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Indexed/Abstracted in: BIOSIS Previews, EMBASE, Scopus, Emerging Sources Citation Index
Online ISSN 1827-1812
Taylor K. L. 1, 2, Cronin J. B. 2, 3, Chapman D. W. 1, 2, Hopkins W. G. 3, Newton M. 2
1 Department of Physiology, Australian Institute of Sport, Canberra, Australia;
2 School of Exercise and Health Sciences, Edith Cowan University, Perth, Australia;
3 Sport Performance Research Institute New Zealand, AUT University, Auckland, New Zealand
AIM: The ratio of force evoked by low- and high-frequency electrical stimulation has been used to quantify neuromuscular fatigue, but its relationship to fatigue in practical performance tests is unclear. The purpose of this study was to investigate the relationship between the ratio and performance of a countermovement jump.
METHODS: Six resistance-trained athletes completed 12 weeks of resistance training in three, 4-wk phases of normal training, deliberate overreaching, and a taper. Instrumented countermovement jumps, maximal voluntary isometric force, and force of the knee extensors elicited by 10- and 100-Hz stimuli were assessed weekly. Relationships between measures were quantified as mean within-subject correlations.
RESULTS: Only small correlations (0.14 to 0.31; between-subject SD ~0.30) were observed between the 10/100-Hz ratio and measures of jump performance, while the correlations with maximum voluntary force and perceived fatigue were small and trivial (-0.10 and -0.06 respectively). The highest mean correlation observed was only -0.32, between perceived fatigue and maximum voluntary force.
CONCLUSION: Fatigue measured by electrical stimulation appears to have little or no role in the fatigue of muscle performance in a practical setting.