Intrinsic aerobic exercise capacity linked to longevity

Low aerobic exercise capacity is a strong predictor of premature morbidity and mortality in both healthy adults and people with cardiovascular disease. In the elderly, poor performance on treadmill- or extended walking tests indicates proximity to future health decline. In order to test the association between aerobic exercise capacity and survivability, a rat model was made through artificial selective breeding.

Laboratory rats of widely varying genetic backgrounds were bred for low or high intrinsic treadmill running capacity. Rats from multiple generations were followed for survivability and assessed for age-related declines in cardiovascular fitness, such as peak oxygen uptake, myocardial function, endurance performance and change in body mass. We found that the average lifespan of rats with innate low exercise capacity was 28-45% shorter than for rats with an inborn high exercise capacity. Likewise, the peak oxygen uptake measured across adulthood was a reliable predictor of lifespan.

As they transitioned to old age, rats with an inborn low capacity for exercise had worse cardiac health by multiple measures (left ventricular myocardial and cardiomyocyte morphology, mean blood pressure, and intracellular calcium handling in both systole and diastole). Moreover, rats with high innate exercise capacities had better sustained physical activity levels, energy expenditures, and lean body mass with age than their low-capacity cohorts.

Since the rats came from a wide variety of backgrounds, the results provide strong evidence that innate capacity for exercise can be linked to longevity, thus aerobic exercise capacity can prove useful in future exploration of the mechanisms behind cardiovascular disease.