Evaluating Change in Body Composition and Impact of Menarche Across a Competitive Season in Elite Collegiate Gymnasts

Abstract

The purpose of this study was to evaluate change in bone mineral density (BMD), BMD percentile (BMDp), lean mass (LM), fat-free mass index, body fat percentage (BF%), and muscle size (mCSA) and quality (EI) in collegiate female gymnasts over a competitive season and characterize the impact of menarche on changes. Twenty gymnasts completed a validated survey to assess age of menarche. Body composition was assessed via whole-body dual-energy X-ray absorptiometry scans at pre- and postseason. mCSA and EI were determined from a panoramic ultrasound scan of the vastus lateralis. Pre- to postseason changes were evaluated using paired sample t tests, and strength of relationships between were analyzed via bivariate correlations and linear regression. Significant losses in body fat percentage (Δ -1.1 ± 1.9%; p = .022) and EI (Δ -5.0 ± 5.8 a.u.; p = .002) were observed. No significant changes were observed in BMDp, mCSA, BMD, LM, or fat-free mass index (p = .310–.869). Age of menarche (15.4 ± 1.5 years) was negatively correlated with Δ BMDp (r = −.454; p = .044) and Δ mCSA (r = −.658; p = .002), explaining 21% and 43% of variation in Δ BMDp and Δ mCSA, respectively. Positive outcomes of gymnastics training, such as gains in LM and mCSA, may be attenuated by delayed menarche, suggested by increased EI and decreased body fat percentage, despite no changes in mCSA or overall LM. These findings may indicate a higher priority of fat utilization within the muscle over muscle and bone growth. Considering menarche as a significant predictor for Δ mCSA, this lack of increase (despite improved EI), may signify increased injury risk resulting from team-specific training style or insufficient energy intake to support appropriate muscle growth.