There have been and still are a number of these devices on the market and the peculiar thing is mostly they're supposed to be used to build your muscles up while you sit and do nothing. One item is a belt type device that you wear around your lower tummy and those electrical pulses running up the cables work your abs and lower back muscles. These devices don't build your muscles up either, of course, because they simply don't get in deep enough to activate muscles. Yet Dr Ho's device, while having the same principles, somehow cures aches and pains.
Recently I used a device similar to what Dr Ho promotes on my back because I've been in pain for a couple of weeks and wanted some relief. The sticky pads were attached to my shoulder blades and the electrical device pulsed up through my muscles for around 10 minutes. It did not feel as though it had helped at the time.
The following day I woke up with the most painful crick neck I've ever had. That is because the electrical pulses in my back muscles were triggering a mild workout along with the muscles around them, however, because the machine actually doesn't massage at all it left my muscles strained and tight, thus causing the severe crick neck which lasted well over a week.
Upon visiting an osteopath and talking to her about my neck and the device I'd used she explained to me that these devices, along with proper massage devices don't get in deep enough into the muscle tissue to work out any tightness and knots. Not only that, she confirmed, the device causes your muscles to spasm and this causes tightness which is also displaced to other muscles around the area the device is used.
My advice if you're thinking of getting a device like this is save your money and put it towards a professional masseuse.