(40) ENERGY AVAILABILITY, BODY COMPOSITION, AND NEUROMUSCULAR PERFORMANCE IN FEMALE RUNNERS

Purpose: Distance running is characterized by high energy demands and an emphasis on maintaining a lean physique. While the prevalence of low energy availability (LEA) has been studied in female athletes, including runners, limited research has examined associations between energy availability (EA), body composition, and neuromuscular (NM) performance. To purpose was to determine EA status, assess body composition and bone mineral density (BMD), and explore relationships between NM performance variables. Methods: Female runners (n = 10; age: 22.9 ± 3.1 yrs) participated. Body composition and BMD (hip, spine) were assessed using dual-energy X-ray absorptiometry (DXA). Exercise energy expenditure (EEE) was measured over three days using wearable monitors, and energy intake (EI) was recorded via a commercial nutrition analysis program. EA was calculated as: EI-EEE (kcal) / fat-free mass (FFM, kg), and athletes were classified as LEA (< 30 kcal/kg FFM/d) or non-LEA (≥30 kcal/kg FFM/d). NM performance was assessed using bilateral force plates for countermovement jump (CMJ) and isometric mid-thigh pull (IMTP), with peak force (absolute and relative) recorded for both, and modified reactive strength index (RSI_mod) measured for CMJ. Due to the small sample size, data were analyzed descriptively (mean ± standard deviation). Spearman correlation coefficients and 95% confidence intervals (CIs) were calculated for the full sample to examine preliminary relationships between body composition parameters, BMD, EA, and NM performance. Results: Table 1 displays values of body composition, EI, EEE, and NM performance by EA status. EA classification identified 40% (n=4) of athletes as LEA (range: 12.6 – 29.1 kcal/kg FFM/d). LEA athletes consumed insufficient total energy (26.9 ± 3.9 kcal/kg/d), carbohydrate (3.1 ± 0.5 g/kg/d), and fat (0.9 ± 0.3 g/kg/d) relative to established recommendations. Spine BMD z-scores were lower in the LEA group (-0.1 ± 1.6; range: -2.4 – 0.8) compared to non-LEA (-0.5 ± 0.5; range: -0.3 – 0.1), while hip BMD z-scores were similar between groups. Spearman correlation analyses revealed strong positive associations between FFM and both CMJ peak force (r = 0.88, 95% CI: [0.57, 0.97]) and CMJ RSI_mod (r = 0.92, 95% CI: [0.69, 0.98]). IMTP peak force was strongly correlated with FFM index (r = 0.80, 95% CI: [0.33, 0.95]). Interestingly, EA status showed a moderate negative correlation with RSI_mod (r = -0.60, 95% CI: [-0.89, 0.04]). CMJ peak force exhibited a moderate positive correlation with hip BMD (r = 0.56; 95% CI: [0.11, 0.88]). Conclusions: A high prevalence of LEA was observed, with athletes failing to meet energy, carbohydrate, and fat intake recommendations. Spine BMD z-scores were low for all athletes, highlighting potential bone health concerns. Practical Applications: Adequate energy and macronutrient intake are critical for maintaining bone health in female distance runners, reinforcing the need for targeted nutritional strategies. Acknowledgements: NSCA Foundation (2024 Graduate Research Grant – Doctoral)