Abstract

Objective: The lower impact on the musculoskeletal system induced by plyometric exercise on sand compared to firm surface might be useful to reduce the stress of intensified training periods or during rehabilitation from injury. The aim of this study was to compare the effects of plyometric training on sand versus a grass surface on muscle soreness, vertical jump height and sprinting ability.

Design: Parallel two-groups, randomized, longitudinal (pretest- posttest) study. Methods: After random allocation, 18 soccer players completed 4 weeks of plyometric training on grass (Grass-group) and 19 players on sand (Sand-group). Before and after plyometric training 10- and 20-m sprint, squat jump (SJ), countermovement jump (CMJ), and eccentric utilization ratio (CMJ/SJ) were determined. Muscle soreness was measured using the Vickers Likert scale.

Results: No training-surface x time-interactions were found for sprint time (P>0.87), whereas a trend was found for SJ (P=0.08), with both groups showing similar improvements (P<0.001). On the other hand, the Grass-group improved CMJ (P=0.03) and CMJ/SJ (P=0.005) significantly (P<0.001) more than players in the Sand-group. In contrast, players in the Sand-group experienced less muscle soreness than the Grass-group (P<0.001).

Conclusions: Plyometric training on sand improved both jumping and sprinting ability and induced less muscle soreness. Grass surface seems to be superior in enhancing CMJ performance while the sand surface showed a trend in greater improvement in SJ. Therefore, plyometric training on different surfaces may be associated to different training-induced effects on some neuromuscular factors related to the efficiency of the stretch-shortening cycle.