Why does the human body use pulse stimulation instead of sine wave and triangle wave stimulation?

Pulse stimulation is developed from acupuncture and electroacupuncture. According to the theory of traditional Chinese medicine, low-frequency electric pulse can promote blood circulation and regulate muscle tension. And can protect health and treat some diseases. At first, because the electronic circuit of low-frequency pulse is simple and easy to produce, many manufacturers of low-frequency pulse therapeutic apparatus made progress. Now they have sine wave pulse therapeutic instrument and triangle wave pulse therapeutic instrument.