Int J Sports Med 1998; 19(7): 468-473
DOI: 10.1055/s-2007-971946
Physiology and Biochemistry

© Georg Thieme Verlag Stuttgart · New York

Manipulation of Knee Extensor Force Using Percutaneous Electrical Myostimulation During Eccentric Actions: Effects on Indices of Muscle Damage in Humans

R. B. Child1 , S. J. Brown2 , S. H. Day3 , J. M. Saxton4 , A. E. Donnelly5
  • 1Muscle Research Centre, Department of Medicine, Liverpool University, Liverpool, UK
  • 2School of Health and Sport Science, University of North London, London, UK
  • 3School of Health and Sport Science, Stafford University, Stafford, UK
  • 4Institute of Sports Medicine and Exercise Science, Sheffield University, Sheffield, UK
  • 5Dept. of Physical education and Sport Science, Limerick University, Limerick, Ireland
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Publikationsverlauf

Publikationsdatum:
09. März 2007 (online)

Percutaneous electrical myostimulation (PES) was used to manipulate the force produced by the knee extensor muscles during eccentric exercise, thereby providing a model to investigate the role of force in muscle damage. Two eccentric exercise bouts of equal work were performed by nine subjects, using fixed voltage PES at 20 Hz (to produce moderate muscle forces) and 100 Hz (to produce high muscle forces). Muscle contractility, serum creatine kinase activity (CK) and muscle soreness (MS) were evaluated before, and up to 14 days after exercise. Data are presented as means ± SEM, and were analysed using repeated measures analysis of variance (ANOVA), t-tests and Wilcoxon tests. Peak forces were higher during the 100 Hz bout than the 20 Hz bout for repetitions 1 (472 ± 60 vs 237 ± 23 New-tons), 10 (381 ± 26 vs 233 ± 26 Newtons), 20 (310 ± 24 vs 218 ± 24 Newtons), all p < 0.01, t-test and 30 (297 ± 27 vs 204 ± 21 New-tons), p < 0.05, t-test. Following the 100 Hz bout, maximum voluntary contractile force (MVC) was lower (p < 0.01, ANOVA), and CK was higher (p < 0.0001, ANOVA) than after the 20 Hz bout. Subjects also reported greater MS on days 2 to 6 (p < 0.05, Wilcoxon test) following the 100 Hz bout. Despite a decline in the stimulated 20:100 Hz tetanic force ratio after each bout (p < 0.01, ANOVA) there was no difference between bouts (p > 0.05, ANOVA). The higher rise in CK and MS after the 100 Hz bout, together with the greater deficit in MVC, suggest that in humans, muscle force is a contributing factor to muscle injury during eccentric actions.

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