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Impact of Maternal Exercise on Mice Offspring Development, Pulmonary Hypertension, and Vascular Remodeling in Chronic Hypoxia. Med Sci Sports Exerc 2024:00005768-990000000-00545. [PMID: 38768014 DOI: 10.1249/mss.0000000000003479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
PURPOSE Chronic, high-altitude hypoxic exposure increases the risk of high-altitude pulmonary hypertension (PH). Emerging evidence shows maternal exercise may improve offspring resistance to disease throughout life. The purpose of this study is to determine if maternal exercise mitigates chronic hypoxic-induced changes in the offspring indicative of high-altitude pulmonary hypertension development. METHODS Female adult C57BL/6 J mice were randomly allocated to nonexercise or exercise conditions. Exercise consisted of voluntary running wheel exercise for four weeks during the perinatal period. Three days after birth, the pups remained at low altitude (normoxia) or were exposed to hypobaric hypoxia of 450 mmHg to simulate ~4500 m altitude exposure until 8 weeks of age. The study consisted of 4 groups: Hypoxia + Nonexercise pregnancy, Hypoxia + Exercise, or the respective, normoxia conditions (Normoxia + Nonexercise or Normoxia + Exercise). Offspring body size, motor function, right ventricular systolic pressure (RVSP), and cardiopulmonary morphology were assessed after 8 weeks in normoxia or hypoxia. RESULTS Both hypoxic groups had smaller body sizes, reduced motor function, increased hematocrit, RVSP, muscularization in medium-sized pulmonary arteries, as well as right ventricular hypertrophy and contractility compared to the normoxic groups (p < 0.05). CONCLUSIONS Chronic hypoxia simulating 4500 m attenuated growth, lowered motor function, and elicited PH development. Voluntary maternal exercise did not significantly decrease RVSP in the offspring, which aligned with a lack of effect to attenuate abnormal body size and cardiopulmonary development due to chronic hypoxia. These findings are preliminary in nature and more powered studies through larger group sizes are required to generalize the results to the population.
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Can Maternal Exercise Prevent High-Altitude Pulmonary Hypertension in Children? High Alt Med Biol 2023; 24:1-6. [PMID: 36695730 DOI: 10.1089/ham.2022.0098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Leslie, Eric, Ann L. Gibson, Laura V. Gonzalez Bosc, Christine Mermier, Sean M. Wilson, and Michael R. Deyhle. Review: can maternal exercise prevent high-altitude pulmonary hypertension in children? High Alt Med Biol. 24:1-6, 2023.-Chronic high-altitude exposure reduces oxygen delivery to the fetus during pregnancy and causes pathologic pulmonary artery remodeling, This increases the risk of high-altitude pulmonary hypertension (PH), which is a particularly fatal disease that is difficult to treat. Therefore, finding ways to prevent high-altitude PH, including during the neonatal period, is preferable. Cardiorespiratory exercise can improve functional capacity and quality of life in patients with high-altitude PH. However, similar to other treatments and surgical procedures, the benefits are not enough to cure the disease after a diagnosis. Cardiorespiratory exercise by mothers during pregnancy (i.e., maternal exercise) has not been previously evaluated to prevent the development of high-altitude PH in children born and living at high altitude. This focused review describes the pathophysiology of high-altitude PH and the potential benefit of maternal exercise for preventing the disease caused by high-altitude pregnancies.
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The effect of prolonged interval and continuous exercise in the heat on circulatory markers of intestinal barrier integrity. Eur J Appl Physiol 2022; 122:2651-2659. [DOI: 10.1007/s00421-022-05049-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 09/09/2022] [Indexed: 11/03/2022]
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Exercise Performed In Hypobaric Hypoxia Increases Markers Of Intestinal Injury And Symptoms Of Gastrointestinal Distress. Med Sci Sports Exerc 2022. [DOI: 10.1249/01.mss.0000880368.46357.f7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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The effect of repetition tempo on cardiovascular and metabolic stress when time under tension is matched during lower body exercise. Eur J Appl Physiol 2022; 122:1485-1495. [PMID: 35394146 DOI: 10.1007/s00421-022-04941-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 03/22/2022] [Indexed: 12/31/2022]
Abstract
PURPOSE To investigate the effect of repetition tempo on cardiovascular and metabolic stress when time under tension (TUT) and effort are matched during sessions of lower body resistance training (RT). METHODS In a repeated-measures, cross-over design, 11 recreationally trained females (n = 5) and males (n = 6) performed 5 sets of belt squats under the following conditions: slow-repetition tempo (SLOW; 10 reps with 4-s eccentric and 2-s concentric) and traditional-repetition tempo (TRAD; 20 reps with 2-s eccentric and 1-s concentric). TUT (60 s) was matched between conditions and external load was adjusted so that lifters were close to concentric muscular failure at the end of each set. External load, total volume load (TVL), impulse (IMP), blood lactate, ratings of perceived exertion (RPE), HR, and muscle oxygenation were measured. RESULTS Data indicated that TVL (p < 0.001), blood lactate (p = 0.017), RPE (p = 0.015), and HR (p < 0.001) were significantly greater during TRAD while external load (p = 0.030) and IMP (p = 0.002) were significantly greater during SLOW. Whether it was expressed as minimal values or change scores, muscle oxygenation was not different between protocols. CONCLUSION When TUT is matched, TVL, cardiovascular stress, metabolic stress, and perceived exertion are greater when faster repetition tempos are used. In contrast, IMP and external load are greater when slower repetition tempos are used.
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Effect of Cardiorespiratory Fitness on Verifying VO2max in Middle-aged and Older Adults. Int J Sports Med 2022; 43:791-796. [PMID: 35468653 DOI: 10.1055/a-1735-3407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We investigated the effect of cardiorespiratory fitness (CRF) on the probability of achieving the verification criterion to confirm that VO2max was obtained in a sample of middle-aged to older adults. Data from twelve men and nine women (60.7±8.5 years, VO2max: 34.8±9.4 mL/kg/min) were used for analysis. Participants had their VO2max measured via a maximal graded exercise test and confirmed using a verification bout on a cycle ergometer. Logistic regression was used to evaluate the effect of CRF (VO2max) on the probability a participant would successfully achieve the verification criterion. Odds ratios are reported to quantify the effect size. No statistically significant relationship was observed between CRF and achieving the verification criterion (β=.081, SE=.0619, Wald=1.420, p=.156). Estimated odds ratio for the effect of CRF on the verification criterion indicated an increase of 8% [Exp(β)=1.08, 95% CI (0.96, 1.22)] in the probability of achieving the verification criterion given a one unit increase in VO2max. Each 1 mL/kg/min increase in VO2max results in an 8% increase in the chance that an individual achieves the verification criterion confirming that VO2max was obtained. Therefore, CRF is likely of practical significance and should be considered when deciding to use a verification trial.
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The combined effects of exercise-induced muscle damage and heat stress on acute kidney stress and heat strain during subsequent endurance exercise. Eur J Appl Physiol 2022; 122:1239-1248. [PMID: 35237867 DOI: 10.1007/s00421-022-04919-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 02/14/2022] [Indexed: 11/30/2022]
Abstract
PURPOSE The purpose of the study was to investigate the combined effect of downhill running and heat stress on muscle damage, as well as on heat strain and kidney stress during subsequent running in the heat. METHODS In a randomized cross-over study, ten non-heat-acclimated, physically active males completed downhill running in temperate (EIMD in Temp) and hot (EIMD in Hot) conditions followed by an exercise-heat stress (HS) test after 3-h seated rest. Blood and urine samples were collected immediately pre- and post-EIMD and HS, and 24 h post-EIMD (post-24 h). Core temperature and thermal sensation were measured to evaluate heat strain. Serum creatine kinase (CK), maximal voluntary isometric contraction of the quadriceps (MVC) and perceived muscle soreness were measured to evaluate muscle damage. Urinary neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) levels were measured to indicate acute kidney stress. RESULTS CK, MVC and perceived soreness were not different between conditions at any timepoints. In the EIMD in Hot condition, urinary NGAL was significantly elevated from pre- to post-HS (pre-HS: 6.56 {1.53-12.24} ng/min, post-HS: 13.72 {7.67-21.46} ng/min, p = 0.034). Such elevation of NGAL or KIM-1 was not found in the EIMD in Temp condition. CONCLUSIONS As compared with downhill running in a temperate environment, downhill running in a hot environment does not appear to aggravate muscle damage. However, elevated NGAL levels following EIMD in a hot environment suggest such exercise may increase risk of mild acute kidney injury during subsequent endurance exercise in the heat.
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Repeated sprint exercise in hypoxia stimulates HIF-1-dependent gene expression in skeletal muscle. Eur J Appl Physiol 2022; 122:1097-1107. [PMID: 35190865 DOI: 10.1007/s00421-022-04909-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Accepted: 01/28/2022] [Indexed: 11/03/2022]
Abstract
PURPOSE Our aim was to determine the effect of repeated sprint exercise in hypoxia on HIF-1 and HIF-1-regulated genes involved in glycolysis, mitochondrial turnover and oxygen transport. We also determined whether genes upregulated by exercise in hypoxia were dependent on the activation of HIF-1 in an in vitro model of exercise in hypoxia. METHODS Eight endurance athletes performed bouts of repeated sprint exercise in control and hypoxic conditions. Skeletal muscle was sampled pre, post and 3 h post-exercise. HIF-1α protein and HIF1A, PDK1, GLUT4, VEGFA, BNIP3, PINK1 and PGC1A mRNA were measured. C2C12 myotubes were exposed to hypoxia and muscle contraction following treatment with a HIF-1α inhibitor to determine whether hypoxia-sensitive gene expression was dependent on HIF-1α. RESULTS Sprint exercise in hypoxia increased HIF-1α protein expression immediately post-exercise [fold change (FC) = 3.5 ± 2.0]. Gene expression of PDK1 (FC = 2.1 ± 1.2), BNIP3 (FC = 2.4 ± 1.4) and VEGFA (FC = 2.7 ± 1.7) increased 3 h post-exercise in hypoxia but not control. PGC1A mRNA increased 3 h post-exercise in control (FC = 5.16) and hypoxia (FC = 5.7 ± 4.1) but there was no difference between the trials. Results from the in vitro experiment showed that hypoxia plus contraction also increased PDK1, BNIP3, and VEGFA gene expression. These responses were inhibited when HIF-1 protein activity was suppressed. CONCLUSION Repeated sprint exercise in hypoxia upregulates some genes involved in glycolytic metabolism, mitochondrial turnover, and oxygen transport. HIF-1α is necessary for the expression of these genes in skeletal muscle cells.
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Abstract
Generally, skeletal muscle adaptations to exercise are perceived through a dichotomous lens where the metabolic stress imposed by aerobic training leads to increased mitochondrial adaptations while the mechanical tension from resistance training leads to myofibrillar adaptations. However, there is emerging evidence for cross over between modalities where aerobic training stimulates traditional adaptations to resistance training (e.g., hypertrophy) and resistance training stimulates traditional adaptations to aerobic training (e.g., mitochondrial biogenesis). The latter is the focus of the current review in which we propose high-volume resistance training (i.e., high time under tension) leads to aerobic adaptations such as angiogenesis, mitochondrial biogenesis, and increased oxidative capacity. As time under tension increases, skeletal muscle energy turnover, metabolic stress, and ischemia also increase, which act as signals to activate the peroxisome proliferator-activated receptor gamma coactivator 1-alpha, which is the master regulator of mitochondrial biogenesis. For practical application, the acute stress and chronic adaptations to three specific forms of high-time under tension are also discussed: Slow-tempo, low-intensity resistance training, and drop-set resistance training. These modalities of high-time under tension lead to hallmark adaptations to resistance training such as muscle endurance, hypertrophy, and strength, but little is known about their effect on traditional aerobic training adaptations.
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Effects Of EIMD In The Heat On Acute Kidney Stress And Heat Strain During Subsequent Endurance Exercise. Med Sci Sports Exerc 2021. [DOI: 10.1249/01.mss.0000763232.35557.59] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Exercise-Based Cardiac Rehabilitation Improves Cognitive Function Among Patients With Cardiovascular Disease. J Cardiopulm Rehabil Prev 2020; 40:407-413. [PMID: 32947322 DOI: 10.1097/hcr.0000000000000545] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
PURPOSE To investigate the effects of cardiac rehabilitation (CR) exercise training on cognitive performance and whether the changes are associated with alterations in prefrontal cortex (PFC) oxygenation among patients with cardiovascular disease. METHODS Twenty (men: n = 15; women: n = 5) participants from an outpatient CR program were enrolled in the study. Each participant completed a cognitive performance test battery and a submaximal graded treadmill evaluation on separate occasions prior to and again upon completion of 18 individualized CR sessions. A functional near-infrared spectroscopy (fNIRS) device was used to measure left and right prefrontal cortex (LPFC and RPFC) oxygenation parameters (oxyhemoglobin [O2Hb], deoxyhemoglobin [HHb], total hemoglobin [tHb], and oxyhemoglobin difference [Hbdiff]) during the cognitive test battery. RESULTS Patients showed improvements in cardiorespiratory fitness (+1.4 metabolic equivalents [METs]) and various cognitive constructs. A significant increase in PFC oxygenation, primarily in the LPFC region, occurred at post-CR testing. Negative associations between changes in cognition (executive function [LPFC O2Hb: r = -0.45, P = .049; LPFC tHb: r = -0.49, P = .030] and fluid composite score [RPFC Hbdiff: r = -0.47, P = .038; LPFC Hbdiff: r = -0.45, P = .048]) and PFC changes were detected. The change in cardiorespiratory fitness was positively associated with the change in working memory score (r = 0.55, P = .016). CONCLUSION Cardiovascular disease patients enrolled in CR showed significant improvements in multiple cognitive domains along with increased cortical activation. The negative associations between cognitive functioning and PFC oxygenation suggest an improved neural efficiency.
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Does Heart Rate Response Confirm The Attainment Of Maximal Oxygen Uptake In Adults 45 Years And Older? Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000670512.81887.1d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Comparison Of Exercise-induced Regulation Of Skeletal Muscle Hif-1α Between Endurance Trained And Untrained Individuals. Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000685460.45197.b6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Exercise-Based Cardiac Rehabilitation Improves Cognitive Function Among CVD Patients. Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000684700.32783.60] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Does Heat Acclimation Upregulate Skeletal Muscle Markers Of Oxidative Metabolism And Mitochondrial Biogenesis? Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000679936.12192.46] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Transcriptional Activation Of Hypoxia Sensitive Genes Following Repeated Sprint Exercise In Hypoxia. Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000683656.70092.a4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Serum MOTS-c Concentrations Are Higher In Older Females Compared To Older Males But Is Not Affected By Physical Activity Status Or Cardiorespiratory Fitness In Young And Older Adults. Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000687352.60611.08] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Relationship between aerobic fitness, antioxidant capacity and the anti-aging hormone, Klotho. GAZZETTA MEDICA ITALIANA ARCHIVIO PER LE SCIENZE MEDICHE 2020. [DOI: 10.23736/s0393-3660.18.03972-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Acute Aerobic Exercise Based Cognitive and Motor Priming: Practical Applications and Mechanisms. Front Psychol 2019; 10:2790. [PMID: 31920835 PMCID: PMC6920172 DOI: 10.3389/fpsyg.2019.02790] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 11/27/2019] [Indexed: 12/12/2022] Open
Abstract
Acute exercise stimulates brain regions involved in motor and cognitive processes. Recent research efforts have explored the benefits of aerobic exercise on brain health and cognitive functioning with positive results reported for both healthy and neurocognitively impaired individuals. Specifically, exercise positioned near therapeutic (both behavioral and physical) activities may enhance outcomes associated with treatment outcomes (e.g., depression or motor skill) through neural plasticity promoting mechanisms (e.g., increased brain flow and oxygenation). This approach has been termed "exercise priming" and is a relatively new topic of exploration in the fields of exercise science and motor control. The authors report on physiological mechanisms that are related to the priming effect. In addition, parameters related to the exercise bout (e.g., intensity, duration) and the idea of combining exercise and therapeutic rehabilitation are explored. This exercise-based priming concept has the potential to be applied to many areas such as education, cognitive therapy, and motor rehabilitation.
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Comparison of Treadmill and Cycle Ergometer Exercise During Cardiac Rehabilitation: A Meta-analysis. Arch Phys Med Rehabil 2019; 101:690-699. [PMID: 31738893 DOI: 10.1016/j.apmr.2019.10.184] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 08/22/2019] [Accepted: 10/23/2019] [Indexed: 10/25/2022]
Abstract
OBJECTIVE To compare treadmill versus cycling-based exercise in cardiac rehabilitation (CR) on functional capacity (FC) outcomes. DATA SOURCE Databases were searched for randomized studies using single modality continuous exercise. STUDY SELECTION Studies implemented a continuous cycling or treadmill protocol for patients with either coronary artery disease (CAD) or chronic heart failure (CHF). The effect of single modality exercise on FC (VO2peak) was analyzed. Differences in the effect of CR on FC was assessed between the mode subgroup (cycling vs treadmill) and disease state subgroup (CAD vs CHF) within both the cycling and treadmill groups. DATA EXTRACTION Data were extracted from 23 studies including 600 patients (mean age 60y, 86% men). DATA SYNTHESIS There was a significant difference in effect size between studies that used cycling, Hedges' g=0.85 (95% confidence interval [95% CI], 0.52-1.17; k=13) and studies that used treadmill exercise, Hedges' g=0.46 (95% CI, 0.22-0.70; k=8). Within cycling studies (n=14), FC was higher among CAD patients, Hedges' g=1.03 (95% CI, 0.65-1.42; k=9) compared to those with CHF, Hedges' g=0.40 (95% CI, 0.09-0.71; k=4, P<.001). Conversely, among treadmill studies (n=9), FC was higher among CHF patients, Hedges' g=0.94 (95% CI, 0.23-1.65; k=2) compared to CAD, Hedges' g=0.33 (95% CI, 0.19-0.47; k=5; P<.01). CONCLUSIONS According to identified studies, when cycling was the primary mode of exercise in CR, there was larger change in FC compared to treadmill exercise. In addition, CAD patients experienced greater gains in FC when cycling was the primary mode of exercise in CR, while CHF patients benefited more from treadmill-based exercise programs.
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Predictors of Fat Oxidation and Caloric Expenditure With and Without Weighted Vest Running. J Strength Cond Res 2019; 35:1865-1872. [DOI: 10.1519/jsc.0000000000003049] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Abstract
The microbiome in the gut is a diverse environment, housing the majority of our bacterial microbes. This microecosystem has a symbiotic relationship with the surrounding multicellular organism, and a balance and diversity of specific phyla of bacteria support general health. When gut bacteria diversity diminishes, there are systemic consequences, such as gastrointestinal and psychological distress. This pathway of communication is known as the microbiome-gut-brain axis. Interventions such as probiotic supplementation that influence microbiome also improve both gut and brain disorders. Recent evidence suggests that aerobic exercise improves the diversity and abundance of genera from the Firmcutes phylum, which may be the link between the positive effects of exercise on the gut and brain. The purpose of this review is to explain the complex communication pathway of the microbiome-gut-brain axis and further examine the role of exercise on influencing this communication highway.
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Effects Of HIIT Training While Using A Breathing-restrictive Mask Compared To Increased Environmental Altitude. Med Sci Sports Exerc 2018. [DOI: 10.1249/01.mss.0000538478.30543.fd] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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High-Velocity Quadriceps Exercises Compared to Slow-Velocity Quadriceps Exercises Following Total Knee Arthroplasty: A Randomized Clinical Study. J Geriatr Phys Ther 2018; 39:147-58. [PMID: 26428903 DOI: 10.1519/jpt.0000000000000071] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND AND PURPOSE Despite improvement in pain and perceived function in older adults following total knee arthroplasty (TKA), objective outcome measures of muscular impairment and ambulatory function demonstrate significant deficits. Evidence suggests that quadriceps power may play a greater role in ambulatory function than measures of strength alone following TKA. The purpose of this study was to compare the effect of high-velocity (HV) quadriceps exercises with that of slow-velocity (SV) quadriceps exercises on functional outcomes and quadriceps power following TKA. METHODS This study was a randomized clinical study conducted in an outpatient physical therapy clinic. Twenty-one participants who were 4 to 6 weeks post unilateral TKA were randomly assigned to an HV or SV group. Participants performed an evidence-based standardized progressive resistance exercise program in addition to HV quadriceps exercises or SV quadriceps exercises. Participants attended 2 sessions per week for 8 weeks. Before and after the 8-week exercise intervention, participants completed a functional questionnaire, health survey, functional testing, and underwent quadriceps strength and power testing. RESULTS Both groups demonstrated improvements in ambulatory outcome measures, strength, speed, and power. The HV group demonstrated significantly greater improvements in distance walked and quadriceps strength than the SV group. LIMITATIONS These data should be considered preliminary because of a small sample size. CONCLUSION HV quadriceps exercises may be an effective rehabilitation strategy in conjunction with a standardized progressive resistance exercise program beginning 4 to 6 weeks after TKA.
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Understanding the factors that effect maximal fat oxidation. J Int Soc Sports Nutr 2018; 15:3. [PMID: 29344008 PMCID: PMC5766985 DOI: 10.1186/s12970-018-0207-1] [Citation(s) in RCA: 120] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Accepted: 01/02/2018] [Indexed: 12/02/2022] Open
Abstract
Lipids as a fuel source for energy supply during submaximal exercise originate from subcutaneous adipose tissue derived fatty acids (FA), intramuscular triacylglycerides (IMTG), cholesterol and dietary fat. These sources of fat contribute to fatty acid oxidation (FAox) in various ways. The regulation and utilization of FAs in a maximal capacity occur primarily at exercise intensities between 45 and 65% VO2max, is known as maximal fat oxidation (MFO), and is measured in g/min. Fatty acid oxidation occurs during submaximal exercise intensities, but is also complimentary to carbohydrate oxidation (CHOox). Due to limitations within FA transport across the cell and mitochondrial membranes, FAox is limited at higher exercise intensities. The point at which FAox reaches maximum and begins to decline is referred to as the crossover point. Exercise intensities that exceed the crossover point (~65% VO2max) utilize CHO as the predominant fuel source for energy supply. Training status, exercise intensity, exercise duration, sex differences, and nutrition have all been shown to affect cellular expression responsible for FAox rate. Each stimulus affects the process of FAox differently, resulting in specific adaptions that influence endurance exercise performance. Endurance training, specifically long duration (>2 h) facilitate adaptations that alter both the origin of FAs and FAox rate. Additionally, the influence of sex and nutrition on FAox are discussed. Finally, the role of FAox in the improvement of performance during endurance training is discussed.
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Gait Retraining From Rearfoot Strike to Forefoot Strike does not change Running Economy. Int J Sports Med 2017; 38:1076-1082. [PMID: 29100250 DOI: 10.1055/s-0043-110225] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Gait retraining is a method for management of patellofemoral pain, which is a common ailment among recreational runners. The present study investigated the effects of gait retraining from rearfoot strike to forefoot strike on running economy, heart rate, and respiratory exchange ratio immediately post-retraining and one-month post-retraining in recreational runners with patellofemoral pain. Knee pain was also measured. Sixteen participants (n=16) were randomly placed in the control (n=8) or experimental (n=8) group. A 10-minute treadmill RE test was performed by all subjects. The experimental group performed eight gait retraining running sessions where foot strike pattern was switched from rearfoot strike to forefoot strike, while the control group received no intervention. There were no significant differences for running economy (p=0.26), respiratory exchange ratio (p=0.258), or heart rate (p=0.248) between the groups. Knee pain reported on a visual analog scale was also significantly reduced (p<0.05) as a result of retraining. The present study demonstrates that retraining from rearfoot strike to forefoot strike did not affect running economy up to one-month post-retraining while reducing running-related patellofemoral pain.
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Birth weight predicted baseline muscular efficiency, but not response of energy expenditure to calorie restriction: An empirical test of the predictive adaptive response hypothesis. Am J Hum Biol 2015; 28:484-92. [PMID: 26680695 DOI: 10.1002/ajhb.22818] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 09/02/2015] [Accepted: 11/21/2015] [Indexed: 12/19/2022] Open
Abstract
OBJECTIVES Aiming to test the evolutionary significance of relationships linking prenatal growth conditions to adult phenotypes, this study examined whether birth size predicts energetic savings during fasting. We specifically tested a Predictive Adaptive Response (PAR) model that predicts greater energetic saving among adults who were born small. METHODS Data were collected from a convenience sample of young adults living in Albuquerque, NM (n = 34). Indirect calorimetry quantified changes in resting energy expenditure (REE) and active muscular efficiency that occurred in response to a 29-h fast. Multiple regression analyses linked birth weight to baseline and postfast metabolic values while controlling for appropriate confounders (e.g., sex, body mass). RESULTS Birth weight did not moderate the relationship between body size and energy expenditure, nor did it predict the magnitude change in REE or muscular efficiency observed from baseline to after fasting. Alternative indicators of birth size were also examined (e.g., low v. normal birth weight, comparison of tertiles), with no effects found. However, baseline muscular efficiency improved by 1.1% per 725 g (S.D.) increase in birth weight (P = 0.037). CONCLUSIONS Birth size did not influence the sensitivity of metabolic demands to fasting-neither at rest nor during activity. Moreover, small birth size predicted a reduction in the efficiency with which muscles convert energy expended into work accomplished. These results do not support the ascription of adaptive function to phenotypes associated with small birth size. © 2015 Wiley Periodicals, Inc. Am. J. Hum. Biol. 28:484-492, 2016. © 2015 Wiley Periodicals, Inc.
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Duration Of The Effects Of Pre-cooling Heat Sensitive Patients With Multiple Sclerosis. Med Sci Sports Exerc 2015. [DOI: 10.1249/01.mss.0000477407.63072.62] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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The effects of acute oral glutamine supplementation on exercise-induced gastrointestinal permeability and heat shock protein expression in peripheral blood mononuclear cells. Cell Stress Chaperones 2015; 20:85-93. [PMID: 25062931 PMCID: PMC4255255 DOI: 10.1007/s12192-014-0528-1] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2014] [Revised: 06/25/2014] [Accepted: 07/14/2014] [Indexed: 02/04/2023] Open
Abstract
Chronic glutamine supplementation reduces exercise-induced intestinal permeability and inhibits the NF-κB pro-inflammatory pathway in human peripheral blood mononuclear cells. These effects were correlated with activation of HSP70. The purpose of this paper is to test if an acute dose of oral glutamine prior to exercise reduces intestinal permeability along with activation of the heat shock response leading to inhibition of pro-inflammatory markers. Physically active subjects (N = 7) completed baseline and exercise intestinal permeability tests, determined by the percent ratio of urinary lactulose (5 g) to rhamnose (2 g). Exercise included two 60-min treadmill runs at 70 % of VO2max at 30 °C after ingestion of glutamine (Gln) or placebo (Pla). Plasma levels of endotoxin and TNF-α, along with peripheral blood mononuclear cell (PBMC) protein expression of HSP70 and IκBα, were measured pre- and post-exercise and 2 and 4 h post-exercise. Permeability increased in the Pla trial compared to that at rest (0.06 ± 0.01 vs. 0.02 ± 0.018) and did not increase in the Gln trial. Plasma endotoxin was lower at the 4-h time point in the Gln vs. 4 h in the Pla (6.715 ± 0.046 pg/ml vs. 7.952 ± 1.11 pg/ml). TNF-α was lower 4 h post-exercise in the Gln vs. Pla (1.64 ± 0.09 pg/ml vs. 1.87 ± 0.12 pg/ml). PBMC expression of IkBα was higher 4 h post-exercise in the Gln vs. 4 h in the Pla (1.29 ± 0.43 vs. 0.8892 ± 0.040). HSP70 was higher pre-exercise and 2 h post-exercise in the Gln vs. Pla (1.35 ± 0.21 vs. 1.000 ± 0.000 and 1.65 ± 0.21 vs. 1.27 ± 0.40). Acute oral glutamine supplementation prevents an exercise-induced rise in intestinal permeability and suppresses NF-κB activation in peripheral blood mononuclear cells.
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Does Heat Acclimation Improve Exercise Capacity at Altitude? A Cross-tolerance Model. Int J Sports Med 2014; 35:975-81. [DOI: 10.1055/s-0034-1368724] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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The Effects of Acute Oral Glutamine Supplementation on Gastrointestinal Permeability and Heat Shock Protein Regulation in Peripheral Blood Mononuclear Cells of Endurance Runners. Med Sci Sports Exerc 2014. [DOI: 10.1249/01.mss.0000493400.27351.20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Early Time Course of Autophagy in Human Peripheral Blood Mononuclear Cells Following Endurance Exercise. Med Sci Sports Exerc 2014. [DOI: 10.1249/01.mss.0000494249.25074.58] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Influence Of Meal Frequency On Insulin, Glucose, And Appetite Control In Obese Women Undergoing A Portion-controlled Weight-loss Intervention. Med Sci Sports Exerc 2014. [DOI: 10.1249/01.mss.0000493208.55647.0d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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A Descending Resistance Training Program Produces Greater Exercise Volume than a Constant Resistance Training Program. Med Sci Sports Exerc 2014. [DOI: 10.1249/01.mss.0000493927.50145.d9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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PTSD symptom reduction with mindfulness-based stretching and deep breathing exercise: randomized controlled clinical trial of efficacy. J Clin Endocrinol Metab 2013; 98:2984-92. [PMID: 23720785 PMCID: PMC3701284 DOI: 10.1210/jc.2012-3742] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Abnormal cortisol levels are a key pathophysiological indicator of post-traumatic stress disorder (PTSD). Endogenous normalization of cortisol concentration through exercise may be associated with PTSD symptom reduction. OBJECTIVE The aim of the study was to determine whether mindfulness-based stretching and deep breathing exercise (MBX) normalizes cortisol levels and reduces PTSD symptom severity among individuals with subclinical features of PTSD. DESIGN AND SETTING A randomized controlled trial was conducted at the University of New Mexico Health Sciences Center. PARTICIPANTS Twenty-nine nurses (28 female) aged 45-66 years participated in the study. INTERVENTION Sixty-minute MBX sessions were conducted semiweekly for 8 weeks. MAIN OUTCOME MEASURES Serum cortisol was measured, and the PTSD Checklist-Civilian version (PCL-C) was performed at baseline and weeks 4, 8, and 16. RESULTS Twenty-nine participants completed the study procedures, 22 (79%) with PTSD symptoms (MBX, n = 11; control, n = 11), and 7 (21%) without PTSD (BASE group). Eight-week outcomes for the MBX group were superior to those for the control group (mean difference for PCL-C scores, -13.6; 95% confidence interval [CI], -25.6, -1.6; P = .01; mean difference for serum cortisol, 5.8; 95% CI, 0.83, 10.8; P = .01). No significant differences were identified between groups in any other items. The changes in the MBX group were maintained at the 16-week follow-up (P = .85 for PCL-C; P = .21 for cortisol). Our data show that improved PTSD scores were associated with normalization of cortisol levels (P < .05). CONCLUSIONS The results suggest that MBX appears to reduce the prevalence of PTSD-like symptoms in individuals exhibiting subclinical features of PTSD.
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Abstract
BACKGROUND Mind-body practices are increasingly used to provide stress reduction for posttraumatic stress disorder (PTSD). Mind-body practice encompasses activities with the intent to use the mind to impact physical functioning and improve health. METHODS This is a literature review using PubMed, PsycINFO, and Published International Literature on Traumatic Stress to identify the effects of mind-body intervention modalities, such as yoga, tai chi, qigong, mindfulness-based stress reduction, meditation, and deep breathing, as interventions for PTSD. RESULTS The literature search identified 92 articles, only 16 of which were suitable for inclusion in this review. We reviewed only original, full text articles that met the inclusion criteria. Most of the studies have small sample size, but findings from the 16 publications reviewed here suggest that mind-body practices are associated with positive impacts on PTSD symptoms. Mind-body practices incorporate numerous therapeutic effects on stress responses, including reductions in anxiety, depression, and anger, and increases in pain tolerance, self-esteem, energy levels, ability to relax, and ability to cope with stressful situations. In general, mind-body practices were found to be a viable intervention to improve the constellation of PTSD symptoms such as intrusive memories, avoidance, and increased emotional arousal. CONCLUSIONS Mind-body practices are increasingly used in the treatment of PTSD and are associated with positive impacts on stress-induced illnesses such as depression and PTSD in most existing studies. Knowledge about the diverse modalities of mind-body practices may provide clinicians and patients with the opportunity to explore an individualized and effective treatment plan enhanced by mind-body interventions as part of ongoing self-care.
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Abstract
Egyptology relies on traditional descriptive methods. Here we show that modern, Internet-based science and statistical methods can be applied to Egyptology. Two four-thousand-year-old sarcophagi in one tomb, one within the other, with skeletal remains of a woman, gave us the opportunity to diagnose a congenital nervous system disorder in the absence of a living nervous system. The sarcophagi were discovered near Thebes, Egypt. They were well preserved and meticulously restored. The skeletal remains suggested that the woman, aged between 50 and 60 years, was Black, possibly of Nubian descent and suffered from syringobulbia, a congenital cyst in the brain stem and upper spinal cord. We employed crowd sourcing, the anonymous responses of 204 Facebook users who performed a matching task of living persons' iris color with iris color of the Udjat eyes, a decoration found on Egyptian sarcophagi, to confirm the ethnicities of the sarcophagus occupants. We used modern fMRI techniques to illustrate the putative extent of her lesion in the brain stem and upper spinal cord deduced from her skeletal remains. We compared, statistically, the right/left ratios, a non-dimensional number, of the orbit height, orbit width, malar height and the infraorbital foramena with the same measures obtained from 32 ancient skulls excavated from the Fayum, North of Thebes. We found that these ratios were significantly different in this skull indicating atrophy of cranial bones on the left. In this instance, Internet science and the use of modern neurologic research tools showed that ancient sarcophagus makers shaped and decorated their wares to fit the ethnicity of the prospective occupants of the sarcophagi. We also showed that, occasionally, human nervous system disease may be recognizable in the absence of a living nervous system.
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Leukocyte Release of IL‐6 in Response to Endotoxin in the Elderly: Effect of Aerobic Capacity. FASEB J 2011. [DOI: 10.1096/fasebj.25.1_supplement.1107.9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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The Effect Of Mild Dehydration On Heat Shock Protein Induction During An Acute Cycling Bout. Med Sci Sports Exerc 2009. [DOI: 10.1249/01.mss.0000355601.55426.4b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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The Influence of Glycerol Ingestion on Physical Performance and Thermoregulatory Responses during Soccer Training Sessions. Med Sci Sports Exerc 2007. [DOI: 10.1249/01.mss.0000272936.97326.1e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Active and passive recovery and acid-base kinetics following multiple bouts of intense exercise to exhaustion. Int J Sport Nutr Exerc Metab 2006; 16:92-107. [PMID: 16676706 DOI: 10.1123/ijsnem.16.1.92] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The purpose of this study was to profile the effect of active versus passive recovery on acid-base kinetics during multiple bouts of intense exercise. Ten males completed two exercise trials. The trials consisted of three exercise bouts to exhaustion with either a 12 min active (20% workload max) or passive recovery between bouts. Blood pH was lower in the passive (p) recovery compared to active (a) throughout the second and third recovery periods [second recovery: 7.18 +/- 0.08 to 7.24 +/- 0.09 (p), 7.23 +/- 0.07 to 7.32 +/- 0.07 (a), P < 0.05; third recovery: 7.17 +/- 0.08 to 7.22 +/- 0.09 (p), 7.23 +/- 0.08 to 7.32 +/- 0.08 (a), P < 0.05]. Exercise performance times did not differ between recovery conditions (P = 0.28). No difference was found between conditions for recovery kinetics (slope and half-time to recovery). Subsequent performance during multiple bouts of intense exercise to exhaustion may not be influenced by blood acidosis or mode of recovery.
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Body Fat Values of Collegiate Athletes. Med Sci Sports Exerc 2006. [DOI: 10.1249/00005768-200605001-01958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Accumulated Oxygen Deficit & pH Recovery during Multiple Bouts of Intense Exercise. Med Sci Sports Exerc 2006. [DOI: 10.1249/00005768-200605001-03035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Active And Passive Recovery & Acid-base Kinetics Following Multiple Bouts Of Intense Exercise. Med Sci Sports Exerc 2005. [DOI: 10.1249/00005768-200505001-00542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Abstract
BACKGROUND The amount of limb-length discrepancy necessary to adversely affect gait parameters in older adults is unknown, with information being largely anecdotal. This investigation was conducted to determine the effects of limb-length discrepancy on gait economy and lower-extremity muscle activity in older adults. METHODS Forty-four men and women ranging in age from fifty-five to eighty-six years with no evidence of limb-length discrepancy of >1 cm participated in the study. Subjects walked on a treadmill at a self-selected normal walking pace with artificial limb-length discrepancies of 0, 2, 3, and 4 cm applied in a randomly selected order. Indirect calorimetry was used to measure oxygen consumption and minute ventilation. Electromyography was used to measure muscle activity of the right and left quadriceps femoris, plantar flexors, gluteus maximus, and gluteus medius. Heart rate, the rating of perceived exertion, and frequency of gait compensation patterns were also measured. RESULTS There was a significant increase in oxygen consumption and the rating of perceived exertion with 2, 3, and 4-cm artificial limb-length discrepancies; a significant increase in heart rate, minute ventilation, and quadriceps activity in the longer limb with 3 and 4-cm artificial limb-length discrepancies; and a significant increase in plantar flexor activity in the shorter limb with a 4-cm artificial limb-length discrepancy compared with the same parameters with no artificial limb-length discrepancy. CONCLUSIONS Both oxygen consumption and the rating of perceived exertion were greater with a 2-cm artificial limb-length discrepancy than they were with no artificial limb-length discrepancy. There appears to be a breakpoint between 2 and 3 cm of artificial limb-length discrepancy in older adults with regard to the effects on most other physiological parameters. A 3-cm artificial limb-length discrepancy is likely to induce significant quadriceps fatigue in the longer limb. Elderly patients with substantial pulmonary, cardiac, or neuromuscular disease may have difficulty walking with a limb-length discrepancy as small as 2 cm.
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EFFECTS OF LEG LENGTH DISCREPANCY ON GAIT ECONOMY AND LOWER EXTREMITY MUSCLE ACTIVITY IN OLDER ADULTS. J Geriatr Phys Ther 2001. [DOI: 10.1519/00139143-200124010-00023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Blood glucose and glucoregulatory hormone responses to solid and liquid carbohydrate ingestion during exercise. INTERNATIONAL JOURNAL OF SPORT NUTRITION 1998; 8:70-83. [PMID: 9534083 DOI: 10.1123/ijsn.8.1.70] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
This study was conducted to compare blood glucose and glucoregulatory hormone responses to the ingestion of solid and liquid carbohydrate (CHO) during prolonged cycling, followed by 30 min of isokinetic cycling. Eight male cyclists randomly completed three cycling trials (LC = liquid CHO, SCE = solid CHO with water equal to LC, SCA = solid CHO + ad libitum water). Each subject cycled for 120 min at 65% of VO2max with CHO ingestion (0.6 g CHO/ kg/hr) at 0, 30, 60, 90, and 120 min. Subjects then completed a 30-min maximal isokinetic ride at 90 rpm. There was no significant (p < .05) difference between the trials for plasma glucose, insulin, glucagon, glycerol, lactate, RER, HR, VO2, RPE, and total work performed during the isokinetic ride. However, serum glucose was significantly lower in the SCE and SCA trials compared to LC at 80 min. The ingestion of a solid food containing CHO, protein, and fat with added water produced similar blood glucose, metabolic, glucoregulatory hormone, and exercise performance responses to those seen with the ingestion of liquid CHO.
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Abstract
The purpose of this investigation was to determine the effects of transdermal estradiol (E2) replacement on substrate utilization during exercise. Amenorrheic females (N = 6) performed three exercise trials following 72 h of placebo (C 72) and 72 and 144 h of medicated transdermal estradiol (E2) treatment (E2 72 and E2 144). Exercise involved 90 min of treadmill running at 65% VO2max followed by timed exercise to exhaustion at 85% VO2max. Resting blood samples were obtained for glucose, insulin, free fatty acids (FFA), and E2. Exercise blood samples were obtained for E2, lactate, epinephrine, and norepinephrine. Rates of appearance and disposal were calculated for glucose and glycerol using a primed, continuous infusion of [6,6-2H] glucose and [2H5] glycerol. Medicated transdermal placement increased E2 significantly at rest, before exercise (35.03 +/- 12.3, 69.5 +/- 20.1, and 73.1 +/- 31.6 pg.mL-1 for the C 72, E2 72, and E2 144 trials, respectively, P < 0.05). Resting FFA increased significantly following E2 treatment (0.28 +/- 0.16, 0.41 +/- 0.27, and 0.40 +/- 0.21 mmol.L-1 for the C 72, E2 72, and E2 144 trials, respectively, P < 0.05). Glucose Ra was significantly decreased during exercise as a result of E2 replacement (21.9 +/- 7.7, 18.9 +/- 6.2, and 18.9 +/- 5.6 mumol.kg-1.min-1 for the C 72, E2 72, and E2 144 trials, respectively, P < 0.05). Average glucose Rd also decreased during exercise as a result of E2 replacement (21.3 +/- 7.8, 18.5 +/- 6.4, and 18.6 +/- 5.8 mumol.kg-1.min-1 for the C 72, E2 72, and E2 144 trials, respectively, P < 0.05). However, the estimated relative contribution of plasma glucose and muscle glycogen to total carbohydrate oxidation was similar among the trials. Epinephrine values were significantly lower late in exercise during the E2 72 and E2 144 trials, compared with the C 72 trial (P < 0.05). These results indicate that elevated E2 levels can alter glucose metabolism at rest and during moderate intensity exercise as a result of decreased gluconeogenesis, epinephrine secretion, and/or glucose transport.
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