Effects of cardiorespiratory fitness on aging: glucose trajectory in a cohort of healthy men.

PURPOSE

We modeled the age-related trajectory of glucose and determined whether cardiorespiratory fitness altered the trajectory in a cohort of men from the Aerobics Center Longitudinal Study.

METHODS

A total of 10,092 men free of diagnosed diabetes, cardiovascular disease, and cancer, ages 20 to 90 years, completed from 2 to 21 health examinations between 1977 and 2005. Cardiorespiratory fitness was measured by a maximal treadmill exercise test and normalized for age. The covariates included waist circumference, hypertension, elevated cholesterol, smoking behavior, and physical activity.

RESULTS

Linear mixed models regression analysis showed that fasting glucose increased at a linear rate with aging. Glucose increased at a yearly rate of 0.17 mg/dL (95% confidence interval: 0.16-0.19). Fitness had little influence on the aging glucose trajectory below age 35, but significantly influenced the trend after age 35 (P for interaction < .001). The aging-related glucose increases in low-fitness men (0.25 mg/dL per year) was greater than average-fitness (0.15 mg/dL per year) and high-fitness (0.13 mg/dL per year) men.

CONCLUSIONS

The aging-related fasting glucose increases in low-fitness men was nearly double that of high-fitness men. Our results may suggest that it is possible to delay the age-related glucose impairment through increasing one's fitness level.