An increased fluid intake leads to feet swelling in 100-km ultra-marathoners - an observational field study. The phenomenon that long-distance swelling developed has already been investigated and described in seventies through Williams. The researchers have demonstrated an increase in extracellular water at that time, but could not explain the cause.The edema were considered as a possible cause of lung edema in a large amount.
We now have a clear context of 76 ultra skiers to show a clear context between fluid supply and volume of feet: the larger the supply of fluid, the sooner it comes to a swelling of the feet. The study is accessible under https://pubmed.ncbi.nlm.nih.gov/22472466/