(RxWiki News) Recent research from Indiana University and the University of Ulm in Germany look at the health effects of running.
Runners should end their run when they feel fatigued because fatigue indicates changes in body mechanics and can thus contribute to injuries as range of motion becomes more difficult to control.
Toward the end of a running session, runners in the study displayed increased motion in their hips, knees and ankles. Prolonged running while fatigued can cause common overuse injuries in the feet (plantar fasciitis) and knees (patellofemoral pain syndrome and iliotibial band syndrome).
Recent research from the University of Ulm at Germany indicates that while fatigue may be a good indication of when to quit running, slight discomfort shouldn't always inhibit runners.
Researchers followed 44 runners taking part in a cross-country, 4,500-kilometer (about 2,800 miles) race to look at how their bodies responded to the high-stress conditions of an ultra-long-distance race.
Runners were followed for 64 days and submitted to a battery of tests along the way, including electrocardiograms, urine and blood tests. Researchers found runners lost an average of 5.4 percent body volume during the course of the race, and 50 percent over the entire race. Runners even exhibited a 7 percent muscle volume loss in the legs.
Despite the daily endurance running, leg muscles actually degenerated because of the immense energy consumption, said study author Uwe Schütz, M.D., a specialist in orthopedics and trauma surgery.
Results also indicate that some leg injuries, such as intermuscular inflammation in the upper or lower legs, are safe to "run through" as risk of further tissue damage is minimal, according to the study.
Joint inflammation, on the other hand, carries with it a greater risk of progression.
The study also found runners lost a mean of 70 percent of visceral fat (the most dangerous kind of body fat, which contributes to heart disease), most of which was lost during the first half of the race.
That means when individuals begin running for the first time,"the effects of fat reduction are more pronounced than in athletes who have been running their whole life," Dr. Schütz said.
"Running is a fantastic way to increase your cardiovascular strength and stamina, but you need to understand your goals and the likely outcomes that are associated with running extreme distances," said Jim Crowell, owner of Integrated Fitness (www.if-fit.com) in Pittsburgh.
Crowell explained how aerobic exercise, such as running can contribute to a loss of muscle strength, whereas anaerobic exercise, including weight-lifting and body weight exercises, build muscle strength and endurance.
"If your desire is to increase your ability to stamina for long running workouts then I would recommend running extreme distances," Crowell said. "But, if your desire is to be an all around athlete I would rather that you mix your training up with weight training, body weight training, and cardiovascular exercise such as running."