Self-reported and objective physical activity in postgastric bypass surgery, obese and lean adults: Association with body composition and cardiorespiratory fitness

Background: This study aimed to 1) describe physical activity (PA) in 15 post gastric bypass surgery (GB), 16 obese (Ob), and 14 lean (L) participants (mean ± se: age = 37.1 ± 1.6, 30.8 ± 1.9, 32.7 ± 2.3 yrs.; BMI = 29.7 ± 1.2, 38.2 ± 0.8, 22.9 ± 0.5 kg/m ², respectively); and 2) test associations between PA, body composition, and cardiorespiratory fitness (VO₂max). Methods: Participants completed a PA questionnaire after wearing accelerometers from 5-7 days. Body composition was determined with DEXA and CT scans, and VO ₂max with open circuit spirometry. ANOVA was used to detect differences between groups, and linear regressions to evaluate associations between PA (self-reported, accelerometer), body composition, and VO ₂max. Results: Self-reported moderate to vigorous PA (MVPA) in GB, Ob, and L participants was 497.7 ± 215.9, 988.6 ± 230.8, and 770.7 ± 249.3 min/week, respectively (P =.51); accelerometer MVPA was 185.9 ± 41.7, 132.3 ± 51.1, and 322.2 ± 51.1 min/week, respectively (P =.03); and steps/day were 6647 ± 141, 6603 ± 377, and 9591 ± 377, respectively (P =.03). Ob showed a marginally higher difference between self-report and accelerometer MVPA (P =.06). Accelerometer-MVPA and steps/day were inversely associated with percent fat (r = -0.53, -0.46), and abdominal fat (r = -0.36, -0.40), and directly associated with VO₂max (r =.36). Conclusions: P A was similar between GB and Ob participants, and both were less active than L. Higher MVPA was associated with higher VO₂max and lower body fat.