Start Getting Fit When You're Young - Here's Why!

Summarized by Robert W. Griffith, MD
February 12, 2004

Introduction

It's long been known that very fit older people are less likely to have heart attacks, stroke, and type 2 diabetes. And this is probably related to a reduction in risk factors for these conditions, such as high blood pressure, high cholesterol levels, and poor glucose tolerance (i.e. abnormally high post-meal glucose levels).

So a natural question is, when should one start trying to avoid these risk factors? A new study reported in the Journal of the American Medical Association suggests that the answer is "the sooner the better".

What was done

A group of physicians from 4 centers in the USA (Birmingham, Chicago, Minneapolis and Oakland) reported on this study, which involved 4,500 men and women between 18 and 30 who were enrolled in the Coronary Artery Risk Development in Young Adults (CARDIA) study. At baseline, in 1985-1986, a treadmill test was done on all participants; the test included up to 9 two-minute stages of increasing difficulty.

Subjects' levels of cardiovascular fitness were classified using the number of 2-minute treadmill stages they could complete:

	Women	Men
Low in fitness	Less than 3 stages	Less than 5 stages
Moderately fit	3 to 4½ stages	5 to 6 stages
Highly fit	More than 4½ stages	More than 6 stages

After 7 years 2,500 of the subjects had a second treadmill test, and all the participants were tested at the 15-year mark.

The researchers estimated the frequency of occurrence of type 2 diabetes, high blood pressure, the metabolic syndrome, and high cholesterol levels, which they presented as the number of cases per 1000 person-years.

What was found

Over the 15-year period, the occurrence rates of diabetes, high blood pressure, metabolic syndrome, and high cholesterol were 2.8, 13, 10.2, and 11.7 per 1000 person-years, respectively.

In the entire study group, the average weight gain after 7 years was 15 pounds, and after 15 years it was 28 pounds. Those who were less fit on the treadmill test were more likely to gain weight, as might be expected.

Those who were 'low in fitness' were 3 to 6 times as likely to develop high blood pressure, diabetes, and the metabolic syndrome as those who were classified as 'highly fit'. However, if the results were adjusted to allow for the body weight at baseline, the increased risk for the 'low in fitness' was reduced to about twice the likelihood as in the 'highly fit'. This shows that the risks involved in being overweight are not completely compensated by being fit.

All these findings were independent of age, race, smoking, and a family history of diabetes, high blood pressure, or early heart attack. The 7-year results from about half the participants fell about midway between those for the full 15-year subjects.

What does this mean?

These findings show clearly that the development of risk factors for heart disease and stroke isn't just the effect of growing older - fitness plays an important part. The benefits of being fit from an early age (starting in your 20s) are not confined to avoiding overweight and feeling good.

That's not to say that getting fit can't be started in middle- or even old-age. It's just that it's much harder to achieve, and the benefits aren't as great as when you've been fit most of your adult life. The bottom line - start young and keep going with a sensible fitness program. Try to do at least 30 minutes' of moderately intensive exercise, such as brisk walking, on most days, or, better, every day of the week.

Source

• Cardiorespiratory fitness in young adulthood and the development of cardiovascular disease risk factors. MR. Carnethon, SS. Gidding, R. Nehgme,  et al., JAMA, 2003, vol. 290, pp. 3092--3100

Related Links
Exercise: A Necessary Component in a Program for Vascular Health
Do You Have the Metabolic Syndrome (Syndrome X)?
Control Your Risk Factors - They're Very Real

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