The biological determinants of performance have been well described for running races up to and including the marathon (42.2 km). Ultramarathon is more complex. Events range from 50 to 5000 km in single or multiple stages, are contested in various environments and terrains, and force athletes to contend with diverse performance-limiting issues such as fueling, hydrating, gastrointestinal distress, muscle damage, and sleep deprivation. Ultramarathons are not simply “long marathons.” Nevertheless, scientific developments over the past decade have inched us toward a more complete picture of the psychophysiological factors underpinning performance. In this Current Opinion, we argue that muscle damage and associated fatigue is the main impediment to performance in long ultramarathons; more performance-limiting than aerobic capacity, running economy, or gastrointestinal distress. To assess an athlete’s tolerance to ultramarathon-specific muscle damage and fatigue, we propose a lab-based protocol comprising downhill running with pre- to post-exercise measures of muscle contractile function following electrical or magnetic stimulation of the quadriceps muscles or their central nerves, muscle damage biomarkers (e.g., creatine kinase, lactate dehydrogenase, and myoglobin), and muscle morphology via imaging techniques. We close by offering training and racing advice on mitigating the deleterious effects of muscle damage. The twofold aims of this paper are (i) to enable athletes and their teams to better prepare for races and (ii) to help medical personnel identify the physiological milieu most likely to afflict the ultrarunner.

表现的生物学决定因素已经被很好地描述为马拉松（42.2 公里）之前的比赛。超级马拉松更复杂。赛事单阶段或多阶段从 50 公里到 5000 公里不等，在各种环境和地形中进行比赛，并迫使运动员应对各种限制表现的问题，例如燃料、补水、胃肠道不适、肌肉损伤和睡眠剥夺。超级马拉松不仅仅是“长距离马拉松”。尽管如此，过去十年的科学发展使我们对支撑表现的心理生理因素有了更完整的了解。在这份当前观点中，我们认为肌肉损伤和相关的疲劳是长距离超级马拉松表现的主要障碍;比有氧能力、跑步经济性或胃肠道不适更能限制性能。为了评估运动员对超级马拉松特异性肌肉损伤和疲劳的耐受性，我们提出了一个基于实验室的方案，包括下坡跑和运动前后肌肉收缩功能的测量，在对股四头肌或其中枢神经进行电或磁刺激后肌肉收缩功能、肌肉损伤生物标志物（例如肌酸激酶、乳酸脱氢酶和肌红蛋白），以及通过成像技术的肌肉形态。最后，我们提供关于减轻肌肉损伤有害影响的训练和比赛建议。本文的双重目标是 （i） 使运动员及其团队能够更好地为比赛做准备，以及 （ii） 帮助医务人员确定最有可能折磨超跑者的生理环境。