The main reason why the legs are prone to cramps when exercising is that the muscles in the legs become dysfunctional, spasming and contracting during exercise, thus producing cramps. The main consideration is that there are underlying disorders in the legs that tend to produce cramps, often including poor blood circulation, abnormal nerve function and abnormal muscle function in the legs. Nerve function abnormalities are mainly seen in peripheral nerves that produce injury, inflammation or due to lumbar diseases that compress nerve roots, resulting in abnormal nerve function and abnormal function during activity, which can lead to abnormal muscle function and thus produce cramping symptoms. Problems with local blood circulation, including local cold or vasculitis, varicose veins, and chronic insufficiency of blood supply to the arteries, all of which can lead to hypoxia and ischemia aggravation during exercise, resulting in muscle function disorders. Muscle problems including calcium or potassium deficiency, muscle injury, strain, intramuscular swelling, or muscle dystrophy can all be aggravated by local abnormalities during exercise, leading to cramping symptoms.