Effect of countermovement on power-force-velocity profile

To study the effect of a countermovement on the lower limb force-velocity (F-v) mechanical profile and to experimentally test the influence of F-v mechanical profile on countermovement jump (CMJ) performance, independently from the effect of maximal power output (P (max)). Fifty-four high-level sprinters and jumpers performed vertical maximal CMJ and squat jump (SJ) against five to eight additional loads ranging from 17 to 87 kg. Vertical ground reaction force data were recorded (1,000 Hz) and used to compute center of mass vertical displacement. For each condition, mean force, velocity, and power output were determined over the entire push-off phase of the best trial, and used to determine individual linear F-v relationships and P (max). From a previously validated biomechanical model, the optimal F-v profile maximizing jumping performance was determined for each subject and used to compute the individual mechanical F-v imbalance (Fv (IMB)) as the difference between actual and optimal F-v profiles. A multiple regression analysis clearly showed (r (2) = 0.952, P < 0.001, SEE 0.011 m) that P (max), Fv (IMB) and lower limb extension range (h (PO)) explained a significant part of the interindividual differences in CMJ performance (P < 0.001) with positive regression coefficients for P (max) and h (PO) and a negative one for Fv (IMB). Compared to SJ, F-v relationships were shifted to the right in CMJ, with higher P (max), maximal theoretical force and velocity (+35.8, 20.6 and 13.3 %, respectively). As in SJ, CMJ performance depends on Fv (IMB), independently from the effect of P (max), with the existence of an individual optimal F-v profile (Fv (IMB) having an even larger influence in CMJ).