Article Title



J Wilkins
T Brown


J. Wilkins, T. Brown

Boise State University, Boise, ID

The new, increased training demands of collegiate sports produce greater injury rate and reduced physical performance for first-year collegiate athletes compared their non-first-year counterparts. Reactive Strength Index (RSI) is reportedly a measure of athletic “explosiveness” that is easily obtained from ground reaction force data and may provide insight into athlete performance and response to training. However, alterations in explosiveness for female, in particular first-year, athletes following offseason training is unknown. PURPOSE: To determine if first-year athletes exhibit similar alterations in athletic explosiveness (i.e., RSI) following off- season training as their non-first year counterparts. METHODS: Twenty-seven athletes (8 first-year) from an NCAA Division I women’s soccer team performed five drop vertical jumps (DVJ) immediately prior to and following offseason training. For the DVJ, participants stepped off a 30 cm plyometric box, landed simultaneously on each limb, and then immediately performed a maximal vertical jump. During each DVJ, reactive strength index (RSI) was quantified by dividing the flight time of the maximal vertical jump by contraction time of the box landing (i.e., time from initial contact to takeoff). Participant-based RSI means were quantified and submitted to a two-way ANOVA to determine the main effect of and interaction between time (pre- vs post-training) and group (first-year vs non-first year), with alpha level 0.05. RESULTS: There was no significant time and group interaction (p = 0.300) or main effect of training (p=0.082, pre: 0.924±0.057 vs. post: 0.983±0.053) on RSI. But, first-year athletes exhibited a significantly lower RSI (p=0.043) compared to non-first year athletes (0.841±0.088 vs. 1.066±0.057). CONCLUSION: First- year athletes were approximately 24% less explosive than non-first year athletes. But, all female athletes exhibited a similar, non- significant (6%) increase in explosiveness following their off-season training.

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