Determinants of recovery from a 161-km ultramarathon An American group examined whether there are variables that provide an indication of an accelerated recovery after a 100 mile run. UltraRauer at a 100 miles run had to complete 400 m runs before and after the race, the CK was measured after the race and a questionnaire had to be filled out.It turned out that the height of the CK is the most important variable after the run.
As a consequence can be concluded that the training is the most important aspect of recovery after an ultramarathon. The study can be found under https://pubmed.ncbi.nlm.nih.gov/27167683/