Two weeks ago I got sick and could not workout at all for a whole week. After the week I felt that I really needed to do a workout, I took it easy and started by doing yoga. A day after doing yoga I felt good and decided to do an aerobic workout that combines strength and endurance. The day after I felt so sore! I Haven't felt that sore in a long time. I could barely more I was in so much pain. Is that normal?
Sometimes illnesses stir up different detoxifying mechanisms in our body. Yoga practices offer a gentle and systematic way to continue that detoxification and elimination from the body. More strenuous physical exercises can flush the elements through our system and our body can sometimes respond in the ways you described - pain, aches, ...
A week without movement can also allow for atrophy of the muscles since they are not being used. Jumping back into a strenuous workout would require muscle fibers to be rebuilt, sometimes experienced as soreness from the lactic acid and/or overworking or overstretching. Did you recall being well hydrated before, during and after?