Differences In Center Of Pressure Complexity Index Across A Collegiate Volleyball Season

Individual athlete monitoring has become more common as improvements in technology have allowed; however, these efforts require a substantial time commitment and expertise. The resulting high-fidelity datasets can become cumbersome and difficult to identify meaningful change across a competitive season. While sport-specific measures may give valuable insight, a more general task may allow for more universal assessments of athletes, regardless of sport or sport-specific position. PURPOSE: To identify if any center of pressure (CoP) metrics, during a quiet stance task, would differ between the early, middle, and late portion of a collegiate volleyball season. METHODS: Sixteen athletes (n = 16) of the University of Montana Women’s Volleyball team participated in the study (181 ± 7 cm, 74 ± 6 kg, 21 ± 2 years). Participants completed 15 weekly 30-second balance assessments on a single force plate (1000 Hz). During all assessments, participants were barefoot, adopted a narrow stance, were free of supportive bracing, and completed the task without visual input. Raw CoP data were digitally filtered, with anteroposterior and mediolateral plane metrics individually derived: Root Mean Square Distance, Total Excursion, Mean Velocity, Mean Frequency, and a Multiscale Entropy Complexity Index (CI). Weekly measures were then averaged by five-week intervals to represent different phases of the competitive season. A Factorial (Plane x Season) MANOVA and subsequent pairwise comparisons were implemented with Bonferroni adjustments. RESULTS: Univariate differences were identified for CI (p = 0.001), with an interaction between plane and season (p = 0.001). Pairwise comparisons revealed differences within the Anteroposterior Plane (Early: 14.5 ± 0.2, Middle: 11.8 ± 0.2, Late: 14.0 ± 0.2). No other metrics displayed statistically significant differences across the season (p ≥ 0.256). CONCLUSIONS: We presently demonstrate that five-week clusters of weekly balance assessments can identify changes in CoP complexity throughout a competitive collegiate season. Previously, a reduction in CoP complexity has been shown in disease and fatigue models. We currently hypothesize the reduction in balance complexity presently noted mid-season may have resulted from overtraining in the early portion of the season.