Relationship of Anthropometric and Training Characteristics with Race Performance in Endurance and Ultra-Endurance Athletes A large number of peculiarities of body construction such as weight, size, BMI, body fat, skin fold thicknesses, lengths and sizes of extremities show a connection with endurance performance. Also training-specific aspects such as volume and intensity have an impact on competition performance.In addition to these aspects, the personal experience in the sense of previously completed competitions and personal best times is central to performance.
If you compare endurance athletes with ultra-endurance athletes (competition duration over 6 hours), it shows that the Ultras will invest more time in training and cover more kilometers at lower speed than so-called ordinary endurance athletes. The whole compilation can be found under https://pubmed.ncbi.nlm.nih.gov/25834701/