Brief physical activity-related psychosocial measures: reliability and construct validity.

BACKGROUND Psychosocial factors have been related to physical activity (PA) and are used to evaluate mediation in PA interventions. METHODS Brief theory-based psychosocial scales were compiled from existing measures and evaluated. Study 1 assessed factor structure and construct validity with self-reported PA and accelerometry in overweight/obese men (N = 441) and women (N = 401). Study 2 assessed 2-week reliability and internal consistency in 49 college students. RESULTS Confirmatory factor analysis indicated good fit in men and women (CFI = .90; RMSEA = .05). Construct validity was supported for change strategies (r = .29-.46), self-efficacy (r = .19-.22) and enjoyment (r = .21-.33) in men and women, and for cons in women (r = -.19 to -.20). PA pros (r = -.02 to .11) and social support (r = -.01 to .12) were not supported for construct validity. Test-retest reliability ICCs ranged from .49-.81. Internal consistency alphas ranged from .55-.90. Reliability was supported for most scales with further testing needed for cons (alphas = .55-.63) and enjoyment (ICC = .49). CONCLUSIONS Many of the brief scales demonstrated adequate reliability and validity, while some need further development. The use of these scales could advance research and practice in the promotion of PA.