penn State College of Medicine, Hershey, Pennsylvania, USA
| | - Victor Ruiz-Velasco
- Heart and Vascular Institute, Penn State College of Medicine, Hershey, Pennsylvania, USA
- Department of Anesthesiology and Perioperative Medicine, Penn State College of Medicine, Hershey, Pennsylvania, USA
| | - Marc P Kaufman
- Heart and Vascular Institute, Penn State College of Medicine, Hershey, Pennsylvania, USA
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Takeda R, Nojima H, Hirono T, Okudaira M, Nishikawa T, Watanabe K. Impact of subtetanic neuromuscular electrical stimulation on cardiac autonomic nervous system in young individuals. J Sports Med Phys Fitness 2024; 64:78-87. [PMID: 37902806 DOI: 10.23736/s0022-4707.23.15352-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2023]
Abstract
BACKGROUND Although subtetanic neuromuscular electrical stimulation (NMES) has been proposed as an exercise training and/or rehabilitation tool, the impact of NMES on the autonomic nervous system (ANS) is unclear. Thus, we hypothesized that NMES would alter ANS, i.e., increase sympathetic activity and decrease parasympathetic activity, in young individuals. METHODS Eighteen healthy young individuals (16 males, mean age: 22 [SD: 4] years, Body Mass Index: 21.7 [2.2] kg/m2) volunteered. Blood pressure (BP), heart rate (HR), and R-R intervals were recorded during 6-minute resting, NMES, and recovery conditions. Short-term heart rate variability analysis of R-R intervals was performed for the frequency and time domains during each condition. Time domain indices included the root mean square of successive R-R interval differences (RMSSD), and the percentage of successive R-R intervals differing by more than 50ms (pRR50%). Frequency domain indices (fast Fourier transform) of R-R intervals included total power (TP), low-frequency (LF) power (0.04-0.15 Hz), and high-frequency (HF) power (0.15-0.4 Hz). RESULTS BP was not altered but HR was significantly increased during NMES (P<0.001), and it returned to the resting level at recovery. RMSSD and pRR50 decreased from resting to NMES and returned at recovery conditions (P<0.05, respectively). TP and HF decreased from resting to NMES and returned at recovery conditions (P<0.05, respectively). LF increased from NMES to recovery (P<0.05). The LF/HF ratio showed no significant differences between conditions (P=0.210). CONCLUSIONS Cardiac ANS fluctuated by subtetanic NMES without BP elevation in healthy young individuals. Parasympathetic but not sympathetic activity was affected by NMES stimulation.
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Affiliation(s)
- Ryosuke Takeda
- School of Health and Sport Science, Laboratory of Neuromuscular Biomechanics, Chukyo University, Toyota, Japan -
| | - Hiroya Nojima
- School of Health and Sport Science, Laboratory of Neuromuscular Biomechanics, Chukyo University, Toyota, Japan
| | - Tetsuya Hirono
- School of Health and Sport Science, Laboratory of Neuromuscular Biomechanics, Chukyo University, Toyota, Japan
- Japan Society for the Promotion of Science, Tokyo, Japan
| | - Masamichi Okudaira
- School of Health and Sport Science, Laboratory of Neuromuscular Biomechanics, Chukyo University, Toyota, Japan
| | - Taichi Nishikawa
- School of Health and Sport Science, Laboratory of Neuromuscular Biomechanics, Chukyo University, Toyota, Japan
- Graduate School of Health and Sport Sciences, Chukyo University, Toyota, Japan
| | - Kohei Watanabe
- School of Health and Sport Science, Laboratory of Neuromuscular Biomechanics, Chukyo University, Toyota, Japan
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Grotle AK, Langlo JV, Holsbrekken E, Stone AJ, Tanaka H, Fadel PJ. Age-related alterations in the cardiovascular responses to acute exercise in males and females: role of the exercise pressor reflex. Front Physiol 2023; 14:1287392. [PMID: 38028783 PMCID: PMC10652405 DOI: 10.3389/fphys.2023.1287392] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 10/09/2023] [Indexed: 12/01/2023] Open
Abstract
Autonomic adjustments of the cardiovascular system are critical for initiating and sustaining exercise by facilitating the redistribution of blood flow and oxygen delivery to meet the metabolic demands of the active skeletal muscle. Afferent feedback from active skeletal muscles evokes reflex increases in sympathetic nerve activity and blood pressure (BP) (i.e., exercise pressor reflex) and contributes importantly to these primary neurovascular adjustments to exercise. When altered, this reflex contributes significantly to the exaggerated sympathetic and BP response to exercise observed in many cardiovascular-related diseases, highlighting the importance of examining the reflex and its underlying mechanism(s). A leading risk factor for the pathogenesis of cardiovascular disease in both males and females is aging. Although regular exercise is an effective strategy for mitigating the health burden of aging, older adults face a greater risk of experiencing an exaggerated cardiovascular response to exercise. However, the role of aging in mediating the exercise pressor reflex remains highly controversial, as conflicting findings have been reported. This review aims to provide a brief overview of the current understanding of the influence of aging on cardiovascular responses to exercise, focusing on the role of the exercise pressor reflex and proposing future directions for research. We reason that this review will serve as a resource for health professionals and researchers to stimulate a renewed interest in this critical area.
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Affiliation(s)
- A. K. Grotle
- Department of Sports, Food and Natural Science, Western Norway University of Applied Sciences, Bergen, Norway
| | - J. V. Langlo
- Department of Sports, Food and Natural Science, Western Norway University of Applied Sciences, Bergen, Norway
| | - E. Holsbrekken
- Department of Sports, Food and Natural Science, Western Norway University of Applied Sciences, Bergen, Norway
| | - A. J. Stone
- Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX, United States
| | - H. Tanaka
- Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX, United States
| | - P. J. Fadel
- Department of Kinesiology, The University of Texas at Arlington, Arlington, TX, United States
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Lee JB, Thompson KMA, Teixeira AL, Burr JF, Millar PJ. Cardiovascular responses to combined mechanoreflex and metaboreflex activation in healthy adults: effects of sex and low- versus high-hormone phases in females. J Appl Physiol (1985) 2023; 135:1102-1114. [PMID: 37795529 DOI: 10.1152/japplphysiol.00775.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 09/08/2023] [Accepted: 09/28/2023] [Indexed: 10/06/2023] Open
Abstract
Females generally have smaller blood pressure (BP) responses to isolated muscle mechanoreflex and metaboreflex activation compared with males, which may explain sex differences in BP responses to voluntary exercise. The mechanoreflex may be sensitized during exercise, but whether mechanoreflex-metaboreflex interactions differ by sex or variations in sex hormones remains unknown. Thirty-one young healthy subjects (females, n = 16) performed unilateral passive cycling (mechanoreflex), active cycling (40% peak Watts), postexercise circulatory occlusion (PECO; metaboreflex), and passive cycling combined with PECO (combined mechanoreflex and metaboreflex activation). Beat-to-beat BP, heart rate, inactive leg vascular conductance, and active leg muscle oxygenation were measured. Ten females underwent exploratory testing during low- and high-hormone phases of their self-reported menstrual cycle or oral contraceptive use. Systolic BP and heart rate responses did not differ between sexes during active cycling [Δ30 ± 9 vs. 29 ± 11 mmHg (males vs. females), P = 0.9; Δ33 ± 8 vs. 35 ± 6 beats/min, P = 0.4] or passive cycling with PECO (Δ26 ± 11 vs. 21 ± 10 mmHg, P = 0.3; Δ14 ± 7 vs. 18 ± 15 beats/min, P = 0.3). Passive cycling with PECO revealed additive, not synergistic, effects for systolic BP [males: Δ23 ± 14 vs. 26 ± 11 mmHg (sum of isolated passive cycling and PECO vs. combined activation); females: Δ26 ± 11 vs. 21 ± 12 mmHg, interaction P = 0.05]. Results were consistent in subset analyses with sex differences in active cycling BP (P > 0.1) and exploratory analyses of hormone phase (P > 0.4). Despite a lack of statistical equivalence, no differences in cardiovascular responses were found during combined mechanoreflex-metaboreflex activation between sexes or hormone levels. These results provide preliminary data regarding the involvement of muscle mechanoreflex-metaboreflex interactions in mediating sex differences in voluntary exercise BP responses.NEW & NOTEWORTHY The muscle mechanoreflex may be sensitized by metabolites during exercise. We show that cardiovascular responses to combined mechanoreflex (passive cycling) and metaboreflex (postexercise circulatory occlusion) activation are primarily additive and do not differ between males and females, or across variations in sex hormones in females. Our findings provide new insight into the contributions of muscle mechanoreflex-metaboreflex interactions as a cause for prior reports that females have smaller blood pressure responses to voluntary exercise.
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Affiliation(s)
- Jordan B Lee
- Human Cardiovascular Physiology Laboratory, Department of Human Health and Nutritional Sciences, College of Biological Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Kyle M A Thompson
- Human Performance and Health Research Lab, Department of Human Health and Nutritional Sciences, College of Biological Sciences, University of Guelph, Guelph, Ontario, Canada
| | - André L Teixeira
- Human Cardiovascular Physiology Laboratory, Department of Human Health and Nutritional Sciences, College of Biological Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Jamie F Burr
- Human Performance and Health Research Lab, Department of Human Health and Nutritional Sciences, College of Biological Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Philip J Millar
- Human Cardiovascular Physiology Laboratory, Department of Human Health and Nutritional Sciences, College of Biological Sciences, University of Guelph, Guelph, Ontario, Canada
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Kashima H, Endo MY, Kanda M, Miura A, Fukuba Y, Mizuno M. High-glycemic index meal acutely potentiates blood pressure response to static handgrip exercise in healthy humans. J Appl Physiol (1985) 2023; 135:609-620. [PMID: 37471212 PMCID: PMC10538994 DOI: 10.1152/japplphysiol.00703.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Revised: 06/26/2023] [Accepted: 07/17/2023] [Indexed: 07/22/2023] Open
Abstract
Blood glucose levels acutely increase postprandially depending on the type of meal consumed. However, it remains unclear whether postprandial hyperglycemia temporally affects cardiovascular responses to static handgrip exercise (SHG-ex). Thus, this study aimed to examine whether increased blood glucose induced by consumption of a high-glycemic index (HGI) meal affects pressor response to SHG-ex. A total of 14 healthy participants (7 women and 7 men) consumed an HGI meal, a low-glycemic index (LGI) meal, or no meal (control). Participants performed 30% maximal voluntary contraction SHG-ex followed by a postexercise muscle ischemia (PEMI) test before the meal and 60 min after consuming the meal. Blood glucose, plasma insulin, and plasma triglyceride levels were measured, and the area under the curve until 60 min (AUC0-60 min) after meal consumption was calculated. The HGI and LGI groups showed higher blood glucose and insulin AUC0-60 min than the control group (P < 0.001). At 60 min after the meal, the changes in blood pressure during SHG-ex were significantly greater in the HGI group, but not in the LGI group, than in the control group. The changes in blood pressure at the onset and end of SHG-ex 60 min after the meal were positively correlated with blood glucose AUC0-60 min (r = 0.321, P = 0.038; r = 0.402, P = 0.008, respectively) and plasma insulin AUC0-60 min (r = 0.339, P = 0.028; r = 0.302, P = 0.052, respectively). However, no association was observed during PEMI. These data suggest that postprandial hyperglycemia and hyperinsulinemia acutely exaggerate pressor response during SHG-ex in healthy young adults.NEW & NOTEWORTHY Postprandial hyperglycemia following consumption of a high-glycemic index (HGI) meal potentiated blood pressure response to static handgrip exercise (SHG-ex) in healthy young adults. These findings provide important insight into the role of the diet on acute circulatory response to exercise in healthy adults.
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Affiliation(s)
- Hideaki Kashima
- Department of Exercise Science and Physiology, School of Health Sciences, Prefectural University of Hiroshima, Hiroshima, Japan
| | - Masako Yamaoka Endo
- Department of Exercise Science and Physiology, School of Health Sciences, Prefectural University of Hiroshima, Hiroshima, Japan
| | - Masako Kanda
- Department of Exercise Science and Physiology, School of Health Sciences, Prefectural University of Hiroshima, Hiroshima, Japan
| | - Akira Miura
- Department of Exercise Science and Physiology, School of Health Sciences, Prefectural University of Hiroshima, Hiroshima, Japan
| | - Yoshiyuki Fukuba
- Department of Exercise Science and Physiology, School of Health Sciences, Prefectural University of Hiroshima, Hiroshima, Japan
- Faculty of Health and Sports Sciences, Hiroshima International University, Hiroshima, Japan
| | - Masaki Mizuno
- Department of Applied Clinical Research, School of Health Professions, University of Texas Southwestern Medical Center, Dallas, Texas, United States
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de Almeida Azevedo R, Jazayeri D, Yeung ST, Khoshreza R, Millet GY, Murias JM, Aboodarda SJ. The effects of pain induced by blood flow occlusion in one leg on exercise tolerance and corticospinal excitability and inhibition of the contralateral leg in males. Appl Physiol Nutr Metab 2022; 47:632-648. [PMID: 35201916 DOI: 10.1139/apnm-2021-0597] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Experiencing pain in one leg can alter exercise tolerance and neuromuscular fatigue (NMF) responses in the contralateral leg; however, the corticospinal modulations to non-local experimental pain induced by blood flow occlusion remain unknown. In three randomized visits, thirteen male participants performed 25% of isometric maximal voluntary contraction (25%IMVC) to task failure with one leg preceded by (i) 6-min rest (CON), (ii) cycling at 80% of peak power output until task failure with the contralateral leg (CYCL) or (iii) CYCL followed by blood flow occlusion (OCCL) during 25%IMVC. NMF assessments (IMVC, voluntary activation [VA] and potentiated twitch [Qtw]) were performed at baseline and task failure. During the 25%IMVC, transcranial magnetic stimulations were performed to obtain motor evoked potential (MEP), silent period (SP), and short intracortical inhibition (SICI). 25%IMVC was shortest in OCCL (105±50s) and shorter in CYCL (154±68s) than CON (219±105s) (P<0.05). IMVC declined less after OCCL (-24±19%) and CYCL (-27±18%) then CON (-35±11%) (P<0.05). Qtw declined less in OCCL (-40±25%) compared to CYCL (-50±22%) and CON (-50±21%) (P<0.05). VA was similar amongst conditions. MEP and SP increased and SICI decreased throughout the task while SP was longer for OCCL compared to CYC condition (P<0.05). The results suggest that pain in one leg diminishes contralateral limb exercise tolerance and NMF development and modulate corticospinal inhibition in males. Novelty: Pain in one leg diminished MVC and twitch force decline in the contralateral limb Experimental pain induced by blood flow occlusion may modulation corticospinal inhibition of the neural circuitries innervating the contralateral exercise limb.
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Affiliation(s)
| | | | | | | | | | - Juan M Murias
- University of Calgary, Faculty of Kinesiology, KNB 434, 2500 University Drive NW, Calgary, Alberta, Canada, T2N1N4;
| | - Saied Jalal Aboodarda
- University of Calgary , Faculty of Kinesiology, 2500 University Drive NW, Calgary, Canada, T2N 1N4;
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Solsona R, Berthelot H, Borrani F, Sanchez AMJ. Mechanical, Cardiorespiratory, and Muscular Oxygenation Responses to Sprint Interval Exercises Under Different Hypoxic Conditions in Healthy Moderately Trained Men. Front Physiol 2022; 12:773950. [PMID: 34975526 PMCID: PMC8716850 DOI: 10.3389/fphys.2021.773950] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 11/19/2021] [Indexed: 01/31/2023] Open
Abstract
Objective: The aim of this study was to determine the effects of sprint interval exercises (SIT) conducted under different conditions (hypoxia and blood flow restriction [BFR]) on mechanical, cardiorespiratory, and muscular O2 extraction responses. Methods: For this purpose, 13 healthy moderately trained men completed five bouts of 30 s all-out exercises interspaced by 4 min resting periods with lower limb bilateral BFR at 60% of the femoral artery occlusive pressure (BFR60) during the first 2 min of recovery, with gravity-induced BFR (pedaling in supine position; G-BFR), in a hypoxic chamber (FiO2≈13%; HYP) or without additional stress (NOR). Peak and average power, time to achieve peak power, rating of perceived exertion (RPE), and a fatigue index (FI) were analyzed. Gas exchanges and muscular oxygenation were measured by metabolic cart and NIRS, respectively. Heart rate (HR) and peripheral oxygen saturation (SpO2) were continuously recorded. Results: Regarding mechanical responses, peak and average power decreased after each sprint (p < 0.001) excepting between sprints four and five. Time to reach peak power increased between the three first sprints and sprint number five (p < 0.001). RPE increased throughout the exercises (p < 0.001). Of note, peak and average power, time to achieve peak power and RPE were lower in G-BFR (p < 0.001). Results also showed that SpO2 decreased in the last sprints for all the conditions and was lower for HYP (p < 0.001). In addition, Δ[O2Hb] increased in the last two sprints (p < 0.001). Concerning cardiorespiratory parameters, BFR60 application induced a decrease in gas exchange rates, which increased after its release compared to the other conditions (p < 0.001). Moreover, muscle blood concentration was higher for BFR60 (p < 0.001). Importantly, average and peak oxygen consumption and muscular oxyhemoglobin availability during sprints decreased for HYP (p < 0.001). Finally, the tissue saturation index was lower in G-BFR. Conclusions: Thus, SIT associated with G-BFR displayed lower mechanical, cardiorespiratory responses, and skeletal muscle oxygenation than the other conditions. Exercise with BFR60 promotes higher blood accumulation within working muscles, suggesting that BFR60 may additionally affect cellular stress. In addition, HYP and G-BFR induced local hypoxia with higher levels for G-BFR when considering both exercise bouts and recovery periods.
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Affiliation(s)
- Robert Solsona
- University of Perpignan Via Domitia (UPVD), Faculty of Sports Sciences, Laboratoire Interdisciplinaire Performance Santé Environnement de Montagne (LIPSEM), UR4640, Perpignan, France.,Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Hugues Berthelot
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Fabio Borrani
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Anthony M J Sanchez
- University of Perpignan Via Domitia (UPVD), Faculty of Sports Sciences, Laboratoire Interdisciplinaire Performance Santé Environnement de Montagne (LIPSEM), UR4640, Perpignan, France.,Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
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Hasegawa D, Hori A, Okamura Y, Baba R, Suijo K, Mizuno M, Sugawara J, Kitatsuji K, Ogata H, Toda K, Hotta N. Aging exaggerates blood pressure response to ischemic rhythmic handgrip exercise in humans. Physiol Rep 2021; 9:e15125. [PMID: 34817113 PMCID: PMC8611780 DOI: 10.14814/phy2.15125] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 11/02/2021] [Accepted: 11/02/2021] [Indexed: 12/23/2022] Open
Abstract
Ischemic skeletal muscle conditions are known to augment exercise-induced increases in blood pressure (BP). Aging is also a factor that enhances the pressor response to exercise. However, the effects of aging on the BP response to ischemic exercise remain unclear. We, therefore, tested the hypothesis that aging enhances the BP response to rhythmic handgrip (RHG) exercise during postexercise muscle ischemia (PEMI). We divided the normotensive participants without cardiovascular diseases into three age groups: young (n = 26; age, 18-28 years), middle-aged (n = 23; age, 35-59 years), and older adults (n = 23; age, 60-80 years). The participants performed RHG exercise with minimal effort for 1 min after rest with and without PEMI, which was induced by inflating a cuff on the upper arm just before the isometric handgrip exercise ended; the intensity was 30% of maximal voluntary contraction force. Under PEMI, the increase in diastolic BP (DBP) from rest to RHG exercise in the older adult group (Δ13 ± 2 mmHg) was significantly higher than that in the young (Δ5 ± 2 mmHg) and middle-aged groups (Δ6 ± 1 mmHg), despite there being no significant difference between the groups in the DBP response from rest to RHG exercise without PEMI. Importantly, based on multiple regression analysis, age remained a significant independent determinant of both the SBP and DBP responses to RHG exercise during PEMI (p < 0.01). These findings indicate that aging enhances the pressor response to ischemic rhythmic exercise.
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Affiliation(s)
- Daisuke Hasegawa
- Graduate School of Life and Health SciencesChubu UniversityKasugaiJapan
- Nagoya Heisei College of Nursing and Medical CareNagoyaJapan
| | - Amane Hori
- Graduate School of Life and Health SciencesChubu UniversityKasugaiJapan
- Japan Society for the Promotion of ScienceTokyoJapan
| | - Yukiko Okamura
- Graduate School of Life and Health SciencesChubu UniversityKasugaiJapan
- College of Life and Health SciencesChubu UniversityKasugaiJapan
| | - Reizo Baba
- Graduate School of Life and Health SciencesChubu UniversityKasugaiJapan
- College of Life and Health SciencesChubu UniversityKasugaiJapan
| | - Kenichi Suijo
- Graduate School of Life and Health SciencesChubu UniversityKasugaiJapan
- College of Life and Health SciencesChubu UniversityKasugaiJapan
| | - Masaki Mizuno
- Department of Applied Clinical ResearchUniversity of Texas Southwestern Medical CenterDallasTexasUSA
| | - Jun Sugawara
- Human Informatics and Interaction Research InstituteNational Institute of Advanced Industrial Science and TechnologyTsukubaJapan
| | - Koji Kitatsuji
- Graduate School of Life and Health SciencesChubu UniversityKasugaiJapan
- College of Life and Health SciencesChubu UniversityKasugaiJapan
| | - Hisayoshi Ogata
- Graduate School of Life and Health SciencesChubu UniversityKasugaiJapan
- College of Life and Health SciencesChubu UniversityKasugaiJapan
| | - Kaoru Toda
- Graduate School of Life and Health SciencesChubu UniversityKasugaiJapan
- College of Life and Health SciencesChubu UniversityKasugaiJapan
| | - Norio Hotta
- Graduate School of Life and Health SciencesChubu UniversityKasugaiJapan
- College of Life and Health SciencesChubu UniversityKasugaiJapan
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10
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Stone AJ, Kaufman MP. Thin-fiber muscle afferents possessing TRPV1 receptors evoke the muscle metaboreflex. Am J Physiol Regul Integr Comp Physiol 2021; 321:R523-R524. [PMID: 34469207 DOI: 10.1152/ajpregu.00203.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Audrey J Stone
- Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, Texas
| | - Marc P Kaufman
- Penn State Heart and Vascular Institute, Pennsylvania State University College of Medicine, Hershey, Pennsylvania
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11
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Salzmann K, Sanchez AMJ, Borrani F. Effects of Blood Flow Restriction on O 2 Muscle Extraction and O 2 Pulmonary Uptake Kinetics During Heavy Exercise. Front Physiol 2021; 12:722848. [PMID: 34539445 PMCID: PMC8441002 DOI: 10.3389/fphys.2021.722848] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 08/03/2021] [Indexed: 11/13/2022] Open
Abstract
This study aimed to determine the effects of three levels of blood flow restriction (BFR) on V˙O2 and O2 extraction kinetics during heavy cycling exercise transitions. Twelve healthy trained males completed two bouts of 10 min heavy intensity exercise without BFR (CON), with 40% or 50% BFR (BFR40 and BFR50, respectively). V˙O2 and tissue saturation index (TSI) were continuously measured and modelled using multiexponential functions. The time constant of the V˙O2 primary phase was significantly slowed in BFR40 (26.4 ± 2.0s; p < 0.001) and BFR50 (27.1 ± 2.1s; p = 0.001) compared to CON (19.0 ± 1.1s). The amplitude of the V˙O2 slow component was significantly increased (p < 0.001) with BFR in a pressure-dependent manner 3.6 ± 0.7, 6.7 ± 0.9 and 9.7 ± 1.0 ml·min−1·kg−1 for CON, BFR40, and BFR50, respectively. While no acceleration of the primary component of the TSI kinetics was observed, there was an increase (p < 0.001) of the phase 3 amplitude with BFR (CON −0.8 ± 0.3% VS BFR40 −2.9 ± 0.9%, CON VS BFR50 −2.8 ± 0.8%). It may be speculated that BFR applied during cycling exercise in the heavy intensity domain shifted the working muscles to an O2 dependent situation. The acceleration of the extraction kinetics could have reached a plateau, hence not permitting compensation for the slowdown of the blood flow kinetics, and slowing V˙O2 kinetics.
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Affiliation(s)
- Killian Salzmann
- Institute of Sport Sciences of University of Lausanne (ISSUL), University of Lausanne, Lausanne, Switzerland
| | - Anthony M J Sanchez
- University of Perpignan Via Domitia (UPVD), Faculty of Sports Sciences, Laboratoire Interdisciplinaire Performance Santé Environnement De Montagne (LIPSEM), Font-Romeu, France
| | - Fabio Borrani
- Institute of Sport Sciences of University of Lausanne (ISSUL), University of Lausanne, Lausanne, Switzerland
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12
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Cui J, Blaha C, Leuenberger UA, Sinoway LI. Sympathetic activation due to limb venous distension is preserved during muscle metaboreceptor stimulation. Am J Physiol Regul Integr Comp Physiol 2021; 321:R21-R28. [PMID: 33978490 DOI: 10.1152/ajpregu.00305.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Venous saline infusions in an arterially occluded forearm evoke reflex increases in muscle sympathetic nerve activity (MSNA) and blood pressure (BP) in humans (venous distension reflex). It is unclear if the inputs from metabolically sensitive skeletal muscle afferents (i.e., muscle metaboreflex) would modify the venous distension reflex. We hypothesized that muscle metaboreceptor stimulation might augment the venous distension reflex. BP (Finapres), heart rate (ECG), and MSNA (microneurography) were assessed in 18 young healthy subjects. In trial A, saline (5% forearm volume) was infused into the veins of an arterially occluded arm (nonhandgrip trial). In trial B, subjects performed 2-min static handgrip followed by postexercise circulatory occlusion (PECO) of the arm. During PECO, saline was infused into the veins of the arm (handgrip trial). In trial A, the infusion increased MSNA and BP as expected (both P < 0.001). In trial B, handgrip significantly raised MSNA, BP, and venous lactic acid concentrations. Venous saline infusion during PECO further raised MSNA and BP (both P < 0.001). The changes in MSNA (Δ8.6 ± 1.5 to Δ10.6 ± 1.8 bursts/min, P = 0.258) and mean arterial pressure (P = 0.844) evoked by the infusion during PECO were not significantly different from those in the nonhandgrip trial. These observations indicate that venous distension reflex responses are preserved during sympathetic activation mediated by the muscle metaboreflex.
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Affiliation(s)
- Jian Cui
- Penn State Hershey Heart and Vascular Institute, Milton S. Hershey Medical Center, Pennsylvania State University College of Medicine, Hershey, Pennsylvania
| | - Cheryl Blaha
- Penn State Hershey Heart and Vascular Institute, Milton S. Hershey Medical Center, Pennsylvania State University College of Medicine, Hershey, Pennsylvania
| | - Urs A Leuenberger
- Penn State Hershey Heart and Vascular Institute, Milton S. Hershey Medical Center, Pennsylvania State University College of Medicine, Hershey, Pennsylvania
| | - Lawrence I Sinoway
- Penn State Hershey Heart and Vascular Institute, Milton S. Hershey Medical Center, Pennsylvania State University College of Medicine, Hershey, Pennsylvania
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13
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Grotle AK, Kaur J, Stone AJ, Fadel PJ. Neurovascular Dysregulation During Exercise in Type 2 Diabetes. Front Physiol 2021; 12:628840. [PMID: 33927637 PMCID: PMC8076798 DOI: 10.3389/fphys.2021.628840] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 03/05/2021] [Indexed: 12/12/2022] Open
Abstract
Emerging evidence suggests that type 2 diabetes (T2D) may impair the ability to properly adjust the circulation during exercise with augmented blood pressure (BP) and an attenuated contracting skeletal muscle blood flow (BF) response being reported. This review provides a brief overview of the current understanding of these altered exercise responses in T2D and the potential underlying mechanisms, with an emphasis on the sympathetic nervous system and its regulation during exercise. The research presented support augmented sympathetic activation, heightened BP, reduced skeletal muscle BF, and impairment in the ability to attenuate sympathetically mediated vasoconstriction (i.e., functional sympatholysis) as potential drivers of neurovascular dysregulation during exercise in T2D. Furthermore, emerging evidence supporting a contribution of the exercise pressor reflex and central command is discussed along with proposed future directions for studies in this important area of research.
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Affiliation(s)
- Ann-Katrin Grotle
- Department of Kinesiology, The University of Texas at Arlington, Arlington, TX, United States
| | - Jasdeep Kaur
- Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX, United States
| | - Audrey J Stone
- Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX, United States
| | - Paul J Fadel
- Department of Kinesiology, The University of Texas at Arlington, Arlington, TX, United States
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14
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Duchateau J, Stragier S, Baudry S, Carpentier A. Strength Training: In Search of Optimal Strategies to Maximize Neuromuscular Performance. Exerc Sport Sci Rev 2021; 49:2-14. [PMID: 33044332 DOI: 10.1249/jes.0000000000000234] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Training with low-load exercise performed under blood flow restriction can augment muscle hypertrophy and maximal strength to a similar extent as the classical high-load strength training method. However, the blood flow restriction method elicits only minor neural adaptations. In an attempt to maximize training-related gains, we propose using other protocols that combine high voluntary activation, mechanical tension, and metabolic stress.
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Affiliation(s)
| | | | | | - Alain Carpentier
- Laboratory for Biometry and Exercise Nutrition, Université Libre de Bruxelles, Brussels, Belgium
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15
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Hammer SM, Alexander AM, Didier KD, Barstow TJ. Influence of blood flow occlusion on muscular recruitment and fatigue during maximal‐effort small muscle‐mass exercise. J Physiol 2020; 598:4293-4306. [DOI: 10.1113/jp279925] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 07/22/2020] [Indexed: 11/08/2022] Open
Affiliation(s)
- Shane M. Hammer
- Department of Kinesiology Kansas State University Manhattan KS USA
| | | | - Kaylin D. Didier
- Department of Kinesiology Kansas State University Manhattan KS USA
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16
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Grotle AK, Macefield VG, Farquhar WB, O'Leary DS, Stone AJ. Recent advances in exercise pressor reflex function in health and disease. Auton Neurosci 2020; 228:102698. [PMID: 32861944 DOI: 10.1016/j.autneu.2020.102698] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 07/01/2020] [Accepted: 07/02/2020] [Indexed: 01/11/2023]
Abstract
Autonomic alterations at the onset of exercise are critical to redistribute cardiac output towards the contracting muscles while preventing a fall in arterial pressure due to excessive vasodilation within the contracting muscles. Neural mechanisms responsible for these adjustments include central command, the exercise pressor reflex, and arterial and cardiopulmonary baroreflexes. The exercise pressor reflex evokes reflex increases in sympathetic activity to the heart and systemic vessels and decreases in parasympathetic activity to the heart, which increases blood pressure (BP), heart rate, and total peripheral resistance through vasoconstriction of systemic vessels. In this review, we discuss recent advancements in our understanding of exercise pressor reflex function in health and disease. Specifically, we discuss emerging evidence suggesting that sympathetic vasoconstrictor drive to the contracting and non-contracting skeletal muscle is differentially controlled by central command and the metaboreflex in healthy conditions. Further, we discuss evidence from animal and human studies showing that cardiovascular diseases, including hypertension, diabetes, and heart failure, lead to an altered exercise pressor reflex function. We also provide an update on the mechanisms thought to underlie this altered exercise pressor reflex function in each of these diseases. Although these mechanisms are complex, multifactorial, and dependent on the etiology of the disease, there is a clear consensus that several mechanisms are involved. Ultimately, approaches targeting these mechanisms are clinically significant as they provide alternative therapeutic strategies to prevent adverse cardiovascular events while also reducing symptoms of exercise intolerance.
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Affiliation(s)
- Ann-Katrin Grotle
- Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX, United States of America
| | | | - William B Farquhar
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, DE, United States of America
| | - Donal S O'Leary
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, United States of America
| | - Audrey J Stone
- Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX, United States of America.
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17
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Hotta N, Hori A, Okamura Y, Baba R, Watanabe H, Sugawara J, Vongpatanasin W, Wang J, Kim HK, Ishizawa R, Iwamoto GA, Mitchell JH, Smith SA, Mizuno M. Insulin resistance is associated with an exaggerated blood pressure response to ischemic rhythmic handgrip exercise in nondiabetic older adults. J Appl Physiol (1985) 2020; 129:144-151. [PMID: 32584663 DOI: 10.1152/japplphysiol.00247.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Patients with type 2 diabetes display an exaggerated pressor response to exercise. However, evidence supporting the association between the magnitude of the pressor response to exercise and insulin resistance-related factors including hemoglobin A1c (HbA1c) or homeostatic model assessment of insulin resistance (HOMA-IR) in nondiabetic subjects has remained sparse and inconclusive. Thus we investigated the relationship between cardiovascular responses to exercise and insulin resistance-related factors in nondiabetic healthy men (n = 23) and women (n = 22) above 60 yr old. We measured heart rate (HR) and blood pressure (BP) responses during: isometric handgrip (IHG) exercise of 30% maximal voluntary contraction, a period of skeletal muscle ischemia (SMI) induced by tourniqueting the arm after IHG, and rhythmic dynamic handgrip (DHG) exercise during SMI. Greater diastolic BP (DBP) responses to DHG with SMI was associated with male sex (r = 0.44, P = 0.02) and higher HbA1c (r = 0.33, P = 0.03), heart-ankle pulse wave velocity (haPWV) (r = 0.45, P < 0.01), and resting systolic BP (SBP) (r = 0.36, P = 0.02). HbA1c persisted as a significant determinant explaining the variance in the DBP response to DHG with SMI in multivariate models despite adjustment for sex, haPWV, and resting SBP. It was also determined that the DBP response to DHG with SMI in a group in which HOMA-IR was abnormal (Δ33 ± 3 mmHg) was significantly higher than that of groups in which HOMA-IR was at intermediate (Δ20 ± 4 mmHg) and normal (Δ23 ± 2 mmHg) levels. These data suggest that even in nondiabetic older adults, insulin resistance is related to an exaggerated pressor response to exercise especially when performed under ischemic conditions.NEW & NOTEWORTHY The diastolic blood pressure response to rhythmic dynamic handgrip exercise under ischemic conditions was demonstrated to be correlated with insulin resistance-related factors in nondiabetic older adults. This finding provides important insight to the prescription of exercise in this particular patient population as the blood pressure response to exercise, especially under ischemic conditions, could be exaggerated to nonsafe levels.
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Affiliation(s)
- Norio Hotta
- College of Life and Health Sciences, Chubu University, Kasugai, Japan
| | - Amane Hori
- Graduate School of Life and Health Sciences, Chubu University, Kasugai, Japan
| | - Yukiko Okamura
- College of Life and Health Sciences, Chubu University, Kasugai, Japan
| | - Reizo Baba
- College of Life and Health Sciences, Chubu University, Kasugai, Japan
| | - Hidehiro Watanabe
- Department of Rehabilitation, Tokai Memorial Hospital, Kasugai, Japan
| | - Jun Sugawara
- Human Informatics and Interaction Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan
| | - Wanpen Vongpatanasin
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Jijia Wang
- Department of Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Han-Kyul Kim
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Rie Ishizawa
- Department of Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Gary A Iwamoto
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Jere H Mitchell
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Scott A Smith
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas.,Department of Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Masaki Mizuno
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas.,Department of Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas
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18
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Smith LJ, Macefield VG, Birznieks I, Burton AR. Effects of tonic muscle pain on fusimotor control of human muscle spindles during isometric ankle dorsiflexion. J Neurophysiol 2019; 121:1143-1149. [DOI: 10.1152/jn.00862.2018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Studies on anesthetized animals have revealed that nociceptors can excite fusimotor neurons and thereby change the sensitivity of muscle spindles to stretch; such nociceptive reflexes have been suggested to underlie the mechanisms that lead to chronic musculoskeletal pain syndromes. However, the validity of the “vicious cycle” hypothesis in humans has yielded results contrasting with those found in animals. Given that spindle firing rates are much lower in humans than in animals, it is possible that some of the discrepancies between human experimental data and those obtained in animals could be explained by differences in background fusimotor drive when the leg muscles are relaxed. We examined the effects of tonic muscle pain during voluntary contractions of the ankle dorsiflexors. Unitary recordings were obtained from 10 fusimotor-driven muscle spindle afferents (6 primary, 4 secondary) supplying the ankle dorsiflexors via a microelectrode inserted percutaneously into the common peroneal nerve. A series of 1-min weak contractions was performed at rest and during 1 h of muscle pain induced by intramuscular infusion of 5% hypertonic saline into the tibialis anterior muscle. We did not observe any statistically significant increases in muscle spindle firing rates of six afferents followed during tonic muscle pain, although discharge variability increased slightly. Furthermore, a participant’s capacity to maintain a constant level of force, while relying on proprioceptive feedback in the absence of visual feedback, was not compromised during pain. We conclude that nociceptive inputs from contracting muscle do not excite fusimotor neurons during voluntary isometric contractions in humans. NEW & NOTEWORTHY Data obtained in the cat have shown that muscle pain causes a marked increase in the firing of muscle spindles, attributed to a nociceptor-driven fusimotor reflex. However, our studies of muscle spindles in relaxed leg muscles failed to find any effect on spindle discharge. Here we showed that experimental muscle pain failed to increase the firing of muscle spindle afferents during weak voluntary contractions, when fusimotor drive sufficient to increase their firing is present.
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Affiliation(s)
- Lyndon J. Smith
- School of Medicine, Western Sydney University, Sydney, New South Wales, Australia
| | - Vaughan G. Macefield
- School of Medicine, Western Sydney University, Sydney, New South Wales, Australia
- Neuroscience Research Australia, Sydney, New South Wales, Australia
- Baker Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Ingvars Birznieks
- Neuroscience Research Australia, Sydney, New South Wales, Australia
- School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
- School of Science and Health, Western Sydney University, Sydney, New South Wales, Australia
| | - Alexander R. Burton
- School of Medicine, Western Sydney University, Sydney, New South Wales, Australia
- Neuroscience Research Australia, Sydney, New South Wales, Australia
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19
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Hureau TJ, Weavil JC, Thurston TS, Broxterman RM, Nelson AD, Bledsoe AD, Jessop JE, Richardson RS, Wray DW, Amann M. Identifying the role of group III/IV muscle afferents in the carotid baroreflex control of mean arterial pressure and heart rate during exercise. J Physiol 2018; 596:1373-1384. [PMID: 29388218 DOI: 10.1113/jp275465] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 01/29/2018] [Indexed: 02/05/2023] Open
Abstract
KEY POINTS We investigated the contribution of group III/IV muscle afferents to carotid baroreflex resetting during electrically evoked (no central command) and voluntary (requiring central command) isometric knee extension exercise. Lumbar intrathecal fentanyl was used to attenuate the central projection of μ-opioid receptor-sensitive group III/IV leg muscle afferent feedback. Spontaneous carotid baroreflex control was assessed by loading and unloading the carotid baroreceptors with a variable pressure neck chamber. Group III/IV muscle afferents did not influence spontaneous carotid baroreflex responsiveness at rest or during exercise. Afferent feedback accounted for at least 50% of the exercise-induced increase in the carotid baroreflex blood pressure and heart rate operating points, adjustments that are critical for an appropriate cardiovascular response to exercise. These findings suggest that group III/IV muscle afferent feedback is, independent of central command, critical for the resetting of the carotid baroreflex blood pressure and heart rate operating points, but not for spontaneous baroreflex responsiveness. ABSTRACT This study sought to comprehensively investigate the role of metabolically and mechanically sensitive group III/IV muscle afferents in carotid baroreflex responsiveness and resetting during both electrically evoked (EVO, no central command) and voluntary (VOL, requiring central command) isometric single-leg knee-extension (15% of maximal voluntary contraction; MVC) exercise. Participants (n = 8) were studied under control conditions (CTRL) and following lumbar intrathecal fentanyl injection (FENT) to inhibit μ-opioid receptor-sensitive lower limb muscle afferents. Spontaneous carotid baroreflex control of mean arterial pressure (MAP) and heart rate (HR) were assessed following rapid 5 s pulses of neck pressure (NP, +40 mmHg) or suction (NS, -60 mmHg). Resting MAP (87 ± 10 mmHg) and HR (70 ± 8 bpm) were similar between CTRL and FENT conditions (P > 0.4). In terms of spontaneous carotid baroreflex responsiveness, FENT did not alter the change in MAP or HR responses to NP (+13 ± 5 mmHg, P = 0.85; +9 ± 3 bpm; P = 0.99) or NS (-13 ± 5 mmHg, P = 0.99; -24 ± 11 bpm; P = 0.49) at rest or during either exercise protocol, which were of a remarkably similar magnitude to rest. In contrast, FENT administration reduced the exercise-induced resetting of the operating point for MAP and HR during both EVO (116 ± 10 mmHg to 100 ± 15 mmHg and 93 ± 14 bpm to 82 ± 10 bpm) and VOL (107 ± 13 mmHg to 100 ± 17 mmHg and 89 ± 10 bpm to 72 ± 10 bpm) exercise bouts. Together, these findings document that group III/IV muscle afferent feedback is critical for the resetting of the carotid baroreflex MAP and HR operating points, independent of exercise-induced changes in central command, but not for spontaneous carotid baroreflex responsiveness.
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Affiliation(s)
- Thomas J Hureau
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.,Geriatric Research, Education, and Clinical Center, Salt Lake City VA Medical Center, Salt Lake City, UT, USA
| | - Joshua C Weavil
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.,Geriatric Research, Education, and Clinical Center, Salt Lake City VA Medical Center, Salt Lake City, UT, USA
| | - Taylor S Thurston
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA
| | - Ryan M Broxterman
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.,Geriatric Research, Education, and Clinical Center, Salt Lake City VA Medical Center, Salt Lake City, UT, USA
| | - Ashley D Nelson
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - Amber D Bledsoe
- Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA
| | - Jacob E Jessop
- Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA
| | - Russell S Richardson
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.,Geriatric Research, Education, and Clinical Center, Salt Lake City VA Medical Center, Salt Lake City, UT, USA.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA
| | - D Walter Wray
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.,Geriatric Research, Education, and Clinical Center, Salt Lake City VA Medical Center, Salt Lake City, UT, USA.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA
| | - Markus Amann
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.,Geriatric Research, Education, and Clinical Center, Salt Lake City VA Medical Center, Salt Lake City, UT, USA.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA.,Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA
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20
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Queme LF, Ross JL, Jankowski MP. Peripheral Mechanisms of Ischemic Myalgia. Front Cell Neurosci 2017; 11:419. [PMID: 29311839 PMCID: PMC5743676 DOI: 10.3389/fncel.2017.00419] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 12/13/2017] [Indexed: 12/18/2022] Open
Abstract
Musculoskeletal pain due to ischemia is present in a variety of clinical conditions including peripheral vascular disease (PVD), sickle cell disease (SCD), complex regional pain syndrome (CRPS), and even fibromyalgia (FM). The clinical features associated with deep tissue ischemia are unique because although the subjective description of pain is common to other forms of myalgia, patients with ischemic muscle pain often respond poorly to conventional analgesic therapies. Moreover, these patients also display increased cardiovascular responses to muscle contraction, which often leads to exercise intolerance or exacerbation of underlying cardiovascular conditions. This suggests that the mechanisms of myalgia development and the role of altered cardiovascular function under conditions of ischemia may be distinct compared to other injuries/diseases of the muscles. It is widely accepted that group III and IV muscle afferents play an important role in the development of pain due to ischemia. These same muscle afferents also form the sensory component of the exercise pressor reflex (EPR), which is the increase in heart rate and blood pressure (BP) experienced after muscle contraction. Studies suggest that afferent sensitization after ischemia depends on interactions between purinergic (P2X and P2Y) receptors, transient receptor potential (TRP) channels, and acid sensing ion channels (ASICs) in individual populations of peripheral sensory neurons. Specific alterations in primary afferent function through these receptor mechanisms correlate with increased pain related behaviors and altered EPRs. Recent evidence suggests that factors within the muscles during ischemic conditions including upregulation of growth factors and cytokines, and microvascular changes may be linked to the overexpression of these different receptor molecules in the dorsal root ganglia (DRG) that in turn modulate pain and sympathetic reflexes. In this review article, we will discuss the peripheral mechanisms involved in the development of ischemic myalgia and the role that primary sensory neurons play in EPR modulation.
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Affiliation(s)
- Luis F Queme
- Department of Anesthesia, Division of Pain Management, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States
| | - Jessica L Ross
- Department of Anesthesia, Division of Pain Management, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States
| | - Michael P Jankowski
- Department of Anesthesia, Division of Pain Management, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States.,Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, United States
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21
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Broxterman RM, Trinity JD, Gifford JR, Kwon OS, Kithas AC, Hydren JR, Nelson AD, Morgan DE, Jessop JE, Bledsoe AD, Richardson RS. Single passive leg movement assessment of vascular function: contribution of nitric oxide. J Appl Physiol (1985) 2017; 123:1468-1476. [PMID: 28860173 DOI: 10.1152/japplphysiol.00533.2017] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Broxterman RM, Trinity JD, Gifford JR, Kwon OS, Kithas AC, Hydren JR, Nelson AD, Morgan DE, Jessop JE, Bledsoe AD, Richardson RS. Single passive leg movement assessment of vascular function: contribution of nitric oxide. J Appl Physiol 123: 1468-1476, 2017. First published August 31, 2017; doi:10.1152/japplphysiol.00533.2017.-The assessment of passive leg movement (PLM)-induced leg blood flow (LBF) and vascular conductance (LVC) is a novel approach to assess vascular function that has recently been simplified to only a single PLM (sPLM), thereby increasing the clinical utility of this technique. As the physiological mechanisms mediating the robust increase in LBF and LVC with sPLM are unknown, we tested the hypothesis that nitric oxide (NO) is a major contributor to the sPLM-induced LBF and LVC response. In nine healthy men, sPLM was performed with and without NO synthase inhibition by intra-arterial infusion of NG-monomethyl-l-arginine (l-NMMA). Doppler ultrasound and femoral arterial pressure were used to determine LBF and LVC, which were characterized by the peak change (ΔLBFpeak and ΔLVCpeak) and area under the curve (LBFAUC and LVCAUC). l-NMMA significantly attenuated ΔLBFpeak [492 ± 153 (l-NMMA) vs. 719 ± 238 (control) ml/min], LBFAUC [57 ± 34 (l NMMA) vs. 147 ± 63 (control) ml], ΔLVCpeak [4.7 ± 1.1 (l-NMMA) vs. 8.0 ± 3.0 (control) ml·min-1·mmHg-1], and LVCAUC [0.5 ± 0.3 (l-NMMA) vs. 1.6 ± 0.9 (control) ml/mmHg]. The magnitude of the NO contribution to LBF and LVC was significantly correlated with the magnitude of the control responses ( r = 0.94 for ΔLBFpeak, r = 0.85 for LBFAUC, r = 0.94 for ΔLVCpeak, and r = 0.95 for LVCAUC). These data establish that the sPLM-induced hyperemic and vasodilatory response is predominantly (~65%) NO-mediated. As such, sPLM appears to be a promising, simple, in vivo assessment of NO-mediated vascular function and NO bioavailability. NEW & NOTEWORTHY Passive leg movement (PLM), a novel assessment of vascular function, has been simplified to a single PLM (sPLM), thereby increasing the clinical utility of this technique. However, the role of nitric oxide (NO) in mediating the robust sPLM hemodynamic responses is unknown. This study revealed that sPLM induces a hyperemic and vasodilatory response that is predominantly NO-mediated and, as such, appears to be a promising simple, in vivo, clinical assessment of NO-mediated vascular function and, therefore, NO bioavailability.
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Affiliation(s)
- Ryan M Broxterman
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center , Salt Lake City, Utah.,Department of Internal Medicine, University of Utah , Salt Lake City, Utah
| | - Joel D Trinity
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center , Salt Lake City, Utah.,Department of Internal Medicine, University of Utah , Salt Lake City, Utah.,Department of Nutrition and Integrative Physiology, University of Utah , Salt Lake City, Utah
| | - Jayson R Gifford
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center , Salt Lake City, Utah.,Department of Internal Medicine, University of Utah , Salt Lake City, Utah
| | - Oh Sung Kwon
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center , Salt Lake City, Utah.,Department of Internal Medicine, University of Utah , Salt Lake City, Utah
| | - Andrew C Kithas
- Department of Internal Medicine, University of Utah , Salt Lake City, Utah
| | - Jay R Hydren
- Department of Nutrition and Integrative Physiology, University of Utah , Salt Lake City, Utah
| | - Ashley D Nelson
- Department of Internal Medicine, University of Utah , Salt Lake City, Utah
| | - David E Morgan
- Department of Anesthesiology, University of Utah , Salt Lake City, Utah
| | - Jacob E Jessop
- Department of Anesthesiology, University of Utah , Salt Lake City, Utah
| | - Amber D Bledsoe
- Department of Anesthesiology, University of Utah , Salt Lake City, Utah
| | - Russell S Richardson
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center , Salt Lake City, Utah.,Department of Internal Medicine, University of Utah , Salt Lake City, Utah.,Department of Nutrition and Integrative Physiology, University of Utah , Salt Lake City, Utah
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Di Lernia D, Serino S, Riva G. Pain in the body. Altered interoception in chronic pain conditions: A systematic review. Neurosci Biobehav Rev 2016; 71:328-341. [DOI: 10.1016/j.neubiorev.2016.09.015] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Revised: 09/14/2016] [Accepted: 09/16/2016] [Indexed: 12/25/2022]
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Venturelli M, Cè E, Limonta E, Bisconti AV, Devoto M, Rampichini S, Esposito F. Central and peripheral responses to static and dynamic stretch of skeletal muscle: mechano- and metaboreflex implications. J Appl Physiol (1985) 2016; 122:112-120. [PMID: 27856718 DOI: 10.1152/japplphysiol.00721.2016] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 11/02/2016] [Accepted: 11/11/2016] [Indexed: 12/21/2022] Open
Abstract
Passive static stretching (SS), circulatory cuff occlusion (CCO), and the combination of both (SS + CCO) have been used to investigate the mechano- and metaboreflex, respectively. However, the effects of dynamic stretching (DS) alone or in combination with CCO (DS + CCO) on the same reflexes have never been explored. The aim of the study was to compare central and peripheral hemodynamic responses to DS, SS, DS + CCO, and SS + CCO. In 10 participants, femoral blood flow (FBF), heart rate (HR), cardiac output (CO), and mean arterial pressure (MAP) were assessed during DS and SS of the quadriceps muscle with and without CCO. Blood lactate concentration [La-] in the lower limb undergoing CCO was also measured. FBF increased significantly in DS and SS by 365 ± 98 and 377 ± 102 ml/min, respectively. Compared with baseline, hyperemia was negligible during DS + CCO and SS + CCO (+11 ± 98 and +5 ± 87 ml/min, respectively). DS generated a significant, sustained increase in HR and CO (∼40s), while SS induced a blunted and delayed cardioacceleration (∼20 s). After CCO, [La-] in the lower limb increased by 135%. Changes in HR and CO during DS + CCO and SS + CCO were similar to DS and SS alone. MAP decreased significantly by ∼5% during DS and SS, did not change in DS + CCO, and increased by 4% in SS + CCO. The present data indicate a reduced mechanoreflex response to SS compared with DS (i.e., different HR and CO changes). SS evoked a hyperemia similar to DS. The similar central hemodynamics recorded during stretching and [La-] accumulation suggest a marginal interaction between mechano- and metaboreflex. NEW & NOTEWORTHY Different modalities of passive stretching administration (dynamic or static) in combination with circulatory cuff occlusion may reduce or amplify the mechano- and metaboreflex. We showed a reduced mechanoreflex response to static compared with dynamic stretching. The lack of increase in central hemodynamics during the combined mechano- and metaboreflex stimulation implicates marginal interactions between these two pathways.
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Affiliation(s)
- Massimo Venturelli
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy; .,Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Emiliano Cè
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
| | - Eloisa Limonta
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
| | | | - Michela Devoto
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
| | - Susanna Rampichini
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
| | - Fabio Esposito
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy.,Center of Sport Medicine, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Don Gnocchi Foundation, Milan, Italy; and
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Venturelli M, Layec G, Trinity J, Hart CR, Broxterman RM, Richardson RS. Single passive leg movement-induced hyperemia: a simple vascular function assessment without a chronotropic response. J Appl Physiol (1985) 2016; 122:28-37. [PMID: 27834672 DOI: 10.1152/japplphysiol.00806.2016] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Revised: 11/03/2016] [Accepted: 11/03/2016] [Indexed: 12/13/2022] Open
Abstract
Passive leg movement (PLM)-induced hyperemia is a novel approach to assess vascular function, with a potential clinical role. However, in some instances, the varying chronotropic response induced by PLM has been proposed to be a potentially confounding factor. Therefore, we simplified and modified the PLM model to require just a single PLM (sPLM), an approach that may evoke a peripheral hemodynamic response, allowing a vascular function assessment, but at the same time minimizing central responses. To both characterize and assess the utility of sPLM, in 12 healthy subjects, we measured heart rate (HR), stroke volume, cardiac output (CO), mean arterial pressure (MAP), leg blood flow (LBF), and calculated leg vascular conductance (LVC) during both standard PLM, consisting of passive knee flexion and extension performed at 1 Hz for 60 s, and sPLM, consisting of only a single passive knee flexion and extension over 1 s. During PLM, MAP transiently decreased (5 ± 1 mmHg), whereas both HR and CO increased from baseline (6.0 ± 1.1 beats/min, and 0.8 ± 0.01 l/min, respectively). Following sPLM, MAP fell similarly (5 ± 2 mmHg; P = 0.8), but neither HR nor CO responses were identifiable. The peak LBF and LVC response was similar for PLM (993 ± 189 ml/min; 11.9 ± 1.5 ml·min-1·mmHg-1, respectively) and sPLM (878 ± 119 ml/min; 10.9 ± 1.6 ml·min-1·mmHg-1, respectively). Thus sPLM represents a variant of the PLM approach to assess vascular function that is more easily performed and evokes a peripheral stimulus that induces a significant hyperemia, but does not generate a potentially confounding, chronotropic response, which may make sPLM more useful clinically. NEW & NOTEWORTHY Using the single passive leg movement (PLM) technique, a variant of the vascular function assessment PLM, we have identified a novel peripheral vascular assessment method that is more easily performed than PLM, which, by not evoking potentially confounding central hemodynamic responses, may be more useful clinically.
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Affiliation(s)
- Massimo Venturelli
- Department of Internal Medicine, Division of Geriatrics, University of Utah, Salt Lake City, Utah; .,Department of Neuroscience, Biomedicine, and Movement Sciences, University of Verona, Verona, Italy
| | - Gwenael Layec
- Department of Internal Medicine, Division of Geriatrics, University of Utah, Salt Lake City, Utah
| | - Joel Trinity
- Department of Internal Medicine, Division of Geriatrics, University of Utah, Salt Lake City, Utah.,Geriatric Research, Education, and Clinical Center, George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah; and
| | - Corey R Hart
- Department of Exercise and Sport Science, University of Utah, Salt Lake City, Utah
| | - Ryan M Broxterman
- Department of Exercise and Sport Science, University of Utah, Salt Lake City, Utah
| | - Russell S Richardson
- Department of Internal Medicine, Division of Geriatrics, University of Utah, Salt Lake City, Utah.,Geriatric Research, Education, and Clinical Center, George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah; and.,Department of Exercise and Sport Science, University of Utah, Salt Lake City, Utah
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Spranger MD, Kaur J, Sala-Mercado JA, Krishnan AC, Abu-Hamdah R, Alvarez A, Machado TM, Augustyniak RA, O'Leary DS. Exaggerated coronary vasoconstriction limits muscle metaboreflex-induced increases in ventricular performance in hypertension. Am J Physiol Heart Circ Physiol 2016; 312:H68-H79. [PMID: 27769997 DOI: 10.1152/ajpheart.00417.2016] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Revised: 10/18/2016] [Accepted: 10/18/2016] [Indexed: 02/07/2023]
Abstract
Increases in myocardial oxygen consumption during exercise mainly occur via increases in coronary blood flow (CBF) as cardiac oxygen extraction is high even at rest. However, sympathetic coronary constrictor tone can limit increases in CBF. Increased sympathetic nerve activity (SNA) during exercise likely occurs via the action of and interaction among activation of skeletal muscle afferents, central command, and resetting of the arterial baroreflex. As SNA is heightened even at rest in subjects with hypertension (HTN), we tested whether HTN causes exaggerated coronary vasoconstriction in canines during mild treadmill exercise with muscle metaboreflex activation (MMA; elicited by reducing hindlimb blood flow by ~60%) thereby limiting increases in CBF and ventricular performance. Experiments were repeated after α1-adrenergic blockade (prazosin; 75 µg/kg) and in the same animals following induction of HTN (modified Goldblatt 2K1C model). HTN increased mean arterial pressure from 97.1 ± 2.6 to 132.1 ± 5.6 mmHg at rest and MMA-induced increases in CBF, left ventricular dP/dtmax, and cardiac output were markedly reduced to only 32 ± 13, 26 ± 11, and 28 ± 12% of the changes observed in control. In HTN, α1-adrenergic blockade restored the coronary vasodilation and increased in ventricular function to the levels observed when normotensive. We conclude that exaggerated MMA-induced increases in SNA functionally vasoconstrict the coronary vasculature impairing increases in CBF, which limits oxygen delivery and ventricular performance in HTN. NEW & NOTEWORTHY We found that metaboreflex-induced increases in coronary blood flow and ventricular contractility are attenuated in hypertension. α1-Adrenergic blockade restored these parameters toward normal levels. These findings indicate that the primary mechanism mediating impaired metaboreflex-induced increases in ventricular function in hypertension is accentuated coronary vasoconstriction.
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Affiliation(s)
- Marty D Spranger
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan
| | - Jasdeep Kaur
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan
| | - Javier A Sala-Mercado
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan
| | - Abhinav C Krishnan
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan
| | - Rania Abu-Hamdah
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan
| | - Alberto Alvarez
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan
| | - Tiago M Machado
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan
| | - Robert A Augustyniak
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan
| | - Donal S O'Leary
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan
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Discovering your inner Gibson: reconciling action-specific and ecological approaches to perception-action. Psychon Bull Rev 2016; 21:1353-70. [PMID: 24683098 DOI: 10.3758/s13423-014-0623-4] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Both the action-specific perception account and the ecological approach to perception-action emphasize the role of action in perception. However, the action-specific perception account demonstrates that different percepts are possible depending on the perceiver's ability to act, even when the same optical information is available. These findings challenge one of the fundamental claims of the ecological approach--that perception is direct--by suggesting that perception is mediated by internal processes. Here, we sought to resolve this apparent discrepancy. We contend that perception is based on the controlled detection of the information available in a global array that includes higher-order patterns defined across interoceptive and exteroceptive stimulus arrays. These higher-order patterns specify the environment in relation to the perceiver, so direct sensitivity to them would be consistent with the ecological claims that perception of the environment is direct and animal-specific. In addition, the action-specific approach provides further evidence for the theory of affordances, by demonstrating that even seemingly abstract properties of the environment, such as distance and size, are ultimately perceived in terms of an agent's action capabilities.
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Mizuno M, Mitchell JH, Smith SA. The exercise pressor reflex in hypertension. THE JOURNAL OF PHYSICAL FITNESS AND SPORTS MEDICINE 2016. [DOI: 10.7600/jpfsm.5.339] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Masaki Mizuno
- Department of Health Care Sciences, University of Texas Southwestern Medical Center
- Internal Medicine, University of Texas Southwestern Medical Center
| | - Jere H. Mitchell
- Internal Medicine, University of Texas Southwestern Medical Center
| | - Scott A. Smith
- Department of Health Care Sciences, University of Texas Southwestern Medical Center
- Internal Medicine, University of Texas Southwestern Medical Center
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Spranger MD, Krishnan AC, Levy PD, O'Leary DS, Smith SA. Blood flow restriction training and the exercise pressor reflex: a call for concern. Am J Physiol Heart Circ Physiol 2015; 309:H1440-52. [PMID: 26342064 PMCID: PMC7002872 DOI: 10.1152/ajpheart.00208.2015] [Citation(s) in RCA: 136] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 08/31/2015] [Indexed: 02/07/2023]
Abstract
Blood flow restriction (BFR) training (also known as Kaatsu training) is an increasingly common practice employed during resistance exercise by athletes attempting to enhance skeletal muscle mass and strength. During BFR training, blood flow to the exercising muscle is mechanically restricted by placing flexible pressurizing cuffs around the active limb proximal to the working muscle. This maneuver results in the accumulation of metabolites (e.g., protons and lactic acid) in the muscle interstitium that increase muscle force and promote muscle growth. Therefore, the premise of BFR training is to simulate and receive the benefits of high-intensity resistance exercise while merely performing low-intensity resistance exercise. This technique has also been purported to provide health benefits to the elderly, individuals recovering from joint injuries, and patients undergoing cardiac rehabilitation. Since the seminal work of Alam and Smirk in the 1930s, it has been well established that reductions in blood flow to exercising muscle engage the exercise pressor reflex (EPR), a reflex that significantly contributes to the autonomic cardiovascular response to exercise. However, the EPR and its likely contribution to the BFR-mediated cardiovascular response to exercise is glaringly missing from the scientific literature. Inasmuch as the EPR has been shown to generate exaggerated increases in sympathetic nerve activity in disease states such as hypertension (HTN), heart failure (HF), and peripheral artery disease (PAD), concerns are raised that BFR training can be used safely for the rehabilitation of patients with cardiovascular disease, as has been suggested. Abnormal BFR-induced and EPR-mediated cardiovascular complications generated during exercise could precipitate adverse cardiovascular or cerebrovascular events (e.g., cardiac arrhythmia, myocardial infarction, stroke and sudden cardiac death). Moreover, although altered EPR function in HTN, HF, and PAD underlies our concern for the widespread implementation of BFR, use of this training mechanism may also have negative consequences in the absence of disease. That is, even normal, healthy individuals performing resistance training exercise with BFR are potentially at increased risk for deleterious cardiovascular events. This review provides a brief yet detailed overview of the mechanisms underlying the autonomic cardiovascular response to exercise with BFR. A more complete understanding of the consequences of BFR training is needed before this technique is passively explored by the layman athlete or prescribed by a health care professional.
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Affiliation(s)
- Marty D Spranger
- Department of Physiology, Michigan State University, East Lansing, Michigan; Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan; Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan;
| | - Abhinav C Krishnan
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan; Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan
| | - Phillip D Levy
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan; Department of Emergency Medicine, Wayne State University School of Medicine, Detroit, Michigan
| | - Donal S O'Leary
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan; Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan
| | - Scott A Smith
- Department of Health Care Sciences, University of Texas Southwestern Medical Center, Dallas, Texas; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
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Chifamba J, Mbangani B, Chimhete C, Gwaunza L, Allen LA, Chinyanga HM. Vasomotor sympathetic outflow in the muscle metaboreflex in low birth weight young adults. Integr Blood Press Control 2015; 8:37-42. [PMID: 26060413 PMCID: PMC4454205 DOI: 10.2147/ibpc.s76382] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
A growing body of evidence suggests that low birth weight (LBW) offspring are associated with long-term structural and functional changes in cardiovascular and neuroendocrine systems. We tested the hypothesis that muscle metaboreflex activation produces exaggerated responses in cardiac autonomic tone (represented by heart rate variability ratio) and cutaneous vascular sympathetic tone (represented by plethysmography pulse wave amplitude) in LBW compared to normal birth weight (NBW) young adults. We recruited 23 LBW (18 females and five males) and 23 NBW (14 females and nine males) University of Zimbabwe students with neonatal clinical cards as proof of birth weight at term. Resting electrocardiogram, pulse waves, and blood pressures were recorded. Participants then underwent a static/isometric handgrip exercise until fatigue and a post-exercise circulatory arrest period of 2 minutes. We observed (results mean ± standard deviation) a greater mean increase in heart rate variability ratio from baseline to exercise for LBW compared to NBW individuals (1.015±1.034 versus [vs] 0.119±0.789, respectively; P<0.05). We also observed a greater mean decrease in plethysmography pulse wave amplitude from baseline to exercise (−1.32±1.064 vs −0.735±0.63; P<0.05) and from baseline to post-exercise circulatory arrest (−0.932±0.998 vs −0.389±0.563; P<0.05) for LBW compared to NBW individuals. We conclude that LBW may be associated with an exaggerated sympathetic discharge in response to muscle metaboreflex.
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Affiliation(s)
- Jephat Chifamba
- Department of Physiology, College of Health Sciences, University of Zimbabwe, Harare, Zimbabwe
| | - Brilliant Mbangani
- Department of Physiology, College of Health Sciences, University of Zimbabwe, Harare, Zimbabwe
| | - Casper Chimhete
- Department of Physiology, College of Health Sciences, University of Zimbabwe, Harare, Zimbabwe
| | - Lenon Gwaunza
- Department of Physiology, College of Health Sciences, University of Zimbabwe, Harare, Zimbabwe
| | - Larry A Allen
- Section of Advanced Heart Failure and Transplantation, University of Colorado School of Medicine, Aurora, CO, USA
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Laurin J, Pertici V, Dousset E, Marqueste T, Decherchi P. Group III and IV muscle afferents: Role on central motor drive and clinical implications. Neuroscience 2015; 290:543-51. [DOI: 10.1016/j.neuroscience.2015.01.065] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 01/27/2015] [Accepted: 01/28/2015] [Indexed: 12/12/2022]
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Yamauchi K, Stone AJ, Kaufman MP. Hindlimb venous distention evokes a pressor reflex in decerebrated rats. Physiol Rep 2014; 2:2/6/e12036. [PMID: 24907299 PMCID: PMC4208660 DOI: 10.14814/phy2.12036] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The distention of small vessels caused by an increase in blood flow to dynamically exercising muscles has been proposed as a stimulus that activates the thin fiber (groups III and IV) afferents evoking the exercise pressor reflex. This theory has been supported by evidence obtained from both humans and animals. In decerebrated unanesthetized rats with either freely perfused femoral arteries or arteries that were ligated 3 days before the experiment, we attempted to provide evidence in support of this theory by measuring arterial pressure, heart rate, and renal sympathetic nerve discharge while retrogradely injecting Ringer's solution in increasing volumes into the femoral vein just as it excited the triceps surae muscles. We found that the pressor response to injection was directly proportional to the volume injected. Retrograde injection of volumes up to and including 1 mL had no significant effect on either heart rate or renal sympathetic nerve activity. Cyclooxygenase blockade with indomethacin attenuated the reflex pressor response to retrograde injection in both groups of rats. In contrast, gadolinium, which blocks mechanogated channels, attenuated the reflex pressor response to retrograde injection in the “ligated rats,” but had no effect on the response in “freely perfused” rats. Our findings are consistent with the possibility that distension of small vessels within exercising skeletal muscle can serve as a stimulus to the thin fiber afferents evoking the exercise pressor reflex. In decerebrated unanesthetized rats with either freely perfused femoral arteries or arteries that were ligated 3 days before the experiment, we attempted to provide evidence in support of this theory by measuring arterial pressure, heart rate, and renal sympathetic nerve discharge while retrogradely injecting Ringer's solution in increasing volumes into the femoral vein just as it excited the triceps surae muscles. Our findings are consistent with the possibility that distension of small vessels within exercising skeletal muscle can serve as a stimulus to the thin fiber afferents evoking the exercise pressor reflex.
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Affiliation(s)
- Katsuya Yamauchi
- Penn State Heart & Vascular Institute, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA
| | - Audrey J Stone
- Penn State Heart & Vascular Institute, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA
| | - Marc P Kaufman
- Penn State Heart & Vascular Institute, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA
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Amano T, Ichinose M, Nishiyasu T, Inoue Y, Koga S, Miwa M, Kondo N. Sweating response to passive stretch of the calf muscle during activation of forearm muscle metaboreceptors in heated humans. Am J Physiol Regul Integr Comp Physiol 2014; 306:R728-34. [PMID: 24598460 DOI: 10.1152/ajpregu.00515.2013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Activation of muscle metaboreceptors and mechanoreceptors has been shown to independently influence the sweating response, while their integrative control effects remain unclear. We examined the sweating response when the two muscle receptors are concurrently activated in different limbs, as well as the blood pressure response. In total, 27 young males performed passive calf muscle stretches (muscle mechanoreceptor activation) for 30 s in a semisupine position with and without postisometric handgrip exercise muscle ischemia (PEMI, muscle metaboreceptor activation) at exercise intensities of 35 and 50% of maximum voluntary contraction (MVC) under hot conditions (ambient temperature, 35°C, relative humidity, 50%). Passive calf muscle stretching alone increased the mean sweating rate significantly on the forehead, chest, and thigh (SRmean) and mean arterial blood pressure (MAP), but not the heart rate (HR), from prestretching levels by 0.04 ± 0.01 mg·cm(2)·min(-1), 4.0 ± 1.3 mmHg (P < 0.05), and -1.0 ± 0.5 beats/min (P > 0.05), respectively. The SRmean and MAP during PEMI were significantly higher than those at rest. The passive calf muscle stretch during PEMI increased MAP significantly by 3.4 ± 1.0 and 2.0 ± 0.7 mmHg for 35 and 50% of MVC, respectively (P < 0.05), but not that of SRmean or HR at either exercise intensity. These results suggest that sweating and blood pressure responses to concurrent activation of the two muscle receptors in different limbs differ and that the influence of calf muscle mechanoreceptor activation alone on the sweating response disappears during forearm muscle metaboreceptor activation.
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Affiliation(s)
- Tatsuro Amano
- Laboratory for Applied Human Physiology, Graduate School of Human Development and Environment, Kobe University, Kobe, Japan
| | - Masashi Ichinose
- Human Integrative Physiology Laboratory, School of Business Administration, Meiji University, Tokyo, Japan
| | - Takeshi Nishiyasu
- Institute of Health and Sports Science, University of Tsukuba, Tsukuba, Japan
| | - Yoshimitsu Inoue
- Laboratory for Human Performance Research, Osaka International University, Osaka, Japan; and
| | - Shunsaku Koga
- Applied Physiology Laboratory, Kobe Design University, Kobe, Japan
| | - Mikio Miwa
- Laboratory for Applied Human Physiology, Graduate School of Human Development and Environment, Kobe University, Kobe, Japan
| | - Narihiko Kondo
- Laboratory for Applied Human Physiology, Graduate School of Human Development and Environment, Kobe University, Kobe, Japan;
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Venturelli M, Amann M, Layec G, McDaniel J, Trinity JD, Fjeldstad AS, Ives SJ, Yonnet G, Richardson RS. Passive leg movement-induced hyperaemia with a spinal cord lesion: evidence of preserved vascular function. Acta Physiol (Oxf) 2014; 210:429-39. [PMID: 24119139 DOI: 10.1111/apha.12173] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Revised: 08/21/2013] [Accepted: 09/20/2013] [Indexed: 12/21/2022]
Abstract
UNLABELLED A spinal cord injury (SCI) clearly results in greater cardiovascular risk; however, accompanying changes in peripheral vascular structure below the lesion mean that the real impact of a SCI on vascular function is unclear. AIM Therefore, utilizing passive leg movement-induced (PLM) hyperaemia, an index of nitric oxide (NO)-dependent vascular function and the central hemodynamic response to this intervention, we studied eight individuals with a SCI and eight age-matched controls (CTRL). METHODS Specifically, we assessed heart rate (HR), stroke volume (SV), cardiac output (CO), mean arterial pressure (MAP), leg blood flow (LBF) and thigh composition. RESULTS In CTRL, passive movement transiently decreased MAP and increased HR and CO from baseline by 2.5 ± 1 mmHg, 7 ± 2 bpm and 0.5 ± 0.1 L min(-1) respectively. In SCI, HR and CO responses were unidentifiable. LBF increased to a greater extent in CTRL (515 ± 41 ∆mL min(-1)) compared with SCI, (126 ± 25 ∆mL min(-1)) (P < 0.05). There was a strong relationship between ∆LBF and thigh muscle volume (r = 0.95). After normalizing ∆LBF for this strong relationship (∆LBF/muscle volume), there was evidence of preserved vascular function in SCI (CTRL: 120 ± 9; SCI 104 ± 11 mL min(-1) L(-1)). A comparison of ∆LBF in the passively moved and stationary leg, to partition the contribution of the blood flow response, implied that 35% of the hyperaemia resulted from cardioacceleration in the CTRL, whereas all the hyperaemia appeared peripheral in origin in the SCI. CONCLUSION Thus, utilizing PLM-induced hyperaemia as marker of vascular function, it is evident that peripheral vascular impairment is not an obligatory accompaniment to a SCI.
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Affiliation(s)
- M. Venturelli
- Department of Neurological, Neuropsychological, Morphological and Movement Sciences; University of Verona; Verona Italy
- Department of Internal Medicine; Division of Geriatrics; University of Utah; Salt Lake City UT USA
| | - M. Amann
- Department of Internal Medicine; Division of Geriatrics; University of Utah; Salt Lake City UT USA
- Geriatric Research, Education, and Clinical Center; George E. Whalen VA Medical Center; Salt Lake City UT USA
- Department of Exercise and Sport Science; University of Utah; Salt Lake City UT USA
| | - G. Layec
- Department of Internal Medicine; Division of Geriatrics; University of Utah; Salt Lake City UT USA
| | - J. McDaniel
- Department of Internal Medicine; Division of Geriatrics; University of Utah; Salt Lake City UT USA
- Geriatric Research, Education, and Clinical Center; George E. Whalen VA Medical Center; Salt Lake City UT USA
| | - J. D. Trinity
- Department of Internal Medicine; Division of Geriatrics; University of Utah; Salt Lake City UT USA
- Geriatric Research, Education, and Clinical Center; George E. Whalen VA Medical Center; Salt Lake City UT USA
| | - A. S. Fjeldstad
- Department of Internal Medicine; Division of Geriatrics; University of Utah; Salt Lake City UT USA
| | - S. J. Ives
- Department of Internal Medicine; Division of Geriatrics; University of Utah; Salt Lake City UT USA
- Geriatric Research, Education, and Clinical Center; George E. Whalen VA Medical Center; Salt Lake City UT USA
| | - G. Yonnet
- Department of Neurology; University of Utah; Salt Lake City UT USA
| | - R. S. Richardson
- Department of Internal Medicine; Division of Geriatrics; University of Utah; Salt Lake City UT USA
- Geriatric Research, Education, and Clinical Center; George E. Whalen VA Medical Center; Salt Lake City UT USA
- Department of Exercise and Sport Science; University of Utah; Salt Lake City UT USA
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Craig ADB. Topographically organized projection to posterior insular cortex from the posterior portion of the ventral medial nucleus in the long-tailed macaque monkey. J Comp Neurol 2014; 522:36-63. [PMID: 23853108 PMCID: PMC4145874 DOI: 10.1002/cne.23425] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Revised: 04/15/2013] [Accepted: 07/03/2013] [Indexed: 12/18/2022]
Abstract
Prior anterograde tracing work identified somatotopically organized lamina I trigemino- and spinothalamic terminations in a cytoarchitectonically distinct portion of posterolateral thalamus of the macaque monkey, named the posterior part of the ventral medial nucleus (VMpo; Craig [2004] J. Comp. Neurol. 477:119-148). Microelectrode recordings from clusters of selectively thermoreceptive or nociceptive neurons were used to guide precise microinjections of various tracers in VMpo. A prior report (Craig and Zhang [2006] J. Comp. Neurol. 499:953-964) described retrograde tracing results, which confirmed the selective lamina I input to VMpo and the anteroposterior (head to foot) topography. The present report describes the results of microinjections of anterograde tracers placed at different levels in VMpo, based on the anteroposterior topographic organization of selectively nociceptive units and clusters over nearly the entire extent of VMpo. Each injection produced dense, patchy terminal labeling in a single coherent field within a distinct granular cortical area centered in the fundus of the superior limiting sulcus. The terminations were distributed with a consistent anteroposterior topography over the posterior half of the superior limiting sulcus. These observations demonstrate a specific VMpo projection area in dorsal posterior insular cortex that provides the basis for a somatotopic representation of selectively nociceptive lamina I spinothalamic activity. These results also identify the VMpo terminal area as the posterior half of interoceptive cortex; the anterior half receives input from the vagal-responsive and gustatory neurons in the basal part of the ventral medial nucleus.
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Affiliation(s)
- A D Bud Craig
- Atkinson Research Laboratory, Barrow Neurological Institute, Phoenix, Arizona, 85013
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Sala-Mercado JA, Spranger MD, Abu-Hamdah R, Kaur J, Coutsos M, Stayer D, Augustyniak RA, O'Leary DS. Attenuated muscle metaboreflex-induced increases in cardiac function in hypertension. Am J Physiol Heart Circ Physiol 2013; 305:H1548-54. [PMID: 24014673 DOI: 10.1152/ajpheart.00478.2013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Sympathoactivation may be excessive during exercise in subjects with hypertension, leading to increased susceptibility to adverse cardiovascular events, including arrhythmias, infarction, stroke, and sudden cardiac death. The muscle metaboreflex is a powerful cardiovascular reflex capable of eliciting marked increases in sympathetic activity during exercise. We used conscious, chronically instrumented dogs trained to run on a motor-driven treadmill to investigate the effects of hypertension on the mechanisms of the muscle metaboreflex. Experiments were performed before and 30.9 ± 4.2 days after induction of hypertension, which was induced via partial, unilateral renal artery occlusion. After induction of hypertension, resting mean arterial pressure was significantly elevated from 98.2 ± 2.6 to 141.9 ± 7.4 mmHg. The hypertension was caused by elevated total peripheral resistance. Although cardiac output was not significantly different at rest or during exercise after induction of hypertension, the rise in cardiac output with muscle metaboreflex activation was significantly reduced in hypertension. Metaboreflex-induced increases in left ventricular function were also depressed. These attenuated cardiac responses caused a smaller metaboreflex-induced rise in mean arterial pressure. We conclude that the ability of the muscle metaboreflex to elicit increases in cardiac function is impaired in hypertension, which may contribute to exercise intolerance.
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Affiliation(s)
- Javier A Sala-Mercado
- Department of Physiology and The Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan
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Ichinose M, Maeda S, Kondo N, Nishiyasu T. Blood pressure regulation II: what happens when one system must serve two masters--oxygen delivery and pressure regulation? Eur J Appl Physiol 2013; 114:451-65. [PMID: 23846841 DOI: 10.1007/s00421-013-2691-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2013] [Accepted: 07/02/2013] [Indexed: 11/30/2022]
Abstract
During high-intensity dynamic exercise, O2 delivery to active skeletal muscles is enhanced through marked increases in both cardiac output and skeletal muscle blood flow. When the musculature is vigorously engaged in exercise, the human heart lacks the pumping capacity to meet the blood flow demands of both the skeletal muscles and other organs such as the brain. Vasoconstriction must therefore be induced through activation of sympathetic nervous activity to maintain blood flow to the brain and to produce the added driving pressure needed to increase flow to the skeletal muscles. In this review, we first briefly summarize the local vascular and neural control mechanisms operating during high-intensity exercise. This is followed by a review of the major neural mechanisms regulating blood pressure during high-intensity exercise, focusing mainly on the integrated activities of the arterial baroreflex and muscle metaboreflex. In high cardiac output situations, such as during high-intensity dynamic exercise, small changes in total peripheral resistance can induce large changes in blood pressure, which means that rapid and fine regulation is necessary to avoid unacceptable drops in blood pressure. To accomplish this rapid regulation, arterial baroreflex function may be modulated in various ways through activation of the muscle metaboreflex and/or other neural mechanisms. Moreover, this modulation of the arterial baroreflex may change over the time course of an exercise bout, or to accommodate changes in exercise intensity. Within this model, integration of arterial baroreflex modulation with other neural mechanisms plays an important role in cardiovascular control during high-intensity exercise.
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Affiliation(s)
- Masashi Ichinose
- Human Integrative Physiology Laboratory, School of Business Administration, Meiji University, Tokyo, Japan
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Fazalbhoy A, Macefield VG, Birznieks I. Tonic muscle pain does not increase fusimotor drive to human leg muscles: implications for chronic muscle pain. Exp Physiol 2013; 98:1125-32. [DOI: 10.1113/expphysiol.2012.071670] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Baudry S, Sarrazin S, Duchateau J. Effects of load magnitude on muscular activity and tissue oxygenation during repeated elbow flexions until failure. Eur J Appl Physiol 2013; 113:1895-904. [PMID: 23471683 DOI: 10.1007/s00421-013-2618-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Accepted: 02/22/2013] [Indexed: 11/30/2022]
Abstract
This study investigated the changes in muscular activity and tissue oxygenation while lifting and lowering a load of 20, 40, 60 or 80 % of one repetition maximum (1RM) with elbow flexor muscles until failure. The surface electromyogram (EMG) was recorded in biceps brachii (BB), brachioradialis (BRD) and triceps brachii (TB). For BB, a tissue oxygenation index (TOI) and a normalized total hemoglobin index (nTHI) were recorded by near-infrared spectroscopy. The number of repetitions decreased with the increase in load (P < 0.001), and the four loading conditions induced a decrease in MVC force immediately after failure (P < 0.001). The average of rectified EMG amplitude (aEMG) of elbow flexors increased for all loads during muscle shortening (SHO) and lengthening (LEN) phases of the movement (P < 0.05), except for the 80 % load during LEN phase. At failure, the aEMG was greater during the SHO than the LEN phase (P < 0.05), except for the 20 % load. TOI decreased for all loads and phases (P < 0.05) but less (P < 0.01) for the 20 % than 60 and 80 % loads (P < 0.01), and for LEN compared with SHO phase. At failure, TOI was negatively associated with aEMG during the SHO (r(2) = 0.99) and LEN (r(2) = 0.82) phases, while TOI and aEMG were positively associated with load magnitude (r(2) > 0.90) in both movement phases. This study emphasizes the influence of load magnitude and movement phase (SHO and LEN) on neuromuscular and oxydative adjustments during movements that involve lifting and lowering a load until failure.
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Affiliation(s)
- Stéphane Baudry
- Laboratory of Applied Biology, Faculty for Motor Sciences, Neuroscience Institute, Université Libre de Bruxelles, 808, Route de Lennik, CP 640, 1070 Brussels, Belgium.
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Spranger MD, Sala-Mercado JA, Coutsos M, Kaur J, Stayer D, Augustyniak RA, O'Leary DS. Role of cardiac output versus peripheral vasoconstriction in mediating muscle metaboreflex pressor responses: dynamic exercise versus postexercise muscle ischemia. Am J Physiol Regul Integr Comp Physiol 2013; 304:R657-63. [PMID: 23427084 DOI: 10.1152/ajpregu.00601.2012] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Muscle metaboreflex activation (MMA) during submaximal dynamic exercise in normal individuals increases mean arterial pressure (MAP) via increases in cardiac output (CO) with little peripheral vasoconstriction. The rise in CO occurs primarily via increases in heart rate (HR) with maintained or slightly increased stroke volume. When the reflex is sustained during recovery (postexercise muscle ischemia, PEMI), HR declines yet MAP remains elevated. The role of CO in mediating the pressor response during PEMI is controversial. In seven chronically instrumented canines, steady-state values with MMA during mild exercise (3.2 km/h) were observed by reducing hindlimb blood flow by ~60% for 3-5 min. MMA during exercise was followed by 60 s of PEMI. Control experiments consisted of normal exercise and recovery. MMA during exercise increased MAP, HR, and CO by 55.3 ± 4.9 mmHg, 42.5 ± 6.9 beats/min, and 2.5 ± 0.4 l/min, respectively. During sustained MMA via PEMI, MAP remained elevated and CO remained well above the normal recovery levels. Neither MMA during dynamic exercise nor during PEMI significantly affected peripheral vascular conductance. We conclude that the sustained increase in MAP during PEMI is driven by a sustained increase in CO not peripheral vasoconstriction.
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Affiliation(s)
- Marty D Spranger
- Department of Physiology and The Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, MI 48201, USA
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Coutsos M, Sala-Mercado JA, Ichinose M, Li Z, Dawe EJ, O'Leary DS. Muscle metaboreflex-induced coronary vasoconstriction limits ventricular contractility during dynamic exercise in heart failure. Am J Physiol Heart Circ Physiol 2013; 304:H1029-37. [PMID: 23355344 DOI: 10.1152/ajpheart.00879.2012] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Muscle metaboreflex activation (MMA) during dynamic exercise increases cardiac work and myocardial O2 demand via increases in heart rate, ventricular contractility, and afterload. This increase in cardiac work should lead to metabolic coronary vasodilation; however, no change in coronary vascular conductance occurs. This indicates that the MMA-induced increase in sympathetic activity to the heart, which raises heart rate, ventricular contractility, and cardiac output, also elicits coronary vasoconstriction. In heart failure, cardiac output does not increase with MMA presumably due to impaired ability to improve left ventricular contractility. In this setting actual coronary vasoconstriction is observed. We tested whether this coronary vasoconstriction could explain, in part, the reduced ability to increase cardiac performance during MMA. In conscious, chronically instrumented dogs before and after pacing-induced heart failure, MMA responses during mild exercise were observed before and after α1-adrenergic blockade (prazosin 20-50 μg/kg). During MMA, the increases in coronary vascular conductance, coronary blood flow, maximal rate of left ventricular pressure change, and cardiac output were significantly greater after α1-adrenergic blockade. We conclude that in subjects with heart failure, coronary vasoconstriction during MMA limits the ability to increase left ventricular contractility.
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Affiliation(s)
- Matthew Coutsos
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, USA
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42
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Craig AD. Cooling, pain, and other feelings from the body in relation to the autonomic nervous system. HANDBOOK OF CLINICAL NEUROLOGY 2013; 117:103-9. [PMID: 24095119 DOI: 10.1016/b978-0-444-53491-0.00009-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
The main sensory input to the autonomic nervous system comes from small-diameter sensory fibers by way of lamina I neurons in the superficial dorsal horn. This pathway supports organotopic homeostatic control of the body's condition, but also human feelings from the body, such as temperature, pain, itch, affective touch, muscle ache, vascular flush, and so on. The anatomical pathways described in this chapter reveal that these feelings are correlates of behavioral homeostatic responses needed to maintain the health of the body. These findings suggest that bodily feelings provide important measures of the body's condition, support emotional well-being and awareness, and can be a significant therapeutic avenue.
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Affiliation(s)
- A D Craig
- Atkinson Research Laboratory, Barrow Neurological Institute, Phoenix, AZ, USA.
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Poon CS, Tin C. Mechanism of augmented exercise hyperpnea in chronic heart failure and dead space loading. Respir Physiol Neurobiol 2012; 186:114-30. [PMID: 23274121 DOI: 10.1016/j.resp.2012.12.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Accepted: 12/14/2012] [Indexed: 12/16/2022]
Abstract
Patients with chronic heart failure (CHF) suffer increased alveolar VD/VT (dead-space-to-tidal-volume ratio), yet they demonstrate augmented pulmonary ventilation such that arterial [Formula: see text] ( [Formula: see text] ) remains remarkably normal from rest to moderate exercise. This paradoxical effect suggests that the control law governing exercise hyperpnea is not merely determined by metabolic CO2 production ( [Formula: see text] ) per se but is responsive to an apparent (real-feel) metabolic CO2 load ( [Formula: see text] ) that also incorporates the adverse effect of physiological VD/VT on pulmonary CO2 elimination. By contrast, healthy individuals subjected to dead space loading also experience augmented ventilation at rest and during exercise as with increased alveolar VD/VT in CHF, but the resultant response is hypercapnic instead of eucapnic, as with CO2 breathing. The ventilatory effects of dead space loading are therefore similar to those of increased alveolar VD/VT and CO2 breathing combined. These observations are consistent with the hypothesis that the increased series VD/VT in dead space loading adds to [Formula: see text] as with increased alveolar VD/VT in CHF, but this is through rebreathing of CO2 in dead space gas thus creating a virtual (illusory) airway CO2 load within each inspiration, as opposed to a true airway CO2 load during CO2 breathing that clogs the mechanism for CO2 elimination through pulmonary ventilation. Thus, the chemosensing mechanism at the respiratory controller may be responsive to putative drive signals mediated by within-breath [Formula: see text] oscillations independent of breath-to-breath fluctuations of the mean [Formula: see text] level. Skeletal muscle afferents feedback, while important for early-phase exercise cardioventilatory dynamics, appears inconsequential for late-phase exercise hyperpnea.
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Affiliation(s)
- Chi-Sang Poon
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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Leal AK, Murphy MN, Iwamoto GA, Mitchell JH, Smith SA. A role for nitric oxide within the nucleus tractus solitarii in the development of muscle mechanoreflex dysfunction in hypertension. Exp Physiol 2012; 97:1292-304. [PMID: 22581746 PMCID: PMC3480555 DOI: 10.1113/expphysiol.2012.065433] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Evidence suggests that the muscle mechanoreflex, a circulatory reflex that raises blood pressure and heart rate (HR) upon activation of mechanically sensitive afferent fibres in skeletal muscle, is overactive in hypertension. However, the mechanisms underlying this abnormal reflex function have yet to be identified. Sensory input from the mechanoreflex is processed within the nucleus tractus solitarii (NTS) in the medulla oblongata. Within the NTS, the enzymatic activity of nitric oxide synthase produces nitric oxide (NO). This centrally derived NO has been shown to modulate muscle reflex activity and serves as a viable candidate for mediating the mechanoreflex dysfunction that develops in hypertension. We hypothesized that mechanoreflex dysfunction in hypertension is mediated by abnormal alterations in NO production in the NTS. Mechanically sensitive afferent fibres were stimulated by passively stretching hindlimb muscle before and after blocking the endogenous production of NO within the NTS via microdialysis of the NO synthase inhibitor L-NAME (1 and 5 mM) in normotensive Wistar-Kyoto rats and spontaneously hypertensive rats (SHRs). Changes in HR and mean arterial pressure in response to stretch were significantly larger in SHRs compared with Wistar-Kyoto rats prior to L-NAME dialysis. Attenuating NO production via L-NAME in normotensive rats recapitulated the exaggerated cardiovascular response to stretch observed in SHRs. Dialysing L-NAME in SHRs further accentuated the increases in HR and mean arterial pressure elicited by stretch. These findings support the contention that reductions in NO production within the NTS contribute to the generation of abnormal cardiovascular control by the skeletal muscle mechanoreflex in hypertension.
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Affiliation(s)
- Anna K. Leal
- Department of Bioengineering, University of Texas Southwestern Medical Center, Dallas, Texas, USA 75390-9174
| | - Megan N. Murphy
- Department of Physical Therapy, University of Texas Southwestern Medical Center, Dallas, Texas, USA 75390-9174
| | - Gary A. Iwamoto
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas, USA 75390-9174
| | - Jere H. Mitchell
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA 75390-9174
| | - Scott A. Smith
- Department of Bioengineering, University of Texas Southwestern Medical Center, Dallas, Texas, USA 75390-9174
- Department of Physical Therapy, University of Texas Southwestern Medical Center, Dallas, Texas, USA 75390-9174
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA 75390-9174
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Power GA, Handrigan GA, Basset FA. Ventilatory response during an incremental exercise test: A mode of testing effect. Eur J Sport Sci 2012. [DOI: 10.1080/17461391.2011.573580] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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Wang HJ, Zucker IH, Wang W. Muscle reflex in heart failure: the role of exercise training. Front Physiol 2012; 3:398. [PMID: 23060821 PMCID: PMC3464681 DOI: 10.3389/fphys.2012.00398] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Accepted: 09/20/2012] [Indexed: 12/25/2022] Open
Abstract
Exercise evokes sympathetic activation and increases blood pressure and heart rate (HR). Two neural mechanisms that cause the exercise-induced increase in sympathetic discharge are central command and the exercise pressor reflex (EPR). The former suggests that a volitional signal emanating from central motor areas leads to increased sympathetic activation during exercise. The latter is a reflex originating in skeletal muscle which contributes significantly to the regulation of the cardiovascular and respiratory systems during exercise. The afferent arm of this reflex is composed of metabolically sensitive (predominantly group IV, C-fibers) and mechanically sensitive (predominately group III, A-delta fibers) afferent fibers. Activation of these receptors and their associated afferent fibers reflexively adjusts sympathetic and parasympathetic nerve activity during exercise. In heart failure, the sympathetic activation during exercise is exaggerated, which potentially increases cardiovascular risk and contributes to exercise intolerance during physical activity in chronic heart failure (CHF) patients. A therapeutic strategy for preventing or slowing the progression of the exaggerated EPR may be of benefit in CHF patients. Long-term exercise training (ExT), as a non-pharmacological treatment for CHF increases exercise capacity, reduces sympatho-excitation and improves cardiovascular function in CHF animals and patients. In this review, we will discuss the effects of ExT and the mechanisms that contribute to the exaggerated EPR in the CHF state.
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Affiliation(s)
- Han-Jun Wang
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center Omaha, NE, USA
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47
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Muller MD, Drew RC, Blaha CA, Mast JL, Cui J, Reed AB, Sinoway LI. Oxidative stress contributes to the augmented exercise pressor reflex in peripheral arterial disease patients. J Physiol 2012; 590:6237-46. [PMID: 23006479 DOI: 10.1113/jphysiol.2012.241281] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Exaggerated blood pressure (BP) responses to dynamic exercise predict cardiovascular mortality in patients with peripheral arterial disease (PAD). However, the underlying mechanisms are unclear and no attempt has been made to attenuate this response using antioxidants. Three physiological studies were conducted in patients with PAD and controls. In Protocol 1, subjects underwent 4 min of low-intensity (0.5-2.0 kg), rhythmic plantar flexion in the supine posture. In Protocol 2, patients with PAD received high-dose ascorbic acid intravenously before exercise. In Protocol 3, involuntary exercise was conducted via electrical stimulation of the tibial nerve. The primary outcome measure was Δ mean arterial pressure (MAP) during the first 20 s of exercise (i.e. the onset of sympathoexcitation by muscle afferents). Compared to controls, patients with PAD had significantly greater ΔMAP during plantar flexion, particularly at 0.5 kg with the most affected leg (11 ± 2 vs. 2 ± 1 mmHg) as well as the least affected leg (7 ± 1 vs. 1 ± 1 mmHg). This augmented response occurred before the onset of claudication pain and was attenuated by ∼50% with ascorbic acid. Electrically evoked exercise also elicited larger haemodynamic changes in patients with PAD compared to controls. Further, the ΔMAP during 0.5 kg plantar flexion inversely correlated with the ankle-brachial index, indicating that patients with more severe resting limb ischaemia have a larger BP response to exercise. The BP response to low-intensity exercise was enhanced in PAD. Chronic limb ischaemia may sensitize muscle afferents and potentiate the BP response to muscle contraction in a dose-dependent manner.
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Affiliation(s)
- Matthew D Muller
- Penn State University College of Medicine, Heart and Vascular Institute, Hershey, PA 17033, USA
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Booghs C, Baudry S, Enoka R, Duchateau J. Influence of neural adjustments and muscle oxygenation on task failure during sustained isometric contractions with elbow flexor muscles. Exp Physiol 2012; 97:918-29. [DOI: 10.1113/expphysiol.2011.064303] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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McDaniel J, Ives SJ, Richardson RS. Human muscle length-dependent changes in blood flow. J Appl Physiol (1985) 2011; 112:560-5. [PMID: 22134694 DOI: 10.1152/japplphysiol.01223.2011] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although a multitude of factors that influence skeletal muscle blood flow have been extensively investigated, the influence of muscle length on limb blood flow has received little attention. Thus the purpose of this investigation was to determine if cyclic changes in muscle length influence resting blood flow. Nine healthy men (28 ± 4 yr of age) underwent a passive knee extension protocol during which the subjects' knee joint was passively extended and flexed through 100-180° knee joint angle at a rate of 1 cycle per 30 s. Femoral blood flow, cardiac output (CO), heart rate (HR), stroke volume (SV), and mean arterial pressure (MAP) were continuously recorded during the entire protocol. These measurements revealed that slow passive changes in knee joint angle did not have a significant influence on HR, SV, MAP, or CO; however, net femoral blood flow demonstrated a curvilinear increase with knee joint angle (r(2) = 0.98) such that blood flow increased by ∼90% (125 ml/min) across the 80° range of motion. This net change in blood flow was due to a constant antegrade blood flow across knee joint angle and negative relationship between retrograde blood flow and knee joint angle (r(2) = 0.98). Thus, despite the absence of central hemodynamic changes and local metabolic factors, blood flow to the leg was altered by changes in muscle length. Therefore, when designing research protocols, researchers need to be cognizant of the fact that joint angle, and ultimately muscle length, influence limb blood flow.
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Affiliation(s)
- John McDaniel
- Louis Stokes Cleveland VA Medical Center, Cleveland, OH, USA.
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