Relationships between torque, velocity and power output during plantarflexion in healthy subjects.

This study investigated the relationships existing between torque, velocity and power output during plantarflexion. Using a Biodex dynamometric system, 15 healthy subjects performed three maximal dynamic tests, ranging from -12 degrees (-0.209 rad) of dorsiflexion to +47 degrees (+0.818 rad) of plantarflexion and one static test (test 4) at an angle of +10 degrees (+0.174 rad). The dynamic assessment included a 30 degrees s-1 (0.52 rad s-1) concentric isokinetic test (test 1) preceded by a 2-sec maximal pre-loading contraction. The other two dynamic tests were performed using the isotonic mode of testing with a selected torque of 27 N m; one of these tests was executed with pre-loading (test 2) while the other was performed without pre-loading (test 3). The results indicated that the dynamic peak torque, the peak power and the peak velocity were obtained in test 1, test 2 and test 3, respectively. These peak values, as well as the values of torque (test 1 and test 4), power (test 2) and velocity (test 3) obtained at a constant angle +10 degrees (+0.174 rad), were selected for the correlation analyses. The results showed that the torque, velocity and power output during plantarflexion were linearly related to one another with significant correlations (0.71 < r < 0.92; p < 0.01). This finding suggests that a common factor of muscular performance is assessed. Furthermore, these results indicated that the maximal torque produced by a subject can be predictive of his or her maximal velocity and power. Consequently, a stronger subject can generate higher velocity and power than a weaker subject when tested with the same load during maximal effort.