How Muscle Shape Changes with Age and Exercise

Muscles change as we get older. This is not news. But what is interesting is how these changes affect the tiny blood vessels, called capillaries, that bring oxygen and nutrients to our muscles. Scientists have known for a while that these capillaries become less dense with age. However, they usually measure this using a simple formula that assumes all muscle fibers are the same shape. This assumption might not be accurate. Muscle fibers change shape and size as we age and depending on their type. So, the usual way of measuring capillaries might be giving us an exaggerated idea of how much they decrease with age.A recent study looked at muscle samples from young and older women. They checked different ways to measure capillaries, including a new method that considers the shape of the muscle fibers. They found that older adults had smaller type II muscle fibers and more irregularly shaped fibers. When they adjusted the usual measurements to account for fiber shape, the differences between young and old muscles became smaller. This means that the capillaries might not be as scarce as previously thought. The study also found that these patterns were the same in both rested and exercised legs, which makes the results more reliable. This research suggests that using shape-sensitive measurements could give us a more accurate picture of how capillaries change with age. It's a step towards better understanding how our muscles work and how they change over time.