Journal Title (Medline/Pubmed accepted abbreviation): Appl Physiol Nutr Metab
Page numbers: 515-525
Summary of background and research design:
Background: Currently, it is thought that influences on body composition development in growing children may come more from physical activity than energy intake. However, only limited conclusions can be drawn because there is a lack of quantitative evidence.
Hypothesis/Purpose: To investigate the effect of increasingly high-intensity exercise on adipocytokines and physiology in overweight and obese children.
Subjects: 27 prepubertal children (ages, 5 to 10 y) with a body mass index [BMI] > 85th percentile (means in intervention and control groups, respectively: age, 8.5 and 8.8 y; weight, 51.6 and 50.1 kg; height, 138.0 and 142.7 cm; waist circumference, 80.0 and 76.6 cm) participated in this study.
Experimental design: Randomized, cross-over
Treatments and protocol: Children were randomized to either a 10-week intervention or standard of care (control), followed by the opposite care 1 week later. The intervention consisted of 3 nutrition classes (3 weeks apart), 2 parental education classes (before and after intervention), and a progressive high-intensity (from 2 to 20 minutes) exercise program twice weekly (total, 1 hour of exercise). High-intensity exercise was defined as ≥ 75% of maximum heart rate (HR), which was measured every 15 seconds during exercise. Three 3-day dietary records were completed (2 weekdays and 1 weekend day). Body composition and blood samples for lipid parameters were analyzed up to 4 times for each type of care.
Summary of research findings:
- There were significant increases in energy expenditure, HR, and activity counts in the intervention cohort compared with the control cohort (P < .0001 for all).
- Changes in HR were associated with energy expenditure (P < .0001).
- Independent factors that correlated with the mean change in HR were attendance (P = .001), grip strength (P = .01), and sex (P = .004).
- Boys exercised at a greater intensity compared with girls in both the first class (P < .0004) and the last class (P < .0001).
- Both sexes increased exercising intensity from first to last class (P < .0001).
- Compared with the control cohort, positive changes were observed in weight (P = .0499), BMI percentile (P = .0299), percent fat mass (P = .0005), percent fat-free mass (P = .0055), and triglycerides (P = .0467) in the intervention cohort.
- Family eating and activity score had a positive change (decreased) during the intervention (P < .0001) that was significantly different compared with the control cohort (P = .01).
- Caloric intake did not significantly change during the study, and it was not correlated with the change in percent fat mass.
- During the crossover control period, the intervention score continued to decrease, but not significantly.
Interpretation of findings/Key practice applications:
The intervention successfully ameliorated the physiologic profiles of overweight and obese children. However, the amount, intensity, and type of physical activities necessary to achieve optimal results have not been determined. Limitations to this study include data from 1 geographic area, no control for socioeconomic status, and parental reports of puberty status.