title: Spontaneous physical activity and obesity: cross-sectional and longitudinal studies in Pima Indians.
abstract: Healthy, nondiabetic Pima Indians [103 males, 77 females; 27 +/- 6 (SD) yr, 97 +/- 25 kg, 33 +/- 9% body fat] were studied in a respiratory chamber in which spontaneous physical activity (SPA) was measured by two microwave sensors. SPA, defined as the percentage of time the subjects were active, varied widely from 4.4 to 17.5%. It was higher in males (9.3 +/- 2.0%) than in females (8.6 +/- 2.3%; P less than 0.05) and was not related to body fatness in either sex. However, SPA accounted for a significant portion of the daily energy expenditure (24-h EE) in males (1,389 +/- 423 kJ/day) and females (1,163 +/- 351 kJ/day) and correlated positively with 24-h EE adjusted for differences in fat-free mass, fat mass, age, and sex (r = 0.42, P less than 0.0001). In 88 siblings, family membership accounted for 57% of the variance in SPA (r(i) = 0.57, P less than 0.02). Body composition was reassessed in a subgroup of 123 subjects (65 males, 58 females) 33 +/- 14 mo later. In males only, SPA correlated inversely to the rate of subsequent body weight change (r = -0.25, P less than 0.05) and the rate of fat-mass change (r = -0.35, P less than 0.005). We conclude that spontaneous physical activity is a familial trait that may play a role in the pathogenesis of obesity.
authors.affiliation: Clinical Diabetes and Nutrition Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, Arizona 85016.
authors.forename: F
authors.initials: F
authors.lastname: Zurlo
authors.forename: R T
authors.initials: RT
authors.lastname: Ferraro
authors.forename: A M
authors.initials: AM
authors.lastname: Fontvielle
authors.forename: R
authors.initials: R
authors.lastname: Rising
authors.forename: C
authors.initials: C
authors.lastname: Bogardus
authors.forename: E
authors.initials: E
authors.lastname: Ravussin
mesh_terms: D000328:Adult; D001835:Body Weight; D003430:Cross-Sectional Studies; D004734:Energy Metabolism; D005192:Family Health; D005260:Female; D006801:Humans; D007198:Indians, North American; D008137:Longitudinal Studies; D008297:Male; D009765:Obesity / Q000208:ethnology / Q000209:etiology*; D005082:Physical Exertion