Feeling sore after aerobic exercise is caused by the accumulation of blood and metabolites in your calf. If you stretch in time, you won't feel sore. If you don't stretch in time, your muscles will still be strong during running, which will harden and make it difficult to stretch, resulting in thick legs.

The nature of aerobics is similar to that of long-distance running, mainly consuming fat. It can help to lose fat in the legs, and it can also make the muscle fibers in the legs thinner and make the muscles slim. Therefore, most of the long-distance runners we see have slender and symmetrical calves. Those sprinters are different. Sprint is mainly anaerobic exercise, which will produce a lot of lactic acid and muscle aches. After running for a long time, their calf muscles will be very developed and explosive.

Leg muscles are sensitive, and there are three main reasons for leg thickening: 1. The fat accumulation on the calf becomes more. 2. The calf is muscular and the muscle fibers are thick. 3. Fat accumulation and muscle calf coexist. The first one is that you are fatter and have more fat on your legs, which can be consumed by long-distance running. The second kind is a sprinter, with little fat but extremely developed muscles. It is very obvious that muscles will expand sharply after exertion.

Therefore, stretching exercise must be done after any exercise, which can not only increase the ductility of muscles, but also transport metabolic wastes in time.

The action of stretching the calf is simple. One leg goes forward, one leg bends backward, and both hands even touch the toes. If you feel pain, hold on for a while, and then change your foot. You can also pull your thighs properly: find a fixed object, or face the wall, stand on one foot, put the other foot on it, lean forward and feel the pain of pulling muscles.