two cents
When I was younger.... One of my checks revealed a little blood in my urine. One of the questions my doc asked was - if I worked out really hard as in long runs and such. The previous day I had worked out hard and he said it was probably that. He asked me to come back and give a sample in two weeks and again in six weeks. No blood either time. Of course I did not work out for a few days before I gave the new samples.