Effects of acute high-intensity exercise on heart rate variability following rapid weight loss in elite wrestlers

Investigating how the autonomic functions of the heart are affected during rapid weight loss practices is extremely important for athletes’ health. This study aimed to investigate how rapid weight loss (3–5%) affects heart rate variability (HRV) in elite wrestlers. Twelve elite freestyle male wrestlers (mean age: 19.8 ± 3.3 years; height: 172.4 ± 4.0 cm; body weight: 76.9 ± 11.6 kg) participated in this study. Body composition and HRV measurements were taken before the wrestlers started to lose weight (14 days before the competition) and after 3–5% of their body weight was lost. HRV measurements in the time domain—RR (time between RR intervals—ms), SDNN (standard deviation of NN intervals), and RMSSD (root mean square of consecutive RR interval differences)—and power values in the high-frequency (HF) and low-frequency (LF) bands and the LF/HF ratio were taken at rest, after warm-up, and during high-intensity exercise and recovery using a Polar Vantage V2 monitor and H10 sensor. The data were analyzed via repeated-measures analysis of variance (ANOVA). The analyses were performed with the statistical program SPSS version 28.0 (IBM Corp., Armonk, NY, USA). Comparisons of differences were performed via two-way ANOVA (2 sessions × 4 times). Bonferroni correction was used for pairwise comparisons. The significance level was set at p < 0.05. No significant changes were observed in the HRV time-domain parameters after short-term rapid weight loss (p > 0.05). However, a significant increase in the LF/HF ratio was detected post-RWL (p < 0.05). Rapid weight loss of up to 5% of total body weight in combat sports did not significantly affect HRV time-domain parameters. A modest increase in the LF/HF ratio was observed, suggesting a potential shift in autonomic balance, although the clinical implications of this finding remain uncertain.