Effects of peak torque angle on the bilateral deficit of knee extensors and flexors at two velocities of contraction

Abstract

Objective: To examine effects of the peak torque angle (PTA) on the bilateral deficit (BD) index at two low velocities of contraction.

Methods: Twenty young men performed right and left knee concentric extension–flexion (1 set, 5 repetitions) unilaterally and bilaterally in an isokinetic dynamometer at 30°/s and 60°/s. The peak torque (PT) from right, left and bilateral tests and their respective PTA were registered. Two BD indexes were determined as the bilateral PT divided by the summation of right and left PT (BDI1) and by the summation of left and right torque values found at the bilateral PTA (BDI2). Additionally, the mean of the absolute differences (MAD) between bilateral and unilateral PTAs was calculated as the mean of the modulus of the difference between bilateral minus right and bilateral minus left values divided.

Results: The knee extensors showed difference between bilateral and unilateral PTA (p<0.01) and effect of velocity on bilateral PTA (p<0.05). MAD was not influenced by the direction of movement (p=0.673), whereas on knee flexors it depended on velocity (p=0.01). Knee extensors and flexors presented higher BDI1 than BDI2 at both velocities (p<0.001). The difference between BDI1 and BDI2 was strongly correlated with MAD (p<0.01).

Conclusion: The BD is generally attributed to neural mechanisms, whereas the BD index was influenced by the PTA. Hence, it is suggested that the angle–torque relationship plays a role on the BD reported because it may enhance the BD index.