Being physically fit during middle age significantly lowers the burden of chronic disease in later life, an observational study suggested.
Men in the highest quintile of fitness as measured in metabolic equivalents (METs) at age 50 had a significantly decreased risk for subsequently developing chronic conditions such as congestive heart failure, stroke, and diabetes, with a hazard ratio (HR) of 0.95 (95% CI 0.94 to 0.96, P<0.001) per MET, according to Jarett D. Berry, MD, of the University of Texas Southwestern Medical Center in Dallas, and colleagues.
Similar results were seen for women with an HR per MET of 0.94 (95% CI 0.91 to 0.96, P<0.001), the researchers reported online in Archives of Internal Medicine.
Numerous studies have chronicled the effects of cardiovascular risk factors such as hypertension and obesity on successful, healthy aging, but the contribution of physical activity has been less established.
In an attempt to quantify this, Berry and colleagues analyzed data from the Cooper Center Longitudinal Study, which began enrolling patients in 1970.
Between 1999 and 2009, 18,670 participants turned 65 and enrolled in Medicare, and were considered the study sample.
At baseline, participants' age averaged about 50, and 21% were women. Most were white and educated, and had a lower prevalence of risk factors compared with the broader population.
Chronic conditions were selected to reflect a wide range of diseases and organ systems, and also included ischemic heart disease, chronic obstructive pulmonary disease, chronic renal disease, colon and lung cancer, and Alzheimer's disease.
Fitness levels were measured on treadmill times adjusted for age and sex. The lowest fitness quintile was at 8.5 METS while the highest quintile was at 14.1 METs.
With a median follow-up of 26 years, men with the highest level of fitness had a rate of chronic conditions of 15.6 (95% CI 15 to 16.2) per 100 person-years, compared with a rate of 28.2 (95% CI 27.4 to 29) per 100 person-years for men with the lowest level.
The corresponding rates for women were 11.4 (95% CI 10.5 to 12.3) versus 20.1 (95% CI 18.7 to 21.6) per 100 person-years, the researchers reported.
Individual characteristics among men that were associated with an increased likelihood of developing chronic conditions were:
- Total cholesterol per 40 mg/dL, HR 1.68 (95% CI 1.38 to 2.04, P<0.001)
- Body mass index per 3 units, HR 1.36 (95% CI 1.13 to 1.63, P=0.001)
- Systolic blood pressure per 20 mm Hg, HR 1.09 (95% CI 1.07 to 1.11, P<0.001)
- Glucose level per 1 mg/dL, HR 1.05 (95% CI 1.03 to 1.07, P<0.001)
- Smoking, no versus yes, HR 0.84 (95% CI 0.80 to 0.87, P<0.001)
Similar associations were seen for women, although the confidence intervals were wider, according to the researchers.
They also calculated morbidity compression ratios, which assess the degree to which chronic diseases are compressed into the last years of life, signifying a better quality of life for more years.
For that analysis, they considered chronic disease among 2,406 individuals who died during the course of follow-up, and found a compression HR of 0.90 (95% CI 0.88 to 0.92) for each MET.
"Thus, higher midlife fitness is associated with the delay in the development of [chronic conditions] to a greater extent than the extension of the lifespan, suggesting the compression of morbidity nearer the end of life," Berry and colleagues explained.
This not only is likely to improve late-life quality of life, but also should lower healthcare costs.
"Our findings have important implications for public health and prevention practice by extending our knowledge of the health benefits of exercise in midlife," they observed.
The results suggest that even a small increase in fitness during middle age could markedly reduce older age chronic conditions.
For instance, an increase in METs of just one to two points at age 50 could be expected to lead to a reduction of 20% in chronic diseases when the individual is 65 and older.
Limitations of the study included its reliance on administrative data and the relatively healthy participants included in the cohort, and the lack of other information such as dietary habits.
In an invited commentary, Diane Bild, MD, of the National Heart, Lung and Blood Institute in Bethesda, Md., pointed out that genetics also plays a role in successful aging and longevity.
She noted that more information about the effects of exercise on later life well-being should emerge from the Lifestyle Interventions and Independence for Elders (LIFE) trial, which is a randomized study of physical activity versus health education in 1,600 older individuals.
LIFE, which is sponsored by Bild's institute and the National Institute on Aging, will examine the effects of fitness on mobility disabilities, but also on multiple secondary measures of health in older individuals.
The Cooper Institute provided funding for the study.
Berry disclosed receiving grants from the University of Texas Southwestern Medical Center, the National Heart, Lung, and Blood Institute, and the American Heart Association, and is on the speakers' bureau for Merck.
- Reviewed by Robert Jasmer, MD Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, BSN, RN, Nurse Planner
Archives of Internal MedicineSource Reference: Willis B, et al "Midlife fitness and the development of chronic conditions in later life" Arch Intern Med 2012; DOI: 10.1001/archinternmed.2012.3400.
Archives of Internal MedicineSource Reference: Bild D "Thriving of the fittest" Arch Intern Med 2012; DOI: 10.1001/archinternmed.2012.3406.