Effects of peak torque angle on the bilateral deficit of knee extensors and flexors at two velocities of contraction
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To examine effects of the peak torque angle (PTA) on the bilateral deficit (BD) index at two low velocities of contraction.
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.
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).
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.
KeywordsIsokinetic contraction Muscle mechanics Biomechanics
Compliance with ethical standards
Conflict of interest
The authors declare that there are no conflicts of interest regarding the data presented in the paper.
The whole protocol was approved by the ethical committee of the Instituto Nacional de Traumatologia e Ortopedia for experiments with humans (allowance n. 477.583), in accordance with the national committee and with the 1964 Helsinki declaration and the latter amendments or comparable ethical standards.
All volunteers who participated in the study were instructed about the procedures and gave a signed written consent.
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