Oxidative stress and severe walking disability among older women.

BACKGROUND Oxidative stress has been implicated in sarcopenia and the loss of muscle strength with aging, but the relationship between oxidative stress and decrease in muscle strength and physical performance has not been well characterized. Serum protein carbonyls are markers of oxidative damage to proteins and are caused by oxidative stress. METHODS Serum protein carbonyls were measured at baseline and compared with a decrease in walking speed and development of severe walking disability (inability to walk or walking speed <0.4 m/sec) over 36 months of follow-up in 545 moderately to severely disabled women, aged > or =65 years, living in the community in Baltimore, Maryland (the Women's Health and Aging Study I). RESULTS After adjusting for age, body mass index, smoking, and chronic diseases, log(e) protein carbonyls (nmol/mg) were associated with a decrease in walking speed over 36 months (P=.002). During follow-up, 154 women (28.2%) developed severe walking disability. After adjusting for the same potential confounders, log(e) protein carbonyls were associated with incident severe walking disability (hazards ratio 1.42, 95% confidence interval, 1.02-1.98, P=.037). CONCLUSION High oxidative stress, as indicated by oxidative damage to proteins, is an independent predictor of decrease in walking speed and progression to severe walking disability among older women living in the community.