Difference of the association between low muscle mass and physical inactivity by sex resulting from the choice of the diagnostic criterion for low muscle mass in elderly Koreans

Abstract

Aim We investigated the difference in the relationship between physical activity and low muscle mass resulting from the choice of diagnostic criterion for low muscle mass.

Methods Our study was cross-sectional, using data from the 2008–2011 National Health and Nutrition Examination Survey. Muscle mass was measured by dual-energy X-ray absorptiometry. Low muscle mass was defined as height-adjusted and weight-adjusted low muscle mass. Odds ratios (ORs) and 95% confidence intervals (CIs) of low muscle mass in relation to physical inactivity were analyzed using multivariate logistic regression analysis.

Results Our study included 3977 older people (1698 men and 2279 women). The prevalence of height-adjusted and weight-adjusted low muscle mass was 4.1% and 11.8%, respectively, in the physically inactive group, and 3.9% and 7.9%, respectively, in the physically active group. The prevalence of weight-adjusted low muscle mass increased by 48% in the physically inactive group in the fully adjusted model (OR, 1.48; 95% CI, 1.13–1.95) and increased by 61% in men and 50% in women (men: OR, 1.61; 95% CI, 1.12–2.31 and women: OR, 1.50; 95% CI, 1.20–2.20) compared with the physically active group. The risk of height-adjusted low muscle mass in men tended to be higher in the physically inactive group than in the physically active group. However, this trend was not observed among women.

Conclusions Physical inactivity was associated with an increased prevalence of low muscle mass in weight-adjusted measures among elderly adults in Korea. Height-adjusted low muscle mass in women is less useful as an indicator of the relationship between low muscle mass and physical inactivity.