Cardiac autonomie reaction to eccentric isokinetic strength training in healthy sexagenarian men

Abstract

Background Heart rate variability (HRV), used as a noninvasive tool to analyze the influence of the autonomie nervous system on the heart, decreases with aging as a consequence of parasympathetic reduction and sympathetic modulation predominance. This fact has an important clinical impact on the elderly, because reduced HRV can be associated with higher cardiovascular morbidity and mortality rates. Purpose To investigate cardiac autonomie reaction to eccentric isokinetic strength training in healthy sexagenarian men. Methodology The HRV of ten healthy sexagenarian men was evaluated before and after 12 weeks of isokinetic eccentric strength training. Electrocardiogram was recorded before and after the training period. Furthermore, to estimate strength gains, the eccentric peak torque of the dominant leg was measured at 60°/s by the same isokinetic dynamometer. Results Mean systolic blood pressure decreased (124.68 (8.19) to 118.56 (10.12)mmHg, p < 0.05) and peak torque increased (extension (205.12 (37.06) to 250.25 (59.45) N.m) and flexion 115.53 (24.87) to 130.96 (26.97) N.m) after the strength training. The frequency domain indices showed a significant training effect (p < 0.05), since low frequency in normalized units and low/high frequency ratio increased, and high frequency in normalized units decreased after the training period. Conclusions Results of the present investigation suggest that Eccentric Isokinetic strength training performed by healthy sexagenarian men increases peak torque and reduces systolic blood pressure. However, an autonomic imbalance towards sympathetic modulation predominance was induced by an unknown mechanism.