Quadriceps sarcopenia and visceral obesity are risk factors for postural instability in the middle-aged to elderly population.

Aim: Aging shifts body composition to comprising more fat and less muscle. Sarcopenia, particularly in the knee extensors, and obesity, particularly visceral obesity, either alone or in combination, may exacerbate age-related physical disability. We investigated the association between age-related quadriceps (Qc) sarcopenia and visceral obesity, as measured by cross-sectional area (CSA), on postural instability.

Methods: Mid-thigh muscle CSA and abdominal visceral and subcutaneous fat area at the level of the umbilicus were assessed from computed tomography (CT) images in 410 apparently healthy independent middle-aged to elderly subjects attending the medical check-up program in Ehime University Hospital. Static postural instability using a posturograph and one-leg standing time with eyes open were assessed.

Results: Both abdominal visceral fat area and Qc muscle CSA corrected by body weight (BW) were associated with static postural instability, in addition to age and sex, while BW-corrected Qc muscle CSA predicted a short one-leg standing time. The combination of Qc sarcopenia, defined as greater than 1 standard deviation below the mean of a young group (age <60 years), and visceral obesity, defined as a visceral fat area of more than 100 cm(2), were associated with static postural instability, while Qc sarcopenia was related to a higher prevalence of one-leg standing time of less than 30 s, irrespective of visceral obesity.

Conclusion: Thigh Qc sarcopenia and visceral obesity are associated with postural instability in middle-aged to elderly subjects. These findings suggest that age-related, site-specific fat and muscle mass alterations are associated with functional impairment.