Purpose:
The aim of the present study was to compare the effects of vertical, horizontal and a combination of both vertical and horizontal plyometric exercises (depth jumping) on running speed.

Methods:
A purposively selected sample of 80 male students were randomly assigned into either a control group or groups training the vertical depth jump, horizontal depth jump or a combination of both. The experimental groups trained twice weekly for 10 weeks, performing 6 sets of 10 repetitions per session. Drop height was increased from 20 to 40 cm according to the step method. Running speed was measured by a 45.72 m dash test before and after the 10-week period.

Results:
Analysis of covariance was applied to compare scores. A pair-wise comparison was performed using Scheffe’s post-hoc test at a 0.05 level of confidence. The results showed significant improvements among the three experimental groups as compared with the control group, whereas a comparison between the three experimental groups was found to be insignificant. The percentage of performance increase from pre-test to post-test running speed was 2.23%, 2.96% and 3.57% for the groups training vertical, horizontal and both vertical and horizontal depth jumps, respectively.

Conclusions:
A combination of both vertical and horizontal depth jumping, with a slightly larger emphasis on horizontal plyometric training, can aid sprinters’ performance.