Can there be any way of quantifying the contributing factors that produce perceived exertion during exercise? How much does glucose variance, hormonal changes, blood volume or pressure contribute to a sense of fatigue?
I recently experienced severe feelings of fatigue during a morning run. For years, I've run in the morning on an empty stomach without severe fatigue. However, in the last several years, I've started eating breakfast before running half of the time.
Question: Since I eat some of the time before running, have I set myself up for possible empty-stomach running problems? Is this a sign that I used to be "trained" to run on an empty stomach?