Hello All. I've been crosfitting for about 6 weeks, but first WOD with deadlift strength piece 2 days ago. Did 10-8-6-4-2. Did pretty well with weight, but as soon as I got home, I felt my low back tighten up. I woke up very stiff and sore, and now day 2 still stiff, and having trouble walking. No sharp pain, which is I assume good, but is this a muscle pull or something worse?