Normal blood vessels are full, but they are not obvious under the cover of adipose tissue. However, people who exercise consume a lot of subcutaneous fat and muscles are exposed under the skin, so there will be obvious blood vessel burst, which will also be seen in some thin people.

People who practice fitness, because their muscles are well exercised at ordinary times, the volume of muscle cells increases, they need more nutrients, and the waste produced by metabolism is more, so the blood flow near the muscles is rich and the blood vessels will thicken accordingly. This is the theory of "use in and waste out". If a person's muscles atrophy, blood vessels will also become thinner.