Has anyone ever had a knot in their muscle? I took a 2 month lay off from the gym and just recently came back. Worked chest and did not go really heavy (or so I thought). Pecs were reasonably sore for a few days, but now a week later there's a fairly big knot in my left upper pec. When I pull my left arm back it feels as if the muscle is still holding lactic acid, still feels sore. When I feel the part that is sore it feels like a hard knot in that area. Right pec is fine. Did I just work the muscle out too hard after the layoff? Kind of concerned that it's not getting better and its been a week. I am due to train chest again tomorrow and don't know if I should. Anyone ever have something like this ?