Clinical and Laboratory Responses of Cross-Country Skiing for a 24-H World Record: Case Report A Finnish group has studied what happens in a ski runner who is traveling for 24 hours at temperatures from -24 ° C to -5 ° C. The athlete reached 406 km and after the burden there was a significant increase in myoglobin, CK, probnp but no increase in troponin T or Tropinin I. After the load, the size of the left ventricle decreased by around 5%.It also came to an increase of parameters of liver and renal function as well as CRP and leukocytes.
Further, a hyponatremia, hypophyosphatemia and hypocalcaemia. The whole case report can be found under https://pubmed.ncbi.nlm.nih.gov/26664265/