Intervention Increases Physical Activity and Healthful Diet Among South African Adolescents Over 54 Months: A Randomized Controlled Trial

Purpose: Scant research has investigated whether health promotion interventions have sustained effects in increasing physical activity and healthful diet among adolescents in sub-Saharan Africa, which is experiencing an epidemiological transition from infectious diseases to noncommunicable diseases as leading causes of mortality. We examined whether an intervention increased adherence to 5-a-day diet and physical activity guidelines during a 54-month postintervention period among South African adolescents and whether its effects weakened at long-term (42 and 54 months postintervention) compared with short-term (3, 6, and 12 months postintervention) follow-up.

Methods: We randomized 18 randomly selected schools serving grade 6 learners (mean age = 12.6) in a township and a semirural area in Eastern Cape Province, South Africa, to one of the two 12-hour interventions: health promotion, targeting healthful diet and physical activity; attention-matched control, targeting sexual risk behaviors. We tested the intervention's effects on adherence to 5-a-day diet and physical activity guidelines using generalized estimating equations logistic regression models adjusting for baseline behavior and clustering within schools.

Results: Health promotion intervention participants had higher odds of meeting 5-a-day diet and physical activity guidelines than control participants. The effect on 5-a-day diet did not weaken at long-term compared with short-term follow-up, but the effect on physical activity guidelines was weaker at long-term follow-up, mainly because of a reduced effect on muscle-strengthening physical activity. The intervention also increased health promotion attitude and intention and health knowledge and reduced binge drinking compared with the control group.

Conclusions: A 12-hour intervention in grade 6 shows promise in increasing self-reported adherence to healthful diet and physical activity guidelines during a 4.5-year postintervention period among South African adolescents.