I thought previously that a man, who has many experience in climbing a mountain, feel easy but losses his calories as much as when he first climbs a mountain. Now my thought is changed. The man will spend much less energy when he climb mountain continuously. When a man climb a mountain long times after, his body will tests several organ to search an energy efficient method even if he know how to climb a mountain. Later when he climb a mountain again, the body will spend much less energy than his first trial because the body will use his organs most energy efficiently.