The impact of resistance training on heart rate variability parameters in physically active young adults.

Background: Heart rate variability (HRV) parameters are an important indicator of cardiovascular health. While it has been well established that aerobic exercise improves HRV, the effects of resistance training on HRV remain less explored.

Objectives: To compare the impact of a resistance training routine on HRV parameters in physically active young adults.

Methods: This observational study included 24 participants, 12 who underwent resistance training and a control group of 12 who underwent moderate-intensity exercise. HRV was assessed during a 15-minute resting period in the supine position with a Polar RS800CX heart rate monitor. The analysis encompassed time-domain metrics (root mean square of successive differences between adjacent normal R-R intervals [RMSSD] and the standard deviation of normal-to-normal R-R intervals [SDNN]), frequency-domain metrics (high-frequency and low-frequency indices, both expressed in normalized units, and the low-frequency/ high-frequency ratio), and non-linear metrics (SD of the Poincaré plot width [SD1] and the SD of the Poincaré plot length [SD2]). HRV parameters were processed in Kubios HRV. Statistical analysis included unpaired t-tests, with significance set at p < 0.05.

Results: The resistance-trained group demonstrated significantly higher RMSSD (75.3 [SD, 28.5] ms) and SDNN (65.8 [SD, 23.1] ms) values than the untrained group (RMSSD: 37.5 [SD, 19.6] ms; SDNN: 40.2 [SD, 14.2] ms; p < 0.01). SD1 and SD2 were also significantly higher in the resistance training group than the control group, reflecting greater parasympathetic activity.

Conclusions: Long-term resistance training was associated with improved parasympathetic modulation, indicating potential cardiovascular benefits and enhanced autonomic function.