Al Andalus Ultra Trail: An Observation of Medical Interventions During a 219-km, 5-Day Ultramarathon Stage Race. At a multi-stap running over 219 km, all medical problems of the runners were registered.
Overall, 56.5% of the runners complained about medical problems.In 22.2% of the runners, there were problems of lower extremity. The whole study can be found under https://pubmed.ncbi.nlm.nih.gov/21860348/