Analysis of Amateur Runners’ Fluid Loss in Relation to their Invested Energy

Abstract

Objective: In this analysis, we look for answers as to how the dehydration level of runners’ changes in relation to their invested energy (measured in watts) in an 11.6km flat area as well as while hiking Hungary’s highest hill, Kékes. Sample and methods: 12 persons were included in the study, all of whom completed the so-called 2018 ‘Kékes peak running race’, a challenge over 11.6km with a 670m rise above sea level. Following this event (two weeks later), they ran another 11.6km on Margaret Island in Budapest where the field is completely flat. Results: In the experiment, during the Kékes peak run the runners delivered 333 watts of power. At the end of this race, a 2% body weight loss was observed which corresponds to approximately 1.5l fluid loss. The 12 runners accomplished the same distance in case of the second run too, but on a completely flat field. On average, the runners delivered 300 watts of power while completing the 11.6km long race. After finishing the flat field run, the participants’ weight decreased by 0.5% on average, which constitutes a less than 0.5l fluid loss. The results clearly show that a 10% elevation in power results in almost 4 times more loss of fluids. These results were also supported by the Urine Specific Gravity (USG) test as the USG growth was significant (p < 0.05) during the Kékes peak run.