Tens machines and circulation boosters

Greg's getting electric for this one, as he tries out a tens machine. Tens (transcutaneous electrical nerve stimulation) is a type of pain relief which uses a mild electrical current. They're marketed at all types of pain - but do they work? The NHS isn't convinced yet. Listener Patrick is one of many who have asked about these devices, so we got in touch with a a professor who's studied them for 40 years. Also - another type of electrotherapy is a circulation booster. These circular devices claim to be able to help sore legs by activating the muscles. On behalf of listener Rick, Greg finds out what the evidence is for their effectiveness.PRODUCER: TOM MOSELEY PRESENTER: GREG FOOT