J Strength Cond Res. 2008 Jan ;22 (1):54-65 18296956 (P,S,E,B,D)
Naruhiro Hori, Robert U Newton, Naoki Kawamori, Michael R McGuigan, Warren A Andrews, Dale W Chapman, Kazunori Nosaka School of Exercise, Biomedical and Health Sciences, Edith Cowan University, Joondalup, Australia.
The purpose of this study was to investigate the effect of weighted jump squat training with and without eccentric braking. Twenty male subjects were divided into two groups (n = 10 per group), Non-Braking Group and Braking Group. The subjects were physically active, but not highly trained. The program for Non-Braking Group consisted of 6 sets of 6 repetitions of weighted jump squats without reduction of eccentric load for 8 weeks.
The training program for the Braking Group consisted of the same sets and repetitions, but eccentric load was reduced by using an electromagnetic braking mechanism. Jump and reach, countermovement jump, static jump, drop jump, one repetition maximum half squat, weighted jump squat, and isometric/isokinetic knee extension/flexion at several different positions/angular velocities were tested pre- and post training intervention.
The Non-Braking Group exhibited greater improvement in peak torque during isokinetic concentric knee flexion at 300 degrees /s [Non-Braking Group: (mean +/- SD) 124.0 +/- 22.6 Nm at pre- and 134.1 +/- 18.4 Nm at post training, and Braking Group: 118.5 +/- 32.7 Nm at pre- and 113.2 +/- 26.7 Nm at post training]. Braking Group exhibited superior adaptations in peak power relative to body mass during weighted jump squat [Non-Braking Group: (mean +/- SD) 49.1 +/- 8.6 W/kg at pre- and 50.9 +/- 6.2 W/kg at post training, and Braking Group: 47.9 +/- 6.9 W/kg at pre- and 53.7 +/- 7.3 W/kg at post training].
It appears that power output in relatively slow movement (weighted jump squat) was improved more in the Braking Group, however strength in high velocity movements (isokinetic knee flexion at 300 degrees /s) was improved more in Non-Braking Group. This study supports load and velocity specific effects of weighted jump squat training.
Weighted jump squats work great for increasing your vertical jump. However they are more effective if you use a weight that doesn't slow down your speed of movement too much. There are other studies to support these findings.
Our recommendation is to get yourself a good weight vest and use that because it allows you to keep using your arms in your jumps. Then get out there and do some box jumps or paused jumps squats to take advantage of this great exercise. Don't go too heavy though. 10-15% of your bodyweight is probably a good rule of thumb.
If you can't get yourself a weight vest some light dumbbells or a medicine ball will do fine as well but you won't be able to use your arms in the same way.
Weighted jump squats are indeed a GREAT vertical jump exercise but if you are after the exercises that produce the greatest results in the least amount of time you need to check out Game Changers: The Most Powerful Vertical Jump Training Methods Known to Man.
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