| Keywords |
Food intake ; Exercise ; Heart rate variability ; Circadian rhythm |
| Abstract |
This study examined the influences of food intake on cardiac autonomic responses to acute bouts of vigorous exercise, reflected by heart rate variability (HRV). On four occasions, six physically fit and young males exercised, in random order, on a cycle ergometer either before and 30 minute, 60 minute, or 90 minute after food intake (505 kcal), each followed by five min of active recovery. Electrocardiogram data was collected for 5 minute intervals in the sitting position, at rest before and after each exercise bout. Measures of heart rate variability obtained from frequency domain analysis of ECG recording were as follows: the low frequency and high frequency components which were calculated as normalized units and their ratio (LF/HF ratio). Analysis of heart rate variability revealed a significant increase in sympathetic activity and a significant decrease in parasympathetic activity (p<0.05) following the meal. Further HRV variables were associated with higher shifts during exercises at postprandial 30min or 60min, as compared to exercise at 90 min after the meal (p<0.05), These results suggest that exercise when performed in fasting or after 90 min following a meal may be effective in minimizing exercise-induced cardiac sympathovagal imbalance. |