Did your running legs become muscles? This is just an illusion. The reason why the legs get thicker is because they didn't exercise much before, and the muscles are congested after sudden exercise. As long as you stop exercising or continue to adapt to your body, this situation will disappear. Running is an aerobic exercise. In principle, this kind of exercise will not promote muscle growth at all. So, you don't have to worry about long running muscles.

The culprit that makes legs thicker is actually not muscle, but thick subcutaneous fat. Because 1 kg of fat is three times the volume of muscle of the same weight! So reducing fat is the way to make your legs look slim. Massage scraping or stretching can indeed reduce the size of the calf by one or two centimeters in a short time, but the effect is not very significant.

Comparison of leg contours with the same muscle mass and different fat mass. The fat content on the left is half that on the right. See which is more like radish legs.

I suggest you continue to run for about 40 minutes every day, five days a week. This can reduce the thickness of subcutaneous fat in the legs. In addition, you'd better do some light strength training, such as squat and heel lifting, and shape your legs by improving your muscles to make them look honest and frank. In addition, do 10 minutes of stretching after each run, and try to stretch the ligaments and muscles of the legs. You can go to major video websites to search for relevant teaching videos.