ABC Everyday Understanding delayed-onset muscle soreness can help you avoid pain and stiffness after exercise. ( Print text only Cancel A few weeks ago, I decided to get back into exercise after taking some time off over the summer. I did my workout, and I was feeling great. But the next day my legs were so stiff and sore I could barely walk. The cause is something scientists call "delayed onset muscle soreness" — or DOMS for short. If you've experienced it, you might be wondering why it happens and whether you can avoid it. We spoke to two exercise scientists to find out.