strength, but strength becomes a priority in sports where heavy weights such as the body must be lifted,
carried or thrown (Sharkey, 1986).
Plyometric exercises have been used successfully over the years to elicit training responses
from athletes. Plyometrics training is almost exclusively applied to extensor Muscle of the legs, and
consists of a vigorous lengthening of the active extensor muscles (eccentric contraction) immediately
followed by a maximal concentric contraction. They are most frequently used as a means of increasing
speed and anaerobic power output in sprinters and jumpers, but the techniques may also be of value to
other types of sportsmen (Watson, 1993; Wausen, 1990). Sharkey (1986) described plyometric
exercises as explosive callisthenic-like exercises which involve the conditioning of the neuromuscular
system to permit faster and more powerful changes of direction such as moving from up and down in
jumping or switching leg positions as in running. The training modes adopted for this study were based
on the principle of plyometrics training.
Therefore, this study focused on the relative effect of depth jumping, rebound jumping and
horizontal jumping over a distance (three modes of plyometrics training) on the leg muscle strength
development of untrained University males.
It was hypothesized that there no significant differences exist in the pretest - posttest leg muscle
strength of subject following a twelve-week depth jumping, rebound jumping and horizontal jumping
over a distance plyometrics programme.