I think my trainer has been anxious to use TRX with me again, after the amount of soreness I suffered after our last workout with it. In all my years of physical activity, I have never had the degree of delayed onset muscle soreness that I often encounter now. I've wondered if my thyroid issues--I know that Graves' Disease can cause muscle fatigue, weakness and soreness--is a contributing factor. I've started to take a supplement recommended for GD that can help with these muscular issues. We'll see if it helps.