Postural effects of acute resistance exercise at different intensities on cardiac autonomic function and blood pressure in trained athletes

The objective of this study was to investigate the influence of acute resistance exercise (RE) on cardiac autonomic function, with specific attention to variations in body posture and exercise intensity.

Ten normotensive men (age: 26.6 ± 1.07 years; weight: 89.83 ± 5.08 kg; height: 182.9 ± 5.06 cm; BMI: 26.83 ± 1.53 kg/m²) participated in a randomized, counter-balanced crossover study. Participants completed six separate sessions of resistance exercise (RE), each session focusing on a specific repetition maximum (RM) level of 5, 10, or 15. Blood pressure (BP), heart rate variability (HRV), and rate-pressure product (RPP) were taken before, immediately after, 10-, 20-, and 30-min post-RE.

The results revealed significant differences (p < 0.05) in systolic BP and HRV, notably during the 15RM squats. RPP was significantly higher in the 15RM squats compared to the leg press (p < 0.05). However, there was no statistically significant difference (p < 0.05) between the 10RM and 15RM for the normalized low-frequency component (nLF). Furthermore, significant differences were observed between squat and leg press exercises in root mean square of successive R-R differences (RMMSD) and normalized units of high frequency (nHF) at the 20-min mark after the 5RM trials. Notably, all RMs exhibited significant variations compared to pre- and post-values in nHF.

This study’s findings illustrate that body posture significantly impacts cardiovascular responses during resistance training. Moreover, utilizing higher repetition schemes is more effective in lowering blood pressure (BP) than high-intensity or low-repetition workouts, especially when performed in a standing position.