Association between redox state of human serum albumin and exercise capacity in older women: A cross-sectional study

Aim: Oxidative stress plays a key role in declining exercise capacity, which is one of the major health problems in old age. The redox state of human serum albumin (HSA) has been considered a biomarker reflecting oxidative stress; however, its relationship to exercise capacity in older people remains to be examined. We aimed to examine the redox state of HSA as a potential biomarker of exercise capacity in community-dwelling older women.

Methods: We analyzed 125 women aged ≥75 years. Exercise capacity was evaluated using 6-min walk distance (6MWD). The redox state of HSA was analyzed using the high-performance liquid chromatography post-column bromocresol green reaction method. The fraction of human mercaptalbumin in HSA (f[HMA]) was considered the redox state of HSA. Pearson's correlation coefficient (r) or Spearman's correlation coefficient (ρ) was used to assess correlations between 6MWD, f(HMA) and HSA. The association between 6MWD and f(HMA) was further examined using multivariate linear regression analysis adjusted for age, diabetes mellitus, renal function, number of medications, HSA and knee extensor isometric strength.

Results: The 6MWD was significantly correlated with f(HMA; ρ = 0.44, P < 0.001), but not with HSA (r = 0.05, P = 0.562). The f(HMA) was not significantly correlated with HSA (ρ = 0.03, P = 0.769). Multivariate linear regression analysis showed that f(HMA) was independently associated with 6MWD (standardized β = 0.27, P = 0.004).

Conclusions: The findings of this study suggest that f(HMA) might serve as a novel biomarker for exercise capacity in community-dwelling older women. Geriatr Gerontol Int 2019; ••: ••-••.