Aerobic fitness is required for sustained periods of hard work and vigorous athletic activity.
The researchers examined 1,294 middle-aged Finnish men with no cardiovascular disease or cancer. They followed the men for approximately 11 years, regularly documenting their physical fitness using stationary bicycle exercise-tolerance tests. They also performed various laboratory tests and tracked cigarette smoking, consumption of alcohol, and body mass. World-class endurance athletes generally have high VO2max readings. They can also exercise longer before experiencing muscle fatigue, exhaustion, or pain in the muscles.