Exercise is work performed against resistance to achieve physical fitness. Most exercise pits your muscles against resistance such as gravity or water. While much of the popularity of exercise revolves around muscle-building and improving your physique, the President's Council on Physical Fitness and Sports places special emphasis on exercises for heart and lung endurance. Efficient heart and lung function supply your body with enough oxygen-rich blood to support your other activities.
The United States Army requires proficiency in running for both male and female soldiers as a mandatory form of heart and lung endurance training. Cardio-respiratory endurance is built by progressive increases in both running speed and duration to assure lower-extremity strength increases at a rate that prevents injuries. Running improves a soldier's ability to use large muscle groups during extended periods of intense activity for combat readiness. In the standard Walk-to-Run Program, the endurance goals require males to run 1 mile in 7 minutes or less and females to run 1 mile in 8 1/2 to 9 minutes. After achieving these benchmarks, endurance is further increased with interval training at alternating fast and slow paces.
Swimming is reported by the Centers for Disease Control and Prevention as the No. 2 most popular form of aerobic, or heart and lung endurance exercise in the United States. Two and a half hours per week of swimming is documented to reduce your risk of death to about half that of an inactive person with no regular exercise program. An advantage of swimming over land-based exercise is the absence of gravity-induced stress on joints and muscles in the relative weightlessness of buoyancy. This allows a longer duration of exercise to develop endurance and stamina.
Bicycle riding is a low impact activity that you can do with great intensity over a long duration and distance -- as much as a "century," or 100 miles in one day. This type of aerobic endurance training is often called "base building" by cyclists. Interval training for aerobic endurance calls for 15 seconds of fast pedaling alternating with 5 minutes at a moderate pace for five repetitions. Longer-than-usual weekly rides and intervals of riding hard enough to achieve 85 percent of your maximum heart rate also improve cardiovascular endurance.
Any exercise that raises your heart rate to between 65 percent and 85 percent of your maximum heart rate for 30 to 60 minutes a day, three to five days a week plus eight to 12 reps of 10 strength-training exercises twice a week will increase your cardiovascular endurance. The physiological results include increased volume of blood pumped per heart beat, lower resting heart rate, higher cardiac output during exercise and stronger breathing muscles with greater oxygen and carbon dioxide exchange during exercise Taken together, these result in greater aerobic fitness and endurance.