Peripheral Vascular and Neuromuscular Responses to Ultramarathon Running

Participation in ultramarathon events has grown substantially in the past decade. However, poor understanding of the physiological outcomes associated with participation in this sport prevents athletes and clinicians from adequately addressing performance and recovery tactics. The purpose of this review was to summarize developments in the literature in the last 10 years regarding acute and chronic responses to ultramarathon running with a focus on the peripheral vascular system, neuromuscular outcomes, and running mechanics. Evidence suggests that there are acute impairments in large artery compliance especially following the longer ultramarathon distances. However, most literature indicates that chronic vascular impairments are not evident in ultramarathon runners. Both central and peripheral fatigue mechanisms contribute to declines in muscle force production that may last up to several weeks in some muscles following an ultramarathon. Alterations in gait kinematics and skeletal muscle oxidative capacity increase the metabolic cost of running over prolonged running distances (> 4 h). Several factors such as elevation changes and nutritional practices make interpretation of findings challenging. Future studies are needed to better understand the interplay among systems and how external factors contribute to these outcomes to optimize performance and inform recovery strategies in this increasingly popular sport.