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Feldpausch JE, Blok AL, Frederick EL, Coburn JW, Malek MH. The Evolution of the Physical Work Capacity at the Fatigue Threshold Test: Past, Present, and Future. J Strength Cond Res 2021; 35:3529-3536. [PMID: 34570058 DOI: 10.1519/jsc.0000000000004124] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
ABSTRACT Feldpausch, JE, Blok, AL, Frederick, EL, Coburn, JW, and Malek, MH. The evolution of the physical work capacity at the fatigue threshold test: past, present, and future. J Strength Cond Res 35(12): 3529-3536, 2021-The assessment of neuromuscular fatigue using surface electromyography has evolved over the past 40 years while maintaining some of the original key features. In this mini-review article, the goal will be to briefly present a history and systems of the physical working capacity at the fatigue threshold (PWCFT). In addition, we will discuss studies that have investigated the effect of different interventions such as supplementation, exercise, and cognitive fatigue to examine what stimuli influence the PWCFT. The latter section of this mini-review will discuss future studies that may provide additional information related to the underlying physiological mechanism(s) that influences the PWCFT. We will conclude with the practical application of PWCFT in health and sports settings.
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Affiliation(s)
- Jennie E Feldpausch
- Physical Therapy Program, Department of Health Care Sciences, College of Pharmacy and Health Sciences, Wayne State University, Detroit, Michigan
- Integrative Physiology of Exercise Laboratory, Department of Health Care Sciences, College of Pharmacy and Health Sciences, Wayne State University, Detroit, Michigan; and
| | - Amanda L Blok
- Physical Therapy Program, Department of Health Care Sciences, College of Pharmacy and Health Sciences, Wayne State University, Detroit, Michigan
- Integrative Physiology of Exercise Laboratory, Department of Health Care Sciences, College of Pharmacy and Health Sciences, Wayne State University, Detroit, Michigan; and
| | - Emily L Frederick
- Physical Therapy Program, Department of Health Care Sciences, College of Pharmacy and Health Sciences, Wayne State University, Detroit, Michigan
- Integrative Physiology of Exercise Laboratory, Department of Health Care Sciences, College of Pharmacy and Health Sciences, Wayne State University, Detroit, Michigan; and
| | - Jared W Coburn
- Department of Kinesiology, California State University, Fullerton, California
| | - Moh H Malek
- Physical Therapy Program, Department of Health Care Sciences, College of Pharmacy and Health Sciences, Wayne State University, Detroit, Michigan
- Integrative Physiology of Exercise Laboratory, Department of Health Care Sciences, College of Pharmacy and Health Sciences, Wayne State University, Detroit, Michigan; and
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Hostrup M, Cairns SP, Bangsbo J. Muscle Ionic Shifts During Exercise: Implications for Fatigue and Exercise Performance. Compr Physiol 2021; 11:1895-1959. [PMID: 34190344 DOI: 10.1002/cphy.c190024] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Exercise causes major shifts in multiple ions (e.g., K+ , Na+ , H+ , lactate- , Ca2+ , and Cl- ) during muscle activity that contributes to development of muscle fatigue. Sarcolemmal processes can be impaired by the trans-sarcolemmal rundown of ion gradients for K+ , Na+ , and Ca2+ during fatiguing exercise, while changes in gradients for Cl- and Cl- conductance may exert either protective or detrimental effects on fatigue. Myocellular H+ accumulation may also contribute to fatigue development by lowering glycolytic rate and has been shown to act synergistically with inorganic phosphate (Pi) to compromise cross-bridge function. In addition, sarcoplasmic reticulum Ca2+ release function is severely affected by fatiguing exercise. Skeletal muscle has a multitude of ion transport systems that counter exercise-related ionic shifts of which the Na+ /K+ -ATPase is of major importance. Metabolic perturbations occurring during exercise can exacerbate trans-sarcolemmal ionic shifts, in particular for K+ and Cl- , respectively via metabolic regulation of the ATP-sensitive K+ channel (KATP ) and the chloride channel isoform 1 (ClC-1). Ion transport systems are highly adaptable to exercise training resulting in an enhanced ability to counter ionic disturbances to delay fatigue and improve exercise performance. In this article, we discuss (i) the ionic shifts occurring during exercise, (ii) the role of ion transport systems in skeletal muscle for ionic regulation, (iii) how ionic disturbances affect sarcolemmal processes and muscle fatigue, (iv) how metabolic perturbations exacerbate ionic shifts during exercise, and (v) how pharmacological manipulation and exercise training regulate ion transport systems to influence exercise performance in humans. © 2021 American Physiological Society. Compr Physiol 11:1895-1959, 2021.
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Affiliation(s)
- Morten Hostrup
- Section of Integrative Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Simeon Peter Cairns
- SPRINZ, School of Sport and Recreation, Auckland University of Technology, Auckland, New Zealand.,Health and Rehabilitation Research Institute, Auckland University of Technology, Auckland, New Zealand
| | - Jens Bangsbo
- Section of Integrative Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
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Low-Dose Ammonium Preconditioning Enhances Endurance in Submaximal Physical Exercises. Sports (Basel) 2021; 9:sports9020029. [PMID: 33669436 PMCID: PMC7920466 DOI: 10.3390/sports9020029] [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: 12/30/2020] [Revised: 02/07/2021] [Accepted: 02/10/2021] [Indexed: 11/17/2022] Open
Abstract
Preconditioning is often used in medicine to protect organs from ischemic damage and in athletes to enhance the performances. We tested whether low-dose ammonium preconditioning (AMP) could have a beneficial effect on physical exercises (PE). We used Cardiopulmonary Exercise Testing (CPET) on a treadmill to investigate the effects of low-dose AMP on the physical exercise capacity of professional track and field athletes and tested twenty-five athletes. Because of the individual differences between athletes, we performed a preliminary treadmill test (Pre-test) and, according to the results, the athletes were randomly allocated into the AMP and control (placebo, PL) group based on the similarity of the total distance covered on a treadmill. In the AMP group, the covered distance increased (11.3 ± 3.6%, p < 0.02) compared to Pre-test. Similarly, AMP significantly increased O2 uptake volume—VO2 (4.6 ± 2.3%, p < 0.03) and pulmonary CO2 output—VCO2 (8.7 ± 2.8%, p < 0.01). Further, the basic blood parameters (pH, pO2, and lactate) shift was lower despite the greater physical exercise progress in the AMP group compared to Pre-test, whereas in the placebo group there were no differences between Pre-test and Load-test. Importantly, the AMP significantly increased red blood cell count (6.8 ± 2.0%, p < 0.01) and hemoglobin concentration (5.3 ± 1.9%, p < 0.01), which might explain the beneficial effects in physical exercise progress. For the first time, we showed that low-dose AMP had clear beneficial effects on submaximal PE.
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Camic CL, Kovacs AJ, VanDusseldorp TA, Hill EC, Enquist EA. Application of the neuromuscular fatigue threshold treadmill test to muscles of the quadriceps and hamstrings. JOURNAL OF SPORT AND HEALTH SCIENCE 2020; 9:628-633. [PMID: 33308813 PMCID: PMC7749211 DOI: 10.1016/j.jshs.2017.06.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 03/28/2017] [Accepted: 04/28/2017] [Indexed: 06/12/2023]
Abstract
PURPOSE The purposes of the present study were: (1) to determine whether the physical working capacity at the fatigue threshold (PWCFT) model that has been used for estimating the onset of neuromuscular fatigue in the vastus lateralis (VL) during incremental treadmill running could also be applied to the vastus medialis (VM), biceps femoris (BF), and semitendinosus (ST) muscles; and (2) if applicable, to compare the running velocities associated with the PWCFT among these muscles. METHODS Eleven subjects (age 21.7 ± 1.8 years) performed an incremental treadmill test to exhaustion with electromyographic signals recorded from the VL, VM, BF, and ST. RESULTS The results indicated there were no significant (p > 0.05) mean differences in the running velocities associated with the PWCFT for the VL (14.4 ± 2.0 km/h), VM (14.3 ± 1.9 km/h), BF (13.8 ± 1.8 km/h), and ST (14.7 ± 2.3 km/h). In addition, there were significant inter-correlations (r = 0.68-0.88) among running velocities associated with the PWCFT of each muscle. Individual results also indicated that 9 of the 11 subjects exhibited identical PWCFT values for at least 3 of the 4 muscles, but there were no uniform patterns for any intra-individual differences. CONCLUSION The findings of the present study suggested that the PWCFT test is a viable method to identify neuromuscular fatigue in the quadriceps and hamstrings during incremental treadmill exercise and results in consistent PWCFT values among these muscles.
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Affiliation(s)
- Clayton L Camic
- Human Performance Laboratory, Exercise and Sport Science, University of Wisconsin-La Crosse, La Crosse, Wisconsin 54601, USA.
| | - Attila J Kovacs
- Human Performance Laboratory, Exercise and Sport Science, University of Wisconsin-La Crosse, La Crosse, Wisconsin 54601, USA
| | - Trisha A VanDusseldorp
- Department of Exercise Science and Sport Management, Kennesaw State University, Kennesaw, Georgia 30144, USA
| | - Ethan C Hill
- Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska 68583, USA
| | - Evan A Enquist
- Department of Kinesiology, University of Alabama, Tuscaloosa, Alabama 35487, USA
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Kalytczak MM, Barros BM, Battazza RA, Bocalini DS, Biasotto-Gonzalez DA, Figueira Junior AJ, Politti F. The Effect of Sodium Bicarbonate Supplementation on Electromyographic Muscle Activity in Healthy, Physically Active Individuals: A Systematic Review. J Diet Suppl 2020; 18:334-350. [PMID: 32449633 DOI: 10.1080/19390211.2020.1766633] [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: 10/24/2022]
Abstract
AIM The aim of this systematic review was to investigate the effects of sodium bicarbonate supplementation on electromyographic (EMG) muscle activity in healthy, physically active individuals. METHODS A systematic review of cross-sectional studies, crossover studies and randomized controlled trials was performed to investigate the effects of sodium bicarbonate supplementation on EMG muscle activity in healthy, physically active individuals. Potentially eligible for the systematic review were identified through searches conducted in the PubMed/MEDLINE, Science Direct and Scopus, considering publications from January 1980 to August 2019. The terms used in the search were: sodium bicarbonate, NaHCO3, alkalosis, alkaloses, electromyography, surface electromyography, electromyographies, electromyogram and EMG. Two independent assessors extracted data from the selected articles. Bias analysis was conducted using the Cochrane Risk of Bias tool and methodological quality was appraised using a checklist created based on the guidelines of the Consolidated Standards of Reporting Trials and the International Society of Electrophysiology and Kinesiology. RESULTS A total of 67 studies were retrieved and seven were included in this review. Only two studies showed significant differences in muscle activity after sodium bicarbonate supplementation. The different EMG signal capturing, processing, and analysis methods used constitute an important limitation to the comparative analyses of the results reported in the studies selected for the present review. CONCLUSION The results found do not allow us to affirm whether EMG may or may not be a safe tool to assess the effects of sodium bicarbonate supplementation on muscle activity.
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Affiliation(s)
| | - Bruna Massaroto Barros
- Postgraduate Program in Rehabilitation Sciences, Nove de Julho University, São Paulo, Brazil
| | | | - Danilo Sales Bocalini
- Postgraduate Program in Physical Education, University Federal do Espírito Santo (EFES), Espírito Santo, Brazil
| | | | | | - Fabiano Politti
- Postgraduate Program in Rehabilitation Sciences, Nove de Julho University, São Paulo, Brazil
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CORREIA-OLIVEIRA CARLOSRAFAELL, LOPES-SILVA JOÃOPAULO, BERTUZZI ROMULO, MCCONELL GLENNK, BISHOP DAVIDJOHN, LIMA-SILVA ADRIANOEDUARDO, KISS MARIAAUGUSTAPEDUTIDAL. Acidosis, but Not Alkalosis, Affects Anaerobic Metabolism and Performance in a 4-km Time Trial. Med Sci Sports Exerc 2017; 49:1899-1910. [DOI: 10.1249/mss.0000000000001295] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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Siegler JC, Marshall PWM, Bishop D, Shaw G, Green S. Mechanistic Insights into the Efficacy of Sodium Bicarbonate Supplementation to Improve Athletic Performance. SPORTS MEDICINE-OPEN 2016; 2:41. [PMID: 27747796 PMCID: PMC5059234 DOI: 10.1186/s40798-016-0065-9] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 09/20/2016] [Indexed: 01/13/2023]
Abstract
A large proportion of empirical research and reviews investigating the ergogenic potential of sodium bicarbonate (NaHCO3) supplementation have focused predominately on performance outcomes and only speculate about underlying mechanisms responsible for any benefit. The aim of this review was to critically evaluate the influence of NaHCO3 supplementation on mechanisms associated with skeletal muscle fatigue as it translates directly to exercise performance. Mechanistic links between skeletal muscle fatigue, proton accumulation (or metabolic acidosis) and NaHCO3 supplementation have been identified to provide a more targeted, evidence-based approach to direct future research, as well as provide practitioners with a contemporary perspective on the potential applications and limitations of this supplement. The mechanisms identified have been broadly categorised under the sections ‘Whole-body Metabolism’, ‘Muscle Physiology’ and ‘Motor Pathways’, and when possible, the performance outcomes of these studies contextualized within an integrative framework of whole-body exercise where other factors such as task demand (e.g. large vs. small muscle groups), cardio-pulmonary and neural control mechanisms may outweigh any localised influence of NaHCO3. Finally, the ‘Performance Applications’ section provides further interpretation for the practitioner founded on the mechanistic evidence provided in this review and other relevant, applied NaHCO3 performance-related studies.
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Affiliation(s)
- Jason C Siegler
- School of Science and Health, Sport and Exercise Science, Western Sydney University, Locked Bag 1792, Penrith, NSW, Australia.
| | - Paul W M Marshall
- School of Science and Health, Sport and Exercise Science, Western Sydney University, Locked Bag 1792, Penrith, NSW, Australia
| | - David Bishop
- Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Melbourne, Australia
| | - Greg Shaw
- Australian Institute of Sport, Canberra, Australia
| | - Simon Green
- School of Science and Health, Sport and Exercise Science, Western Sydney University, Locked Bag 1792, Penrith, NSW, Australia.,School of Medicine, Western Sydney University, Sydney, Australia
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Zak RB, Camic CL, Hill EC, Monaghan MM, Kovacs AJ, Wright GA. Acute effects of an arginine-based supplement on neuromuscular, ventilatory, and metabolic fatigue thresholds during cycle ergometry. Appl Physiol Nutr Metab 2014; 40:379-85. [PMID: 25781198 DOI: 10.1139/apnm-2014-0379] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The purpose of the present study was to examine the effects of an acute dose of an arginine-based supplement on the physical working capacity at the fatigue threshold (PWCFT), lactate threshold (LT), ventilatory threshold (VT), and peak oxygen uptake during incremental cycle ergometry. This study used a double-blinded, placebo-controlled, within-subjects crossover design. Nineteen untrained men (mean age ± SD = 22.0 ± 1.7 years) were randomly assigned to ingest either the supplement (3.0 g of arginine, 300 mg of grape seed extract, and 300 mg of polyethylene glycol) or placebo (microcrystalline cellulose) and performed an incremental test on a cycle ergometer for determination of PWCFT, LT, VT, and peak oxygen uptake. Following a 1-week period, the subjects returned to the laboratory and ingested the opposite substance (either supplement or placebo) prior to completing another incremental test to be reassessed for PWCFT, LT, VT, and peak oxygen uptake. The paired-samples t tests indicated there were significant (P < 0.05) mean differences between the arginine and placebo conditions for the PWCFT (192 ± 42 vs. 168 ± 53 W, respectively) and VT (2546 ± 313 vs. 2452 ± 342 mL·min(-1)), but not the LT (135 ± 26 vs. 138 ± 22 W), absolute peak oxygen uptake (3663 ± 445 vs. 3645 ± 438 mL·min(-1)), or relative peak oxygen uptake (46.5 ± 6.0 vs. 46.2 ± 5.0 mL·kg(-1)·min(-1)). These findings suggested that the arginine-based supplement may be used on an acute basis for delaying the onset of neuromuscular fatigue (i.e., PWCFT) and improving the VT in untrained individuals.
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Affiliation(s)
- Roksana B Zak
- Department of Kinesiology, Mississippi State University, Mississippi State, MS 39762, USA
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Camic CL, Kovacs AJ, Enquist EA, VanDusseldorp TA, Hill EC, Calantoni AM, Yemm AJ. An electromyographic-based test for estimating neuromuscular fatigue during incremental treadmill running. Physiol Meas 2014; 35:2401-13. [PMID: 25390736 DOI: 10.1088/0967-3334/35/12/2401] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The purposes of the present study were two fold: (1) to determine if the model used for estimating the physical working capacity at the fatigue threshold (PWCFT) from electromyographic (EMG) amplitude data during incremental cycle ergometry could be applied to treadmill running to derive a new neuromuscular fatigue threshold for running, and (2) to compare the running velocities associated with the PWCFT, ventilatory threshold (VT), and respiratory compensation point (RCP). Fifteen college-aged subjects (21.5 ± 1.3 y, 68.7 ± 10.5 kg, 175.9 ± 6.7 cm) performed an incremental treadmill test to exhaustion with bipolar surface EMG signals recorded from the vastus lateralis. There were significant (p < 0.05) mean differences in running velocities between the VT (11.3 ± 1.3 km h(-1)) and PWCFT (14.0 ± 2.3 km h(-1)), VT and RCP (14.0 ± 1.8 km h(-1)), but not the PWCFT and RCP. The findings of the present study indicated that the PWCFT model could be applied to a single continuous, incremental treadmill test to estimate the maximal running velocity that can be maintained prior to the onset of neuromuscular fatigue. In addition, these findings suggested that the PWCFT, like the RCP, may be used to differentiate the heavy from severe domains of exercise intensity.
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Affiliation(s)
- Clayton L Camic
- Human Performance Laboratory, Exercise and Sport Science, University of Wisconsin-La Crosse, La Crosse, Wisconsin 54601, USA
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Bergstrom HC, Housh TJ, Cochrane KC, Jenkins NDM, Lewis RW, Traylor DA, Zuniga JM, Schmidt RJ, Johnson GO, Cramer JT. An examination of neuromuscular and metabolic fatigue thresholds. Physiol Meas 2013; 34:1253-67. [PMID: 24021781 DOI: 10.1088/0967-3334/34/10/1253] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This study examined the relationships among the physical working capacity at the fatigue threshold (PWCFT), the power outputs associated with the gas exchange threshold (PGET) and the respiratory compensation point (PRCP), and critical power (CP) to identify possible physiological mechanisms underlying the onset of neuromuscular fatigue. Ten participants (mean ± SD age: 20 ± 1 years) performed a maximal incremental cycle ergometer test to determine the PWCFT, PGET, and PRCP. CP was determined from the 3 min all-out test. The PWCFT (197 ± 55 W), PRCP (212 ± 50 W), and CP (208 ± 63 W) were significantly greater than the PGET (168 ± 40 W), but there were no significant differences among the PWCFT, PRCP, and CP. All thresholds were significantly inter-4 (r = 0.794-0.958). The 17% greater estimates for the PWCFT than PGET were likely related to differences in the physiological mechanisms that underlie these fatigue thresholds, while the non-significant difference and high correlation between the PWCFT and the PRCP suggested that hyperkalemia may underlie both thresholds. Furthermore, it is possible that the 5% lower estimate of the PWCFT than CP could more accurately reflect the demarcation of the heavy from severe exercise intensity domains.
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Affiliation(s)
- Haley C Bergstrom
- Human Performance Laboratory, Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE, USA
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Peart DJ, Siegler JC, Vince RV. Practical Recommendations for Coaches and Athletes. J Strength Cond Res 2012; 26:1975-83. [DOI: 10.1519/jsc.0b013e3182576f3d] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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12
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Camic CL, Housh TJ, Hendrix CR, Zuniga JM, Bergstrom HC, Schmidt RJ, Johnson GO. The influence of the muscle fiber pennation angle and innervation zone on the identification of neuromuscular fatigue during cycle ergometry. J Electromyogr Kinesiol 2011; 21:33-40. [DOI: 10.1016/j.jelekin.2010.09.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2010] [Revised: 09/28/2010] [Accepted: 09/28/2010] [Indexed: 11/30/2022] Open
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VANHATALO ANNI, MCNAUGHTON LARSR, SIEGLER JASON, JONES ANDREWM. Effect of Induced Alkalosis on the Power-Duration Relationship of "All-out" Exercise. Med Sci Sports Exerc 2010; 42:563-70. [DOI: 10.1249/mss.0b013e3181b71a4a] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Camic CL, Housh TJ, Johnson GO, Hendrix CR, Zuniga JM, Mielke M, Schmidt RJ. An EMG frequency-based test for estimating the neuromuscular fatigue threshold during cycle ergometry. Eur J Appl Physiol 2009; 108:337-45. [DOI: 10.1007/s00421-009-1239-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/28/2009] [Indexed: 11/28/2022]
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15
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Stout JR, Cramer JT, Zoeller RF, Torok D, Costa P, Hoffman JR, Harris RC, O'Kroy J. Effects of β-alanine supplementation on the onset of neuromuscular fatigue and ventilatory threshold in women. Amino Acids 2006; 32:381-6. [PMID: 17136505 DOI: 10.1007/s00726-006-0474-z] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2006] [Accepted: 10/30/2006] [Indexed: 11/30/2022]
Abstract
This study examined the effects of 28 days of beta-alanine supplementation on the physical working capacity at fatigue threshold (PWCFT), ventilatory threshold (VT), maximal oxygen consumption (VO2-MAX), and time-to-exhaustion (TTE) in women. Twenty-two women (age+/-SD 27.4+/-6.1 yrs) participated and were randomly assigned to either the beta-alanine (CarnoSyn) or Placebo (PL) group. Before (pre) and after (post) the supplementation period, participants performed a continuous, incremental cycle ergometry test to exhaustion to determine the PWCFT, VT, VO2-MAX, and TTE. There was a 13.9, 12.6 and 2.5% increase (p<0.05) in VT, PWCFT, and TTE, respectively, for the beta-alanine group, with no changes in the PL (p>0.05). There were no changes for VO2-MAX (p>0.05) in either group. Results of this study indicate that beta-alanine supplementation delays the onset of neuromuscular fatigue (PWCFT) and the ventilatory threshold (VT) at submaximal workloads, and increase in TTE during maximal cycle ergometry performance. However, beta-alanine supplementation did not affect maximal aerobic power (VO2-MAX). In conclusion, beta-alanine supplementation appears to improve submaximal cycle ergometry performance and TTE in young women, perhaps as a result of an increased buffering capacity due to elevated muscle carnosine concentrations.
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Affiliation(s)
- J R Stout
- Department of Health and Exercise Science, University of Oklahoma, Norman, OK 73019-6081, USA.
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16
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Malek MH, Coburn JW, Weir JP, Beck TW, Housh TJ. The effects of innervation zone on electromyographic amplitude and mean power frequency during incremental cycle ergometry. J Neurosci Methods 2006; 155:126-33. [PMID: 16510193 DOI: 10.1016/j.jneumeth.2006.01.019] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2005] [Accepted: 01/18/2006] [Indexed: 11/18/2022]
Abstract
The purpose of this study was to examine the effects of electrode placements over the innervation zone (IZ), as well as proximal and distal to the IZ, on the patterns for the absolute and normalized electromyographic (EMG) amplitude and mean power frequency (MPF) versus power output relationships during incremental cycle ergometry. Fifteen men [mean +/- S.D. age = 24.3 +/- 2.4 years; VO2max = 47.3 +/- 4.9 ml kg(-1) min(-1)] performed incremental cycle ergometry tests to exhaustion. Surface EMG signals were recorded simultaneously from bipolar electrode arrangements placed on the vastus lateralis (VL) muscle over the IZ, as well as proximal and distal to the IZ. Polynomial regression analyses were used to describe the relationships for absolute and normalized EMG amplitude (microVrms and %max) and MPF (Hz and %max) versus power output (%max) for each subject at the three electrode placement sites. In addition, separate one-way repeated measures ANOVAs were used to examine mean differences between the three sites for absolute and normalized EMG amplitude and MPF at power outputs of 80, 110, 140, and 170 W. The results of the polynomial regression analyses revealed that the best fit model for each site for the absolute and normalized EMG amplitude versus power output relationship was linear for 11 subjects and quadratic for 2 subjects. The remaining two subjects exhibited both linear and quadratic patterns that were site-dependent. For EMG MPF, 10 subjects exhibited significant relationships (linear and/or quadratic) across power outputs for at least one site. In addition, there were significant (P < 0.05) mean differences between the electrode placement sites for absolute EMG amplitude, but not absolute EMG MPF at 80, 110, 140, and 170 W. There were no significant (P > 0.05) mean differences, however, between the three sites for normalized EMG amplitude or MPF at 80, 110, 140, and 170 W. These findings indicated that the placement of bipolar electrodes over the IZ, as well as proximal and distal to the IZ, had no effect on the pattern of the normalized EMG amplitude versus power output relationship or the mean normalized EMG amplitude and MPF values. Thus, during cycle ergometry, normalized EMG amplitude values (but not absolute values) can be compared between studies that have utilized various electrode placement sites on the VL.
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Affiliation(s)
- Moh H Malek
- University of Nebraska-Lincoln, Human Performance Laboratory, Department of Nutrition and Health Sciences, Lincoln, NE 68583-0806, USA.
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Malek MH, Housh TJ, Coburn JW, Weir JP, Schmidt RJ, Beck TW. The effects of interelectrode distance on electromyographic amplitude and mean power frequency during incremental cycle ergometry. J Neurosci Methods 2006; 151:139-47. [PMID: 16122806 DOI: 10.1016/j.jneumeth.2005.06.025] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2005] [Revised: 06/24/2005] [Accepted: 06/28/2005] [Indexed: 11/17/2022]
Abstract
The purpose of this study was to examine the effects of interelectrode distance (IED) on the relationships of absolute and normalized EMG amplitude and mean power frequency (MPF) versus power output during incremental cycle ergometry. Eleven adults (mean +/- S.D. age = 24.2 +/- 2.6 y; V(O2max) = 49.4 +/- 8.3 ml kg(-1) min(-1)) performed incremental cycle ergometry tests. Surface EMG signals were recorded simultaneously from bipolar electrode arrangements placed over the VL muscle with IEDs of 20, 40, and 60 mm. Polynomial regression analyses were used to describe the relationships for absolute and normalized EMG amplitude (muV(rms) and % max) and MPF (Hz and % max) versus power output (%max) for each subject at the three IEDs. In addition, separate one-way repeated measures ANOVAs were used to examine mean differences between the three IEDs for absolute and normalized EMG amplitude and MPF at power outputs of 80, 110, 140, and 170 W. The results of the polynomial regression revealed that the best fit model for each IED for the absolute and normalized EMG amplitude was linear for six of the 11 subjects and quadratic for five of the subjects. For EMG MPF, four of the 11 subjects exhibited significant relationships (linear or quadratic) across power outputs for at least one IED. The one-way repeated measures ANOVAs revealed significant mean differences between the IEDs for absolute EMG amplitude and MPF at 80, 110, 140, and 170 W. There were no significant mean differences, however, between the IEDs for normalized EMG amplitude or MPF at 80, 110, 140, and 170 W. The results of the study indicated that there were no consistent patterns of responses between individual subjects for EMG amplitude or MPF versus power output relationships for IEDs of 20, 40, and 60 mm during incremental cycle ergometry. The current findings supported the process of normalization for EMG amplitude and MPF data obtained during cycle ergometry when comparisons are made for different IEDs.
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Affiliation(s)
- Moh H Malek
- Human Performance Laboratory, Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, 110 Ruth Leverton Hall, Lincoln, NE 68583-0806, USA.
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Stout J, Eckerson J, Ebersole K, Moore G, Perry S, Housh T, Bull A, Cramer J, Batheja A. Effect of creatine loading on neuromuscular fatigue threshold. J Appl Physiol (1985) 2000; 88:109-12. [PMID: 10642369 DOI: 10.1152/jappl.2000.88.1.109] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The purpose of this investigation was to determine the effect of creatine (Cr) loading on the onset of neuromuscular fatigue by monitoring electromyographic fatigue curves from the vastus lateralis muscle using the physical working capacity at the fatigue threshold (PWC(FT)) test. Using a double-blind random design, 15 women athletes [mean age 19.0 +/- 2.0 (SD) yr] from the university crew team received a placebo (n = 8; 20 g glucose) or Cr (n = 7; 5 g Cr monohydrate + 20 g glucose) four times per day for 5 consecutive days. Analysis of covariance was used to analyze the data (covaried for presupplementation PWC(FT) values). The adjusted mean postsupplementation PWC(FT) value for the Cr group (mean = 186 W) was significantly (P < 0.05) higher than that of the placebo group (mean = 155 W). These findings suggest that Cr loading may delay the onset of neuromuscular fatigue.
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Affiliation(s)
- J Stout
- Exercise Science Department, Creighton University, Omaha, Nebraska 68178, USA.
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Evetovich TK, Housh TJ, Johnson GO, Evans SA, Stout JR, Bull AJ, Smith DB, Evetovich MM. Effect of workbout duration on the physical working capacity at fatigue threshold (PWCFT) test. ERGONOMICS 1996; 39:314-321. [PMID: 8851535 DOI: 10.1080/00140139608964461] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The purpose of this study was twofold: (1) to determine the effect of increasing the duration of the workbout at each power output during the physical working capacity at fatigue threshold (PWCFT) test from 2 to 3 or 4 min, and (2) to examine the time to exhaustion during continuous workbouts at the PWCFT. Twelve adult males (means +/- SD = 22.4 +/- 3.0 years) volunteered to perform three PWCFT tests using workbout durations of 2, 3, and 4 min. Following the determination of the PWCFT values, nine of the subjects performed continuous workbouts at PWCFT2 and PWCFT4 for as long as possible. The mean PWCFT value using 4-min workbouts (PWCFT4 = 168.8 +/- 45.1 W) was significantly less (p < 0.05, 19.1%) than that using 2-min workbouts (PWCFT2 = 208.9 +/- 59.0 W). However, only two subjects were able to complete 60 min at PWCFT4 and none of the subjects were able to complete 60 min at PWCFT2. Therefore, although increasing the duration of the workbout at each power output resulted in a lower PWCFT4, these findings do not support a recommendation for a change in the PWCFT test protocol.
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Affiliation(s)
- T K Evetovich
- Human Performance Laboratory, University of Nebraska-Lincoln 68588-0229, USA
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Matson LG, Tran ZV. Effects of sodium bicarbonate ingestion on anaerobic performance: a meta-analytic review. INTERNATIONAL JOURNAL OF SPORT NUTRITION 1993; 3:2-28. [PMID: 8388767 DOI: 10.1123/ijsn.3.1.2] [Citation(s) in RCA: 86] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Many researchers have investigated the effects of induced metabolic alkalosis, by ingestion of sodium bicarbonate, on anaerobic exercise performance. But the results have been inconsistent and often contradictory. The purpose of this review was to synthesize the varied findings using a meta-analytic approach. Twenty-nine investigations met our inclusion criteria. Results show that NaHCO3 ingestion clearly results in a more alkaline extracellular environment. The dosage, however, was only moderately related to the increase in pH and HCO3-. Overall, performance was enhanced but the range of effect sizes was large, -0.12 to 2.87. In studies that measured time to exhaustion, there was a mean 27 +/- 20% increase in duration. The treatment effect, however, was only weakly related to the degree of induced alkalosis. But in comparing the 19 studies that showed a positive treatment effect with the 16 that showed no effect, the former were associated with a greater increase in pH following ingestion of a somewhat larger dosage, and a greater decrease in pH with exercise.
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Affiliation(s)
- L G Matson
- School of Kinesiology & Physical Education, University of Northern Colorado, Greeley 80639
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