Physiological And Psychological Predictors Of Physical Activity Among Adults With Severe Obesity

Over 9% of Americans have severe obesity (SO; BMI > 40) and the proportion with SO has increased by 600% during the past 20 years. SO is associated with multiple comorbidities, increased mortality, reduced mobility, lower physical activity (PA), and increased social stigma and distress. Few past studies have examined physiological, psychological, and social factors associated with PA among adults with SO. PURPOSE: This study evaluated the relationship of body fat, functional performance, and psychosocial functioning to PA among adults with SO. METHODS: 38 community-residing adults (age = 49.4 + 13.3; 89% female) with SO (BMI = 46.9 ± 5.4) were recruited to participate in a 6-week randomized intervention study designed to increase standing and walking time. At baseline, all participants completed assessments of PA (one-week ActiGraph data; International Physical Activity Questionnaire (IPAQ)), body fat (body mass index (BMI), waist circumference (WC)), functional performance (sit-to-stand test, 60-ft. walk test), and psychosocial functioning (perceived stigma, perceived stress scale (PSS)). Baseline measures were analyzed with correlation and regression to identify predictors of PA. RESULTS: : Greater ActiGraph % sedentary time was associated with larger WC (r = 0.508, p = 0.004) and higher BMI (r = 0.35, p = 0.057). Regression analysis indicated that together they account for 25% of the variance in sedentary time (F(2,27) = 4.72, p = .018). ActiGraph light activity was associated with lower WC (r = -0.47, p = 0.008), but with higher PSS (r = 0.39, p = 0.034). Together they account for 33% of the variance in light activity (F(2,27) = 6.70, p = .004). IPAQ hours of sitting were associated with higher BMI (r = 0.40, p = 0.032) but with lower PSS (r = -0.38, p = 0.040). Together they account for 26% of the variance in sitting behavior (F(2,26) = 4.53, p = .021). PA measures were not associated with functional performance or perceived stigma assessments. CONCLUSIONS: Among adults with SO, greater WC was the strongest predictor of sedentary behavior and lighter PA. Higher BMI also predicted greater sitting/sedentary behavior. Surprisingly, higher perceived stress predicted greater activity. Thus, WC may be especially useful in predicting PA in this population, but perceived stress also may be associated with greater PA.