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 cm², 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. Geriatr Gerontol Int 2010; 10: 233–243.