What is the muscle shocker used for in physical therapy?

See below. The use of electricity in physical therapy has been around for a long time. Muscle stimulation can be used to rehab weak muscles, treat muscle spasm and encourage healing of muscle injuries. The useof skin electrical stimulation (tens) has also been usedfor years as a treatment for various pain conditions. In patients withparalysis, electrical stimulation is used to keep muscles in good shape.
TENS unit. You are probably referring to the tens unit ( a transdermal electrical nerve stimulator) which gives tiny shocks of electrical stimulation delivered from the skin by tiny electrodes. This therapy is often effective in controlling muscle and spinal pain when used in a physcial therapy situation.