LAUSR

The aim of this study was to examine the cardiac autonomic nervous system differences following either continuous vs. discontinuous exercise in males and females. Forty-seven healthy male and female subjects (M=19, F=28; Age=36.95±13.79) underwent a baseline test for VO2peak and tilt table testing. They were assigned to a one-month control period before returning to repeat the testing and then begin one month of either continuous aerobic treadmill work for 30 min at 70% peak heart rate (N=23) or 3 bouts of 10 min at 70% of peak heart rate with two 10-min break periods in between (N=24). Following exercise, both groups demonstrated a significant improvement in VO2peak (p<0.001). Treatment differences were detected while tilted in continuous as a decreases in the percentage of instances within an hour that the normal sinus interval exceeds 50 ms (p=0.036) and in the high-frequency component (p=0.023). While supine, the discontinuous group saw reduction in heart rate (p=0.004), and an increase in high-frequency (p=0.018). These data suggest that for healthy people either continuous or discontinuous aerobic training is effective in improving measures of fitness; however discontinuous is better able to improve supine indices of vagal activity on heart rate variability.