ACUTE EFFECTS OF DIFFERENT TYPES OF SQUAT CONTRACTION ON SUBSEQUENT DROP JUMP PERFORMANCE IN REGARDS TO POSTACTIVATION POTENTIATION

Abstract

Recent literature has repeatedly demonstrated the ability to enhance subsequent performance by exploiting a postactivation potentiation response in muscle groups. However no investigation has looked to compare different types of muscular contraction on subsequent drop jump performance. The purpose of this study was to investigate the effects of either a dynamic, eccentric or isometric muscle contraction upon subsequent drop jump performance. Nine competitive male rugby players (mean ± SD: age 21.2 ± 0.79 years, body mass 95.3 ± 13.51 kg, height 180.3 ± 8.43 cm, back squat 1RM 178.3 ± 20.82 kg) performed a baseline measure drop jump, they each then performed the set intervention protocol of a dynamic, eccentric or isometric back squat followed by 7 minutes of recovery time. Peak force, time to peak force, peak rate of force development, reactive strength index and jump height were assessed using an AMTI force platform (AMTI, USA). The results reported that there was no significant effect found for peak force (p<0.05), time to peak force (p<0.05), peak rate of force development (p<0.05), reactive strength index (p<0.05) or jump height (p<0.05) following each of the contraction interventions. However an individual analysis of “responders” found a significant difference (p<0.05) in peak force following the dynamic contraction intervention. Consequently the results suggest that the use of any contraction type has no significant effect upon subsequent drop jump performance in male collegiate players, however the individual analysis shows scope for further research into the protocol used for a larger population. From the findings of this research strength and conditioning coaches can accept that although there is no significant difference of different contraction types on subsequent drop jump performance, there is also no significant negative effect.