Do low levels of physical activity in female adolescents cause overweight and obesity? Objectively measured physical activity levels of periurban and rural adolescents
Background. The increase in obesity levels in South African adolescents is attributed to an energy imbalance such that physical inactivity is causally related to adiposity. However, in some settings obesity occurs in spite of high physical activity levels.
Objectives. To examine objectively measured physical activity levels of rural black female and male adolescents from periurban to rural settings in relation to weight status, and specifically the direction and strength of the associations.
Methods. Seven-day accelerometry-derived pedometry data (step counts and activity energy expenditure) were collected for 178 adolescents (85 females, 93 males; age 13.7 - 18.0 years) living in six demographic surveillance site villages. Anthropometric measures were body mass index (kg/m2), waist circumference (cm) and sum of skinfolds (mm). Weight status was determined using international growth standards for stunting, underweight (UW), normal weight (NW), overweight (OW) and obesity (OB).
Results. Females had greater adiposity and lower 7-day average step counts and activity energy expenditure, and achieved fewer days at ≥10 000 steps and more days at <5 000 steps (p<0.05). The age and gender-weighted prevalences for female/male stunting, UW-NW, OW-OB, <5 000 steps/day and ≥12 500 steps/day were 12.4%/20.7%, 74.3%/99.1%, 25.8%/0.9%, 12.3%/0.9% and 50%/64.9%, respectively (females v. males, p<0.05). In multivariate models (weighted and adjusting for age, gender, village, season), step counts and activity energy expenditure were positively related to adiposity measures (p<0.05).
Conclusion. Both UW-NW and OW-OB periurban to rural adolescents were active to highly active on most days of the week. Physical activity was directly associated with adiposity measures.