Exercise Endurance Affects Every Tissue

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A large research project in young adult rats has found that all bodily tissues tested respond to exercise training. More than 35,000 biological molecules respond and adapt to endurance exercise over time, including tissues from organs not usually associated with exercise.

Researchers also found differences in responses between male and female rats that were more widespread than anticipated, highlighting the importance of including animals of both sexes in preclinical research.

The NIH-funded effort used data from thousands of analyses of 19 tissue types and identified molecular changes in genes, proteins and metabolites. Findings are published in a group of papers in Nature.

While molecular changes were seen in all tissues, the way in which each tissue responded was unique. For example, effects on the functions of mitochondria—cellular hubs for energy production and metabolism—were observed across the body yet the specific changes observed differed depending on the tissue.

Mitochondria in the adrenal gland responded substantially to endurance training, including a change in regulation of nearly half the mitochondria-associated genes. This was surprising; adrenal glands had not been previously explored in detail for their role in exercise.

Additionally, differences were found in molecular responses to endurance exercise between young male and female rats in most tissues tested, including the brain, adrenal gland, lung and fat tissue. The findings could play a role in researching how exercise interventions could be recommended for men or women experiencing conditions such as obesity.

The data is helping scientists create a map of molecular changes in the body following exercise. Studies in rats allow for analysis of a wider range of tissue types compared to human studies. The resulting knowledge will guide researchers in analyzing the human data.

Researchers are currently conducting an exercise study in humans to better understand why the body responds to exercise and how much the response varies for people of different ages, sexes, body compositions and fitness levels. This research was funded by the NIH Common Fund in collaboration with NIA, NIAMS and NIDDK.