Data came from the Coronary Artery Risk Development in Young Adults (CARDIA) study, which began in January 1984 and ended in December 2001. The fitness study involved 4,487 black and white men and women, who were ages 18 to 30 at the time of their enrollment.

They participated through four clinical centers – in Birmingham, AL, Chicago, IL, Minneapolis, MN, and Oakland, CA. Birmingham also served as the study’s Coordinating Center.

All participants were followed for 15 years, but 2,478 of them had their cardiopulmonary fitness tested again after 7 years in order to measure changes in fitness.

Cardiopulmonary fitness was measured with an exercise treadmill test, which included up to nine, 2-minute stages of progressive difficulty. Women were classified as “low” in fitness if they completed less than 6 minutes of exercise and men if they completed less than 10 minutes. Women who completed 6-9 minutes of exercise were classified as “moderately” fit and men if they completed 10-12 minutes. Those who completed more exercise were classified as “highly” fit.

Other findings include:

• Results were the same for black and white adults, as well as men and women.
• Those who were low or moderately fit had twice the risk of high blood pressure, diabetes, and metabolic syndrome as those who were highly fit. Moreover the risk increased directly as fitness level dropped.
• Weight gain was inversely related to fitness over the course of the study.
• Of those who retook the treadmill test after 7 years, the average weight gain was about 15 pounds. The average weight gain after 15 years was about 28 pounds.