Studies Find Aerobic Fitness Equals Independence in Later Years

The folks at Cenegenics have taken a hard look at the benefits of aerobic fitness for people in their 60s, 70s and 80s. They’ve reviewed recent medical studies and concluded that, yes, aerobic fitness matters – particularly if you want to live independently in later years. Not only that, but the recent studies show that overall mortality is cut by as much as 70% among the “highly fit” elderly.

In fact, a significant study of more than 15,000 veterans whose average age was 60, published in the January 2008 Circulation (a journal of the American Heart Association), found that men who were “highly fit” had a 50% – 70% lower mortality risk than their “low-fit” counterparts.

Lead author on the study Peter Kokkinos even stated that to attain the associated health benefits, it only takes “moderate levels of physical activity like 30 minutes a day, five days a week of brisk walking.”

But it’s also well documented that maximal oxygen intake decreases between 20 to 60 years old and is projected to deteriorate at a similar rate into retirement. The faculty of Physical Education and Health and Department of Health of Public Health Sciences along with the faculty of medicine at the University of Toronto, (Ontario, Canada) examined the “likelihood that a deterioration of aerobic fitness will lead to a loss of independence in old age.”

Published in the March 2008 British Journal of Sports Medicine, the short review study investigated maximal aerobic power, which they had postulated two decades earlier as an important factor that influenced the quality of life in the aged and allowed for independent living.

A look at the study. They used traditional relative units—ml/[kg.min]—to describe any functional losses with aging. In previous cross-sectional studies, a “typical sedentary man . . . showed maximal aerobic power decreasing fairly steadily from perhaps 45 ml/[kg.min] at age 20 to about 25 ml/ [kg.min] at age 60.”

For women, the deterioration begins around age 35, decreasing from “young adult value of perhaps 38 ml/[kg.min] to 25/[kg.min] at age 60.” And, according to their abstract, a 1995 U.S. study (Jackson, AS et al) found “an accumulation of body fat and a decrease in habitual physical activity accounted for about half of the age-related decrease.”

The Canadian researchers hypothesized that independence would be “challenged when the maximal aerobic power had dropped to 12-15 ml/ [kg.min]”—based on a study by Bonjer, FH that “demonstrated an exponential relationship between the duration of aerobic exercise and the relative intensity that was tolerated.”

The result? Efforts over an eight-hour day that demanded more than 40%-50% of a subject’s maximal aerobic power produced fatigue. A decrease of 4 METS in the elderly person’s maximal aerobic power—METS are metabolic equivalents, a measurement of energy demands on exercise—would indicate the individual could only “sustain a very limited range of activities requiring less than 2 METS.”

For comparison, resting equates to 1 MET; a light workout is 2-4 METS; a vigorous run is 8 METS. In other words, this elderly individual would only have the energy capacity for resting, which makes dependent living inevitable! Just standing, per a 2006 study by Weiss et al, showed that in their oldest subjects, “demanded half of their maximal oxygen intake of 13 ml/[kg.min].”

What the findings mean to you. After analyzing numerous studies, researchers found the following outcome, as stated in their abstract:

• Available data suggest a loss of 5 ml/ [kg.min] per decade continues in old and very old subjects.
• The maximal oxygen intake compatible with continued independence is about 15-18 ml/[kg.min], reached at 80-85 years in sedentary elderly people.
• A regular exercise program can slow or reverse the loss of aerobic fitness, reducing the individual’s biological age and prolonging independence.
• Progressive aerobic training can boost the aerobic power of elderly subjects by at least 5-6 ml/[kg.min], potentially delaying the loss of dependence by as much as 10-12 years.