Accumulative Competitive Season Training Stress Affects Neuromuscular Function and Increases Injury Risk in Uninjured D1 Female Athletes

Abstract

Previous research has shown that acute competition training stress negatively affects neuromuscular function which can perpetuate a predisposition to injury. This study's aim was to investigate the effect of accumulated competition training stress effect on neuromuscular function and incidence of increased injury risk in uninjured female D1 soccer players. Neuromuscular function was evaluated in fifteen female division I soccer athletes who played >85% of competitive season competitions who were tested for mobility/stability, leg length symmetry, and vertical power at three different points across the competitive season (pre, mid, and post time blocks). Leg length symmetry was measured from the anterior superior iliac spine to the lateral malleolus prior to Y-balance testing. The Y-balance testing measures unilateral anterior, posteromedial, and posterolateral reach achieved in single leg stance using metrics that include L/R normalized composite reach (NCOMP), L/R normalized antiorior reach (NANT), and L/R NCOMP/NANT segmental differences across time. Injury risk was evaluated using validated objective criteria that included: (NCOMP total reach <94% of limb length*3), (NANT reach distance <84% leg length) along with NCOMP and NANT asymmetries >4.0. Maximal vertical power (MVP) was measured via vertical jump. Multiple repeated measures ANOVAs evaluated NCOMP, NANT, MVP, and leg length symmetry across time with LSD post hoc testing when relevant (X ± SD). A significant main effect was found [F(1, 14) = 62.92, p < 0.001; η2 =0.82] with training stress and neuromuscular function without affecting maximal vertical power. Eighty percent of subject's bilateral NCOMP scores fell below the YBT reach standard at midseason (ES = 0.95, p = 0.02) while all subjects NANT reach distance remained below the reach threshold (ES = 0.74, p = 0.003) indicating a 6.5× and 2.5× greater injury risk, respectively. Competition stress affected neuromuscular function without affecting maximal power, which negatively impacted stability and increased injury risk.

Female Soccer Periodization on Anaerobic Power/Capacity

“…Although not significant, the preseason training period also had a positive impact on anaerobic capacity indicating that recovery potential lessoned, a key physiological metric in soccer. The nature in which athletes enter the competitive season can have a significant impact on physical performance throughout the competitive season (17,24), suggesting precompetitive season strength and conditioning during the precompetitive season training period is important to avoid decrements in physical anaerobic power and reduction in injury risk (13,17,23). Furthermore, the competitive season is known to be especially difficult to manage programming, not due to the lack of training stimulus but rather the lack of adequate rest (1,24).…”

“…Previous studies have reported performance decrements as a result of a reduced muscle mass (20,24), which our sample did not experience. Although training volume increases significantly with practice and game play during the competitive season (13), the amount of high-intensity activity that is performed during that time varies individually (20,23). Contrariwise, overreaching, or more specifically non functional over-reaching (NFOR) is defined as performance decrements or stagnation sustained for longer than 2 weeks (19).…”

“…Previously published data have empirically shown that seasonal changes in performance measures that include anaerobic performance occur within elite soccer athletes (5,8,23). However, the literature is sparse exploring anaerobic performance patterns in female collegiate soccer athletes, particularly across the full ATC.…”