Legs cannot be straightened by exercise, the straightness or curvature of the legs is mostly determined by genes, that is, the genes play a major role in determining the straightness or curvature of the legs. There are some factors that can be influenced by acquired factors, such as lack of calcium or bone fracture, which can make the leg shape change to a certain extent. But there is no way to straighten the legs through exercise, exercise can only change the density of the bone, can change the muscle content, can also improve the strength of the legs, but the shape of the legs can not be changed through exercise.