A novel approach to improving squat jump performance: the pre-loading squat jumps

The present study aimed to explore the acute effects of a novel preloading strategy on squat jump (SJ) kinetic and kinematic from 0 to 50% body mass. Twenty-one male college athletes (mean ± SD: age = 23.29 ± 3.15 yrs, body mass = 75.50 ± 6.20 kg, height = 178.07 ± 6.45 cm and body fat percentage = 13.71 ± 5.45%) completed three different jump tasks across two testing sessions: SJ, preloading SJ (10 - 50% body mass) and countermovement jump (CMJ). Applying preloading before SJ resulted in significant, trivial to small increases in jump height (F(5,15) = 3.76 , P = 0.01, η² = 0.16). However, there was no significant effect of preloading on peak power, peak force and peak velocity. The maximum peak power (5128.28 ± 459.38 W vs. 5047.97 ± 447.67 W, P = 0.04; g = 0.17) and maximum peak force (1810.72 ± 150.35 N vs. 1775.50 ± 155.54 N, P = 0.03; g = 0.25) were at the load of 20% body mass, which was significantly higher than SJ. The jump height, peak force and peak velocity in the 10 - 50% body mass preloading SJ tests were not significantly different from those in the CMJ. Preloading before a SJ results in meaningful improvements in jump performance, particularly in peak power. Athletes in sports requiring high jump performance can use preloading SJ strategies to enhance lower limb explosive power and jump height.