Electrically evoked and voluntary maximal isometric tension in relation to dynamic muscle performance in elderly male subjects, aged 69 years
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The dynamic performance and electrically evoked mechanical properties of elderly triceps surae muscle have been investigated in 9 men, aged 69 yr. Dynamic performance consisted of cycling on a force bicycle and a vertical jump off two feet from a force platform.
The results showed that the time to peak tension (TPT) and half relaxation time (1/2 RT) were significantly greater (p<0.001) by 30 ms and 22 ms and the supramaximal twitch (Pt) and tetanic (20 H−P020) tensions and maximal voluntary contraction (MVC) were less by 45 N (−33%), 708 N (−49%), and 899 N (−43%) in the elderly compared with young male control subjects. On the force platform, the height jumped (Ht), maximal force exerted (P), take-off velocity (VT), net impulse (NI) and peak power output (\(\dot W\)) were less by 18.6 cm, 173 N, 0.9 ms−1, 52 Ns and 1120 w respectively. Similar differences of power, force and velocity were observed on the force bicycle. The reduction of\(\dot W\) in the elderly was associated with the contractile characteristics of the leg muscle. The loss of contractile speed and capacity to generate force in old people was reflected in their inability to develop power during the performance of a maximal vertical jump and cycling.
Key wordsExercise Triceps surae Anaerobic power output Force platform and bicycle Electrical stimulation
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