Relationship of locus of control to physical activity among people with and without diabetes.

OBJECTIVE: To examine the relationship between locus of control (LOC) (internal and external) and physical activity in Pima Indians and to determine whether this relationship is affected by the presence of diabetes. RESEARCH DESIGN AND METHODS: A population-based sample of 580 Pima Indians was recruited from an ongoing research study. LOC was measured on a 1-40 modified Rotter scale, and past year total physical activity (leisure and work physical activity levels combined) was measured by interviewer-administered questionnaire. RESULTS: Among both men and women without diabetes, individuals with an internal LOC (score 1-16) were significantly (P < 0.01) more active than those with an external (score 17-40) LOC (70 vs. 30 median metabolic equivalent [MET] hours per week for men: 12 vs. 5 median MET hours per week for women). Controlled for age and BMI, an internal LOC was significantly associated with a higher level of physical activity among men (P = 0.04) and women (P = 0.001) without diabetes, but not among those with diabetes. CONCLUSIONS: Nondiabetic Pima Indians with an internal LOC are more physically active than those with an external LOC. Enhancing perceptions of internal control may influence physical activity and thus have implications for diabetes prevention.