Everyone's back is different, therefore you may experience discomfort if your back is sensitive and you use higher strength settings. So please use the App to find the right strength setting for you. You can adjust strength from 0 (off) to 7 (very strong) - so there should be one which is comfortable for you. We recommend starting on lower strength and working your way up to avoid discomfort.
Remember, the fingers are pushing to release stress from your back. That may feel a little strange at first, but that’s a by-product of the tension being released. As treatment goes on, you should feel yourself relaxing, making treatment more comfortable and enabling you to sustain a higher strength setting.