Inter-limb Asymmetries, Power, And Internal Training Loads In NCAA Division I Female Soccer Athletes

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Periodic testing and workload monitoring throughout a competitive season can help athletes and coaches periodize training to optimize performance. In particular, vertical jump testing to assess power output and inter-limb asymmetries can be used to monitor athlete-readiness. PURPOSE: To evaluate the relationship between internal training loads, power output, and inter-limb asymmetries throughout a competitive soccer season. METHODS: National Collegiate Athletic Association (NCAA) Division I female soccer players (N = 21) were evaluated at all practices and games using a team-based heart rate monitoring system to assess internal training load via Banister’s training impulse score (TRIMP). At the beginning of each week, athletes performed a dynamic warmup followed by maximal bilateral (CMJ) and single leg (SL) countermovement vertical jump tests using a hands-on-hips method assessed via a digital contact mat. The best of two trials were used for each jump test. An asymmetry index (ASY) was calculated by dividing dominant by non-dominant SL height. Linear mixed effects models were used to assess changes in TRIMP, CMJ, and ASY throughout the season. Repeated measures correlations were used to determine relationships between weekly changes in TRIMP, CMJ and ASY using an absolute ASY score. Significance was set at p < 0.05. Descriptive statistics are presented as mean ± standard deviation. RESULTS: Time main effects were observed for weekly changes in TRIMP (573 ± 150au; p < 0.001) and CMJ (43.1 ± 0.8 cm; p = 0.01) over the season. No changes in ASY were observed (2.0 ± 1.5%; p = 0.09). There was a significant weak correlation between CMJ and ASY (r = 0.17; p = 0.04), but no other relationships between TRIMP, CMJ, and ASY were observed (p > 0.05). CONCLUSIONS: Changes in internal workload and power output were apparent throughout the season. Although no significant changes in ASY were seen, an inverse correlation between ASY and power output was observed, which may impact on-field performance. Declines in peak power along with higher asymmetry rates have been associated with increased injury risk. Proper athlete management programs that incorporate systematic monitoring and periodic testing may help to mitigate these risks by affording the opportunity for early interventions designed to improve athlete readiness.