The shortest ultra-marathon is the 50-km run (Figure 1). What is an Ultramarathon?Īn ultra-marathon is any running event where the running distance is longer than the traditional race length of a marathon of 42.195 km. Specifically, studies with a practical relevance for the athlete, the coach and the physician were considered. Studies investigating swimmers, cyclists, triathletes or other sports were excluded. All articles were then sorted so that only studies (i.e., case reports and original papers) on running were taken into consideration. The keywords were “ultra-marathon” and “ultra marathon.” This search resulted in more than 700 articles. For this purpose, we have searched all scientific papers on ultra-marathon in Scopus ( until March 2018. The aim of this narrative review is to present the current state of knowledge on the topic of physiology and pathophysiology of ultra-marathon running. With the increase in the number of races and finishers ( Nikolaidis and Knechtle, 2018a), ultra-marathons-defined as any running distance longer than the marathon distance-became more and more interesting for scientific research. In recent years and decades, races longer than the classical marathon distance (42.195 km) have experienced a boom. Considering the increased number of participants in ultra-marathons, the findings of the present review would have practical applications for a large number of sports scientists and sports medicine practitioners working in this field. Ultra-marathoners often suffer from upper respiratory infections after an ultra-marathon. An ultra-marathon often leads to a temporary reduction in renal function. Liver enzymes can also considerably increase during an ultra-marathon.

Ultra-marathoners often suffer from digestive problems and gastrointestinal bleeding after an ultra-marathon is not uncommon. Furthermore, an ultra-marathon can lead to changes in the heart as shown by changes in cardiac biomarkers, electro- and echocardiography. An ultra-marathon can lead to an increase in creatine-kinase to values of 100,000–200,000 U/l depending upon the fitness level of the athlete and the length of the race. The most common injuries in ultra-marathoners involve the lower limb, such as the ankle and the knee. In longer ultra-marathons, ~50–60% of the participants experience musculoskeletal problems. These changes are usually temporary, depending on intensity and duration of the performance, and usually normalize after the race. An ultra-marathon can also lead to changes in biomarkers indicating a pathological process in specific organs or organ systems such as skeletal muscles, heart, liver, kidney, immune and endocrine system. An ultra-marathon in combination with other risk factors, such as extreme weather conditions (either heat or cold) or the country where the race is held, can lead to exercise-associated hyponatremia.

An ultra-marathon leads to an energy deficit resulting in a reduction of both body fat and skeletal muscle mass. The fastest ultra-marathon race times are generally achieved at the age of 35–45 years or older for both women and men, and the age of peak performance increases with increasing race distance or duration. Women are slower than men, but the sex difference in performance decreased in recent years to ~10–20% depending upon the length of the ultra-marathon. Previous experience (e.g., number of finishes in ultra-marathon races and personal best marathon time) is the most important predictor variable for a successful ultra-marathon performance followed by specific anthropometric (e.g., low body mass index, BMI, and low body fat) and training (e.g., high volume and running speed during training) characteristics. Ultra-marathoners are older and have a larger weekly training volume, but run more slowly during training compared to marathoners. Female ultra-marathoners account for ~20% of the total number of finishers. A typical ultra-marathoner is male, married, well-educated, and ~45 years old. The number of ultra-marathon races and the number of official finishers considerably increased in the last decades especially due to the increased number of female and age-group runners. In this overview, we summarize the findings of the literature with regards to physiology and pathophysiology of ultra-marathon running.

2Exercise Physiology Laboratory, Nikaia, Greece.

1Institute of Primary Care, University of Zurich, Zurich, Switzerland.

10k in a hundred days