Runners Live Longer and Have Fewer Disabilities

By Todd Neale
PALO ALTO, 12 aug 2008-- Regular running in middle age and beyond may lengthen lifespans and retard the disabilities of aging, a longitudinal study showed. Runners ages 50 to 72 had a 40% reduced risk of being moderately disabled or of dying after a 21-year follow-up than healthy controls, Eliza Chakravarty, M.D., of Stanford, and colleagues reported in the Aug. 11 issue of the Archives of Internal Medicine. Disability and survival curves continued to diverge between groups after the 21-year follow-up as participants approached their ninth decade of life, they added.
"Our findings of decreased disability in addition to prolonged survival among middle-age and older adults participating in routine physical activities further support recommendations to encourage moderate to vigorous physical activity at all ages," the researchers said.
The study began in 1984, when 538 members of a nationwide running club for those 50 and older and 423 healthy controls -- Stanford faculty and staff members ages 26 to 70 -- were recruited to complete yearly questionnaires.
At baseline, runners were younger (mean age 58 versus 62), leaner, more likely to be male, and less likely to smoke than the controls (P<0.001 for all).
Both groups had little disability -- measured using the Health Assessment Questionnaire Disability Index (HAQ-DI), which asked the participants about their level of difficulty in completing eight tasks -- but runners had a significantly lower mean score compared with controls (P<0.001).
Two previous reports on this cohort showed that disability was decreased and survival was increased in runners at eight and 13 years of follow-up.
A total of 284 runners and 156 controls completed the study through 21 years of follow-up, and the results extended the previous findings.
Disability scores increased with time for both groups, but at a significantly greater rate for the controls (0.016 points/year versus 0.007, P<0.001). Runners had significantly lower mean disability levels at all time points.
Runners took longer to reach various levels of disability compared with controls -- for example, it took 2.6 years for controls to reach a mean HAQ-DI score of 0.075 and 8.7 years for runners, for a difference of 6.2 years (95% CI 3.9 to 8.9).
Among participants who had a baseline disability score of zero, runners had a significantly lower risk of being moderately disabled (HR 0.62, 95% CI 0.46 to 0.84).
Through follow-up, 15% of runners died compared with 34% of controls (P<0.001). In a multivariate analysis, runners were 39% less likely to die than controls (HR 0.61, 95% CI 0.45 to 0.82).
Rates of death were higher in controls than in runners for cardiovascular disease (P=0.001), cancer (P=0.004), neurological disease (P=0.007), infections (P<0.001), and other causes (P<0.001).
The study's findings were similar when the participants were divided into ever-runners -- those who ran regularly for more than one month at some point in their lives -- and never-runners.
The authors suggested several possible reasons for the disability and survival advantages found in runners, including "increased cardiovascular fitness and improved aerobic capacity and organ reserve, increases in skeletal mass and metabolic adaptations of muscle with decreased frailty, lower levels of circulating inflammatory markers, improved response to vaccinations, and improved higher-order cognitive functions."
They acknowledged some limitations, including the self-reported data, possible self-selection bias, and potential confounding by unmeasured lifestyle variables.
In addition, they said, the results of the study may not be generalizable beyond the mostly white and college-educated study population.
The study was supported by grants from the National Institute of Arthritis and Musculoskeletal and Skin Diseases and the National Institute on Aging.
The authors made no financial disclosures.
Primary source: Archives of Internal MedicineSource reference:Chakravarty E, et al "Reduced disability and mortality among aging runners: a 21-year longitudinal study" Arch Intern Med 2008; 168: 1638-1646.