April 29, 2008 — Following a regular exercise routine through middle age can delay biological aging by up to 12 years, according to a review reported in the April 10 Online First issue of the British Journal of Sports Medicine.

"Some 20 years ago our laboratory suggested that one of the most important factors influencing the quality of life in very old people was the maintenance of sufficient aerobic power to allow independent living," writes R.J. Shephard, from the University of Toronto in Toronto, Ontario, Canada. "It was argued that a progressive age-related deterioration in various aspects of physical fitness brought most sedentary elderly people to the point where they lacked the necessary functional capacity somewhere between 80 and 90 years of age. Depending on the living environment and the degree of social support that was available, the limiting maximal aerobic power was estimated to be 12–15 ml/[kg.min]."

During most of adult life, aging is typically associated with a decrease in maximal oxygen intake of about 5 mL/(kg x minute) per decade. If similar losses continue into old age, maximal oxygen intake eventually becomes low enough that ordinary activities of independent daily living become intolerably fatiguing.

Based on his previous study, Dr. Shephard also suggested that a suitable progressive program of endurance training could increase the maximal aerobic power of a middle-aged adult by 5 to 10 mL/(kg x minute). This effect could theoretically offset the anticipated age-related loss of 5 mL/(kg x minute) per decade and reduce effective biological age by 10 years or more, thereby allowing a corresponding prolongation of independence.

This present review assessed the probability that a deterioration of aerobic fitness would lead to a loss of independence in old age because of the progressive deterioration of maximal aerobic power seen in middle-aged adults, even if they are initially healthy.

Without intervention, maximal oxygen intake decreases below a threshold of 18 mL/(kg x minute) in men and 15 mL/(kg x minute) in women at 80 to 85 years of age, most likely leading to loss of independence.

Review of the available evidence suggests that a regular program of aerobic exercise can slow or reverse functional deterioration, lowering biological age by at least 10 years, and potentially prolonging independence by a similar amount.

The importance of deteriorating aerobic fitness vs other potential causes of age-related dependency still needs to be elucidated. However, this review suggests that clinicians should encourage their middle-aged and elderly patients to participate in regular aerobic activity because it can address many of the issues of both functional loss and chronic disease.

"Regular exercise substantially reduces the risks of obesity, maturity onset diabetes mellitus, hypertension, myocardial infarction, some forms of stroke, several forms of cancer and osteoporosis, not only in middle age but also during the retirement years," Dr. Shephard concludes. "It is also helpful in rehabilitation following such critical incidents as a myocardial infarction or congestive heart failure. Regular aerobic exercise may have some impact on the likelihood of becoming blind because of a reduced risk of maturity onset diabetes mellitus, and catastrophic falls are less likely if regular aerobic exercise maintains muscle power, balance and coordination."

Dr. Shephard has disclosed no relevant financial relationships.

Brit J Sports Med. Published online April 10, 2008.

Clinical Context

Study Highlights

• Significant predictors of dependency in older subjects are age, maximal oxygen uptake, and the presence of disease.
• A 14% increase in risk for dependency is seen with each 1-mL/(kg x minute) decrease in maximal aerobic power.
• A loss of 5 mL/(kg x minute) per decade in maximal aerobic power has been observed in older and much older subjects.
• In cross-sectional studies of peak oxygen intake in older adults, a decline of 16% per decade has been observed with a minimal value of 18 mL/(kg x minute) in men and 15 mL/(kg x minute) in women observed for living independently.
• Independence is challenged when maximal aerobic power decreases to 12 to 15 mL/(kg x minute), and fatigue is more likely if effort in an 8-hour day demanded more than 40% to 50% of an individual's maximal aerobic power.
• In the oldest subjects, even standing demanded half of their maximal oxygen intake of 13 mL/(kg x minute).
• The ordinary activities of living can become intolerably fatiguing for the oldest persons.
• The risk for functional loss is lower among those who maintained or increased physical activity and had a much lower risk for the development of disability as determined by the Health Assessment Questionnaire Disability Index in 1 prospective study.
• Participation in a home-based exercise program by frail older persons (> 75 years) was associated with improved gait speed and chair stand in another study.
• Conservation of maximal oxygen intake thus increases the likelihood of independence in healthy elderly persons.
• Progressive aerobic training can boost maximal aerobic power by at least 5 to 6 mL/(kg x minute), potentially delaying the loss of independence by as much as 10 to 12 years.
• Programs of aerobic training show a trend towards greater gain in aerobic power with longer duration: 12.9% with an 8- to 10-week program, 14.1% with a 12- to 18-week program, and 16.9% with a 24- to 52-week program.
• A gain of 25% is equivalent to a maximal oxygen intake of 6 mL/(kg x minute) and a decrease in biological age of 12 years.
• Reasons for loss of aerobic power and physical activity include social constraints such as lack of a partner or transportation problems.
• The author noted that participation in group exercise programs can counter the social isolation of elderly persons in addition to conserving maximal oxygen intake to retain functional independence.
• The author recommends regular aerobic activity among elderly people to counteract the effects of functional loss and chronic disease.

Pearls for Practice

• A decline of 16% per decade in aerobic power is expected in older persons, resulting in greater risk for dependency.
• Exercise programs reduce the rate of decline in aerobic capacity and reduce the risk for dependency in elderly subjects.

CME Test