Gluteal muscle composition differentiates fallers from non-fallers in community dwelling older adults

Background: Impaired balance, loss of mobility and falls are major problems associated with changes in muscle in older adults. However, the extent to which muscle composition and related performance measures for different lower limb muscles are associated with falls in older individuals is unclear. This study evaluated lower limb muscle attenuation, intramuscular adipose tissue (IMAT) infiltration and muscle performance in older fallers and non-fallers. Methods: For this cross-sectional study, fifty-eight community dwelling older individuals (>65 years) were classified into fallers (n = 15) or non-fallers (n = 43). Computed tomography (CT) was used to determine muscle attenuation and intramuscular adipose tissue (IMAT) of multiple thigh and hip muscles. Muscle performance was assessed with isokinetic dynamometry. Results: For both groups, Rectus Femoris showed the highest muscle attenuation and lowest IMAT infiltration, and Gluteus Maximus and Gluteus Medius/Minimus muscles had the lowest muscle attenuation and highest IMAT infiltration. Fallers exhibited lower muscle attenuation and higher IMAT infiltration than non-faller participants in most muscles, where the gluteal muscles were the most affected (p < 0.05). Fallers also showed a lower peak hip abduction torque (p < 0.05). There were significant associations (r = 0.31 to 0.53) between joint torques and muscle composition, with the strongest associations between Gluteus Medius/Minimus and hip abduction strength. Conclusions: While fallers were generally differentiated from non-fallers by muscle composition, the most affected muscles were the proximal gluteal muscles of the hip joint accompanied by lower hip abduction strength, which may contribute to impaired balance function and increased risk for falls.