10 signs your muscle pain is a sign of something worse

You know that playing tennis all weekend will leave you sore on Monday or that putting in that extra tough workout in the gym is going to make you pay later when going downstairs (oh, your quads!). When you perform activity above and beyond what your body is accustomed to, “a byproduct of energy use is produced, called lactic acid, which is a chemical that causes soreness,” explains physical medicine and rehabilitation specialist, Dr George Kannankeril. Lactic acid usually dissipates in about an hour, but delayed onset muscle soreness can last for one or two days.