The Association Between Muscle Strength, Thigh Circumference, and Serving Efficiency in Elite Male Volleyball Players: A Prospective Observational Longitudinal Study

Background and Aim: The identification of factors that optimize competitive performance is a primary focus for athletes and coaches in any sport, particularly variables that are modifiable through tailored nutritional and training strategies. Since data regarding volleyball remain scarce, this investigation aimed to explore the association between the baseline preseason anthropometry, body composition, and dietary habits of elite adult male volleyball players and the key performance indicators (KPIs) retrieved as match-by-match data during an official tournament. Methods: Nineteen elite male volleyball players (mean age: 23.79 ± 5.72 years; BMI: 23.88 ± 1.97 kg/m2) underwent comprehensive assessments. Anthropometric data and muscle strength (MS) were evaluated via body circumferences and handgrip dynamometry, respectively. Body composition was analyzed using bioelectrical impedance vector analysis (BIVA), while Mediterranean diet adherence was assessed with the validated Mediterranean diet adherence score (MEDAS) questionnaire, all measured cross-sectionally at one time point, identified as the baseline preseason phase of the competitive season. The tournament KPIs included serving, attack, and reception efficiencies, and block points per set were retrieved longitudinally during each match of the competitive season. Data were analyzed utilizing correlation and linear mixed-model regressions. Results: Right-hand MS correlated positively with higher MEDAS scores (ρ = 0.488, p < 0.05). Furthermore, both right-hand MS (β = 1.005, 95% CI [0.178, 1.831], p = 0.026) and thigh circumference (β = 3.030, 95% CI [0.083, 5.977], p = 0.046) were found to be positively associated with higher serving efficiency (adjusted R2m ≈ 0.12). Conclusions: Monitoring muscle strength and thigh circumference alongside targeted nutritional and training strategies may be considered in elite male volleyball, as these factors were associated with serving efficiency. However, due to the observational nature of the research, our findings require replication in larger, multicenter intervention studies.