Final answer:
Soccer players generally operate at a substantial fraction of their VO2max for the duration of a game, with high-intensity bursts potentially reaching peak VO2max, balanced by lower intensity periods.
Step-by-step explanation:
Soccer players typically play at varying intensities of their maximum oxygen uptake, or VO2max, during a soccer game. VO2max is a measure of the maximum volume of oxygen an athlete can use and is indicative of their aerobic endurance. While the specific percentage can vary based on the position played, the intensity of the game, and the fitness level of the player, it is generally understood that players operate at a substantial fraction of their VO2max for the duration of a game. This is due to the constant running, sprinting, and aerobic demand of soccer. However, the exact percentage is not stated in the given examples.
In instances of high-intensity activities, such as sprints to the ball or pursuing an opponent, players may reach peak levels of exertion nearing their VO2max for short bursts. But over the whole duration of the game, which includes periods of lower intensity, the average tends to be lower. The sustained effort over the approximately 90-minute game requires a blend of aerobic and anaerobic energy systems. During the most intense moments, players might use mainly anaerobic respiration, similar to hurdlers, providing energy for short-term, high-intensity activity.