While training, your Biorexin muscles may get warm but you shouldn't feel pain. Before you begin a new exercise program, we suggest that you get in touch with a health care service provider. If you are over 50, we suggest that you start with the lightest resistance band. Ideally, it's a good idea to choose a 3-pack with a light resistance band. Just don't go for the heaviest band in the beginning or you may hurt yourself in the Electro Keto process. 3.