Cardiac autonomic responses to high-intensity kettlebell training in untrained young women: A pilot study

Background: and purpose: The autonomic recovery after exercise provides information about the cardiovascular overload employed during the training session. The autonomic response over a training course is unclear in exercises performed at high intensities, such as kettlebell training. The study aimed to characterize the cardiac autonomic modulation after exercise in three distinct phases of a high-intensity kettlebell training program in young women.

Methods: Ten women (25.0 ± 2.9 years; 23.4 ± 3.0 kg/m²) were submitted to 10 weeks of training divided into three phases (three times a week). The autonomic response was measured in the pre-exercise and at 10, 20, and 30 min of recovery and evaluated temporal and linear analysis of heart rate variability (HRV) indices.

Results: vigorous intensity was performed in the sessions (75-86% HRmax). There was a significant reduction of HRV measured during post-exercise recovery (p < 0.05). In the initial two phases, the parasympathetic activity did not rebound to pre-exercise values (p < 0.05), and sympathetic was increased significantly until the end of the recovery period (p < 0.05). The third phase demonstrated the resumption of almost all the HRV indices at pre-exercise values at 20 min of recovery (p > 0.05).

Conclusion: The high-intensity kettlebell training program reduces HRV to 30 min of recovery (phases I and II). In the last phase (III), HRV components returned in 20 min. In addition, the program promoted improvement in aerobic fitness.