Some of most electrifying March Madness moments actually happen on the sidelines.

During timeouts or other breaks in the action, look for trainers affixing electrodes to the area around an athlete’s injured muscle or joint. The wires plug into a small device that sends electrical signals to temporarily relieve pain.

“Most of the players just call it the blue box,” said Ron Burch, CEO of the Biowave, a company that markets one such device.

Electrical muscle stimulation (EMS) has been used for some time as a way to relieve pain and rehabilitate injuries. Norwalk, Connecticut-based Biowave has patented a technology that delivers signals at two different frequencies to reach injuries well below the skin’s surface into joints.

Low frequency signals block the transmission of pain signals along the body’s nerve fibers, Burch explained. But these signals at less than 180 hertz can’t pass through the skin. Higher frequency signals at 1,000 hertz or greater are needed to go through skin. Biowave’s technology pairs the low-frequency signal with the higher frequency signal to deliver the therapy deep into the injured tissue. Treatment typically takes 30 minutes but some athletes may plug in during a timeout; even a few minutes can be enough to bring some pain relief, Burch said.

The U.S. Food and Drug Administration granted 510(k) clearance for Biowave’s device in 2005. While there are other electrical stimulation devices that deliver low-frequency signals to injured areas, they require needle electrodes that go into the tissue. That’s not practical for athletes, particularly during game situations, Burch said. Other devices that use surface electrodes can’t adequately penetrate the skin.

The BiowavePRO neuromodulation pain therapy system is used primarily in football, which is the sport where the technology was studied in clinical trials. About 75 percent of NFL teams use Biowave’s device, Burch said. The device was introduced to basketball teams in 2008 and now half of NBA teams use it. It’s also used by some professional baseball and hockey teams.

Burch said that 50 NCAA teams use the technology, including the Duke University Blue Devils. Last year, the Durham, North Carolina university purchased five Biowave devices to treat athletes on campus and on the road. Jose Fonseca, head athletic trainer for Duke men’s basketball, said he used the Biowave device during the team’s 2010 NCAA basketball championship run.

Athletic teams comprise Biowave’s main customer base. But the company is also targeting additional markets. Burch said physical therapists and orthopedic surgeons can use the technology to help patients rehabilitate after surgery. The company is also marketing to Veterans Affairs system hospitals to help veterans recovering from injuries sustained in Iraq and Afghanistan.