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Effect of physical training on heart-period variability in obese children
1Department of Pediatrics, Medical College of Georgia, Augusta 30912, USA.
Insights
Physical training improves cardiac autonomic function in obese children. Exercise favorably alters heart-period variability, reducing sympathetic-parasympathetic imbalance.
Area of Science:
- Pediatrics
- Cardiology
- Exercise Physiology
Background:
- Heart-period variability (HPV) reflects cardiac autonomic activity and predicts health outcomes.
- Obesity in children is associated with altered autonomic function.
- The impact of physical training on HPV in obese children remains under-investigated.
Purpose of the Study:
- To investigate the effects of a structured physical training program on cardiac autonomic function in obese children.
- To assess changes in heart-period variability parameters following a 4-month exercise intervention.
Main Methods:
- Thirty-five obese children were randomized into physical training and control groups.
- The training group engaged in 4 months of exercise (5 days/week, 40 min/day).
- Measurements included cardiovascular fitness, body fat percentage, and resting heart-period variability parameters.
Main Results:
- The trained group showed significant reductions in submaximal heart rate and body fat percentage.
- Vagal tone, assessed by the root mean square of successive differences, significantly increased in the trained group.
- Physical training led to favorable shifts in autonomic balance, decreasing sympathetic activity markers and the sympathetic-parasympathetic ratio.
Conclusions:
- Physical training positively modulates cardiac autonomic function in obese children.
- Exercise intervention leads to a more balanced autonomic nervous system profile, characterized by reduced sympathetic dominance.
Objective:
The beat-to-beat variability in electrocardiogram intervals (RR, i.e., heart-period variability) provides information on cardiac autonomic activity that predicts arrhythmias and mortality rate in animals and adults. We determined the effect of physical training on heart-period variability in obese children.
Methods:
Thirty-five subjects were randomly assigned to physical training and control groups. The training involved 4 months of exercise, 5 days per week, 40 minutes per day. Cardiovascular fitness was measured with submaximal heart rate during supine cycling; percentage of body fat was measured with dual-energy absorptiometry; and resting heart-period variability parameters were measured in a supine position. A pretraining to posttraining change score was computed for each variable. The effect of the training was determined by comparing the changes of the training and control groups.
Results:
Compared with the control group, the trained group (1) reduced submaximal heart rate and percentage of body fat (p < 0.01); (2) increased in the root mean square of successive differences, a time-domain parameter reflective of vagal tone (p < 0.05); (3) decreased in low-frequency power expressed as a percentage of total power, a frequency-domain index of combined sympathetic and vagal activity (p < 0.03); and (4) decreased in the ratio of low- to high-frequency power, an index of sympathetic-parasympathetic balance (p < 0.01).
Conclusions:
In obese children, physical training alters cardiac autonomic function favorably by reducing the ratio of sympathetic to parasympathetic activity.