Exercise therapy is effective in decreasing pain and improving function for those with chronic low back pain.[50] It also appears to reduce recurrence rates for as long as six months after the completion of program[61] and improves long-term function.[57] There is no evidence that one particular type of exercise therapy is more effective than another.[62] The Alexander technique appears useful for chronic back pain,[63] and there is tentative evidence to support the use of yoga.[64] Transcutaneous electrical nerve stimulation (TENS) has not been found to be effective in chronic low back pain.[65] Evidence for the use of shoe insoles as a treatment is inconclusive.[51] Peripheral nerve stimulation, a minimally-invasive procedure, may be useful in cases of chronic low back pain that do not respond to other measures, although the evidence supporting it is not conclusive, and it is not effective for pain that radiates into the leg.[66]