Cardiovascular responses after isometric handgrip exercise at different intensities in healthy men

Abstract

The 30% maximal voluntary contraction protocol for isometric handgrip exercise is widely used to improve the cardiovascular system. However, it is unknown whether intensity modulation affects these responses. Objective: To analyze acute cardiovascular responses after isometric handgrip exercise performed at different intensities. Twenty-three healthy men participated in this cross-over study. The volunteers performed three experimental sessions: 4x2 minutes of contraction at 30% (S30) MVC and 4x2 minutes of contraction at 50% (S50) MVC, besides control (CS). Blood pressure (BP) as well as time (SDNN, RMSSD and PNN50) and frequency (LF, HF and LF/HF) domain heart rate variability parameters were obtained before and after sessions. None of the experimental sessions promoted statistically significant changes in systolic and diastolic BP (p> 0.05 for all). After S50, there was a smaller increase in SDNN five minutes after the exercise (S50: +5±6, S30: +20±5, SC: +10±2 ms, p <0.05) and higher LF/HF after 20 minutes (S50: +1.59±0.80, S30: -0.49±0.49, SC: +0.39±0.49, p <0.05) compared to the other sessions. In conclusion, BP responses to isometric handgrip exercise are similar between intensities; however, the most intense exercise promoted a greater increase in sympathetic modulation and decrease in parasympathetic modulation after exercise.