Exercise is linked to a longer, healthier life but the mechanisms are unclear. To determine how exercise and health are linked, Tucker shows in Preventive Medicine that physical activity is associated with longer telomeres, which are linked to reduced cellular aging.
Exercise reduces the risk of many chronic diseases, including diabetes and hypertension, and is linked to a longer, healthier life. One mechanism by which exercise may lead to a longer life is by slowing down telomere shortening. Telomeres are DNA structures at the end of chromosomes (packages of DNA), and they shorten each time cells divide. The length of a telomere can be determined by sequencing the DNA and counting the length of a specific repetitive sequence. Shorter telomeres are linked to aging and death.
Previous research has shown mixed results about the relationship of exercise and telomere length. Tucker recently published a study in Preventive Medicine that attempts to examine this relationship under more controlled conditions. He used data from 5823 individuals aged 20 to 84 from the National Health and Nutrition Examination Survey, a US-based survey conducted by the Centers for Disease Control and Prevention (CDC). This survey includes data on telomere length over four years, as well as data on physical activity, age, body mass index, smoking, and alcohol use. Physical activity was parsed into “sedentary”, “insufficient”, “low”, “moderate”, or “high” categories using both absolute and relative cutoffs.
Telomere length is strongly linked to age; it is known that older individuals have shorter telomeres. In addition to this pattern, Tucker found that relative physical activity was linked to telomere length once other demographic variables were accounted for. Individuals who engaged in high levels of physical activity had significantly longer telomeres than all other individuals, but there were no differences between the groups with moderate, low, or no physical activity. The frequency of short telomeres (those that are in the lowest 25% of telomere length) also decreased in groups with higher physical activity.
These results confirm that high levels of physical activity are associated with longer telomeres, providing a telomere based link between exercise and health. However, it may be that exercise is linked to telomere length because individuals who exercise are also leading healthier lives in other ways, for example, by not smoking, or because exercise reduces stress, depression, and improves sleep. Tucker’s results do, however, suggest that current exercise guidelines are too low, as the observed effects were specific to individuals with the highest amounts of physical activity.
Written By: C.I. Villamil