Don’t dismiss the downsides of endurance training

By Sabrina Gonzales

Too much of a good thing is bad, and this principle applies to endurance training. Regular rigorous physical activity coupled with adequate rest is highly recommended for those seeking ways to improve their health. However, beyond a certain point, the health benefits gained from regular exercise seem to diminish.

For running, expert consensus has estimated this point to be a speed of seven to eight miles per hour (11 to 13 kilometers per hour), a distance of 20 miles (32 kilometers) a week, and training frequency of five times a week–anything more results in an increased risk for injuries and can produce chronic wear-and-tear, ultimately becoming detrimental to one’s health. Let’s have a closer look at some of the common medical conditions endurance athletes face.

Overuse Injuries

Overuse injuries are a set of medical conditions caused by repetitive damage to the body as a result of engaging in high impact sports like distance running. These include patellofemoral syndrome or runner’s knee, iliotibial band friction syndrome, Achilles tendinopathy, and plantar fasciitis. Patients experience pain on the knee, heel or underside of the foot, usually exacerbated with movement. Overuse injuries can frequently be traced to an error in training such as a sudden increase in mileage, changes in footwear or terrain, or running too much in general.

Expert consensus has estimated this point to be a speed of seven to eight miles per hour (11 to 13 kilometers per hour), a distance of 20 miles (32 kilometers) a week, and training frequency of five times a week–anything more results in an increased risk for injuries

Exercise-induced Asthma

Although regular exercise has been known to improve an athlete’s lung capacity and breathing mechanics, recurrent damage to the lining of air passages (airway epithelium) from endurance training can result in a condition known as exercise-induced asthma. Inhaling cold, dry air at high flows for prolonged periods of time can cause dehydration of the epithelium and chronic respiratory changes. Patients experience coughing and wheezing, and worsened performance when exercising. Swimmers are especially at risk for this condition because of the long hours of training in chlorinated pools.

Athlete’s Heart

The increased popularity of endurance training in recent years has placed the spotlight on elite athletes who experience sudden death. This is a rare albeit potential event, occurring in one per 100,000 marathoners. Several authors point to a condition of cardiac remodeling known as “athlete’s heart” as a possible underlying cause. Athlete’s heart is a particular set of adaptive changes in the structure of the heart, including an increase in ventricular volume and wall thickness, which develops due to the sustained rise in cardiac workload associated with excessive endurance activities. Although these changes are not actually pathologic, several experts believe this condition can predispose to the development of scarring in the heart muscles, which in turn makes the heart prone to rhythm disturbances. Previous studies have shown a three-fold rise in incidence of heart scarring in seemingly healthy marathoners, and an association between rigorous training and a higher risk for arrhythmias.

Prevention Is Key

In most cases, these conditions can be dealt with medically; however, they generally cannot be completely reversed. Thus, prevention remains to be crucial in the management of these conditions.

For overuse injuries, the best treatment is to allow your body to rest and recover. Application of ice and intake of anti-inflammatory medications can help minimize pain and swelling. Specific exercises are beneficial for certain injuries such as heel lifts for Achilles tendinopathy. A supervised rehabilitation program and modification of activities such as substituting cycling for running may be necessary. In order to facilitate complete recovery, slow and gradual return to specific sports is important.

Majority of these conditions can be avoided with proper training techniques. Warm-up exercises have been shown to be beneficial for preventing both overuse injuries and exercise-induced asthma. Heat and moisture devices can also be used when training in cold climates or harsh conditions.

Rehydration is also important; for endurance events, it is recommended to take in approximately 150 to 300 ml of water every 15 to 20 minutes. To achieve maximal health benefits and avoid the development of athlete’s heart, a 2012 study in Missouri suggests that daily strenuous endurance training should not be performed for more than an hour a day. The authors also recommend slowing down or resting intermittently during training and for people older than 50 years, to lessen the duration and intensity of their endurance training.

Rehydration is also important; for endurance events, it is recommended to take in approximately 150 to 300 ml of water every 15 to 20 minutes

Everything in Moderation

Numerous health benefits, including decreased risks of stroke and heart disease, and lower mortality overall, can be derived from an active lifestyle. However, it is important to learn how to balance physical activity and recovery. It is essential for endurance athletes to adopt specific training principles to enable the body to recover fully, avoid the development of injuries, and optimize training. Too much of a good thing may be bad, but when done in moderation, you will be able to reap its utmost benefits.

References:

Incidence of Injury and Disease Among Former Athletes: A Review, by Kelly Friery. Journal of Exercise Physiology, 2008 April 2; 11(2):26-45.

Respiratory Health of Elite Athletes – Preventing Airway Injury: A Critical Review, by Pascale Kippelen, Kenneth Fitch, Sandra Doreen Anderson, Valerie Bougault, Louis-Philippe Boulet, Kenneth William Rundell, Malcolm Sue-Chu and Donald McKenzie. Br J Sports Med 2012; 46:471-476.

Common Problems in Endurance Athletes, by David Cosca, MD and Franco Navazio, MD, PhD. Am Fam Physician, 2007 July 15; 76(2):237-244.

Overuse Injuries in Female Athletes, by Alan Ivkovic, Miljenko Franic, Ivan Bojanic and Marko Pecina. Croat Med J, 2007 Dec; 48(6):767-778.

Cardiovascular Damage Resulting from Chronic Excessive Endurance Exercise, by Harshal Patil, MD, James O’Keefe, MD, Carl Lavie, MD, Anthony Magalski, MD, Robert Vogel, MD and Peter McCullough, MD. Missouri Medicine 2012; 109(4):312-321.

The Heart of Trained Athletes: Cardiac Remodeling and the Risks of Sports, Including Sudden Death, by Barry Maron, MD and Antonio Pelliccia, MD. Circulation 2006; 114:1633-1644