OBJECTIVE:
To evaluate the effects of isokinetic eccentric training of the knee extensors on Hamstring/Quadriceps (H/Q) torque and surface electromyogram (SEMG) ratio in healthy subjects.
METHODS:
Twenty active, healthy men, with an average age of 22.5±2.1 years; body mass of 67.8±9.5 kg; height of 1.72±0.10 m; and body mass index (BMI) of 22.5±2.0 kg/m2, were evaluated for torque (isometric and eccentric 30o/s and 120o/s) and SEMG of the knee extensors and flexors, before and after 6 weeks of isokinetic eccentric training (30o/s) of the knee extensors.
RESULTS:
Knee extensor torque increased in all modes and speeds evaluated (P<0.01), the H/Q torque ratio declined in all measurements (P<0.01), but the H/Q SEMG ratio remained at pre-training values (P>0.05). The torque/SEMG correlation was weak (r<0.3; P>0.05) for all modes of contraction, pre-and post-training. However, there were significant differences (P>0.01) in the comparison between the eccentric (30o/s and 120o/s) and isometric modes, pre-and post-training.
CONCLUSIONS:
Isokinetic eccentric training of the knee extensors increased the difference in torque H/Q ratio, but did not alter the SEMG H/Q ratio. This suggests that adaptation by increasing the torque, associated with eccentric training, did not alter the recruitment of motor units assessed by SEMG.
exercise; electromyography; movement; knee; muscle strength