It’s well-established that regular physical activity provides a number of benefits to your muscles, organs and bones and can increase both the quality and the length of your life, but is it possible to take it too far? When it comes to ultra-endurance running, the answer may be yes. In a recent literature review, researchers analyzed the available data and determined that ultra-endurance running may pose a risk to the long-term health of athletes.
The authors of the review compiled data from a variety of ultra-endurance events around the world, including single-stage, multi-stage, road, trail, uphill and downhill races, and while they determined that “acute adverse events” are rare, there appears to be a growing body of evidence to suggest that these events may lead to long-term health problems. Specifically, athletes who train for and participate in these types of races risk “potential maladaptation in key organ systems, including cardiovascular, respiratory, musculoskeletal, renal, immunological, gastrointestinal, neurological and integumentary systems.”
Additionally, they found that youth and masters athletes are at a greater risk for these types of health complications, as are female athletes due to interactions between energy availability and sex hormone concentrations.
The cardiovascular system
Research has established that while regular aerobic exercise improves the health of your heart and cardiovascular system, regular endurance exercise training has a significant impact on the heart both from a structural and a functional standpoint. The authors of the review point to research demonstrating that the hearts of endurance athletes undergo a structural remodeling, most notable a large increase in the size of the right ventricle and atria. This can lead to tissue scarring and arrhythmias, which, they note, is related to a higher mortality rate in the general population. The long-term consequences of this in endurance athletes, however, is yet to be explored.
The respiratory system
Studies have shown that an athlete’s lung function is impaired following an ultra-endurance event, sometimes for days or even weeks. This is because, during these events, your airways are unable to warm, humidify and purify the air at a fast enough rate before it gets to your lungs. This unconditioned air then cools and dehydrates the lining of your lungs and airways, causing inflammation that can stimulate bronchial smooth muscle constriction, airway narrowing and subsequent obstruction. While this is an acute issue, research shows that when this happens repeatedly, it can lead to long-term damage and injury to the muscles involved in your respiratory system.
The musculoskeletal system
Not surprisingly, ultra-endurance athletes are at a higher risk for injuries to their bones, joints, cartilage, muscles, tendons, ligaments and bursae. The authors note that while recreational running tends to have a positive effect on muscle and bone strength, regular high-volume running is known to increase the risk of osteopenia (reduced bone mass) and stress fractures. Competitive endurance running has also been associated with a higher instance of hip and knee osteoarthritis compared to that seen in the general population, as well as back pain.
The renal system
The researchers explain that the risk of kidney damage can be increased by factors such as endurance running in extreme environments, severe muscle damage due to high biomechanical loads, low rates of fluid intake resulting in dehydration, the ingestion of nonsteroidal anti-inflammatory drugs (NSAIDs) and genetic predisposition. Of course, ultra-endurance running combines many of these factors, and while renal failure at an ultra event is extremely rare, little is known about the long-term consequences of repeated kidney stress during ultra races.
The bottom line
The authors of the review conclude that regular moderate physical activity provides a number of health benefits, and those benefits can also be derived from participation in ultra-endurance events and the sport can generally be considered a safe and healthy pastime. “However, it should also be recognized that with increased participation in [ultra-endurance events] comes an increased risk that susceptible individuals may experience chronic maladaptations leading to adverse effects on health and possible long-term health problems in later life,” they add. For this reason, more research is needed on the long-term health effects of ultra-endurance racing, particularly in more vulnerable populations, to ensure runners can participate in these events in a safe and healthy way.