Comparison of gluteus medius strength between individuals with obesity and normal-weight individuals: a cross-sectional study

Abstract

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. Individuals with obesity 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 person with obesity can compensate for these changes. Therefore, the aim of this study was to compare gluteus medius strength between individuals with obesity and normal-weight individuals using a digital hand-held dynamometer.

Methods: Twenty-five participants with obesity (BMI > 35 kg/m²) 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 participants with obesity than in normal-weight.

Conclusions: These findings suggest that people with obesity could have the same or less strength (PCA) to move more mass, which may imply a relative weakness that induces functional limitations.

Keywords: Hip; Muscle weakness; Obesity.

Fig. 1

a Posterior and b superior view of the position used to measure gluteus medius strength

Fig. 2

Diagrams showing a schematic summary of the participants recruited for this study

Fig. 3

Comparative graphs showing the difference between the RGM and LGM. Legends: a RGM in N; b LGM in N; c RGM in N/kg; d LGM in N/kg

Fig. 4

Ordering diagram of the principal components. Legends: RGM – right gluteus medius strength in N/kg; LGM – left gluteus medius strength in N/kg; RGM N – right gluteus medius strength in N; LGM N – left gluteus medius strength in N. Control (green ellipse) and obesity (orange ellipse) groups

Fig. 5

Means and standard errors of factor loads of the main components for the control and obesity groups. Legends: a first main component; b second main component