I recently replaced running with biking for my workouts. Reason being, I get very light headed and my feet feel the burning sensation quite quickly into my run. After I run (lets say 4 miles), I feel dizzy and my head is not in a very pleasant feeling. I understand the burning sensation in the calves and legs would slowly get better and better with more muscle. I'm curious as to what causes the fatigue and the light nauseous feeling after running? I had the same thing happen the first time I went on a 10-15mile bike ride, but it only happened once when biking. I get this feeling every time after running.
Feel free to add tags that I'm sure I've missed. Thank you.