Document Detail

Muscle-Damaging Exercise Affects Isokinetic Torque More at Short Muscle Length.
MedLine Citation:
PMID:  21273917     Owner:  NLM     Status:  Publisher    
Skurvydas, A, Brazaitis, M, and Kamandulis, S. Muscle-damaging exercise affects isokinetic torque more at short muscle length. J Strength Cond Res 25(X): 000-000, 2011-The aim of this study was to investigate the differences in the length-dependent changes in quadriceps muscle torque during voluntary isometric and isokinetic contractions performed after severe muscle-damaging exercise. Thirteen physically active men (age = 23.8 ± 3.2 years, body weight = 77.2 ± 4.5 kg) performed stretch-shortening cycle (SSC) exercise comprising 100 drop jumps with 30-second intervals between each jump. Changes in the voluntary and electrically evoked torque in concentric and isometric conditions at different muscle lengths, muscle soreness, and plasma creatine kinase (CK) activity were assessed within 72 hours after SSC exercise. Isokinetic knee extension torque decreased significantly (p < 0.05) at all joint angles after SSC exercise. At 2 minutes and at 72 hours after SSC exercise, the changes in knee torque were significantly smaller at 80° (where 180° = full knee extension) than at 110-130°. At 2 minutes after SSC exercise, the optimal angle for isokinetic knee extension torque shifted by 9.5 ± 8.9° to a longer muscle length (p < 0.05). Electrically induced torque at low-frequency (20-Hz) stimulation decreased significantly more at a knee joint angle of 130° than at 90°. The subjects felt acute muscle pain and CK activity in the blood increased to 1,593.9 ± 536.2 IU·L within 72 hours after SSC exercise (p < 0.05). This study demonstrates that the effect of muscle-damaging exercise on isokinetic torque is greatest for contractions at short muscle lengths. These findings have practical importance because the movements in most physical activities are dynamic in nature, and the decrease in torque at various points in the range of motion during exercise might affect overall performance.
Albertas Skurvydas; Marius Brazaitis; Sigitas Kamandulis
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-1-27
Journal Detail:
Title:  Journal of strength and conditioning research / National Strength & Conditioning Association     Volume:  -     ISSN:  1533-4287     ISO Abbreviation:  -     Publication Date:  2011 Jan 
Date Detail:
Created Date:  2011-1-28     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9415084     Medline TA:  J Strength Cond Res     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Department of Applied Physiology and Physiotherapy, Lithuanian Academy of Physical Education, Kaunas, Lithuania.
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