My brother and I were on a bike ride; we both weigh the same and ride similar bikes. We both were wearing a hear rate monitor. His average heart rate was 20 ticks over mine; according to his heart rate monitor he burned 20% more calories than I.
Correct me if I'm wrong, but my understanding is that a calorie is a unit of measure of energy. Regardless of our fitness level shouldn't it take the same amount of energy to get our similar loads down the road?