@Florida Guy did you notice any symptom changes?
Yes, my pulse rate which was always high went down and blood pressure which was always a little high went down as well. Those are the only things I tried to measure but the vagus does a lot of other things. Since mecfs those numbers tended to be low though on occasion I see a higher heart rate so I haven't used it in a while. I will use it again today and check my bp and pulse to see how it is going
The tens unit was originally intended to be an easy way to exercise. People who are very severe can't exercise at all and may lose the ability to stand and walk. Using something like the tens may be a way to strengthen muscles that have lost their ability. I saw a post someone said they got pem from using a tens same as if they had done exercise and the muscles ached. That is likely from a too high setting for too long. You can set the power so low you can't feel it, that works for the vagus-ear treatment. A higher setting makes the muscles contract and release on a pulsing basis
A low setting and short session might be just right for exercising the muscle without pem. Its a form of pacing since we can do a certain amount of movement or exercise without going over our limits. Someone completely or mostly bedbound could over a period of time carefully tone their muscles until they are able to walk again possibly. Its a theory, might not work or might be too complicated for some. But tens units are used in physical therapy along with regular stretching and exercise. This system has been used with paralyzed patients to maintain muscle mass
Also, since you are only working one muscle group at a time, its unlikely to wear you out or give a crash. At the most, the muscles being worked on might feel some pem but not in the rest of the body. I'm thinking that if a certain setting for 10 minutes gives pem the next day, then try 5 minutes until you hit the sweet spot
The tens I bought cost about $20 and I've seen them cheaper, the ear clips were $8 and you are all set. The tens includes the connector pads that people use for exercise but you need the ear clips for comfort.