Purpose: The objectives of this study were to examine 1) whether changes in total physical activity (PA; counts per minute, cpm) and time spent in moderate to vigorous PA (MVPA) are associated with changes in adiposity and 2) whether energy intake influences the relationship between changes in PA and changes in adiposity in overweight Hispanic adolescents.
Methods: Analysis included 38 overweight (body mass index, >85th percentile) Hispanic adolescents with complete pretest and posttest data on relevant variables after participating in a 16-wk intervention. The intervention treatment did not influence PA, so the sample was combined and the randomization group was adjusted for in the analysis. Body composition by dual-energy x-ray absorptiometry, 7-d PA by accelerometry, and dietary intake by 3-d diet records were assessed before and after intervention.
Results: Within individuals, the mean increase of PA (n = 19) and mean decrease of PA (n = 19) was approximately 105 cpm. A 100-cpm increase in total PA was associated with a decrease of 1.3 kg of fat mass and 0.8% body fat after adjusting for pretest adiposity, PA, age, sex, and treatment (P < 0.05). Controlling for energy intake modestly strengthened the relationships between total PA and fat mass and percent body fat. Changes in MVPA were not related to changes in adiposity after controlling for total PA (P > 0.05).
Conclusions: Increasing total PA by 28% (100 cpm) was associated with a decrease of 1.4 kg of fat mass and 1% body fat for 16 wk in overweight Hispanic adolescents independent of intervention group assignment. Increases in total PA, compared with MVPA, may be sufficient to improve body composition in overweight Hispanic adolescents.
1Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA; 2Doheny Eye Institute and the Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, CA; and 3Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, CA
Address for correspondence: Michael I. Goran, Ph.D., 2250 Alcazar St, Suite 200, Clinical Sciences Centre, University of Southern California, Health Science Campus, Los Angeles, CA 90033; E-mail: firstname.lastname@example.org.
Submitted for publication February 2009.
Accepted for publication July 2009.