Differences in Gait Biomechanics in Obese and Healthy Young Adults

Abstract

Obesity is considered a risk factor for knee osteoarthritis (KOA). Patients with KOA display alterations in gait biomechanics, which contribute to development and progression of the disease. However, this research has focused on older adults, and it is unclear if young obese individuals display similar aberrant biomechanics. Also, it is unclear if obesity contributes to KOA or results from the associated decline in physical activity. PURPOSE: To compare knee kinematics and kinetics during walking between healthy-weight and obese young adults. METHODS: 15 healthy weight (males = 7, age = 20.42±1.4 years, body mass index = 21.5±1.1) and 15 obese (males = 7, age = 21.2±1.2 years, body mass index = 33.5±3.7) healthy young adults were recruited and categorized using body mass index (BMI). Obesity was defined as having a BMI≥30. Three-dimensional kinematics and kinetics were collected while participants walked overground at standardized (1 m/s) and self-selected speeds. Independent samples t-tests were used to compare peak vertical ground reaction force (vGRF), vGRF loading rate, peak knee extension moment, peak knee adduction moment, and knee flexion excursion between groups. Forces and loading rates were normalized to body weight (BW) and joint moments were normalized to the product of body weight and height. RESULTS: Gait biomechanics did not differ between groups during walking at a self-selected speed with the exception that obese subjects displayed lesser knee flexion excursion (6.54° vs. 10.22°, p<0.001). However, when walking at a standardized speed, obese subjects displayed a greater average (0.32 vs. 0.30 N/s/BW, p=0.002) and instantaneous vertical LR (46.17 vs. 35.02 N/s/BW, p<0.001) vGRF loading rates and lesser knee flexion excursion (5.52° vs. 7.67°, p=0.04). CONCLUSIONS: These results suggest that obesity may contribute to the development of KOA via greater vertical loading rates rather than resulting from it. Future prospective studies are needed to identify the relationship of higher loading rates on knee joint health.