1
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Vieira-Lara MA, Bakker BM. The paradox of fatty-acid β-oxidation in muscle insulin resistance: Metabolic control and muscle heterogeneity. Biochim Biophys Acta Mol Basis Dis 2024; 1870:167172. [PMID: 38631409 DOI: 10.1016/j.bbadis.2024.167172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2023] [Revised: 03/18/2024] [Accepted: 04/09/2024] [Indexed: 04/19/2024]
Abstract
The skeletal muscle is a metabolically heterogeneous tissue that plays a key role in maintaining whole-body glucose homeostasis. It is well known that muscle insulin resistance (IR) precedes the development of type 2 diabetes. There is a consensus that the accumulation of specific lipid species in the tissue can drive IR. However, the role of the mitochondrial fatty-acid β-oxidation in IR and, consequently, in the control of glucose uptake remains paradoxical: interventions that either inhibit or activate fatty-acid β-oxidation have been shown to prevent IR. We here discuss the current theories and evidence for the interplay between β-oxidation and glucose uptake in IR. To address the underlying intricacies, we (1) dive into the control of glucose uptake fluxes into muscle tissues using the framework of Metabolic Control Analysis, and (2) disentangle concepts of flux and catalytic capacities taking into account skeletal muscle heterogeneity. Finally, we speculate about hitherto unexplored mechanisms that could bring contrasting evidence together. Elucidating how β-oxidation is connected to muscle IR and the underlying role of muscle heterogeneity enhances disease understanding and paves the way for new treatments for type 2 diabetes.
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Affiliation(s)
- Marcel A Vieira-Lara
- Laboratory of Pediatrics, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands.
| | - Barbara M Bakker
- Laboratory of Pediatrics, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands.
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2
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Pignanelli C, Robertson AA, Hirsch SM, Power GA, Burr JF. The addition of blood flow restriction during resistance exercise does not increase prolonged low-frequency force depression. Exp Physiol 2024; 109:738-753. [PMID: 38562023 PMCID: PMC11061635 DOI: 10.1113/ep091753] [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: 01/23/2024] [Accepted: 03/15/2024] [Indexed: 04/04/2024]
Abstract
At a given exercise intensity, blood flow restriction (BFR) reduces the volume of exercise required to impair post-exercise neuromuscular function. Compared to traditional exercise, the time course of recovery is less clear. After strenuous exercise, force output assessed with electrical muscle stimulation is impaired to a greater extent at low versus high stimulation frequencies, a condition known as prolonged low-frequency force depression (PLFFD). It is unclear if BFR increases PLFFD after exercise. This study tested if BFR during exercise increases PLFFD and slows recovery of neuromuscular function compared to regular exercise. Fifteen physically active participants performed six low-load sets of knee-extensions across four conditions: resistance exercise to task failure (RETF), resistance exercise to task failure with BFR applied continuously (BFRCONT) or intermittently (BFRINT), and resistance exercise matched to the lowest exercise volume condition (REVM). Maximal voluntary contraction (MVC) force output, voluntary activation and a force-frequency (1-100 Hz) curve were measured before and 0, 1, 2, 3, 4 and 24 h after exercise. Exercise to task failure caused similar reductions at 0 h for voluntary activation (RETF = 81.0 ± 14.2%, BFRINT = 80.9 ± 12.4% and BFRCONT = 78.6 ± 10.7%) and MVC force output (RETF = 482 ± 168 N, BFRINT = 432 ± 174 N, and BFRCONT = 443 ± 196 N), which recovered to baseline values between 4 and 24 h. PLFFD occurred only after RETF at 1 h supported by a higher frequency to evoke 50% of the force production at 100 Hz (1 h: 17.5 ± 4.4 vs. baseline: 15 ± 4.1 Hz, P = 0.0023), BFRINT (15.5 ± 4.0 Hz; P = 0.03), and REVM (14.9 ± 3.1 Hz; P = 0.002), with a trend versus BFRCONT (15.7 ± 3.5 Hz; P = 0.063). These findings indicate that, in physically active individuals, using BFR during exercise does not impair the recovery of neuromuscular function by 24 h post-exercise.
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Affiliation(s)
- Christopher Pignanelli
- Department of Human Health & Nutritional SciencesUniversity of GuelphGuelphOntarioCanada
| | - Alexa A. Robertson
- Department of Human Health & Nutritional SciencesUniversity of GuelphGuelphOntarioCanada
| | - Steven M. Hirsch
- Faculty of Kinesiology and Physical EducationUniversity of TorontoTorontoOntarioCanada
| | - Geoffrey A. Power
- Department of Human Health & Nutritional SciencesUniversity of GuelphGuelphOntarioCanada
| | - Jamie F. Burr
- Department of Human Health & Nutritional SciencesUniversity of GuelphGuelphOntarioCanada
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3
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Cintron HE, Heyburn JJ, Sterner RL, Dankel SJ. Blood Flow Restricted Electrical Stimulations to Prevent or Attenuate Symptoms of Muscle Damage. Res Sports Med 2024; 32:213-224. [PMID: 36314854 DOI: 10.1080/15438627.2022.2132862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 09/26/2022] [Indexed: 06/16/2023]
Abstract
The objective of this study was to determine if performing electrical stimulations (E-STIM) under blood flow restriction (BFR) would result in a greater protective effect against symptoms of muscle damage. 18 individuals (9 females) completed a damaging bout of exercise followed by a low frequency E-STIM treatment protocol on both arms, one of which was completed under BFR. The treatment protocol was then repeated 24-hours post-exercise. There were main effects of time for muscle thickness (pre: 3.5 cm; 48 h post: 3.8 cm; BF10 = 88.476), discomfort (pre: 0.0 au; 48 h post: 4.2 au; BF10 = 241.996), and isometric strength (pre: 278 N; 48 h post: 232 N; BF10 = 10,289.894) which all changed as a result of the damaging exercise protocol, but there were no differences between conditions [all Bayes Factors (BF10) < 0.28]. The effectiveness of low frequency E-STIM for preventing the onset of exercise-induced muscle damage would not appear to be enhanced if performed under BFR.
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Affiliation(s)
- Hannah E Cintron
- Department of Health and Exercise Science, Exercise Physiology Laboratory, Rowan University, Glassboro, NJ, USA
| | - Jessica J Heyburn
- Department of Health and Exercise Science, Exercise Physiology Laboratory, Rowan University, Glassboro, NJ, USA
| | - Robert L Sterner
- Department of Health and Exercise Science, Exercise Physiology Laboratory, Rowan University, Glassboro, NJ, USA
| | - Scott J Dankel
- Department of Health and Exercise Science, Exercise Physiology Laboratory, Rowan University, Glassboro, NJ, USA
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4
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Bou T, Ding W, Liu H, Gong W, Jia Z, Dugarjaviin M, Bai D. A genome-wide landscape of mRNAs, miRNAs, lncRNAs, and circRNAs of skeletal muscles during dietary restriction in Mongolian horses. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. PART D, GENOMICS & PROTEOMICS 2023; 46:101084. [PMID: 37150091 DOI: 10.1016/j.cbd.2023.101084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 04/21/2023] [Accepted: 04/27/2023] [Indexed: 05/09/2023]
Abstract
The proportion of different muscle fibers is essential for the horse breed's aptitude for athletic activities. Adaptation of locomotor muscle is correlated with altered physiologic conditions. To investigate the adaptive changes of muscle fiber phenotype and transcriptome in horse skeletal muscle during dietary restriction (DR). The muscle fiber type distribution and deep RNA-seq analysis of detecting differentially expressed mRNAs (DEGs), miRNA (DEMIRs), lncRNAs (DELs), circRNAs (DECs), and their function analysis were investigated in gluteus medius muscle of Mongolian horses during DR. A total of 1433 DEGs, 5 DEMIRs, 329 DELs, and 53 DECs were identified. Differing from non-uniform muscle fiber type changing, functional enrichment analysis showed that most downregulated DEGs were associated in muscle contraction, fuel energy metabolism, and protein balance. Linkages between non-coding RNA and mRNA landscape were detected from their functional changes. Our study provides new insights into the expressional changes of mRNA and non-coding RNA in horse skeletal muscles during DR, which might improve our understanding of the molecular mechanisms regulating muscle adaption during DR for racing horses.
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Affiliation(s)
- Tugeqin Bou
- Key Laboratory of Equus Germplasm Innovation (Co-construction by Ministry and Province), Ministry of Agriculture and Rural Affairs; Inner Mongolia Key Laboratory of Equine Genetics, Breeding and Reproduction; Equus Research Center, College of Animal Science, Inner Mongolia Agricultural University, Hohhot 010018, China. https://twitter.com/@BTvgqin
| | - Wenqi Ding
- Key Laboratory of Equus Germplasm Innovation (Co-construction by Ministry and Province), Ministry of Agriculture and Rural Affairs; Inner Mongolia Key Laboratory of Equine Genetics, Breeding and Reproduction; Equus Research Center, College of Animal Science, Inner Mongolia Agricultural University, Hohhot 010018, China
| | - Huiying Liu
- Key Laboratory of Equus Germplasm Innovation (Co-construction by Ministry and Province), Ministry of Agriculture and Rural Affairs; Inner Mongolia Key Laboratory of Equine Genetics, Breeding and Reproduction; Equus Research Center, College of Animal Science, Inner Mongolia Agricultural University, Hohhot 010018, China
| | - Wendian Gong
- Key Laboratory of Equus Germplasm Innovation (Co-construction by Ministry and Province), Ministry of Agriculture and Rural Affairs; Inner Mongolia Key Laboratory of Equine Genetics, Breeding and Reproduction; Equus Research Center, College of Animal Science, Inner Mongolia Agricultural University, Hohhot 010018, China
| | - Zijie Jia
- Key Laboratory of Equus Germplasm Innovation (Co-construction by Ministry and Province), Ministry of Agriculture and Rural Affairs; Inner Mongolia Key Laboratory of Equine Genetics, Breeding and Reproduction; Equus Research Center, College of Animal Science, Inner Mongolia Agricultural University, Hohhot 010018, China
| | - Manglai Dugarjaviin
- Key Laboratory of Equus Germplasm Innovation (Co-construction by Ministry and Province), Ministry of Agriculture and Rural Affairs; Inner Mongolia Key Laboratory of Equine Genetics, Breeding and Reproduction; Equus Research Center, College of Animal Science, Inner Mongolia Agricultural University, Hohhot 010018, China
| | - Dongyi Bai
- Key Laboratory of Equus Germplasm Innovation (Co-construction by Ministry and Province), Ministry of Agriculture and Rural Affairs; Inner Mongolia Key Laboratory of Equine Genetics, Breeding and Reproduction; Equus Research Center, College of Animal Science, Inner Mongolia Agricultural University, Hohhot 010018, China.
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5
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Brown LJ, Gasser AN, Sterner RL, Dankel SJ. The impact of blood flow restricted electrical stimulations on recovery from muscle damage. Clin Physiol Funct Imaging 2023; 43:103-108. [PMID: 36372737 DOI: 10.1111/cpf.12797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 11/09/2022] [Accepted: 11/10/2022] [Indexed: 11/15/2022]
Abstract
BACKGROUND Both electrical stimulations (E-STIM) and blood flow restriction (BFR) have been shown to treat symptoms of exercise-induced muscle damage, but little is known about their combined effects which was the purpose of this study. METHODS Individuals completed one set of eccentric elbow flexion exercises to induce muscle damage. Forty-eight hours later, E-STIM was applied using an interferential current administered to both arms for 20 min; however, only one arm completed the E-STIM protocol while also undergoing repeated bouts of BFR (full occlusion for 2 min separated by a 1-min rest intervals). Discomfort and isometric strength were assessed immediately before the damaging exercise, immediately before the treatments, and 0, 10, and 30 min posttreatment. RESULTS A total of 22 individuals (11 females) completed the study. There were no interactions with respect to discomfort (BF10 = 0.008) or isometric strength (BF10 = 0.009) indicating that the addition of BFR did not alter the effectiveness of E-STIM. There was a main effect of time indicating that the damaging exercise was successful at depressing torque (pre: 284 N, post: 199 N; BF10 = 2.70e9) and inducing discomfort (pre: 0 au, post: 6.4 au; BF10 = 3.21e17). While isometric strength did not recover with the E-STIM treatments, discomfort was reduced at each the immediate post (5.3 au; BF10 = 56 294) 10-min post (5.0 au; BF10 = 46 163), and 30-min post (4.9 au; BF10 = 707 600) time points. CONCLUSION E-STIM may be useful for treating discomfort, but does not appear capable of recovering strength associated with muscle damage. The efficacy of E-STIM would not appear to be enhanced if performed under BFR.
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Affiliation(s)
- LaNiece J Brown
- Exercise Physiology Laboratory, Department of Health and Exercise Science, Rowan University, Glassboro, New Jersey, USA
| | - Alexa N Gasser
- Exercise Physiology Laboratory, Department of Health and Exercise Science, Rowan University, Glassboro, New Jersey, USA
| | - Robert L Sterner
- Exercise Physiology Laboratory, Department of Health and Exercise Science, Rowan University, Glassboro, New Jersey, USA
| | - Scott J Dankel
- Exercise Physiology Laboratory, Department of Health and Exercise Science, Rowan University, Glassboro, New Jersey, USA
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6
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Hering GO, Bertschinger R, Stepan J. A quadriceps femoris motor pattern for efficient cycling. PLoS One 2023; 18:e0282391. [PMID: 36928839 PMCID: PMC10019633 DOI: 10.1371/journal.pone.0282391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 02/13/2023] [Indexed: 03/18/2023] Open
Abstract
In cycling, propulsion is generated by the muscles of the lower limbs and hips. After the first reports of pedal/crank force measurements in the late 1960s, it has been assumed that highly trained athletes have better power transfer to the pedals than recreational cyclists. However, motor patterns indicating higher levels of performance are unknown. To compare leg muscle activation between trained (3.5-4.2 W/kgbw) and highly trained (4.3-5.1 W/kgbw) athletes we applied electromyography, lactate, and bi-pedal/crank force measurements during a maximal power test, an individual lactate threshold test and a constant power test. We show that specific activation patterns of the rectus femoris (RF) and vastus lateralis (VL) impact on individual performance during high-intensity cycling. In highly trained cyclists, we found a strong activation of the RF during hip flexion. This results in reduced negative force in the fourth quadrant of the pedal cycle. Furthermore, we discovered that pre-activation of the RF during hip flexion reduces force loss at the top dead center (TDC) and can improve force development during subsequent leg extension. Finally, we found that a higher performance level is associated with earlier and more intense coactivation of the RF and VL. This quadriceps femoris recruitment pattern improves force transmission and maintains propulsion at the TDC of the pedal cycle. Our results demonstrate neuromuscular adaptations in cycling that can be utilized to optimize training interventions in sports and rehabilitation.
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Affiliation(s)
- Gernot O. Hering
- Department of Sport and Health Science, University of Konstanz, Konstanz, Germany
- * E-mail:
| | - Raphael Bertschinger
- Department of Sport and Health Science, University of Konstanz, Konstanz, Germany
| | - Jens Stepan
- Department of Sport and Health Science, University of Konstanz, Konstanz, Germany
- Department of Obstetrics and Gynecology, Paracelsus Medical University, Salzburg, Austria
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7
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Sawada T, Okawara H, Nakashima D, Ikeda K, Nagahara J, Fujitsuka H, Hoshino S, Maeda Y, Katsumata Y, Nakamura M, Nagura T. Constant Load Pedaling Exercise Combined with Electrical Muscle Stimulation Leads to an Early Increase in Sweat Lactate Levels. SENSORS (BASEL, SWITZERLAND) 2022; 22:9585. [PMID: 36559954 PMCID: PMC9784187 DOI: 10.3390/s22249585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 12/06/2022] [Accepted: 12/06/2022] [Indexed: 06/17/2023]
Abstract
A novel exercise modality combined with electrical muscle stimulation (EMS) has been reported to increase cardiovascular and metabolic responses, such as blood lactate concentration. We aimed to examine the effect of constant load pedaling exercise, combined with EMS, by non-invasively and continuously measuring sweat lactate levels. A total of 22 healthy young men (20.7 ± 0.8 years) performed a constant load pedaling exercise for 20 min at 125% of the pre-measured ventilatory work threshold with (EMS condition) and without (control condition) EMS stimulation. Blood lactate concentration was measured by blood samples obtained from the earlobe every minute. Sweat lactate was monitored in real time using a sensor placed on the forearm. The sweat lactate threshold (sLT) was defined as the point of increase in sweat lactate. sLT occurred significantly earlier in the EMS condition than in the control condition. In the single regression analysis, the difference in sLT between the two conditions, as the independent variable, was a significant predictor of the difference in blood lactate concentrations at the end of the exercise (p < 0.05, r = −0.52). Sweat lactate measurement may be a noninvasive and simple alternative to blood lactate measurement to determine the effectiveness of exercise combined with EMS.
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Affiliation(s)
- Tomonori Sawada
- Department of Orthopaedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
| | - Hiroki Okawara
- Department of Orthopaedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
| | - Daisuke Nakashima
- Department of Orthopaedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
| | - Kaito Ikeda
- Department of Orthopaedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
| | - Joji Nagahara
- Department of Orthopaedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
| | - Haruki Fujitsuka
- Department of Orthopaedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
| | - Sosuke Hoshino
- Department of Orthopaedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
| | - Yuta Maeda
- Department of Orthopaedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
| | - Yoshinori Katsumata
- Institute for Integrated Sports Medicine, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
- Department of Cardiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
| | - Masaya Nakamura
- Department of Orthopaedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
| | - Takeo Nagura
- Department of Orthopaedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
- Department of Clinical Biomechanics, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
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8
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Cohen JN, Kuikman MA, Politis-Barber V, Stairs BE, Coates AM, Millar PJ, Burr JF. Blood flow restriction and stimulated muscle contractions do not improve metabolic or vascular outcomes following glucose ingestion in young, active individuals. J Appl Physiol (1985) 2022; 133:75-86. [DOI: 10.1152/japplphysiol.00178.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Glucose ingestion and absorption into the blood stream can challenge glycemic regulation and vascular endothelial function. Muscular contractions in exercise promote a return to homeostasis by increasing glucose uptake and blood flow. Similarly, muscle hypoxia supports glycemic regulation by increasing glucose oxidation. Blood flow restriction (BFR) induces muscle hypoxia during occlusion and reactive hyperemia upon release. Thus, in the absence of exercise, electric muscle stimulation (EMS) and BFR may offer circulatory and glucoregulatory improvements. In 13 healthy, active participants (27±3yr, 7 female) we tracked post-glucose (oral 100g) glycemic, cardiometabolic and vascular function measures over 120min following four interventions: 1) BFR, 2) EMS, 3) BFR+EMS or 4) Control. BFR was applied at 2min intervals for 30min (70% occlusion), EMS was continuous for 30min (maximum-tolerable intensity). Glycemic and insulinemic responses did not differ between interventions (partial η2=0.11-0.15, P=0.2); however, only BFR+EMS demonstrated cyclic effects on oxygen consumption, carbohydrate oxidation, muscle oxygenation, heart rate, and blood pressure (all P<0.01). Endothelial function was reduced 60min post-glucose ingestion across interventions and recovered by 120min (5.9±2.6% vs 8.4±2.7%; P<0.001). Estimated microvascular function was not meaningfully different. Leg blood flow increased during EMS and BFR+EMS (+656±519mL•min-1, +433±510mL•min-1; P<0.001); however, only remained elevated following BFR intervention 90min post-glucose (+94±94mL•min-1; P=0.02). Superimposition of EMS onto cyclic BFR did not preferentially improve post-glucose metabolic or vascular function amongst young, active participants. Cyclic BFR increased blood flow delivery 60min beyond intervention, and BFR+EMS selectively increased carbohydrate usage and reduced muscle oxygenation warranting future clinical assessments.
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Affiliation(s)
- Jeremy N. Cohen
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Megan A. Kuikman
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Valerie Politis-Barber
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Brienne E. Stairs
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Alexandra M. Coates
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Philip J. Millar
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Jamie F. Burr
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
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9
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Miura H, Ishikawa M, Murakami A, Tamura Y, Deguchi K. Effects of Arm-cranking Training with Electrical Muscle Stimulation on Vessel Function. Int J Sports Med 2021; 43:34-40. [PMID: 34243211 DOI: 10.1055/a-1510-9135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
This study aimed to determine whether arm-cranking training with electrical muscle stimulation (EMS) results in a greater improvement in vessel function than performing the same exercise without EMS. First, nine healthy young men performed two 20-min arm-cranking trials at 50% V˙O2max with and without EMS applied to the lower limbs. The flow-mediated vasodilation (FMD) of the right brachial artery was measured using a high-resolution ultrasound device. Both FMD and normalized FMD were increased significantly after the arm-cranking with EMS trial, and significant differences were observed between the two trials. Second, 16 healthy adult men were randomly assigned to either the arm-cranking exercise training (A) group or arm-cranking training with EMS (A+EMS) group. The subjects were engaged in 20 min of arm-cranking at 50% V˙O2max twice a week for 8 weeks with/without EMS applied to the lower limbs. The FMD increased significantly after A+EMS training session and the FMD in A+EMS group was significantly higher than that in the A group. These results indicate that acute/chronic endurance arm-cranking with EMS applied to the lower limbs improves the brachial artery endothelial function more markedly than the same exercise without EMS.
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Affiliation(s)
- Hajime Miura
- Laboratory for Applied Physiology, Institutes of Socio-Arts and Sciences, Tokushima University, Tokushima, Japan
| | - Mizuki Ishikawa
- Department of Physical Therapy, Faculty of Health Science, Osaka Yukioka College of Health Science, Osaka, Japan
| | - Ayako Murakami
- Center for Faculty-wide General Education, Shikoku University,Tokushima, Japan
| | - Yasuaki Tamura
- Department of Rehabilitation Medicine, Tokushima Prefecture Naruto Hospital, Naruto, Japan
| | - Kenichi Deguchi
- Department of Rehabilitation Medicine, Tokushima Prefecture Naruto Hospital, Naruto, Japan
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10
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Bjørnsen T, Wernbom M, Paulsen G, Markworth JF, Berntsen S, D'Souza RF, Cameron-Smith D, Raastad T. High-frequency blood flow-restricted resistance exercise results in acute and prolonged cellular stress more pronounced in type I than in type II fibers. J Appl Physiol (1985) 2021; 131:643-660. [PMID: 33955259 DOI: 10.1152/japplphysiol.00115.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Myocellular stress with high-frequency blood flow-restricted resistance exercise (BFRRE) was investigated by measures of heat shock protein (HSP) responses, glycogen content, and inflammatory markers. Thirteen participants [age: 24 ± 2 yr (means ± SD), 9 males] completed two 5-day blocks of seven BFRRE sessions, separated by 10 days. Four sets of unilateral knee extensions to failure at 20% of one-repetition maximum (1RM) were performed. Muscle samples obtained before, 1 h after the first session in the first and second block (acute 1 and acute 2), after three sessions (day 4), during the "rest week," and at 3 (post 3) and 10 days postintervention (post 10) were analyzed for HSP70, αB-crystallin, glycogen [periodic acid-Schiff (PAS) staining], mRNAs, miRNAs, and CD68+ (macrophages) and CD66b+ (neutrophils) cell numbers. αB-crystallin translocated from the cytosolic to the cytoskeletal fraction after acute 1 and acute 2 (P < 0.05) and immunostaining revealed larger responses in type I than in type II fibers (acute 1, 225 ± 184% vs. 92 ± 81%, respectively, P = 0.001). HSP70 was increased in the cytoskeletal fraction at day 4 and post 3, and immunostaining intensities were more elevated in type I than in type II fibers at day 4 (206 ± 84% vs. 72 ± 112%, respectively, P <0.001), during the rest week (98 ± 66% vs. 42 ± 79%, P < 0.001), and at post 3 (115 ± 82% vs. 28 ± 78%, P = 0.003). Glycogen content was reduced in both fiber types, but most pronounced in type I, which did not recover until the rest week (-15% to 29%, P ≤ 0.001). Intramuscular macrophage numbers were increased by ∼65% postintervention, but no changes were observed in muscle neutrophils. We conclude that high-frequency BFRRE with sets performed till failure stresses both fiber types, with type I fibers being most affected.NEW & NOTEWORTHY BFRRE has been reported to preferentially stress type I muscle fibers, as evidenced by HSP responses. We extend these findings by showing that the HSP responses occur in both fiber types but more so in type I fibers and that they can still be induced after a short-term training period. Furthermore, the reductions in glycogen content of type I fibers after strenuous frequent BFRRE in unaccustomed subjects can be prolonged (≥5 days), probably due to microdamage.
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Affiliation(s)
- Thomas Bjørnsen
- Department of Sport Science and Physical Education, Faculty of Health and Sport Sciences, University of Agder, Kristiansand, Norway.,Norwegian Olympic Federation, Oslo, Norway
| | - Mathias Wernbom
- Department of Health and Rehabilitation, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden.,The Rydberg Laboratory for Applied Sciences, Halmstad University, Halmstad, Sweden.,Department of Food and Nutrition, and Sport Science, Center for Health and Performance, University of Gothenburg, Göteborg, Sweden
| | - Gøran Paulsen
- Norwegian Olympic Federation, Oslo, Norway.,Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway
| | | | - Sveinung Berntsen
- Department of Sport Science and Physical Education, Faculty of Health and Sport Sciences, University of Agder, Kristiansand, Norway
| | - Randall F D'Souza
- Liggins Institute, University of Auckland, Auckland, New Zealand.,Discipline of Nutrition, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - David Cameron-Smith
- Liggins Institute, University of Auckland, Auckland, New Zealand.,Singapore Institute for Clinical Sciences, Agency for Science, Technology, and Research, Singapore.,Human Potential Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Truls Raastad
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway
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11
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Slysz JT, Boston M, King R, Pignanelli C, Power GA, Burr JF. Blood Flow Restriction Combined with Electrical Stimulation Attenuates Thigh Muscle Disuse Atrophy. Med Sci Sports Exerc 2021; 53:1033-1040. [PMID: 33105390 DOI: 10.1249/mss.0000000000002544] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE This study aimed to investigate the effects of blood flow restriction (BFR) combined with electrical muscle stimulation (EMS) on skeletal muscle mass and strength during a period of limb disuse. METHODS Thirty healthy participants (22 ± 3 yr; 23 ± 3 kg·m-2) were randomly assigned to control (CON; n = 10), BFR alone (BFR; n = 10), or BFR combined with EMS (BFR + EMS; n = 10). All participants completed unloading of a single leg for 14 d, with no treatment (CON), or while treated with either BFR or BFR + EMS (twice daily, 5 d·wk-1). BFR treatment involved arterial three cycles of 5-min occlusion using suprasystolic pressure, each separated by 5 min of reperfusion. EMS (6 s on, 15 s off; 200 μs; 60 Hz; 15% maximal voluntary contraction [MVC]) was applied continuously throughout the three BFR cycles. Quadriceps muscle mass (whole-thigh lean mass via dual-energy x-ray absorptiometry and vastus lateralis [VL] muscle thickness via ultrasound) and strength (via knee extension MVC) were assessed before and after the 14-d unloading period. RESULTS After limb unloading, whole-thigh lean mass decreased in the control group (-4% ± 1%, P < 0.001) and BFR group (-3% ± 2%, P = 0.001), but not in the BFR + EMS group (-0.3% ± 3%, P = 0.8). VL muscle thickness decreased in the control group (-4% ± 4%, P = 0.005) and was trending toward a decrease in the BFR group (-8% ± 11%, P = 0.07) and increase in the BFR + EMS group (+5% ± 10%, P = 0.07). Knee extension MVC decreased over time (P < 0.005) in the control group (-18% ± 15%), BFR group (-10% ± 13%), and BFR + EMS group (-18% ± 15%), with no difference between groups (P > 0.5). CONCLUSION Unlike BFR performed in isolation, BFR + EMS represents an effective interventional strategy to attenuate the loss of muscle mass during limb disuse, but it does not demonstrate preservation of strength.
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Hering GO, Stepan J. The Maximal Lactate Steady State Workload Determines Individual Swimming Performance. Front Physiol 2021; 12:668123. [PMID: 33981254 PMCID: PMC8107465 DOI: 10.3389/fphys.2021.668123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 03/31/2021] [Indexed: 11/13/2022] Open
Abstract
The lactate threshold (LT) and the strongly related maximal lactate steady state workload (MLSSW) are critical for physical endurance capacity and therefore of major interest in numerous sports. However, their relevance to individual swimming performance is not well understood. We used a custom-made visual light pacer for real-time speed modulation during front crawl to determine the LT and MLSSW in a single-exercise test. When approaching the LT, we found that minute variations in swimming speed had considerable effects on blood lactate concentration ([La-]). The LT was characterized by a sudden increase in [La-], while the MLSSW occurred after a subsequent workload reduction, as indicated by a rapid cessation of blood lactate accumulation. Determination of the MLSSW by this so-called "individual lactate threshold" (ILT)-test was highly reproducible and valid in a constant speed test. Mean swimming speed in 800 and 1,500 m competition (S-Comp) was 3.4% above MLSSW level and S-Comp, and the difference between S-Comp and the MLSSW (Δ S-Comp/MLSSW) were higher for long-distance swimmers (800-1,500 m) than for short- and middle-distance swimmers (50-400 m). Moreover, Δ S-Comp/MLSSW varied significantly between subjects and had a strong influence on overall swimming performance. Our results demonstrate that the MLSSW determines individual swimming performance, reflects endurance capacity in the sub- to supra-threshold range, and is therefore appropriate to adjust training intensity in moderate to severe domains of exercise.
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Affiliation(s)
- Gernot O Hering
- Department of Sport and Health Science, University of Konstanz, Konstanz, Germany
| | - Jens Stepan
- Department of Sport and Health Science, University of Konstanz, Konstanz, Germany.,Department of Obstetrics and Gynaecology, Paracelsus Medical University, Salzburg, Austria
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Ferguson RA, Mitchell EA, Taylor CW, Bishop DJ, Christiansen D. Blood-flow-restricted exercise: Strategies for enhancing muscle adaptation and performance in the endurance-trained athlete. Exp Physiol 2021; 106:837-860. [PMID: 33486814 DOI: 10.1113/ep089280] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2020] [Accepted: 01/19/2021] [Indexed: 12/15/2022]
Abstract
NEW FINDINGS What is the topic of this review? Blood-flow-restricted (BFR) exercise represents a potential approach to augment the adaptive response to training and improve performance in endurance-trained individuals. What advances does it highlight? When combined with low-load resistance exercise, low- and moderate-intensity endurance exercise and sprint interval exercise, BFR can provide an augmented acute stimulus for angiogenesis and mitochondrial biogenesis. These augmented acute responses can translate into enhanced capillary supply and mitochondrial function, and subsequent endurance-type performance, although this might depend on the nature of the exercise stimulus. There is a requirement to clarify whether BFR training interventions can be used by high-performance endurance athletes within their structured training programme. ABSTRACT A key objective of the training programme for an endurance athlete is to optimize the underlying physiological determinants of performance. Training-induced adaptations are governed by physiological and metabolic stressors, which initiate transcriptional and translational signalling cascades to increase the abundance and/or function of proteins to improve physiological function. One important consideration is that training adaptations are reduced as training status increases, which is reflected at the molecular level as a blunting of the acute signalling response to exercise. This review examines blood-flow-restricted (BFR) exercise as a strategy for augmenting exercise-induced stressors and subsequent molecular signalling responses to enhance the physiological characteristics of the endurance athlete. Focus is placed on the processes of capillary growth and mitochondrial biogenesis. Recent evidence supports that BFR exercise presents an intensified training stimulus beyond that of performing the same exercise alone. We suggest that this has the potential to induce enhanced physiological adaptations, including increases in capillary supply and mitochondrial function, which can contribute to an improvement in performance of endurance exercise. There is, however, a lack of consensus regarding the potency of BFR training, which is invariably attributable to the different modes, intensities and durations of exercise and BFR methods. Further studies are needed to confirm its potential in the endurance-trained athlete.
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Affiliation(s)
- Richard A Ferguson
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
| | - Emma A Mitchell
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
| | - Conor W Taylor
- Ineos Grenadiers Cycling Team, Bollin House, Wilmslow, UK
| | - David J Bishop
- Institute for Health and Sport (iHeS), Victoria University, Melbourne, Victoria, Australia
| | - Danny Christiansen
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA
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Kortianou EA, Papafilippou EK, Karagkounis A. Respiratory, cardiac and metabolic responses during electrical muscle stimulation in quadriceps muscle versus comparable voluntary muscle contractions. Scandinavian Journal of Clinical and Laboratory Investigation 2020; 81:12-17. [PMID: 33215943 DOI: 10.1080/00365513.2020.1846210] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Electrical Muscle Stimulation (EMS) and voluntary muscle contraction (VMC) are both acceptable rehabilitative modalities to preserve muscle strength loss. The study aimed to compare respiratory, metabolic, and cardiac parameters during quadriceps muscle contraction (QMC) using either EMS or VMC with comparable generated low intensity muscle force. Thirty healthy non-smoker males, age 20-58 years with normal BMI and low to moderate physical activity, underwent two 20-min sessions of comparable QMC using EMS vs VMC at the same day. The BIODEX III isokinetic dynamometer was used to assess maximum isometric force and the comparable force generated during each condition (EMS vs VMC), while the METAMAX 3B portable metabolic system was used to measure continuously the physiological parameters. Tolerable EMS was used (mean: 33 ± 1.5 mA, at 75 Hz). Each contraction lasted 10 sec followed by 20 sec rest. Paired t-tests were used for comparisons between sessions. A relatively low proportion of maximum isometric force (EMS: 8.5% vs VMC: 8.6%) and torque (EMS: 16 ± 1.3 vs VMC: 16 ± 1.1 Nm) were generated during each session. Mean minute ventilation (EMS: 10.8 L vs VMC: 9.8 L), tidal volume (EMS: 0.6 L vs VMC: 0.5 L), O2 uptake (EMS: 0.31 L/min vs VMC: 0.26 L/min) and O2 pulse (EMS: 3.9 ml/beat vs VMC: 3.6 ml/beat) were different between sessions (p ≤ .05); while heart rate (EMS: 72 beats/min vs VMC: 71 beats/min) was equal. Quadriceps muscle EMS induces higher respiratory and metabolic responses compared to equal magnitude VMC in healthy males.
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Affiliation(s)
- Eleni A Kortianou
- Clinical Exercise Physiology and Rehabilitation Laboratory, Department of Physiotherapy, School of Health Sciences, University of Thessaly, Lamia, Greece
| | - Evangelia K Papafilippou
- Clinical Exercise Physiology and Rehabilitation Laboratory, Department of Physiotherapy, School of Health Sciences, University of Thessaly, Lamia, Greece
| | - Andonis Karagkounis
- Clinical Exercise Physiology and Rehabilitation Laboratory, Department of Physiotherapy, School of Health Sciences, University of Thessaly, Lamia, Greece
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Tomita A, Kawade S, Moritani T, Watanabe K. Novel perspective on contractile properties and intensity-dependent verification of force-frequency relationship during neuromuscular electrical stimulation. Physiol Rep 2020; 8:e14598. [PMID: 33230975 PMCID: PMC7683877 DOI: 10.14814/phy2.14598] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 08/24/2020] [Accepted: 08/28/2020] [Indexed: 12/16/2022] Open
Abstract
PURPOSE The aims of the present study were: (a) to examine the effect of the stimulus intensity on force-frequency and torque fluctuation-frequency relationships during Neuromuscular electrical stimulation; and (b) to identify a novel parameter that can be used to evaluate muscle contractile properties. METHODS Electrically elicited joint torque involving the quadriceps femoris muscle was recorded during neuromuscular electrical stimulation at two different stimulus intensities in 19 healthy men. Stimulation frequencies were set at 5-40 Hz with a duration of 10 s. Evoked joint torque was compared among all stimulation frequencies between the two stimulus intensities (68 and 113 V). The torque fluctuation at each stimulation frequency as the change in the contraction pattern was also compared between the intensities. Torque and torque fluctuation were normalized at each frequency by the largest torque or torque fluctuation, respectively. We extracted a novel parameter: the arrival point of tetanic contraction based on force-frequency and torque fluctuation-frequency curves. RESULTS There were significant differences in normalized torque at 5-25 and 40 Hz and in normalized torque fluctuation at 15-30 and 40 Hz between the two stimulus intensities. Extracted parameters showed no significant difference between the intensities. CONCLUSION The results suggest that force-frequency relationships during neuromuscular electrical stimulation are influenced by the intensity of stimulation applied to the quadriceps femoris muscle. However, we consider that it is possible to simultaneously evaluate contractile properties using the novel parameter.
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Affiliation(s)
- Aya Tomita
- Laboratory of Neuromuscular BiomechanicsFaculty of Liberal Arts and Sciences and School of International Liberal StudiesChukyo UniversityNagoyaJapan
| | | | | | - Kohei Watanabe
- Laboratory of Neuromuscular BiomechanicsFaculty of Liberal Arts and Sciences and School of International Liberal StudiesChukyo UniversityNagoyaJapan
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Tobias IS, Galpin AJ. Moving human muscle physiology research forward: an evaluation of fiber type-specific protein research methodologies. Am J Physiol Cell Physiol 2020; 319:C858-C876. [DOI: 10.1152/ajpcell.00107.2020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Human skeletal muscle is a heterogeneous tissue composed of multiple fiber types that express unique contractile and metabolic properties. While analysis of mixed fiber samples predominates and holds value, increasing attention has been directed toward studying proteins segregated by fiber type, a methodological distinction termed “fiber type-specific.” Fiber type-specific protein studies have the advantage of uncovering key molecular effects that are often missed in mixed fiber homogenate studies but also require greater time and resource-intensive methods, particularly when applied to human muscle. This review summarizes and compares current methods used for fiber type-specific protein analysis, highlighting their advantages and disadvantages for human muscle studies, in addition to recent advances in these techniques. These methods can be grouped into three categories based on the initial processing of the tissue: 1) muscle-specific fiber homogenates, 2) cross sections of fiber bundles, and 3) isolated single fibers, with various subtechniques for performing fiber type identification and protein quantification. The relative implementation for each unique methodological approach is analyzed from 83 fiber type-specific studies of proteins in live human muscle found in the literature to date. These studies have investigated several proteins involved in a wide range of cellular functions that are important to muscle tissue. The second half of this review summarizes key findings from this ensemble of fiber type-specific human protein studies. We highlight examples of where this analytical approach has helped to improve understanding of important physiological topics such as insulin sensitivity, muscle hypertrophy, muscle fatigue, and adaptation to different exercise programs.
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Affiliation(s)
- Irene S. Tobias
- Biochemistry and Molecular Exercise Physiology Laboratory, Center for Sport Performance, California State University, Fullerton, California
| | - Andrew J. Galpin
- Biochemistry and Molecular Exercise Physiology Laboratory, Center for Sport Performance, California State University, Fullerton, California
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17
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Wernbom M, Aagaard P. Muscle fibre activation and fatigue with low-load blood flow restricted resistance exercise-An integrative physiology review. Acta Physiol (Oxf) 2020; 228:e13302. [PMID: 31108025 DOI: 10.1111/apha.13302] [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: 01/10/2019] [Revised: 05/12/2019] [Accepted: 05/17/2019] [Indexed: 12/13/2022]
Abstract
Blood flow-restricted resistance exercise (BFRRE) has been shown to induce increases in muscle size and strength, and continues to generate interest from both clinical and basic research points of view. The low loads employed, typically 20%-50% of the one repetition maximum, make BFRRE an attractive training modality for individuals who may not tolerate high musculoskeletal forces (eg, selected clinical patient groups such as frail old adults and patients recovering from sports injury) and/or for highly trained athletes who have reached a plateau in muscle mass and strength. It has been proposed that achieving a high degree of muscle fibre recruitment is important for inducing muscle hypertrophy with BFRRE, and the available evidence suggest that fatiguing low-load exercise during ischemic conditions can recruit both slow (type I) and fast (type II) muscle fibres. Nevertheless, closer scrutiny reveals that type II fibre activation in BFRRE has to date largely been inferred using indirect methods such as electromyography and magnetic resonance spectroscopy, while only rarely addressed using more direct methods such as measurements of glycogen stores and phosphocreatine levels in muscle fibres. Hence, considerable uncertainity exists about the specific pattern of muscle fibre activation during BFRRE. Therefore, the purpose of this narrative review was (1) to summarize the evidence on muscle fibre recruitment during BFRRE as revealed by various methods employed for determining muscle fibre usage during exercise, and (2) to discuss reported findings in light of the specific advantages and limitations associated with these methods.
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Affiliation(s)
- Mathias Wernbom
- Center for Health and Performance, Department of Food and Nutrition and Sport Science University of Gothenburg Gothenburg Sweden
- Department of Health and Rehabilitation, Institute of Neuroscience and Physiology, Sahlgrenska Academy University of Gothenburg Gothenburg Sweden
| | - Per Aagaard
- Department of Sports Sciences and Clinical Biomechanics, SDU Muscle Research Cluster (SMRC) University of Southern Denmark Odense M Denmark
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Blackwood SJ, Katz A. Isoproterenol enhances force production in mouse glycolytic and oxidative muscle via separate mechanisms. Pflugers Arch 2019; 471:1305-1316. [PMID: 31451903 PMCID: PMC6814637 DOI: 10.1007/s00424-019-02304-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 07/22/2019] [Accepted: 08/13/2019] [Indexed: 02/04/2023]
Abstract
Fight or flight is a biologic phenomenon that involves activation of β-adrenoceptors in skeletal muscle. However, how force generation is enhanced through adrenergic activation in different muscle types is not fully understood. We studied the effects of isoproterenol (ISO, β-receptor agonist) on force generation and energy metabolism in isolated mouse soleus (SOL, oxidative) and extensor digitorum longus (EDL, glycolytic) muscles. Muscles were stimulated with isometric tetanic contractions and analyzed for metabolites and phosphorylase activity. Under conditions of maximal force production, ISO enhanced force generation markedly more in SOL (22%) than in EDL (8%). Similarly, during a prolonged tetanic contraction (30 s for SOL and 10 s for EDL), ISO-enhanced the force × time integral more in SOL (25%) than in EDL (3%). ISO induced marked activation of phosphorylase in both muscles in the basal state, which was associated with glycogenolysis (less in SOL than in EDL), and in EDL only, a significant decrease (16%) in inorganic phosphate (Pi). ATP turnover during sustained contractions (1 s EDL, 5 s SOL) was not affected by ISO in EDL, but essentially doubled in SOL. Under conditions of maximal stimulation, ISO has a minor effect on force generation in EDL that is associated with a decrease in Pi, whereas ISO has a marked effect on force generation in SOL that is associated with an increase in ATP turnover. Thus, phosphorylase functions as a phosphate trap in ISO-mediated force enhancement in EDL and as a catalyzer of ATP supply in SOL.
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Affiliation(s)
- Sarah J Blackwood
- Åstrand Laboratory of Work Physiology, Swedish School of Sport and Health Sciences, GIH, Box 5626, S-114 86, Stockholm, Sweden
| | - Abram Katz
- Åstrand Laboratory of Work Physiology, Swedish School of Sport and Health Sciences, GIH, Box 5626, S-114 86, Stockholm, Sweden.
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Mathes S, Vanmunster M, Bloch W, Suhr F. Evidence for skeletal muscle fiber type-specific expressions of mechanosensors. Cell Mol Life Sci 2019; 76:2987-3004. [PMID: 30701284 PMCID: PMC11105595 DOI: 10.1007/s00018-019-03026-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 01/10/2019] [Accepted: 01/23/2019] [Indexed: 01/30/2023]
Abstract
Mechanosensors govern muscle tissue integrity and constitute a subcellular structure known as costameres. Costameres physically link the muscle extracellular matrix to contractile and signaling 'hubs' inside muscle fibers mainly via integrins and are localized beneath sarcolemmas of muscle fibers. Costameres are the main mechanosensors converting mechanical cues into biological events. However, the fiber type-specific costamere architecture in muscles is unexplored. We hypothesized that fiber types differ in the expression of genes coding for costamere components. By coupling laser microdissection to a multiplex tandem qPCR approach, we demonstrate that type 1 and type 2 fibers indeed show substantial differences in their mechanosensor complexes. We confirmed these data by fiber type population-specific protein analysis and confocal microscopy-based localization studies. We further show that knockdown of the costamere gene integrin-linked kinase (Ilk) in muscle precursor cells results in significantly increased slow-myosin-coding Myh7 gene, while the fast-myosin-coding genes Myh1, Myh2, and Myh4 are downregulated. In parallel, protein synthesis-enhancing signaling molecules (p-mTORSer2448, p < 0.05; p-P70S6KThr389, tendency with p < 0.1) were reduced upon Ilk knockdown. However, overexpression of slow type-inducing NFATc1 in muscle precursor cells did not change Ilk or other costamere gene expressions. In addition, we demonstrate fiber type-specific costamere gene regulation upon mechanical loading and unloading conditions. Our data imply that costamere genes, such as Ilk, are involved in the control of muscle fiber characteristics. Further, they identify costameres as muscle fiber type-specific loading management 'hubs' and may explain adaptation differences of muscle fiber types to mechanical (un)loading.
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Affiliation(s)
- Sebastian Mathes
- Department of Molecular and Cellular Sport Medicine, German Sport University Cologne, Cologne, Germany
| | - Mathias Vanmunster
- Exercise Physiology Research Group, Department of Movement Sciences, Biomedical Sciences Group, KU Leuven, Tervuursevest 101, Bus 1500, 3001, Leuven, Belgium
| | - Wilhelm Bloch
- Department of Molecular and Cellular Sport Medicine, German Sport University Cologne, Cologne, Germany
| | - Frank Suhr
- Department of Molecular and Cellular Sport Medicine, German Sport University Cologne, Cologne, Germany.
- Exercise Physiology Research Group, Department of Movement Sciences, Biomedical Sciences Group, KU Leuven, Tervuursevest 101, Bus 1500, 3001, Leuven, Belgium.
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COPITHORNE DAVIDB, RICE CHARLESL. Neuromuscular Function and Blood Flow Occlusion with Dynamic Arm Flexor Contractions. Med Sci Sports Exerc 2019; 52:205-213. [DOI: 10.1249/mss.0000000000002091] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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21
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Christiansen D. Molecular stressors underlying exercise training-induced improvements in K + regulation during exercise and Na + ,K + -ATPase adaptation in human skeletal muscle. Acta Physiol (Oxf) 2019; 225:e13196. [PMID: 30288889 DOI: 10.1111/apha.13196] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 09/12/2018] [Accepted: 09/28/2018] [Indexed: 12/28/2022]
Abstract
Despite substantial progress made towards a better understanding of the importance of skeletal muscle K+ regulation for human physical function and its association with several disease states (eg type-II diabetes and hypertension), the molecular basis underpinning adaptations in K+ regulation to various stimuli, including exercise training, remains inadequately explored in humans. In this review, the molecular mechanisms essential for enhancing skeletal muscle K+ regulation and its key determinants, including Na+ ,K+ -ATPase function and expression, by exercise training are examined. Special attention is paid to the following molecular stressors and signaling proteins: oxygenation, redox balance, hypoxia, reactive oxygen species, antioxidant function, Na+ ,K+ , and Ca2+ concentrations, anaerobic ATP turnover, AMPK, lactate, and mRNA expression. On this basis, an update on the effects of different types of exercise training on K+ regulation in humans is provided, focusing on recent discoveries about the muscle fibre-type-dependent regulation of Na+ ,K+ -ATPase-isoform expression. Furthermore, with special emphasis on blood-flow-restricted exercise as an exemplary model to modulate the key molecular mechanisms identified, it is discussed how training interventions may be designed to maximize improvements in K+ regulation in humans. The novel insights gained from this review may help us to better understand how exercise training and other strategies, such as pharmacological interventions, may be best designed to enhance K+ regulation and thus the physical function in humans.
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Affiliation(s)
- Danny Christiansen
- Department of Nutrition, Exercise and Sports (NEXS) University of Copenhagen Copenhagen Denmark
- Institute for Health and Sport (IHES) Victoria University Melbourne Victoria Australia
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Mitchell EA, Martin NRW, Bailey SJ, Ferguson RA. Critical power is positively related to skeletal muscle capillarity and type I muscle fibers in endurance-trained individuals. J Appl Physiol (1985) 2018; 125:737-745. [DOI: 10.1152/japplphysiol.01126.2017] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The asymptote [critical power (CP)] and curvature constant ( W′) of the hyperbolic power-duration relationship can predict performance within the severe-intensity exercise domain. However, the extent to which these parameters relate to skeletal muscle morphology is less clear, particularly in endurance-trained individuals, who, relative to their lesser-trained counterparts, possess skeletal muscles that can support high levels of oxygen transport and oxidative capacity, i.e., elevated type I fiber proportion and cross-sectional area (CSA) and capillarity. Fourteen endurance-trained men performed a maximal incremental test to determine peak oxygen uptake (V̇o2peak; 63.2 ± 4.1 ml·min−1·kg−1, mean ± SD) and maximal aerobic power (406 ± 63 W) and three to five constant-load tests to task failure for the determination of CP (303 ± 52 W) and W′ (17.0 ± 3.0 kJ). Skeletal muscle biopsies were obtained from the vastus lateralis and analyzed for percent proportion of fiber types, CSA, and indexes of capillarity. CP was positively correlated with the percent proportion ( r = 0.79; P = 0.001) and CSA ( r = 0.73; P = 0.003) of type I fibers, capillary-to-fiber ratio ( r = 0.88; P < 0.001), and capillary contacts around type I fibers ( r = 0.94; P < 0.001) and type II fibers ( r = 0.68; P = 0.008). W′ was not correlated with any morphological variables. These data reveal a strong positive association between CP and skeletal muscle capillarity. Our findings support the assertion that CP is an important parameter of aerobic function and offer novel insights into the physiological bases of CP. NEW & NOTEWORTHY This investigation demonstrated very strong positive correlations between critical power and skeletal muscle capillarity, particularly around type I fibers, and type I fiber composition. These correlations were demonstrated in endurance-trained individuals expected to possess well-adapted skeletal muscles, such as high levels of oxygen transport structures and high oxidative capacities, supporting the view that critical power is an important parameter of aerobic function. In contrast, the curvature constant W′ was not associated with fiber type composition or capillarity.
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Affiliation(s)
- Emma A. Mitchell
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, United Kingdom
| | - Neil R. W. Martin
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, United Kingdom
| | - Stephen J. Bailey
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, United Kingdom
| | - Richard A. Ferguson
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, United Kingdom
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Christiansen D, Murphy RM, Bangsbo J, Stathis CG, Bishop DJ. Increased FXYD1 and PGC-1α mRNA after blood flow-restricted running is related to fibre type-specific AMPK signalling and oxidative stress in human muscle. Acta Physiol (Oxf) 2018; 223:e13045. [PMID: 29383885 PMCID: PMC5969286 DOI: 10.1111/apha.13045] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 01/01/2018] [Accepted: 01/24/2018] [Indexed: 12/24/2022]
Abstract
Aim This study explored the effects of blood flow restriction (BFR) on mRNA responses of PGC‐1α (total, 1α1, and 1α4) and Na+,K+‐ATPase isoforms (NKA; α1‐3, β1‐3, and FXYD1) to an interval running session and determined whether these effects were related to increased oxidative stress, hypoxia, and fibre type‐specific AMPK and CaMKII signalling, in human skeletal muscle. Methods In a randomized, crossover fashion, 8 healthy men (26 ± 5 year and 57.4 ± 6.3 mL kg−1 min−1) completed 3 exercise sessions: without (CON) or with blood flow restriction (BFR), or in systemic hypoxia (HYP, ~3250 m). A muscle sample was collected before (Pre) and after exercise (+0 hour, +3 hours) to quantify mRNA, indicators of oxidative stress (HSP27 protein in type I and II fibres, and catalase and HSP70 mRNA), metabolites, and α‐AMPK Thr172/α‐AMPK, ACC Ser221/ACC, CaMKII Thr287/CaMKII, and PLBSer16/PLB ratios in type I and II fibres. Results Muscle hypoxia (assessed by near‐infrared spectroscopy) was matched between BFR and HYP, which was higher than CON (~90% vs ~70%; P < .05). The mRNA levels of FXYD1 and PGC‐1α isoforms (1α1 and 1α4) increased in BFR only (P < .05) and were associated with increases in indicators of oxidative stress and type I fibre ACC Ser221/ACC ratio, but dissociated from muscle hypoxia, lactate, and CaMKII signalling. Conclusion Blood flow restriction augmented exercise‐induced increases in muscle FXYD1 and PGC‐1α mRNA in men. This effect was related to increased oxidative stress and fibre type‐dependent AMPK signalling, but unrelated to the severity of muscle hypoxia, lactate accumulation, and modulation of fibre type‐specific CaMKII signalling.
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Affiliation(s)
- D. Christiansen
- Institute of Sport, Exercise and Active Living (ISEAL); Victoria University; Melbourne Vic. Australia
| | - R. M. Murphy
- Department of Biochemistry and Genetics; La Trobe Institute for Molecular Science; La Trobe University; Melbourne Vic. Australia
| | - J. Bangsbo
- Department of Nutrition, Exercise and Sports (NEXS); University of Copenhagen; Copenhagen N Denmark
| | - C. G. Stathis
- Institute of Sport, Exercise and Active Living (ISEAL); Victoria University; Melbourne Vic. Australia
| | - D. J. Bishop
- Institute of Sport, Exercise and Active Living (ISEAL); Victoria University; Melbourne Vic. Australia
- School of Medical and Health Sciences; Edith Cowan University; Perth WA Australia
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Valkovič L, Chmelík M, Krššák M. In-vivo 31P-MRS of skeletal muscle and liver: A way for non-invasive assessment of their metabolism. Anal Biochem 2017; 529:193-215. [PMID: 28119063 PMCID: PMC5478074 DOI: 10.1016/j.ab.2017.01.018] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 01/13/2017] [Accepted: 01/19/2017] [Indexed: 01/18/2023]
Abstract
In addition to direct assessment of high energy phosphorus containing metabolite content within tissues, phosphorus magnetic resonance spectroscopy (31P-MRS) provides options to measure phospholipid metabolites and cellular pH, as well as the kinetics of chemical reactions of energy metabolism in vivo. Even though the great potential of 31P-MR was recognized over 30 years ago, modern MR systems, as well as new, dedicated hardware and measurement techniques provide further opportunities for research of human biochemistry. This paper presents a methodological overview of the 31P-MR techniques that can be used for basic, physiological, or clinical research of human skeletal muscle and liver in vivo. Practical issues of 31P-MRS experiments and examples of potential applications are also provided. As signal localization is essential for liver 31P-MRS and is important for dynamic muscle examinations as well, typical localization strategies for 31P-MR are also described.
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Affiliation(s)
- Ladislav Valkovič
- High-field MR Centre, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria; Oxford Centre for Clinical Magnetic Resonance Research (OCMR), University of Oxford, Oxford, United Kingdom; Department of Imaging Methods, Institute of Measurement Science, Slovak Academy of Sciences, Bratislava, Slovakia.
| | - Marek Chmelík
- High-field MR Centre, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria; Christian Doppler Laboratory for Clinical Molecular MR Imaging, Vienna, Austria; Institute for Clinical Molecular MRI in Musculoskeletal System, Karl Landsteiner Society, Vienna, Austria
| | - Martin Krššák
- High-field MR Centre, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria; Christian Doppler Laboratory for Clinical Molecular MR Imaging, Vienna, Austria; Division of Endocrinology and Metabolism, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
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Buehler T, Bally L, Dokumaci AS, Stettler C, Boesch C. Methodological and physiological test-retest reliability of (13) C-MRS glycogen measurements in liver and in skeletal muscle of patients with type 1 diabetes and matched healthy controls. NMR IN BIOMEDICINE 2016; 29:796-805. [PMID: 27074205 DOI: 10.1002/nbm.3531] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Revised: 02/04/2016] [Accepted: 03/08/2016] [Indexed: 06/05/2023]
Abstract
Glycogen is a major substrate in energy metabolism and particularly important to prevent hypoglycemia in pathologies of glucose homeostasis such as type 1 diabetes mellitus (T1DM). (13) C-MRS is increasingly used to determine glycogen in skeletal muscle and liver non-invasively; however, the low signal-to-noise ratio leads to long acquisition times, particularly when glycogen levels are determined before and after interventions. In order to ease the requirements for the subjects and to avoid systematic effects of the lengthy examination, we evaluated if a standardized preparation period would allow us to shift the baseline (pre-intervention) experiments to a preceding day. Based on natural abundance (13) C-MRS on a clinical 3 T MR system the present study investigated the test-retest reliability of glycogen measurements in patients with T1DM and matched controls (n = 10 each group) in quadriceps muscle and liver. Prior to the MR examination, participants followed a standardized diet and avoided strenuous exercise for two days. The average coefficient of variation (CV) of myocellular glycogen levels was 9.7% in patients with T1DM compared with 6.6% in controls after a 2 week period, while hepatic glycogen variability was 13.3% in patients with T1DM and 14.6% in controls. For comparison, a single-session test-retest variability in four healthy volunteers resulted in 9.5% for skeletal muscle and 14.3% for liver. Glycogen levels in muscle and liver were not statistically different between test and retest, except for hepatic glycogen, which decreased in T1DM patients in the retest examination, but without an increase of the group distribution. Since the CVs of glycogen levels determined in a "single session" versus "within weeks" are comparable, we conclude that the major source of uncertainty is the methodological error and that physiological variations can be minimized by a pre-study standardization. For hepatic glycogen examinations, familiarization sessions (MR and potentially strenuous interventions) are recommended. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Tania Buehler
- Department of Clinical Research and Department of Radiology, University of Bern, Switzerland
| | - Lia Bally
- Division of Endocrinology, Diabetes and Clinical Nutrition, Inselspital Bern, Switzerland
| | - Ayse Sila Dokumaci
- Department of Clinical Research and Department of Radiology, University of Bern, Switzerland
| | - Christoph Stettler
- Division of Endocrinology, Diabetes and Clinical Nutrition, Inselspital Bern, Switzerland
| | - Chris Boesch
- Department of Clinical Research and Department of Radiology, University of Bern, Switzerland
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Morales-Alamo D, Losa-Reyna J, Torres-Peralta R, Martin-Rincon M, Perez-Valera M, Curtelin D, Ponce-González JG, Santana A, Calbet JAL. What limits performance during whole-body incremental exercise to exhaustion in humans? J Physiol 2015; 593:4631-48. [PMID: 26250346 DOI: 10.1113/jp270487] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 07/29/2015] [Indexed: 12/13/2022] Open
Abstract
To determine the mechanisms causing task failure during incremental exercise to exhaustion (IE), sprint performance (10 s all-out isokinetic) and muscle metabolites were measured before (control) and immediately after IE in normoxia (P(IO2) 143 mmHg) and hypoxia (P(IO2): 73 mmHg) in 22 men (22 ± 3 years). After IE, subjects recovered for either 10 or 60 s, with open circulation or bilateral leg occlusion (300 mmHg) in random order. This was followed by a 10 s sprint with open circulation. Post-IE peak power output (W(peak)) was higher than the power output reached at exhaustion during IE (P < 0.05). After 10 and 60 s recovery in normoxia, W(peak) was reduced by 38 ± 9 and 22 ± 10% without occlusion, and 61 ± 8 and 47 ± 10% with occlusion (P < 0.05). Following 10 s occlusion, W(peak) was 20% higher in hypoxia than normoxia (P < 0.05), despite similar muscle lactate accumulation ([La]) and phosphocreatine and ATP reduction. Sprint performance and anaerobic ATP resynthesis were greater after 60 s compared with 10 s occlusions, despite the higher [La] and [H(+)] after 60 s compared with 10 s occlusion recovery (P < 0.05). The mean rate of ATP turnover during the 60 s occlusion was 0.180 ± 0.133 mmol (kg wet wt)(-1) s(-1), i.e. equivalent to 32% of leg peak O2 uptake (the energy expended by the ion pumps). A greater degree of recovery is achieved, however, without occlusion. In conclusion, during incremental exercise task failure is not due to metabolite accumulation or lack of energy resources. Anaerobic metabolism, despite the accumulation of lactate and H(+), facilitates early recovery even in anoxia. This points to central mechanisms as the principal determinants of task failure both in normoxia and hypoxia, with lower peripheral contribution in hypoxia.
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Affiliation(s)
- David Morales-Alamo
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, 35017, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), Las Palmas de Gran Canaria, Spain
| | - José Losa-Reyna
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, 35017, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), Las Palmas de Gran Canaria, Spain
| | - Rafael Torres-Peralta
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, 35017, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), Las Palmas de Gran Canaria, Spain
| | - Marcos Martin-Rincon
- Research Institute of Biomedical and Health Sciences (IUIBS), Las Palmas de Gran Canaria, Spain.,Department of Sports and Informatics, Pablo de Olavide University, Seville, Spain
| | - Mario Perez-Valera
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, 35017, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), Las Palmas de Gran Canaria, Spain
| | - David Curtelin
- Research Institute of Biomedical and Health Sciences (IUIBS), Las Palmas de Gran Canaria, Spain.,Emergency Medicine Department, Complejo Hospitalario Universitario Insular-Materno Infantil de Las Palmas de Gran Canaria, Avenida Marítima del Sur, s/n, 35016, Las Palmas de Gran Canaria, Spain
| | - Jesús Gustavo Ponce-González
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, 35017, Las Palmas de Gran Canaria, Spain
| | - Alfredo Santana
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, 35017, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), Las Palmas de Gran Canaria, Spain.,Clinical Genetics Unit, Complejo Hospitalario Universitario Insular-Materno Infantil de Las Palmas de Gran Canaria, Avenida Marítima, del Sur, s/n, 35016, Las Palmas de Gran Canaria, Spain
| | - José A L Calbet
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, 35017, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), Las Palmas de Gran Canaria, Spain
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27
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Takahashi H, Kamei A, Osawa T, Kawahara T, Takizawa O, Maruyama K. ¹³C MRS reveals a small diurnal variation in the glycogen content of human thigh muscle. NMR IN BIOMEDICINE 2015; 28:650-655. [PMID: 25881007 DOI: 10.1002/nbm.3298] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 02/17/2015] [Accepted: 03/09/2015] [Indexed: 06/04/2023]
Abstract
There is marked diurnal variation in the glycogen content of skeletal muscles of animals, but few studies have addressed such variations in human muscles. (13)C MRS can be used to noninvasively measure the glycogen content of human skeletal muscle, but no study has explored the diurnal variations in this parameter. This study aimed to investigate whether a diurnal variation in glycogen content occurs in human muscles and, if so, to what extent it can be identified using (13)C MRS. Six male volunteers were instructed to maintain their normal diet and not to perform strenuous exercise for at least 3 days before and during the experiment. Muscle glycogen and blood glucose concentrations were measured six times in 24 h under normal conditions in these subjects. The glycogen content in the thigh muscle was determined noninvasively by natural abundance (13)C MRS using a clinical MR system at 3 T. Nutritional analysis revealed that the subjects' mean carbohydrate intake was 463 ± 137 g, being approximately 6.8 ± 2.4 g/kg body weight. The average sleeping time was 5.9 ± 1.0 h. The glycogen content in the thigh muscle at the starting point was 64.8 ± 20.6 mM. Although absolute and relative individual variations in muscle glycogen content were 7.0 ± 2.1 mM and 11.3 ± 4.6%, respectively, no significant difference in glycogen content was observed among the different time points. This study demonstrates that normal food intake (not fat and/or carbohydrate rich), sleep and other daily activities have a negligible influence on thigh muscle glycogen content, and that the diurnal variation of the glycogen content in human muscles is markedly smaller than that in animal muscles. Moreover, the present results also support the reproducibility and availability of (13)C MRS for the evaluation of the glycogen content in human muscles.
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Affiliation(s)
- Hideyuki Takahashi
- Department of Sports Science, Japan Institute of Sports Sciences, Tokyo, Japan
| | - Akiko Kamei
- Department of Sports Science, Japan Institute of Sports Sciences, Tokyo, Japan
| | - Takuya Osawa
- Department of Sports Science, Japan Institute of Sports Sciences, Tokyo, Japan
| | - Takashi Kawahara
- Medical Center, Japan Institute of Sports Sciences, Tokyo, Japan
| | - Osamu Takizawa
- Research & Collaboration Department, Siemens Japan K.K., Tokyo, Japan
| | - Katsuya Maruyama
- Research & Collaboration Department, Siemens Japan K.K., Tokyo, Japan
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Brull A, de Luna N, Blanco-Grau A, Lucia A, Martin MA, Arenas J, Martí R, Andreu AL, Pinós T. Phenotype consequences of myophosphorylase dysfunction: insights from the McArdle mouse model. J Physiol 2015; 593:2693-706. [PMID: 25873271 DOI: 10.1113/jp270085] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 04/10/2015] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS This is the first study to analyse the effect of muscle glycogen phosphorylase depletion in metabolically different muscle types. In McArdle mice, muscle glycogen phosphorylase is absent in both oxidative and glycolytic muscles. In McArdle mice, the glycogen debranching enzyme (catabolic) is increased in oxidative muscles, whereas the glycogen branching enzyme (anabolic) is increased in glycolytic muscles. In McArdle mice, total glycogen synthase is decreased in both oxidative and glycolytic muscles, whereas the phosphorylated inactive form of the enzyme is increased in both oxidative and glycolytic enzymes. In McArdle mice, glycogen content is higher in glycolytic muscles than in oxidative muscles. Additionally, in all muscles analysed, the glycogen content is higher in males than in females. The maximal endurance capacity of the McArdle mice is significantly lower compared to heterozygous and wild-type mice. ABSTRACT McArdle disease, caused by inherited deficiency of the enzyme muscle glycogen phosphorylase (GP-MM), is arguably the paradigm of exercise intolerance. The recent knock-in (p.R50X/p.R50X) mouse disease model allows an investigation of the phenotypic consequences of muscle glycogen unavailability and the physiopathology of exercise intolerance. We analysed, in 2-month-old mice [wild-type (wt/wt), heterozygous (p.R50X/wt) and p.R50X/p.R50X)], maximal endurance exercise capacity and the molecular consequences of an absence of GP-MM in the main glycogen metabolism regulatory enzymes: glycogen synthase, glycogen branching enzyme and glycogen debranching enzyme, as well as glycogen content in slow-twitch (soleus), intermediate (gastrocnemius) and glycolytic/fast-twitch (extensor digitorum longus; EDL) muscles. Compared with wt/wt, exercise capacity (measured in a treadmill test) was impaired in p.R50X/p.R50X (∼48%) and p.R50X/wt mice (∼18%). p.R50X/p.R50X mice showed an absence of GP-MM in the three muscles. GP-MM was reduced in p.R50X/wt mice, especially in the soleus, suggesting that the function of 'slow-twitch' muscles is less dependent on glycogen catabolism. p.R50X/p.R50X mice showed increased glycogen debranching enzyme in the soleus, increased glycogen branching enzyme in the gastrocnemius and EDL, as well as reduced levels of mucle glycogen synthase protein in the three muscles (mean ∼70%), reflecting a protective mechanism for preventing deleterious glycogen accumulation. Additionally, glycogen content was highest in the EDL of p.R50X/p.R50X mice. Amongst other findings, the present study shows that the expression of the main muscle glycogen regulatory enzymes differs depending on the muscle phenotype (slow- vs. fast-twitch) and that even partial GP-MM deficiency affects maximal endurance capacity. Our knock-in model might help to provide insights into the importance of glycogen on muscle function.
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Affiliation(s)
- Astrid Brull
- Neuromuscular and Mitochondrial Disorders Laboratory, Vall d'Hebron Research Institute, Universitat Autònoma de Barcelona, Barcelona, Spain.,Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Spain
| | - Noemí de Luna
- Neuromuscular and Mitochondrial Disorders Laboratory, Vall d'Hebron Research Institute, Universitat Autònoma de Barcelona, Barcelona, Spain.,Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Spain
| | - Albert Blanco-Grau
- Neuromuscular and Mitochondrial Disorders Laboratory, Vall d'Hebron Research Institute, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Alejandro Lucia
- Universidad Europea, Madrid, Spain.,Instituto de Investigación 'i+12', Madrid, Spain
| | | | | | - Ramon Martí
- Neuromuscular and Mitochondrial Disorders Laboratory, Vall d'Hebron Research Institute, Universitat Autònoma de Barcelona, Barcelona, Spain.,Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Spain
| | - Antoni L Andreu
- Neuromuscular and Mitochondrial Disorders Laboratory, Vall d'Hebron Research Institute, Universitat Autònoma de Barcelona, Barcelona, Spain.,Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Spain
| | - Tomàs Pinós
- Neuromuscular and Mitochondrial Disorders Laboratory, Vall d'Hebron Research Institute, Universitat Autònoma de Barcelona, Barcelona, Spain.,Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Spain
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29
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Rat skeletal muscle glycogen degradation pathways reveal differential association of glycogen-related proteins with glycogen granules. J Physiol Biochem 2015; 71:267-80. [PMID: 25875859 DOI: 10.1007/s13105-015-0407-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 03/23/2015] [Indexed: 10/23/2022]
Abstract
Glycogenin, glycogen-debranching enzyme (GDE) and glycogen phosphorylase (GP) are important enzymes that contribute to glycogen particle metabolism. In Long-Evans Hooded rat whole muscle homogenates prepared from extensor digitorum longus (EDL, fast-twitch) and soleus (SOL, oxidative, predominantly slow twitch), it was necessary to include α-amylase, which releases glucosyl units from glycogen, to detect glycogenin but not GDE or GP. Up to ∼12 % of intramuscular glycogen pool was broken down using either in vitro electrical stimulation or leaving muscle at room temperature >3 h (delayed, post-mortem). Electrical stimulation did not reveal glycogenin unless α-amylase was added, although in post-mortem muscle ∼50 and ∼30 % of glycogenin in EDL and SOL muscles, respectively, was detected compared to the amount detected with α-amylase treatment. Single muscle fibres were dissected from fresh or post-mortem EDL muscles, mechanically skinned to remove surface membrane and the presence of glycogenin, GDE and GP as freely diffusible proteins (i.e. cytoplasmic localization) compared by Western blotting. Diffusibility of glycogenin (∼20 %) and GP (∼60 %) was not different between muscles, although GDE increased from ∼15 % diffusible in fresh muscle to ∼60 % in post-mortem muscle. Under physiologically relevant circumstances, in rat muscle and within detection limits: (1) The total cellular pool of glycogenin is always associated with glycogen granules, (2) GDE is associated with glycogen granules with over half the total pool associated with the outer tiers of glycogen, (3) GP is only ever weakly associated with glycogen granules and (4) addition of α-amylase is necessary in order to detect glycogenin, but not GDE or GP.
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30
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Affiliation(s)
- Raymond A Swanson
- Department of Neurology, University of California, San Francisco, CA, 94143, USA,
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31
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Neels JG, Grimaldi PA. Physiological functions of peroxisome proliferator-activated receptor β. Physiol Rev 2014; 94:795-858. [PMID: 24987006 DOI: 10.1152/physrev.00027.2013] [Citation(s) in RCA: 117] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The peroxisome proliferator-activated receptors, PPARα, PPARβ, and PPARγ, are a family of transcription factors activated by a diversity of molecules including fatty acids and fatty acid metabolites. PPARs regulate the transcription of a large variety of genes implicated in metabolism, inflammation, proliferation, and differentiation in different cell types. These transcriptional regulations involve both direct transactivation and interaction with other transcriptional regulatory pathways. The functions of PPARα and PPARγ have been extensively documented mainly because these isoforms are activated by molecules clinically used as hypolipidemic and antidiabetic compounds. The physiological functions of PPARβ remained for a while less investigated, but the finding that specific synthetic agonists exert beneficial actions in obese subjects uplifted the studies aimed to elucidate the roles of this PPAR isoform. Intensive work based on pharmacological and genetic approaches and on the use of both in vitro and in vivo models has considerably improved our knowledge on the physiological roles of PPARβ in various cell types. This review will summarize the accumulated evidence for the implication of PPARβ in the regulation of development, metabolism, and inflammation in several tissues, including skeletal muscle, heart, skin, and intestine. Some of these findings indicate that pharmacological activation of PPARβ could be envisioned as a therapeutic option for the correction of metabolic disorders and a variety of inflammatory conditions. However, other experimental data suggesting that activation of PPARβ could result in serious adverse effects, such as carcinogenesis and psoriasis, raise concerns about the clinical use of potent PPARβ agonists.
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Affiliation(s)
- Jaap G Neels
- Institut National de la Santé et de la Recherche Médicale U 1065, Mediterranean Center of Molecular Medicine (C3M), Team "Adaptive Responses to Immuno-metabolic Dysregulations," Nice, France; and Faculty of Medicine, University of Nice Sophia-Antipolis, Nice, France
| | - Paul A Grimaldi
- Institut National de la Santé et de la Recherche Médicale U 1065, Mediterranean Center of Molecular Medicine (C3M), Team "Adaptive Responses to Immuno-metabolic Dysregulations," Nice, France; and Faculty of Medicine, University of Nice Sophia-Antipolis, Nice, France
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32
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Jensen VFH, Mølck AM, Bøgh IB, Lykkesfeldt J. Effect of insulin-induced hypoglycaemia on the peripheral nervous system: focus on adaptive mechanisms, pathogenesis and histopathological changes. J Neuroendocrinol 2014; 26:482-96. [PMID: 24921897 DOI: 10.1111/jne.12170] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2014] [Revised: 05/22/2014] [Accepted: 06/05/2014] [Indexed: 12/31/2022]
Abstract
Insulin-induced hypoglycaemia (IIH) is a common acute side effect in type 1 and type 2 diabetic patients, especially during intensive insulin therapy. The peripheral nervous system (PNS) depends on glucose as its primary energy source during normoglycaemia and, consequently, it may be particularly susceptible to IIH damage. Possible mechanisms for adaption of the PNS to IIH include increased glucose uptake, utilisation of alternative energy substrates and the use of Schwann cell glycogen as a local glucose reserve. However, these potential adaptive mechanisms become insufficient when the hypoglycaemic state exceeds a certain level of severity and duration, resulting in a sensory-motor neuropathy with associated skeletal muscle atrophy. Large myelinated motor fibres appear to be particularly vulnerable. Thus, although the PNS is not an obligate glucose consumer, as is the brain, it appears to be more prone to IIH than the central nervous system when hypoglycaemia is not severe (blood glucose level ≤ 2 mm), possibly reflecting a preferential protection of the brain during periods of inadequate glucose availability. With a primary focus on evidence from experimental animal studies investigating nondiabetic IIH, the present review discusses the effect of IIH on the PNS with a focus on adaptive mechanisms, pathogenesis and histological changes.
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Affiliation(s)
- V F H Jensen
- Department of Veterinary Disease, Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Department of Diabetes Toxicology and Safety Pharmacology, Novo Nordisk A/S, Maaloev, Denmark
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Watanabe K, Taniguchi Y, Moritani T. Metabolic and cardiovascular responses during voluntary pedaling exercise with electrical muscle stimulation. Eur J Appl Physiol 2014; 114:1801-7. [PMID: 24867595 DOI: 10.1007/s00421-014-2906-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Accepted: 05/03/2014] [Indexed: 11/26/2022]
Abstract
PURPOSE We aimed to test the effect of additional electrical muscle stimulation (EMS) during moderate-intensity voluntary pedaling exercise on metabolic and cardiovascular responses. METHODS Eleven healthy male subjects performed moderate-intensity pedaling exercise at a constant workload (80% of ventilatory threshold) for 20 min while EMS was applied to thigh muscles from 5 to 10 min and from 15 to 20 min during the exercise. RESULTS A significantly higher oxygen uptake (VO₂), heart rate, and respiratory gas exchange ratio were observed during the exercise periods with EMS despite the constant workload. These changes were accompanied by an elevated blood lactate concentration, suggesting the existence of additional fast-twitch motor unit (MU) recruitment during the exercise with EMS. CONCLUSION Our data suggest that the use of intermittent EMS during a constant load exercise mimics the high-intensity interval training, possibly due to additional fast-twitch MU recruitment and co-contractions of the quadriceps and hamstrings muscles, leading to higher anaerobic metabolism and a lower mechanical efficiency.
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Affiliation(s)
- Kohei Watanabe
- School of International Liberal Studies, Chukyo University, Nagoya, Japan,
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Noninvasive monitoring of training induced muscle adaptation with 31P-MRS: fibre type shifts correlate with metabolic changes. BIOMED RESEARCH INTERNATIONAL 2013; 2013:417901. [PMID: 23998123 PMCID: PMC3749530 DOI: 10.1155/2013/417901] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 06/02/2013] [Accepted: 06/11/2013] [Indexed: 11/23/2022]
Abstract
Purpose. To evaluate training induced metabolic changes noninvasively with 31P magnetic resonance spectroscopy (31P-MRS) for measuring muscle fibre type adaptation.
Methods. Eleven volunteers underwent a 24-week training, consisting of speed-strength, endurance, and detraining (each 8 weeks). Prior to and following each training period, needle biopsies and 31P-MRS of the resting gastrocnemius muscle were performed. Fibre type distribution was analyzed histologically and tested for correlation with the ratios of high energy phosphates ([PCr]/[Pi], [PCr]/[βATP] and [PCr + Pi]/[βATP]). The correlation between the changes of the 31P-MRS parameters during training and the resulting changes in fibre composition were also analysed. Results. We observed an increased type-II-fibre proportion after speed-strength and detraining. After endurance training the percentage of fast-twitch fibres was reduced. The progression of the [PCr]/[Pi]-ratio was similar to that of the fast-twitch fibres during the training. We found a correlation between the type-II-fibre proportion and [PCr]/[Pi] (r = 0.70, P < 0.01) or [PCr]/[βATP] (r = 0.69, P < 0.01); the correlations between its changes (delta) and the fibre-shift were significant as well (delta[PCr]/[Pi] r = 0.66, delta[PCr]/[βATP] r = 0.55, P < 0.01). Conclusion. Shifts in fibre type composition and high energy phosphate metabolite content covary in human gastrocnemius muscle. Therefore 31P-MRS might be a feasible method for noninvasive monitoring of exercise-induced fibre type transformation.
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35
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Fredsted A, Gissel H, Ortenblad N, Clausen T. Effects of β₂-agonists on force during and following anoxia in rat extensor digitorum longus muscle. J Appl Physiol (1985) 2012; 112:2057-67. [PMID: 22492937 DOI: 10.1152/japplphysiol.01558.2011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Electrical stimulation of isolated muscles may lead to membrane depolarization, gain of Na(+), loss of K(+) and fatigue. These effects can be counteracted with β(2)-agonists possibly via activation of the Na(+)-K(+) pumps. Anoxia induces loss of force; however, it is not known whether β(2)-agonists affect force and ion homeostasis in anoxic muscles. In the present study isolated rat extensor digitorum longus (EDL) muscles exposed to anoxia showed a considerable loss of force, which was markedly reduced by the β(2)-agonists salbutamol (10(-6) M) and terbutaline (10(-6) M). Intermittent stimulation (15-30 min) clearly increased loss of force during anoxia and reduced force recovery during reoxygenation. The β(2)-agonists salbutamol (10(-7)-10(-5) M) and salmeterol (10(-6) M) improved force development during anoxia (25%) and force recovery during reoxygenation (55-262%). The effects of salbutamol on force recovery were prevented by blocking the Na(+)-K(+) pumps with ouabain or by blocking glycolysis with 2-deoxyglucose. Dibutyryl cAMP (1 mM) or theophylline (1 mM) also improved force recovery remarkably. In anoxic muscles, salbutamol decreased intracellular Na(+) and increased (86)Rb uptake and K(+) content, indicating stimulation of the Na(+)-K(+) pumps. In fatigued muscles salbutamol induced recovery of excitability. Thus β(2)-agonists reduce the anoxia-induced loss of force, leading to partial force recovery. These data strongly suggest that this effect is mediated by cAMP stimulation of the Na(+)-K(+) pumps and that it is not related to recovery of energy status (PCr, ATP, lactate).
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Affiliation(s)
- A Fredsted
- Department of Biomedicine, Aarhus University, Denmark.
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Abstract
Mammalian skeletal muscle comprises different fiber types, whose identity is first established during embryonic development by intrinsic myogenic control mechanisms and is later modulated by neural and hormonal factors. The relative proportion of the different fiber types varies strikingly between species, and in humans shows significant variability between individuals. Myosin heavy chain isoforms, whose complete inventory and expression pattern are now available, provide a useful marker for fiber types, both for the four major forms present in trunk and limb muscles and the minor forms present in head and neck muscles. However, muscle fiber diversity involves all functional muscle cell compartments, including membrane excitation, excitation-contraction coupling, contractile machinery, cytoskeleton scaffold, and energy supply systems. Variations within each compartment are limited by the need of matching fiber type properties between different compartments. Nerve activity is a major control mechanism of the fiber type profile, and multiple signaling pathways are implicated in activity-dependent changes of muscle fibers. The characterization of these pathways is raising increasing interest in clinical medicine, given the potentially beneficial effects of muscle fiber type switching in the prevention and treatment of metabolic diseases.
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Affiliation(s)
- Stefano Schiaffino
- Venetian Institute of Molecular Medicine, Department of Biomedical Sciences, University of Padova, Consiglio Nazionale delle Ricerche Institute of Neurosciences, and Department of Human Anatomy and Physiology, University of Padova, Padova, Italy
| | - Carlo Reggiani
- Venetian Institute of Molecular Medicine, Department of Biomedical Sciences, University of Padova, Consiglio Nazionale delle Ricerche Institute of Neurosciences, and Department of Human Anatomy and Physiology, University of Padova, Padova, Italy
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Wildman R, Kerksick C, Campbell B. Carbohydrates, Physical Training, and Sport Performance. Strength Cond J 2010. [DOI: 10.1519/ssc.0b013e3181bdb161] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Gray SR, Söderlund K, Ferguson RA. ATP and phosphocreatine utilization in single human muscle fibres during the development of maximal power output at elevated muscle temperatures. J Sports Sci 2008; 26:701-7. [PMID: 18409101 DOI: 10.1080/02640410701744438] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
In this study, we examined the effect of muscle temperature (Tm) on adenosine triphosphate (ATP) and phosphocreatine utilization in single muscle fibres during the development of maximal power output in humans. Six male participants performed a 6-s maximal sprint on a friction-braked cycle ergometer under both normal (Tm = 34.3 degrees C, s = 0.6) and elevated (T(m) = 37.3 degrees C, s = 0.2) muscle temperature conditions. During the elevated condition, muscle temperature of the legs was raised, passively, by hot water immersion followed by wrapping in electrically heated blankets. Muscle biopsies were taken from the vastus lateralis before and immediately after exercise. Freeze-dried single fibres were dissected, characterized according to myosin heavy chain composition, and analysed for ATP and phosphocreatine content. Single fibres were classified as: type I, IIA, IIAX25 (1 - 25% IIX isoform), IIAX50 (26 - 50% IIX), IIAX75 (51 - 75% IIX), or IIAX100 (76 - 100% IIX). Maximal power output and pedal rate were both greater (P < 0.05) during the elevated condition by 258 W (s = 110) and 22 rev . min(-1) (s = 6), respectively. In both conditions, phosphocreatine content decreased significantly in all fibre types, with a greater decrease during the elevated condition in type IIA fibres (P < 0.01). Adenosine triphosphate content was also reduced to a greater (P < 0.01) extent in type IIA fibres during the elevated condition. The results of the present study indicate that after passive elevation of muscle temperature, there was a greater decrease in ATP and phosphocreatine content in type IIA fibres than in the normal trial, which contributed to the higher maximal power output.
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Affiliation(s)
- Stuart R Gray
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
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Cook SB, Clark BC, Ploutz-Snyder LL. Effects of exercise load and blood-flow restriction on skeletal muscle function. Med Sci Sports Exerc 2008; 39:1708-13. [PMID: 17909396 DOI: 10.1249/mss.0b013e31812383d6] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
UNLABELLED Resistance training at low loads with blood flow restriction (BFR) (also known as Kaatsu) has been shown to stimulate increases in muscle size and strength. It is unclear how occlusion pressure, exercise intensity, and occlusion duration interact, or which combination of these factors results in the most potent muscle stimulus. PURPOSE To determine the effect of eight BFR protocols on muscle fatigue (decrement in maximal voluntary contraction (MVC) after the performance of exercise), and to compare the decrement in MVC with the currently recommended resistance exercise intensity (~80% MVC). METHODS During five test sessions, 21 subjects (14 males and 7 females, 27.7 +/- 4.9 yr) completed nine protocols, each consisting of three sets of knee extensions (KE) to failure. One protocol was high-load (HL) exercise (80% MVC) with no BFR, and the other eight were BFR at varying levels of contraction intensity (20 or 40% MVC), occlusion pressure (partial (~160 mm Hg) or complete (~300 mm Hg)), and occlusion duration (off during the rest between sets or continuously applied). To evaluate each protocol, MVC were performed before and after exercise, and the decrement in force was calculated. RESULTS Three sets of KE at 20% MVC with continuous partial occlusion (20%(ConPar)) resulted in a greater decrement in MVC compared with HL (31 vs 19%, P = 0.001). None of the other BFR protocols were different from the HL protocol, nor were they different from 20%(ConPar) (P > 0.05). CONCLUSION All BFR protocols elicited at least as much fatigue as HL, even though lower loads were used. The 20%(ConPar) protocol was the only one that elicited significantly more fatigue than HL. Future research should evaluate protocol training effectiveness and overall safety of BFR exercise.
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Affiliation(s)
- Summer B Cook
- Musculoskeletal Research Laboratory, Department of Exercise Science, Syracuse University, Syracuse, NY 13244-5040, USA.
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Abstract
Repeated, intense use of muscles leads to a decline in performance known as muscle fatigue. Many muscle properties change during fatigue including the action potential, extracellular and intracellular ions, and many intracellular metabolites. A range of mechanisms have been identified that contribute to the decline of performance. The traditional explanation, accumulation of intracellular lactate and hydrogen ions causing impaired function of the contractile proteins, is probably of limited importance in mammals. Alternative explanations that will be considered are the effects of ionic changes on the action potential, failure of SR Ca2+release by various mechanisms, and the effects of reactive oxygen species. Many different activities lead to fatigue, and an important challenge is to identify the various mechanisms that contribute under different circumstances. Most of the mechanistic studies of fatigue are on isolated animal tissues, and another major challenge is to use the knowledge generated in these studies to identify the mechanisms of fatigue in intact animals and particularly in human diseases.
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Wernbom M, Augustsson J, Thomeé R. The influence of frequency, intensity, volume and mode of strength training on whole muscle cross-sectional area in humans. Sports Med 2007; 37:225-64. [PMID: 17326698 DOI: 10.2165/00007256-200737030-00004] [Citation(s) in RCA: 331] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Strength training is an important component in sports training and rehabilitation. Quantification of the dose-response relationships between training variables and the outcome is fundamental for the proper prescription of resistance training. The purpose of this comprehensive review was to identify dose-response relationships for the development of muscle hypertrophy by calculating the magnitudes and rates of increases in muscle cross-sectional area induced by varying levels of frequency, intensity and volume, as well as by different modes of strength training. Computer searches in the databases MEDLINE, SportDiscus and CINAHL were performed as well as hand searches of relevant journals, books and reference lists. The analysis was limited to the quadriceps femoris and the elbow flexors, since these were the only muscle groups that allowed for evaluations of dose-response trends. The modes of strength training were classified as dynamic external resistance (including free weights and weight machines), accommodating resistance (e.g. isokinetic and semi-isokinetic devices) and isometric resistance. The subcategories related to the types of muscle actions used. The results demonstrate that given sufficient frequency, intensity and volume of work, all three types of muscle actions can induce significant hypertrophy at an impressive rate and that, at present, there is insufficient evidence for the superiority of any mode and/or type of muscle action over other modes and types of training. Tentative dose-response relationships for each variable are outlined, based on the available evidence, and interactions between variables are discussed. In addition, recommendations for training and suggestions for further research are given.
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Affiliation(s)
- Mathias Wernbom
- mLundberg Laboratory for Human Muscle Function and Movement Analysis, Department of Orthopaedics, Sahlgrenska University Hospital, Göteborg University, Göteborg, Sweden.
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Lanza IR, Wigmore DM, Befroy DE, Kent-Braun JA. In vivo ATP production during free-flow and ischaemic muscle contractions in humans. J Physiol 2006; 577:353-67. [PMID: 16945975 PMCID: PMC2000678 DOI: 10.1113/jphysiol.2006.114249] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The aim of this study was to determine how ATP synthesis and contractility in vivo are altered by ischaemia in working human skeletal muscle. The hypotheses were: (1) glycolytic flux would be higher during ischaemic (ISC) compared to free-flow (FF) muscle contractions, in compensation for reduced oxidative ATP synthesis, and (2) ischaemic muscle fatigue would be related to the accumulation of inhibitory metabolic by-products rather than to the phosphorylation potential ([ATP]/[ADP][P(i)]) of the muscle. Twelve healthy adults (6 men, 6 women) performed six intermittent maximal isometric contractions of the ankle dorsiflexors (12 s contract, 12 s relax), once with intact blood flow and once with local ischaemia by thigh cuff inflation to 220 Torr. Intracellular phosphorous metabolites and pH were measured non-invasively with magnetic resonance spectroscopy, and rates of ATP synthesis through oxidative phosphorylation, anaerobic glycolysis, and the creatine kinase reaction were determined. The force-time integral declined more during ISC (66 +/- 3% initial) than FF (75 +/- 2% initial, P = 0.002), indicating greater fatigue in ISC. [ATP] was preserved in both protocols, indicating matching of ATP production and use under both conditions. Glycolytic flux (mm s(-1)) was similar during FF and ISC (P = 0.16). Total ATP synthesis rate was lower during ISC, despite adjustment for the greater muscle fatigue in this condition (P < 0.001). Fatigue was linearly associated with diprotonated inorganic phosphate (FF r = 0.94 +/- 0.01, ISC r = 0.92 +/- 0.02), but not phosphorylation potential. These data provide novel evidence that ATP supply and demand in vivo are balanced in human skeletal muscle during ischaemic work, not through higher glycolytic flux, but rather through increased metabolic economy and decreased rates of ATP consumption as fatigue ensues.
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Affiliation(s)
- Ian R Lanza
- Kinesiology Department, Totman 108, University of Massachusetts, Amherst, MA 01003, USA
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Field ML, Khan O, Abbaraju J, Clark JF. Functional compartmentation of glycogen phosphorylase with creatine kinase and Ca2+ATPase in skeletal muscle. J Theor Biol 2006; 238:257-68. [PMID: 16005021 DOI: 10.1016/j.jtbi.2005.05.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2004] [Revised: 03/16/2005] [Accepted: 05/11/2005] [Indexed: 11/28/2022]
Abstract
This manuscript discusses aspects of functional compartmentation in the regulation of metabolism. The functional consequences of enzymes coupling between creatine kinase, glycogen phosphorylase and sarcoplasmic reticular Ca2+ ATPase is examined. It is proposed that the coupling of creatine kinase and glycogen phosphorylase classifies as a novel class of diazyme complex with an important regulatory role in the inhibition of glycogenolysis at rest. In addition it is suggested that creatine kinase, glycogen phosphorylase and the sarcoplasmic reticular Ca2+ ATPase may couple to form a three-enzyme complex. From a consideration of the structure and chemical catalysis of the putative three-enzyme complex, a novel net reaction for glycogenolysis in the vicinity of the sarcoplasmic reticulum is suggested (Phosphocreatine+Glycogen+H(+)Creatine+Glycogen(n)(-1)+Glucose-1-Phosphate). The three-enzyme complex may also have an important role in inhibiting glycogenolysis at rest as well as improving the efficiency of high-energy phosphate transfer.
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Affiliation(s)
- Mark L Field
- The Cardiothoracic Centre, Thomas Drive, Liverpool L14 3PE, UK.
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Gustafsson T, Ameln H, Fischer H, Sundberg CJ, Timmons JA, Jansson E. VEGF-A splice variants and related receptor expression in human skeletal muscle following submaximal exercise. J Appl Physiol (1985) 2005; 98:2137-46. [PMID: 15661835 DOI: 10.1152/japplphysiol.01402.2004] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
VEGF-A contributes to muscle tissue angiogenesis following aerobic exercise training. The temporal response of the VEGF-A isoforms and their target receptors has not been comprehensively profiled in human skeletal muscle. We combined submaximal exercise with and without reduced leg blood flow to establish whether ischemia-induced metabolic stress was an important physiological stimuli responsible for regulating the VEGF-A system in humans. Nine healthy men performed two 45-min bouts of one-leg knee-extension exercise, with and without blood flow restriction. Muscle biopsies were obtained at rest and 2 and 6 h after exercise. Expression (mRNA) of the VEGF-A splice variants and related receptors [VEGF receptor (VEGFR)-1, VEGFR-2, and neuropilin-1] was determined by using qPCR. VEGF-A(total) expression increased more robustly after exercise with reduced blood flow, and initially this principally reflected an increase in VEGF-A(165). Six hours after exercise, there was a relatively greater increase in VEGF-A(189), and this response was not influenced by blood flow conditions. VEGFR-1 mRNA expression increased 2 h after exercise, and neuropilin-1 expression was transiently reduced, while all three receptors increased by 6 h. There was no evidence for the expression of the inhibitory VEGF-A(165B) variant in human skeletal muscle. Our study, reflecting both VEGF-A ligand and receptors, implicates metabolic perturbation as a regulator of human muscle angiogenesis and demonstrates that VEGF-A splice variants are distinctly regulated. Our findings also indicate that all three receptor genes exhibit different pretranslational regulation, in response to exercise in humans.
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Affiliation(s)
- T Gustafsson
- Karolinska Institute, Berzelius Väg 35, Stockholm 171 77, Sweden
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Hamada T, Kimura T, Moritani T. Selective fatigue of fast motor units after electrically elicited muscle contractions. J Electromyogr Kinesiol 2004; 14:531-8. [PMID: 15301772 DOI: 10.1016/j.jelekin.2004.03.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2003] [Revised: 03/02/2004] [Accepted: 03/18/2004] [Indexed: 10/26/2022] Open
Abstract
The aim of the present study was to elucidate the electrophysiological manifestations of selective fast motor unit (MU) activation by electrical stimulation (ES) of knee extensor muscles. In six male subjects, test contraction measurement at 40% maximal voluntary contraction (MVC) was performed before and at every 5 min (5, 10, 15 and 20 min) during 20-min low intensity intermittent exercise of either ES or voluntary contractions (VC) at 10% MVC (5-s isometric contraction and 5-s rest cycles). Both isolated intramuscular MU spikes obtained from three sets of bipolar fine-wire electrodes and surface electromyogram (EMG) were simultaneously recorded and were analyzed by means of a computer-aided intramuscular spike amplitude-frequency analysis and frequency power spectral analysis, respectively. Results indicated that mean MU spike amplitude, particularly those MUs with relatively large amplitude, was significantly reduced while those MUs with small spike amplitude increased their firing rate during the 40% MVC test contraction after the ES. This was accompanied by the increased amplitude of surface EMG (rmsEMG). However, no such significant changes in the intramuscular and surface EMGs were observed after VC. These findings indicated differential MU activation patterns in terms of MU recruitment and rate coding characteristics during ES and VC, respectively. Our data strongly suggest the possibility of "an inverse size principle" of MU recruitment during ES.
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Affiliation(s)
- Taku Hamada
- Laboratory of Applied Physiology, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan
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Hamada T, Hayashi T, Kimura T, Nakao K, Moritani T. Electrical stimulation of human lower extremities enhances energy consumption, carbohydrate oxidation, and whole body glucose uptake. J Appl Physiol (1985) 2004; 96:911-6. [PMID: 14594864 DOI: 10.1152/japplphysiol.00664.2003] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Our laboratory has recently demonstrated that low-frequency electrical stimulation (ES) of quadriceps muscles alone significantly enhanced glucose disposal rate (GDR) during euglycemic clamp (Hamada T, Sasaki H, Hayashi T, Moritani T, and Nakao K. J Appl Physiol 94: 2107–2112, 2003). The present study is further follow-up to examine the acute metabolic effects of ES to lower extremities compared with voluntary cycle exercise (VE) at identical intensity. In eight male subjects lying in the supine position, both lower leg (tibialis anterior and triceps surae) and thigh (quadriceps and hamstrings) muscles were sequentially stimulated to cocontract in an isometric manner at 20 Hz with a 1-s on-off duty cycle for 20 min. Despite small elevation of oxygen uptake by 7.3 ± 0.3 ml·kg-1·min-1 during ES, the blood lactate concentration was significantly increased by 3.2 ± 0.3 mmol/l in initial period (5 min) after the onset of the ES ( P < 0.01), whereas VE showed no such changes at identical oxygen uptake (7.5 ± 0.3 ml·kg-1·min-1). ES also induced enhanced whole body carbohydrate oxidation as shown by the significantly higher respiratory gas exchange ratio than with VE ( P < 0.01). These data indicated increased anaerobic glycolysis by ES. Furthermore, whole body glucose uptake determined by GDR during euglycemic clamp demonstrated a significant increase during and after the cessation of ES for at least 90 min ( P < 0.01). This post-ES effect was significantly greater than that of the post-VE period ( P < 0.01). These results suggest that ES can substantially enhance energy consumption, carbohydrate oxidation, and whole body glucose uptake at low intensity of exercise. Percutaneous ES may become a therapeutic utility to enhance glucose metabolism in humans.
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Affiliation(s)
- Taku Hamada
- Laboratory of Applied Physiology, Graduate School of Human and Environmental Studies, Kyoto University, Japan
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Darques JL, Bendahan D, Roussel M, Giannesini B, Tagliarini F, Le Fur Y, Cozzone PJ, Jammes Y. Combined in situ analysis of metabolic and myoelectrical changes associated with electrically induced fatigue. J Appl Physiol (1985) 2003; 95:1476-84. [PMID: 12819224 DOI: 10.1152/japplphysiol.00230.2003] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Electrical muscle stimulation (Mstim) at a low or high frequency is associated with failure of force production, but the exact mechanisms leading to fatigue in this model are still poorly understood. Using 31P magnetic resonance spectroscopy (31PMRS), we investigated the metabolic changes in rabbit tibialis anterior muscle associated with the force decline during Mstim at low (10 Hz) and high (100 Hz) frequency. We also simultaneously recorded the compound muscle mass action potential (M-wave) evoked by direct muscle stimulation, and we analyzed its post-Mstim variations. The 100-Hz Mstim elicited marked M-wave alterations and induced mild metabolic changes at the onset of stimulation followed by a paradoxical recovery of phosphocreatine (PCr) and pH during the stimulation period. On the contrary, the 10-Hz Mstim produced significant PCr consumption and intracellular acidosis with no paradoxical recovery phenomenon and no significant changes in M-wave characteristics. In addition, the force depression was linearly linked to the stimulation-induced acidosis and PCr breakdown. These results led us to conclude that force failure during 100-Hz Mstim only results from an impaired propagation of muscle action potentials with no metabolic involvement. On the contrary, fatigue induced by 10-Hz Mstim is closely associated with metabolic changes with no alteration of the membrane excitability, thereby underlining the central role of muscle energetics in force depression when muscle is stimulated at low frequency. Finally, our results further indicate a reduction of energy cost of contraction when stimulation frequency is increased from 10 to 100 Hz.
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Affiliation(s)
- J L Darques
- Laboratoire de Physiopathologie Respiratoire, UPRES EA 2201, Institut Jean Roche, Faculté de Médecine, Université de la Méditerranée, Bd Pierre Dramard, 13916 Marseille Cedex 20, France.
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Rico-Sanz J. Progressive decrease of intramyocellular accumulation of H+ and Pi in human skeletal muscle during repeated isotonic exercise. Am J Physiol Cell Physiol 2003; 284:C1490-6. [PMID: 12570984 DOI: 10.1152/ajpcell.00419.2002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The purpose of this study was to evaluate the hypotheses that accumulation of hydrogen ions and/or inorganic phosphate (Pi) in skeletal muscle increases with repeated bouts of isotonic exercise. (31)P-Magnetic resonance spectroscopy was used to examine the gastrocnemius muscle of seven highly aerobically trained females during four bouts of isotonic plantar flexion. The exercise bouts (EX1-4) of 3 min and 18 s were separated by 3 min and 54 s of complete rest. Muscle ATP did not change during the four bouts. Phosphocreatine (PCr) degradation during EX1 (13.3 +/- 2.4 mmol/kg wet weight) was higher (P < 0.01) compared with EX3-4 (9.7 +/- 1.6 and 9.6 +/- 1.8 mmol/kg wet weight, respectively). The intramyocellular pH at the end of EX1 (6.87 +/- 0.05) was significantly lower (P < 0.001) than those of EX2 (6.97 +/- 0.02), EX3 (7.02 +/- 0.01), and EX4 (7.02 +/- 0.02). Total Pi and diprotonated Pi were significantly higher (P < 0.001) at the end of EX1 (17.3 +/- 2.7 and 7.8 +/- 1.6 mmol/kg wet weight, respectively) compared with the values at the end of EX3 and EX4. The monoprotonated Pi at the end of EX1 (9.5 +/- 1.2 mmol/kg wet weight) was also significantly higher (P < 0.001) than that after EX4 (7.5 +/- 1.1 mmol/kg wet weight). Subjects' rating of perceived exertion increased (P < 0.001) toward exhaustion as the number of exercises progressed (7.1 +/- 0.4, EX1; 8.0 +/- 0.3, EX2; 8.5 +/- 0.3, EX3; and 9.0 +/- 0.4, EX4; scale from 0 to 10). The present results indicate that human muscle fatigue during repeated intense isotonic exercise is not due to progressive depletion of high energy phosphates nor to intracellular accumulation of hydrogen ions, total, mono-, or diprotonated Pi.
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Affiliation(s)
- J Rico-Sanz
- Copenhagen Muscle Research Center, The Panum Institute, University of Copenhagen, Copenhagen DK-2100, Denmark.
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