Force/velocity and power/velocity relationships in squat exercise

The purpose of this study was to describe the force/velocity and power/velo city relationships obtained during squat exercise. The maximal force (F-0) was extrapolated from the force/velocity relationship and compared to the i sometric force directly measured with the aid of a force platform placed un der the subject's feet. Fifteen international downhill skiers [mean (SD) ag e 22.4 (2.6) years, height 178 (6.34) cm and body mass 81.3 (7.70) kg] perf ormed maximal dynamic and isometric squat exercises on a guided barbell. Th e dynamic squats were performed with masses ranging from 60 to 180 kg, whic h were placed on the shoulders. The force produced during the squat exercis e was linearly related to the velocity in each subject (r(2) = 0.83-0.98, P < 0.05-0.0001). The extrapolated F-0 was 23% higher than the measured isom etric force (P < 0.001), and the two measurements were not correlated. This may be attributed to the position of the subject, since the isometric forc e was obtained at a constant angle (90 degrees of knee flexion), whereas th e dynamic forces were measured through a range of movements (from 90 degree s to 180 degrees). The power/velocity relationship was parabolic in shape f or each subject (r(2) = 0.94-0.99), P < 0.01-0.0001). However, the curve ob tained exhibited only an ascending part. The highest power was produced aga inst the lightest load (i.e., 60 kg). The maximal power (W-max) and optimal velocity were never reached. The failure to observe the descending part of the power/velocity curve may be attributed to the upper limitation of the velocities studied. Nevertheless, the extrapolation of W-max from the power /velocity equation showed that it would be reached for a load close to body mass, or even under unloaded conditions.