Knee flexor and extensor muscles performance comparison in youth team sports with and without jumping

Abstract This study aims to compare the performance of knee flexor and extensor muscles in young athletes of team sports with and without jumping as specific movement. There were two groups with young male athletes: the jumping group (n 46, volleyball, basketball and handball athletes) and group without jumping characteristics (n=44, futsal and soccer athletes). To evaluate the muscle performance of the flexors and extensors of the knee, we used an isokinetic dynamometer at a speed of 60°/s in concentric mode. The variables analyzed were peak torque normalized by body mass (PT), total work (TW), power (POW) and agonist/antagonist ratio (I:Q). To estimate unilateral deficits, we considered the values of the I:Q ratio less than 50%, and for bilateral deficits, asymmetries between the limbs greater than 10% for PT. There were no significant differences in the performance of knee flexor and extensor muscles between the groups, limbs and their interaction. When comparing significant deficits in PT and in the I:Q Ratio, a greater number of athletes in the jumping group showed imbalances in the I:Q ratio in the dominant limb (58.6% versus 25%, p=0.001). In the intragroup comparison, the group of athletes without jumping characteristics showed a difference between the limbs in the variables PT of extensors and flexors, in the flexors POW and in the I:Q ratio. Young athletes practicing team sports, regardless of the group, showed muscle asymmetries, and we suggest the insertion prevention programs in order to minimize them.