I am a 52 year old woman in good shape. I run a 5k in about 30 minutes without effort. Lately I have been swimming more than running, though yesterday I ran on pavement for about 30 minutes at a good clip to get in a quick workout in a busy day. I live in Phoenix and the outdoor temp was about 85. After I finished, I had the taste of blood in my mouth, though no visible blood in my saliva.