Comparison of gluteus medius strength between obese and eutrophic individuals: a cross-sectional study

Background: The hip abductor muscles, primarily the gluteus medius, play an important role in stabilizing the pelvis during gait. Gluteus medius weakness is associated with biomechanical changes and musculoskeletal disorders. Obese individuals can have great difficulty maintaining abductor muscular function due to being overweight and possibly experiencing a decrease in muscle mass. However, it is still unclear whether the musculature of obese individuals can compensate for these changes. Therefore, the aim of this study was to compare gluteus medius strength between obese and normal-weight individuals using a digital hand-held dynamometer.Methods: Twenty-five obese (BMI > 35 kg/m2) participants were matched for sex, age, and height with normal-weight individuals. Gluteus medius strength was measured by a single examiner using a belt-stabilized hand-held digital dynamometer placed on the knee of the individuals positioned in lateral decubitus. Three measurements were recorded with rest intervals, and only the highest value measured for each limb was used for analysis. The differences between pairs were calculated, and the normality of the data was assessed using the Shapiro-Wilk test (p < 0.05). The matrices of the variables were standardized and analysed using principal component analysis (PCA).Results: For the strength variables (Newtons) on both sides, no significant differences were detected between the groups (p > 0.05). However, significant differences were detected in these variables between the groups (p < 0.05) when the measurements were normalized to body weight (Newtons/kilograms). PCA indicated that both the absolute and normalized values of strength are lower in obese than in normal-weight individuals.Conclusions: These findings indicate that obese individuals have the same or less strength (PCA) to move more mass, which may suggest a relative weakness that induces functional limitations.Trial registration: The study was approved by the UNIOESTE Human Research Ethics Committee (#1.180.202) in July 2015.