Exercise is great, and the benefits are well known. Clear mind, stronger body, better immunity.

But sometimes weird stuff can happen to your body after some heavy aerobic exercise that can be a little alarming. For example, tasting a bloody or metallic tang in your mouth after a massive run. According to sports medicine doctor Jordan Metzel, cited in Women's Health, there's a simple biological reason for this occurrence. If you push yourself on a run, it's likely that your red blood cells are being put under stress and they then release heme or iron, which explains the metallic taste at the back of your throat. It's temporary, and nothing to worry about. Obviously, if you taste blood all the time it is a cause for concern and you need to see a doctor. Metzel went on to explain that if you have a runny nose after a 10k it's caused by exercise-induced rhinitis, which is caused by your nasal passages getting irritated by the pollutants and irritants in the air as you run. Nitrogen dioxide is a big trigger, so it makes sense that it would be worse outside with all those car exhausts as opposed to in a pristine gym.