Other crucial physical characteristics matter, too, aside from basic body measurements. A gymnast looking to win gold on the balance beam obviously must have excellent balance, and that comes from having an exceptional inner ear. Top-notch tennis players must have extraordinary eyesight to keep track of the ball whizzing back and forth across the court. In most cases, runners can't easily swap between distance running and sprinting. Sprinters tend to have more fast-twitch fibers in their muscles.
Athletes' bodily processes also matter. For example, how efficiently do their bodies use oxygen? Lots of countries have training facilities that mimic high-altitude conditions to prepare their competitors for adverse, low-oxygen settings. Events at the Mexico City 1968 summer games were held at an altitude of more than 7,500 feet (or about 2,300 meters), and it quickly became apparent that many of the athletes in attendance were suffering from the thinner atmosphere at such an elevation. However, if an event had a short duration, such as sprinting, jumping, throwing or weightlifting, then the altitude proved advantageous. But for athletes whose events required a lengthy (more than about two minutes) performance, such as long-distance running, swimming or cycling, then it wasn't helpful [source: Olympics.org].