Aerobic activity, which is an exercise that is accomplished in the presence of oxygen, is one of the best ways to improve the strength of the heart and lungs and become more physically fit going forward. Though some people believe that elite levels of exercise can actually harm the body and break down joints, there is no real evidence to support this, especially if athletes give themselves enough time to recover after each bout of intense activity.

This is good news for people who love marathons and run them regularly. While endurance runners should receive regular physical examinations from doctors to make sure there is no rare underlying medical condition, they will almost always be given the go-ahead to compete in long-distance sports. Regular long-distance runs will strengthen the heart, make it easier for the heart to pump blood, and promote blood vessel growth. Marathon running also makes it much easier for the lungs to deliver oxygen to the muscles via the bloodstream, which is a basic measure of fitness.

Marathon training nearly always involves very high quantities of exercise. When runners continue to train over the course of many years, they can achieve elite fitness levels. Men and women who are very fit can expect to live longer and will have less of a risk of contracting heart disease, hypertension, diabetes, cancer, and a wide range of other potentially devastating diseases.

Marathon runners who are interested in reaching elite fitness levels should be open to speed workouts, fartlek runs, hill runs, and cross-training. Typical cross-training activities can range from bicycling and hiking to walking and swimming. Individuals who have suffered a leg injury and are trying to maintain their current fitness levels might want to try water walking, which increases the heart-rate while going easy on the joints in the legs and ankles.

Athletes ultimately should not fear exercising too much in an attempt to reach fitness levels that are generally considered to be elite by specialists in sports medicine. In fact, it is much riskier to live a sedentary lifestyle than it is to become a fitness fanatic. Runners and other athletes can expect to minimize their body fat and build strong hearts and lungs that will allow them to carry excellent cardio health well into their golden years.