I know this problem because I practice not only Sanda, but also Muay Thai. However, this is not the root cause of thinning. The reason for this may be ligament strain, which has nothing to do with bones. Orthopedics personnel can't know that their occupational category is bone. Of course, asymmetric movement may also cause carelessness and irregular legs. Many people who lose weight think that running can make their legs thinner, but it is not. Generally, the forefoot landing in long-distance running will cause the calf to thicken, which is beneficial to the kicking force in Sanda and Muay Thai. Legs used to be thin, but now they are relatively thick when they retire! If you land with your heel first, it will help your legs lose weight and make them thinner!
After my left leg was kicked again in the game, the kicking power of my left leg was much reduced, and it was not as high as before. My left leg was slightly inward and not very straight.
If you still run long-distance running in the morning to practice physical strength, pull the ligament after running and focus on the leg with only problems, which is conducive to recovery!