Physiological and training characteristics of recreational marathon runners A British group has studied what variables influence the marathon time in hobbylons. In 97 female and male runners they have examined various physiological variables as well as aspects of the training.It showed the faster runner much more trained as slower runners. The route per training session was longer with the faster than slower runners.
And the running speed correlated with the lactic shaft and the lactate blanking point. The whole work can be found under https://pubmed.ncbi.nlm.nih.gov/29200895/