Differences in the psychophysiological response between normal weight and overweight young recreational athletes in strength training

Background: Strength training is widely recognized for its benefits in young recreational athletes, yet limited research has explored its effects on heart rate variability (HRV) across different body compositions. This study aimed to analyse the autonomic modulation differences between normal-weight and overweight recreational athletes during strength training. Methods: A total of 63 male recreational athletes (23.8 ± 3.6 years, 174.9 ± 8.2 cm, 70.8 ± 11.7 kg) were categorized into normal-weight (Body Mass Index < 25) (N = 38) and overweight (Body Mass Index > 25) (N = 25) groups. Participants performed three sets of 10 repetitions at 70% 1RM for both squats and bench press. HRV parameters, including RMSSD, SDNN, and PNN50, were measured before, during, and after training. Additionally, heart rate (HR), rate of perceived exertion (RPE), and strength levels were assessed. Results: HR significantly increased during training in both groups, with a greater post-exercise HR elevation observed in the normal-weight group. HRV parameters (RMSSD, SDNN, PNN50) decreased significantly during training in the normal-weight group, indicating greater autonomic stress. RPE increased post-exercise in both groups, while the overweight group demonstrated higher baseline strength levels. Conclusion: Strength training induced acute autonomic stress in both groups, with greater HRV suppression observed in normal-weight athletes, suggesting a higher physiological demand. In contrast, overweight athletes displayed better baseline strength levels and potentially greater adaptability to strength training. These findings highlight the need for individualized training prescriptions based on body composition to optimize performance and recovery in recreational athletes.