Early Physical Activity Adoption Predicts Longer-Term Physical Activity Among Individuals Inactive at Baseline.

BACKGROUND: To examine the relationship between early physical activity (PA) adoption (2, 3, and 4 mo) and longer-term PA adherence (1 y) among individuals who were inactive at baseline and received a lifestyle intervention. METHODS: Participants (n = 637) received weekly behavioral weight loss sessions, calorie reduction, and PA goals (50-175 min/wk progression). PA was assessed via self-reported measures at baseline, months 2 to 4, and 1 year. RESULTS: PA at months 2 to 4 was significantly correlated with PA at 1 year (rs = .29-.35, P < .01). At all early time points, those failing to meet the prescribed PA goal (early nonadopters) engaged in significantly less PA at 1 year than those meeting the early PA goal (initial adopters). For example, using 2-month criteria, initial adopters engaged in 108.3 minutes per week more at 1 year compared with early nonadopters (P < .01) and had 2.8 times the odds (95% confidence interval, 1.9-4.2) of meeting the 1-year PA goal (≥175 min/wk, P < .01). CONCLUSIONS: Failure to achieve PA goals at 2, 3, or 4 months results in less overall PA at 1 year. Thus, PA observed as early as month 2 may be a useful indicator for identifying at-risk individuals who may benefit from more intensive PA intervention strategies.