Both aerobic exercise and resistance exercise are recommended for the treatment of people with knee pain. However, pain can be a barrier to participating in exercise at a moderate or vigorous intensity. Electrical stimulation of muscles holds potential to allow effective exercise to be completed at tolerable intensities. Transcutaneous electrical nerve stimulation (TENS) is the use of very low electric currents produced by a device to stimulate the nerves, to treat pain. Neuromuscular electrical stimulation (NMES) uses low electrical current to cause muscles to contract.