Muscle performance following eccentric exercise with different muscle lengths
Keywords:isokinetic dynamometry, concentric torque, isometric toque
The effects of short and long muscle length eccentric exercise on selected muscle performance indicators were investigated in two separate sessions. Using an isokinetic dynamometer at 1.05 rad/s, seven healthy male (21±1 years) volunteers randomly underwent the two exercise sessions, one on each leg, 14 days apart. During each session, subjects had to accomplish 12 sets of 10 maximal voluntary efforts in seated and prone positions to achieve rectus femoris short and long muscle length, respectively. Muscle performance indicators (eccentric peak torque, concentric peak torque and isometric peak torque at 60o and 110o knee flexion) were assessed pre-exercise and 24, 48, 72 as well as 96 h post exercise. Except eccentric peak torque that revealed significant (p<.05) decline at 24 hours post long muscle length eccentric exercise, the others significant differences (p<0.05) were found only after short muscle length eccentric exercise in comparison to pre exercise values and also was found that short muscle length caused significant greater decline (p<.05) compared to long muscle length eccentric exercise. In conclusion, the present results, in contrast to the majority of published studies, indicates that short muscle length quadriceps eccentric exercise causes greater muscle performance decline than the corresponding long muscle length.