12.02.2013
by Salynn Boyles
Contributing Writer, MedPage Today
Exercise training was found to have a small to moderate effect on fasting insulin and insulin resistance in children and teens, according to a meta-analysis.
The analysis of 24 studies revealed that exercise training could lead to measurable improvements in clinically relevant insulin outcomes, including fasting insulin (11.4 U/ml, 95% CI 5.2-17.5) and homeostatic model assessment insulin resistance (2.0, 95% CI 0.4-3.6), reported Michael V. Fedewa, MA, of the University of Georgia in Athens, and colleagues.
The findings suggest that regular physical activity may be an effective strategy for the prevention and treatment of type 2 diabetes in this age group, they wrote in the January issue of Pediatrics.
The relationship was consistent across gender, race, and age, indicating that the meta-analysis was an accurate estimate of the magnitude of the effect of exercise in children and adolescents, they added.
“Although the relatively small body of published literature did not allow for a thorough analysis of the effect of frequency, duration, intensity, mode, or volume of exercise, the beneficial effects of exercise training on fasting insulin and insulin resistance are clear,” they wrote.
Regular exercise, along with lifestyle modification, has been shown to reduce the development of insulin resistance or slow its progression in adults. Several studies have also shown that aerobic and resistance training can improve the regulation of glucose in pediatric populations.
Although there is ample evidence that physical activity and exercise is of benefit in the prevention of type 2 diabetes in adults, no meta-analytic reviews of exercise and fasting insulin have been previously reported in at-risk children.
The newly published systematic review examined 32 effects from 24 studies that included a total of 1,599 children from ages 6 to 19. More than half were female.
The analysis was limited to randomized controlled trials, done between 1999 and 2013, and selected by using combinations of multiple terms including adolescent, pediatric, youth, exercise training, physical activity, diabetes, and insulin. The authors found 546 studies of which 4.4% met all inclusion criteria.
Effects were derived from treatment groups of normal weight, overweight, and obese participants with a mean body mass index (BMI) of 27.2 kg/m2.
Exercise training consisted of 3.2 sessions per week, 53.4 minutes at a moderate to vigorous intensity physical activity per session for 15.5 weeks, when reported.
A variety of training interventions were used across studies, including resistance training, aerobic training, and circuit training, as well as nontraditional games and active play.
15 effects measuring the effect on insulin resistance. Estimated effects were independently calculated by multiple researchers, and conflicts were resolved before calculating the overall effect.
Effect size values were calculated by subtracting the mean change in the comparison condition from the mean change in the exercise condition, and dividing the difference by the pooled standard deviation of the baseline scores.
The cumulative results from the 32 effects found that exercise training effectively reduced fasting insulin levels in children and teens with a mean effect size equal to 0.48 (95% CI 0.22-0.74, z=3.57, P<0.001).
In the multilevel, intercept-only model, the mean effect size was 0.54 (95% CI 0.21-0.87) with significant variance (0.537, z=2.55, P=0.011) between the effects.
Twenty-six (81.3%) of the 32 effects were larger than zero.
Similar results were found for insulin resistance, as the cumulative results of 15 effects from 12 studies were in agreement that exercise training effectively reduces insulin resistance with a mean effect size of 0.31 (95% CI 0.06-0.56, z=3.29, P<0.05). Twelve (80% ) of the 15 effects were larger than zero.
“Our results are unique in that they provide a quantitative estimate of the effect of exercise on outcome measures of insulin, while assessing the influence of potential moderators, including BMI and sexual maturation,” the researchers wrote.
They added that exercise seems to be most effective for improving insulin status in children and teens with high BMIs.
“Obese adolescents showed significantly greater insulin resistance than their lean peers, which may provide a ‘floor effect’ and greater room for improvement after training in overweight and obese adolescents,” they wrote.
The effect of exercise training on fasting insulin was not affected by pubertal status.
Also, the analysis revealed no difference between aerobic or resistance training protocols, leading the researchers to conclude that “the most important component of an exercise program designed to target fasting insulin and insulin resistance in children and adolescents may not be ‘how’ they are encouraged to move but simply that they are encouraged to move at all.”
The researchers reported no external funding for this research, and they declared no potential conflicts of interest.
Reviewed by Zalman S. Agus, MD Emeritus Professor, Perelman School of Medicine at the University of Pennsylvania and Dorothy Caputo, MA, BSN, RN, Nurse Planner
Primary Source
Pediatrics
Source Reference: Fedewa MV, et al “Exercise and insulin resistance in youth: a meta-analysis” Pediatr 2013; DOI: 10.1542/peds.2013-2718.