In healthy older adults around 71 years old, eight weeks of aerobic exercise increases the number of capillaries surrounding muscle fibers, with greater increases in type II fibers than type I. However, this change does not lead to greater muscle growth when followed by 12 weeks of strength training compared to strength training alone.

In older adults who are healthy, muscle growth from consistent strength training is not affected by how many blood vessels are already present in the muscle before training begins.

Doing light weightlifting with a band that restricts blood flow for six weeks can make both slow and fast muscle fibers in older people grow bigger by about 20%, even without heavy lifting.

In healthy older adults, doing aerobic exercise before resistance training leads to a smaller increase in blood flow to the thigh muscle after lifting weights, which may reflect more efficient energy use by the muscle.

In healthy older adults, doing resistance exercises like weight lifting can lead to an increase in the number of small blood vessels surrounding muscle fibers, even if they have not previously done aerobic exercise.

Even though muscles got bigger, the actual muscle fibers didn’t get thicker or change type—so the growth might be due to other factors like fluid or connective tissue.