Effect of obesity on posture and hip joint moments during a standing task, and trunk forward flexion motion

Objective: Effects of obesity on trunk forward flexion motion in sitting and standing, and postural adaptations and hip joint moment for a standing work task. Design: Cross-sectional comparison of obese and normal weight groups. Subjects: Ten obese subjects (waist girth 121.216.8 cm, body mass index (BMI) 38.96.6 kg m-2) and 10 age- and height-matched normal weight subjects (waist girth 79.66.4 cm, BMI 21.71.5 kg m-2). Methods: Trunk motion during seated and standing forward flexion, and trunk posture, hip joint moment and hip-to-bench distance during a simulated standing work task were recorded. Results: Forward flexion motion of the thoracic segment and thoracolumbar spine was decreased for the obese group with no change in pelvic segment and hip joint motion. Obese subjects showed a more flexed trunk posture and increased hip joint moment and hip-to-bench distance for a simulated standing work task. Conclusions: Decreased range of forward flexion motion, differing effects within the trunk, altered posture during a standing work task and concomitant increases in hip joint moment give insight into the aetiology of functional decrements and musculoskeletal pain seen in obesity.