Aerobic exercise and snoring in overweight children: a randomized controlled trial

Nutrition Research Newsletter, Dec, 2006

Currently, 37% of children 6 to 11 years of age in the United States are overweight ([greater than or equal to] 85th percentile BMI-for-sex and -age). The prevalence of sleep-disordered breathing may be increasing as a result of the childhood obesity epidemic. The prevalence of sleep-disordered breathing in children is estimated at 2%; however, obese children are more susceptible than lean ones to sleep-disordered breathing (for example, obstructive sleep apnea). Sleep disturbances in adolescents have been linked to obesity and inactivity. Among adults, sleep apnea is associated with obesity. Exercise training has been shown to ameliorate both obesity and sleep apnea in adults. The effect of exercise on symptoms of sleep-disordered breathing in overweight children is unknown. The researchers hypothesized that overweight children's symptoms of sleep-disordered breathing would improve in a dose-response fashion in response to an exercise program.

Healthy but overweight (BMI [greater than or equal to] 85th percentile) 7 to 11 year old children were recruited from public schools for a randomized controlled trial of exercise effects on diabetes risk. One hundred children (53% black, 41% male) were randomly assigned to a control group (n = 27), a low-dose exercise group (n = 36), or a high-dose exercise group (n = 37). Exercise groups underwent a 13 [+ or -] 1.5 week after-school program that provided 20 or 40 min per day of aerobic exercise (average heart rate = 164 beats per minute). Group changes were compared on BMI z-score and four Pediatric Sleep Questionnaire scales: Snoring, sleepiness, behavior, and a summary scale, sleep-related breathing disorders. Analyses were adjusted for age.

Both the high-dose and low-dose exercise groups improved more than the control group on the snoring scale. The high-dose exercise group improved more than the low-dose exercise and control groups on the summary scale. No group differences were found for changes on sleepiness, behavior, or BMI z-score. At baseline, 25% screened positive for sleep-disordered breathing; half improved to a negative screen after intervention.

Overweight children show a moderate level of sleep-disordered breathing symptomatology, particularly snoring. Engaging in 20 to 40 min per day of vigorous aerobic exercise, preferably in an organized setting, appears to be helpful in ameliorating symptoms of sleep-disordered breathing in overweight children. This effect was independent of weight change, because the randomized groups did not differ on change in their BMI z-scores. One-quarter of the overweight children in this study screened positive for sleep-disordered breathing; one-half of these children improved to a negative screen after intervention. This randomized trial in a community sample of children at risk for sleep-disordered breathing as a result of their overweight status provides evidence supporting routine clinical prescription of regular aerobic activity in overweight children to ameliorate sleep-disordered breathing symptoms, which may be more common than expected.

In summary, sleep-disordered breathing may be more common among overweight children than is generally realized. One-quarter of the overweight children in this community sample screened positive for sleep-disordered breathing. Engaging in 40 min per day of vigorous aerobic exercise for 10 to 15 weeks seems to improve symptoms of sleep-disordered breathing in overweight children. Achieving this level of physical activity (40 min per day, 5 days per week, heart rate > 150 beats per min) among children in ordinary circumstances is likely to require 1 h per day of physical activity. This experimental evidence adds to the knowledge base about the benefits of physical activity on overweight children's health, even when weight loss does not occur.

C. Davis, J. Tkacz, M. Gregoski, et al. Aerobic Exercise and Snoring in Overweight Children: A Randomized Controlled Trial. Obes Res; 14:1985-1991 (November 2006). [Correspondence: Catherine L. Davis, Georgia Prevention Institute, Medical College of Georgia, 1499 Walton Way, HS1711, Augusta, GA 30912. E-mail: cadavis@mcg.edu.]