ACUTE EFFECT OF AEROBIC AND STRENGTH EXERCISE ON HEART RATE VARIABILITY AND BAROREFLEX SENSITIVITY IN MEN WITH AUTONOMIC DYSFUNCTION

The extent to which postexercise cardiac autonomic control depends on exercise modality remains unclear, particularly among individuals with autonomic dysfunction (cardiac autonomic dysfunction [CADysf]). This study compared heart rate variability (HRV) and baroreflex sensitivity (BRS) responses to acute aerobic exercise (AE) and strength exercise (SE) in men with CADysf. Twenty men were assigned into control (n = 10: 33.8 +/- 3.0 years; 23.7 +/- 1.5 kg.m(-2)) and CADysf (n = 10: 36.2 +/- 9.8 years; 28.4 +/- 2.6 kg.m(-2)) groups. Cardiac autonomic dysfunction underwent AE, SE, and a nonexercise control day (control session [CTL]) in a randomized, counter-balanced order. Heart rate variability and BRS were assessed in a supine position during 25 minutes of recovery after AE, SE, and CTL. Both HRV indices (p <= 0.05; effect size [Cohen's d]: >1.4) and BRS at rest were significantly lower in CADysf than those in controls (p < 0.01; effect size [Cohen's d]: >= 1.36). In CADysf, postexercise increases in heart rate, sympathetic activity (low-frequency [LF] band), and sympathovagal balance (LF:high-frequency [HF] ratio), as well as decreases in R-R interval, parasympathetic activity (HF band), and BRS were observed in AE (p <= 0.05; effect size [Cohen's d]: >= 1.31) and SE (p <= 0.05; effect size [Cohen's d]: >= 0.79) vs. CTL, but changes were larger after AE than SE (p <= 0.05; effect size [Cohen's d]: >= 0.73). In conclusion, both AE and SE elicited postexercise changes in HRV and BRS among CADysf men, primarily reflected by lowered vagal modulation, increased sympathovagal balance, and a delayed BRS recovery pattern. However, those changes seem to be more likely to occur after AE than SE.