Assessment of heart rate variability, performance and body composition in Muay Thai athletes: Clinical trial

Abstract

INTRODUCTION: Muay Thai combines upper and lower limb strikes and has gained worldwide recognition. In this sport, assessing heart rate variability (HRV) and body composition using bioelectrical impedance analysis (BIA) is essential for monitoring training load and athlete performance. OBJECTIVES: To investigate the relationship between HRV parameters, performance in the frequency speed kick test (FSKT), and body composition in amateur Muay Thai athletes. METHODOLOGY: A cross-sectional study was conducted with 37 fighters to evaluate the acute response during the execution of the 10-s FSKT. HRV was measured both at rest and during the test, along with body composition assessment via BIA. Then, 22 athletes participated in a clinical trial, undergoing an eight-week strength training program combined with nutritional guidance. In both phases, athletes were assessed using the FSKT-10s and FSKT-mult tests, bioelectrical impedance analysis (BIA), and HRV analysis. RESULTS: In the cross- sectional study, an acute effect on autonomic modulation was observed during the FSKT- 10s, characterized by increased sympathetic activation and vagal withdrawal. Additionally, the number of kicks showed a positive correlation with fat-free mass and specific HRV parameters, while the kick fatigue index correlated inversely with parasympathetic indices and directly with sympathetic indices. In the clinical trial, after eight weeks of intervention, there was a significant increase in the number of kicks (in both the FSKT-10s and FSKT- mult), an increase in fat-free mass and basal metabolism, as well as an improvement in parasympathetic modulation, evidenced by increases in RMSSD, pNN50, high-frequency band amplitude, and SD1 of HRV. CONCLUSION: Integrating strength training with nutritional guidance leads to significant improvements in performance, body composition, and autonomic balance in Muay Thai athletes. Furthermore, acute HRV assessment during performance tests highlights the importance of monitoring autonomic responses to optimize training and prevent fatigue.