http://www.medscape.com/viewarticle/573636

Regular Exercise Through Middle Age May Delay Biological Aging CME


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 12­15 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.
Learning Objectives for This Educational Activity
Upon completion of this activity, participants will be able to:

1. Describe the rate of loss of maximal oxygen intake in older persons.
2. Identify interventions to delay or reduce dependency in older persons.

Clinical Context

Regular exercise reduces the risk for obesity, diabetes mellitus,
hypertension, and heart disease not only in middle age but also in the
retirement years, and the maintenance of aerobic power in older years may be
associated with the ability to maintain independence. Sedentary elderly
persons may lose physical fitness with age to the point of losing
independence, and increased physical activity may be a way to prevent this
deterioration as well as manage chronic disease.

This is a review of the literature on aerobic capacity in older persons to
determine the rate of loss of aerobic power with age and interventions that
may postpone this loss and maintain independence.
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.

According to this review by Shephard, independence is likely to be
challenged in older persons when maximal aerobic power decreases to which of
the following ranges of levels?
5 to 8 mL/(kg x minute)
9 to 11 mL/(kg x minute)
12 to 15 mL/(kg x minute)
16 to 19 mL/(kg x minute)

According to this review by Shephard, an aerobic training program that
results in a gain of 25% in maximal aerobic power is most likely to be
equivalent to reducing the biological age of an older person by how many
years?
2 years
5 years
9 years
12 years