Athlete-specific force asymmetry monitoring in collegiate volleyball: a prospective observational cohort.

OBJECTIVE: To compare jump performance and inter-limb force asymmetry between male and female collegiate volleyball athletes, examine short-term in-season stability and identify which asymmetry metrics best support applied monitoring and reconditioning decisions. METHODS: In a prospective cohort, NCAA Division I volleyball athletes (23 males, 18 females) completed weekly bilateral countermovement jumps (CMJ). Inter-limb asymmetry indices for peak force, braking force, and rate of force development (RFD) were computed as the absolute percentage difference between limbs (100·|Right-Left|/max[Right, Left]) and summarized using 5-week centered rolling means. Between-sex comparisons used two-tailed tests with Benjamini-Hochberg false discovery rate control. Athlete profiles were derived via k-means clustering on the three asymmetry features, and a shallow decision tree identified the most informative metric. RESULTS: Males produced higher absolute jump outputs, whereas inter-limb asymmetry magnitudes were modest (approximately 5%-11%) and overlapped substantially between sexes; no between-sex differences in peak-force, braking-force, or RFD asymmetry remained significant after correction (all q = 0.207). A post hoc power analysis indicated that the observed RFD asymmetry effect (d = 0.40) had limited power, so moderate sex differences cannot be excluded. Group trajectories of asymmetry were relatively stable across the competitive window. Clusters derived from asymmetry features were distinct, and the decision tree consistently prioritized RFD asymmetry as the primary feature distinguishing asymmetry-based profiles, with peak force asymmetry secondary and braking asymmetry less discriminative. CONCLUSIONS: In-season CMJ force asymmetry in collegiate volleyball was small, largely overlapping between sexes, and showed limited systematic drift at the group level. RFD asymmetry emerged as the primary descriptor of asymmetry-based profiles but should be interpreted cautiously alongside more stable CMJ outputs. Summarizing weekly asymmetry with 5-week centered rolling means provides coach-ready signals for athlete-specific, profile-based monitoring rather than sex-based thresholds and offers guidance for structuring asymmetry-based monitoring and prioritizing training and reconditioning emphases.