Active leg stiffness and energy stored in the muscles during maximal counter movement jump in the aged.
The purpose of this study was to examine the effects of age on active leg stiffness adjustment, electromyogram (EMG) activities and energy stored during eccentric and concentric phases in performing a maximal functional task involving stretch-shorten cycle. Ten young (24.3+/-2 years) and 10 old (68.6+/-5 years) healthy male subjects were filmed during maximal performance of counter movement jump (CMJ) and squat jump (SJ) on force plate. Integrated EMG (IEMG), ground reaction force (GRF), active leg stiffness, energy stored/returned and active work done by the muscles were compared between two groups on eccentric (ECC) and concentric (CON) phases of CMJ. The GRF, leg stiffness and energy stored in ECC and GRF, IEMG, energy returned and active work in CON were less in the elderly (p<0.05). These results demonstrate that the neuromuscular function of adjusting active stiffness, storing elastic energy and optimizing the performance may decrease with age during CMJ.
Liu
Yu
Y
Department of Kinesiology, Chinese Culture University, 55, Hwa Kang Road, Yang-Ming-Shan, Taipei, Taiwan. yliu@faculty.pccu.edu.tw
Peng
Chien-Hua
CH
Wei
Shun-Hwa
SH
Chi
Jung-Chun
JC
Tsai
Feng-Ren
FR
Chen
Jia-Yean
JY
D000328:Adult; D000368:Aged; D004576:Electromyography; D004734:Energy Metabolism; D015444:Exercise / Q000502:physiology*; D006801:Humans; D007866:Leg / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D013997:Time Factors