Effects of weight status and barriers on physical activity adoption among previously inactive women

This study examined self-reported physical activity (PA) barriers, and their effects on PA behavior change at 3 and 12 months among 280 previously inactive women enrolled in a PA promotion trial. Effect modification of baseline barriers by baseline weight status on PA behavior change was also examined. At baseline and month 12, obese women reported significantly greater PA barriers compared with normal and overweight women (P < 0.05). Individual barriers that were more likely to be elevated for obese vs. normal and overweight participants at baseline were feeling too overweight, feeling self-conscious, reporting minor aches and pains, and lack of self-discipline. Also, weight status moderated the effect of PA barriers on PA behavior change from baseline to month 3 (P < 0.05), but not to month 12 (P = 0.637), with obese participants reporting high barriers achieving 70 min/week fewer than those with low barriers (P < 0.05). Finally, the interaction between barriers (high vs. low) and weight status (obese vs. normal), shows PA barriers had a detrimental PA effect among obese participants that was 122.5 min/week (95% confidence interval (CI) = 15.7, 229.4; P < 0.05) lower than their effect on normal-weight participants. These results suggest that for obese women, PA barriers have quantifiable effects on PA behavior change. This study has implications for the design of future weight loss and PA interventions, suggesting that a comprehensive assessment of PA barriers is a prerequisite for appropriate tailoring of behavioral PA interventions.