Effect of cross training by eccentric isotonic knee extensor training at fast velocity on muscle performance of untrained leg in Thai male

Abstract

Purpose: This study aim to investigate effect of cross training by eccentric isotonic knee extensor training at fast velocity on muscle performance of untrained leg in Thai males. Participants: Twenty healthy males aged 19.80 ± 0.83 years participated in this study. They were divided into two groups; training (TG) and control (CG) groups (n=10 each). Methods: The TG trained unilateral eccentric isotonic exercise of right leg 3 times/week for 6 weeks on Biodex system 4 pro at velocity of 180o/s. The CG received no exercise except strength testing of both legs. Concentric isokinetic peak torque (CPT) and eccentric isokinetic peak torque (EPT) of knee extensor muscle of both legs was tested at pre and post training period. Analysis: CPT and EPT were analyzed using a group (CG, TG)×leg (trained, untrained×time (pre, post) multivariate analysis. When there were multivariate significances, the two-way mixed ANOVA was used and then the Bonferroni’s test was used for the post hoc analysis. The change of CPT and EPT between pre and post training were analyzed using a group (CG, TG)×leg (trained, untrained) multivariate analysis. When there were multivariate significances, the unpaired t-test was used. Results: There were not significant differences in CPT and EPT between trained and untrained legs in both groups and both times. At pre-training period, there were significant differences in EPT of trained leg between CG and TG (p=0.024) (113.09 ± 23.97 and 90.16 ± 28.71 Nm, respectively). After 6 weeks of training, EPT of TG in both trained and untrained legs (135.44 ± 54.90 and 114.12 ± 36.19 Nm, respectively) were greater than in those of CG (62.13 ± 12.62 and 52.52 10.09 Nm, respectively) (p=0.001). The change of CPT only trained leg (44.93 ± 39.88 Nm) in TG was greater than CG (8.67 ± 17.32 Nm) (p=0.021) but the changes of EPT in both trained and untrained legs of TG (83.38 ± 57.16 and 65.50 ± 35.58 Nm, respectively) were greater than those of CG (-3.4 ± 10.41 and -4.69 ± 12.43 Nm, respectively) (p=0.001). In TG, there were significant differences in CPT and EPT between pre and post training in both trained (p<0.001) and untrained (p=0.001 and p<0.001, respectively) legs. Conclusions: Eccentric isotonic knee extensor training at fast velocity can increase CPT and EPT of knee extensor muscle of untrained leg, especially for EPT, the same type of contraction that used in training protocol, which also significantly increase when compare to control group. Clinical implication: The findings of this study could be a guideline for planning an appropriate strength training exercise for knee extensor muscle on untrained leg in patients with unilateral leg immobilization.