increase muscel in buttock

Yes, there is a way to increase muscle mass, including in the gluteus muscles. It involves electrical muscle stimulation, or EMS. When I was in rehab after my injury nine years ago, I was invited to participate in a clinical trial involving this modality. They placed electrode pads on my glutes and provided intermittent stimulation (10 seconds on, 10 minutes off, 30 mA and 300 µs phase width - using only the amount of stimulation to elicit a strong contraction) 24 hours a day, four days per week (the research nurse did not work three days a week). It was a phase 1 trial to see if this stimulation was safe and could be tolerated by people, and indeed it was. I was the only patient to be on the trial more than one month, and indeed I continued four eight months in a row. At the last inspection as the trial was winding up, the nurse observed that I had gained quite a bit of muscle mass. When I asked her how much, she said she had measured it or taking a photo at the beginning since the objective was to assess safety, not efficacy, but it was noticeable.

A few months later I was able to acquire an FES bike which provides stimulation to quadriceps, hamstrings, and gluteus, during my work out which range from one hour to almost 3. And I do that to or three times per week (now using Close to 140 mA). Eight years later, I am still using the bike and have not had any pressure sores. When I ask the staff at bedtime if I have any skin integrity issue in my glutes, the answer is always "no", and I have been told on occasion "but at least you have some muscle mass there, unlike most of the other wheelchair users". I have also noticed a substantial increase in muscle bulk in my leg muscles, with circumference or girth increasing by a couple of centimeters.

Here is an article on the technology:
www.scientificamerican.com/article/how-to-get-fit-using-electrical-muscle-stimulation-ems/

You can buy units as little as $50, for up to $500 or more. Most commercially available units can be set manually to determine the time on and the time off. But very few of them Will allow an off time of more than three minutes. If your objective is to have gentle stimulation all day long, you may want to choose a duty cycle of 10 seconds on and 90 seconds off on one Side of the buttocks, and then alternate to the same 10 seconds on, 90 seconds off on the other side before returning back to the previous side. This way you will be contracting each muscle 10 seconds every three minutes.

Note that electrical stimulation is much easier to tolerate if you cannot feel the muscle. That is my situation on the glutes, which is why I can tolerate high current levels. On my pectoral muscle is where I do have feeling, I noticed that simply increasing the stimulation by a few milliamps, say from 12 up to 15, can change the sensation from tolerable to intolerable. Start low, go slow. I hope this helps.

Well sure, that would have been ideal. However, I have other data that confirms the efficacy. I have seen results of research studies of FES bike users, and they have a 90% lower incidence of pressure sores. That's good enough for me!