I received an e-mail message recently from an angry doctor. He'd torn his hamstring running on a beach and spent eight weeks -- a total of 20 hours -- in physical therapy. Then his insurer said the physical therapy was not covered. He couldn't understand it. The therapy cost $150 a session, and he said it was 'clearly beneficial and cost-effective.' (He added, though, that after eight weeks he was not yet running again.) Hmm. I also tore my hamstring running, but my doctor never mentioned physical therapy. Instead he referred me for platelet-rich plasma, an experimental treatment that involves having my own blood platelets injected into the torn tendon. The cost, including the radiologist's fee, an ultrasound and the plasma injection, was $2,200. My insurer would not pay, which made sense to me because the plasma treatment is considered experimental. It might work; then again, it might not. But the letter the angry doctor had received from his insurer made me wonder whether physical therapy was different from the plasma treatment. Is there rigorous evidence showing it works? Unlike the doctor's insurer, my health insurance companies have always covered physical therapy for sports injuries. Yet their willingness to do so is not necessarily an indication that the therapy is effective. The orthopedists in my town seem reflexively to write a prescription for physical therapy whenever I or any of my friends go to them with sports injuries. That, of course, is no indication, either. When I've gone to physical therapy, the treatments I've had -- ice and heat, massage, ultrasound -- always seemed like a waste of time. I usually went once or twice before stopping. My doctor at the Hospital for Special Surgery in New York, Joseph Feinberg, seems to share my opinion. 'Very often, I think the hot packs, cold packs, ultrasound and electrostimulation are unnecessary,' he said, adding, 'For sure, in many cases these modalities are a waste of time.' So has physical therapy been tested for garden-variety sports injuries like tendinosis? Or is it just accepted without much question by people who urgently want to get better? It depends, says James J. Irrgang, a researcher in the department of orthopedic surgery at the University of Pittsburgh and president of the orthopedic section of the American Physical Therapy Association. 'There is a growing body of evidence that supports what physical therapists do, but there is a lot of voodoo out there, too,' Irrgang said. 'You can waste a lot of time and money on things that aren't very helpful.' Sometimes, manual stretching by a physical therapist can actually eliminate a sports injury, he said. His two examples are manual stretching of the shoulder for shoulder impingement syndromes, in which the shoulder blade rubs on a major tendon, the rotator cuff, and manual stretching of the ankle for ankle sprains. They are the exceptions. More common are the 'voodoo' treatments, he said. And what might those be? None other than ice and heat and ultrasound, Irrgang said. Also, he said, there is no evidence showing laser and release -- a massage technique -- to be effective in helping injuries heal. Ice and heat, Irrgang said, 'can control pain a little bit' but 'are not going to take care of the problem.' The underlying injury remains. When I asked Irrgang for studies showing what worked, I was a bit surprised. To put it kindly, they left much to be desired. Researchers would mix treatments -- stretching and massage and orthotic shoe inserts, for example. If patients said they felt better, it was impossible to know why. Some of the studies involved as few as four participants. And the researchers did not always assign subjects randomly to one treatment or another to see which one worked better. In addition, researchers routinely failed to follow a standard method of data analysis called intention to treat. It means that when you look at results, you include even people who dropped out of your study. After all, people are dropping out for a reason. Often it is because the treatment is not helping, or is making them feel worse. Those remaining might be having a placebo effect or might be getting better despite, rather than because of, the treatment. And even if those remaining are actually being helped, when the dropouts are not counted, the treatment will end up looking better than it really is. It is hard to defend such work, Irrgang said. 'There are limitations,' he said. 'There is room for improvement.' To help physical therapists identify the best treatments for specific conditions and to minimize variations in practice, the orthopedic section of the American Physical Therapy Association is trying to put together clinical guidelines that assess and grade the evidence for treatments. So far, one review of evidence for treating a common sports injury -- heel pain, or plantar fasciitis -- has been published. Others are in the works on knee ligament instability, knee meniscus and cartilage problems, Achilles tendinopathies and low back pain. Irrgang was part of the group that assessed the treatments for heel pain. The doctors concluded that for plantar fasciitis, physical therapy treatments like massage, stretching and taping have little evidence to support them. There is some evidence, not particularly convincing, that stretching can provide short-term pain relief. But the best treatment for plantar fasciitis, orthotic inserts for your shoes, is the only one with a body of consistent (though not definitive) research behind it, and it may not even require a physical therapist. It does not even require a doctor. And, the studies indicate, off-the-shelf orthotics are just as effective as custom-made ones. Even orthotics, though, provide only temporary relief. There is no evidence to support the use of prefabricated or custom foot orthotics for long-term (a year) pain management or functional improvement, the review concluded. Irrgang, who has also been involved with the reviews that are in progress, gave a preview of some of the strongest findings. Stretching, he said, appears to help sprained ankles heal faster, especially if is combined with exercises -- strengthening and range of motion. And studies have found that a common treatment, taping an ankle to immobilize it, may slow healing. There are good studies showing that Achilles tendinosis heals faster if patients do eccentric muscle contractions, like calf raises. Hamstring strains and pulls may heal better if patients do strengthening exercises. Why go to a physical therapist for as many as 20 sessions, though, in order to do strengthening exercises? Why not just go to a gym? Good question, Irrgang said. You can do exercises on your own at a gym, he said, but if you go to a physical therapist first, the therapist can do an evaluation and tell you what muscles are weak or tight, can design a personal exercise program and can teach you the exercises. 'If you have access to a gym, you might go to physical therapy for one or two sessions, learn what to do and then return to physical therapy in a few weeks to check on your progress,' Irrgang said. 'Often, you don't need to go to physical therapy three times a week or five times a week.' With all that voodoo physical therapy out there, though, how can you tell if what you are getting is helping or useless? It's not easy, Irrgang said. 'You just have to be very inquisitive,' he said. 'The physical therapist should be able to explain the various treatment options. You should ask about the benefits and risks, and ask what is the evidence that it will work.' And if the therapist can't give you good answers, he added, you might want to rethink your choice of therapist. 