CiteKey:: cheuvrontFluidReplacementPerformance2007
Bibliography:: Cheuvront, Samuel N, Scott J Montain, and Michael N Sawka. “Fluid Replacement and Performance During the Marathon:” Sports Medicine 37, no. 4 (2007): 353–57. https://doi.org/10.2165/00007256-200737040-00020.
TABLE Modified, FirstImported as "First Imported"FROM ""WHERE related != nullAND contains(related, "cheuvrontFluidReplacementPerformance2007")
Overall Notes
FirstImported:: 2025/06/12 11:04
Abstract
The primary purpose of this review is to relate a universal strategy for replacing fluids to optimise marathon performance. A secondary purpose is to examine common ‘matters of debate’ that may modify fluid needs to include the importance of realistic convective air flow, metabolic water production and waters of association with glycogen. The metabolic demands of marathon running can result in substantial sweat losses and levels of dehydration consistent with compromised endurance performance. Recommendations are provided to individualise fluid intakes with the goal of preventing excessive dehydration (>2% body mass) as well as weight gain. The minor importance of ‘matters of debate’ to fluid replacement is also discussed
Hypothesis
There was not one presented.
Methodology
They did a heat balance based on thermal energy generated with the expulsion from evaporative heat transfer. They used skin temperatures and heat transfer coefficients for running derived elsewhere. See page 355.
Results
Pace and bodyweight impact hydration requirements substantially. Without drinking anything, BW losses were approximately 5%. Drinking 1 L/h generally created BW gain, which is also harmful for performance.
Significance
As a 70 kg person, drinking 0.5 L/h at 4 hour pace for a marathon in summer conditions (28C 30% RH) would keep me above the 2% BW loss threshold until right before the end of the race (mile 25.8).
To experiment, I would like to perform my own measurements on sweat losses and see if it compares to their assumed value for my weight (0.855 L/h)
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Imported: 06/12/25 23:20 pm
This is the ultimate threshold i should try and avoid
I am approximately 70 kg, meaning 0.5 L/h would keep me above the threshold right up until the very end (41.5). 1 L/k would be very excessive.
Warm means 28C 30% RH, cool means 14C 70 RH, selected as averages of common marathons
Interesting point I didn’t even think to worry about. Fortunate that metabolic production perfectly cancels out respiratory losses.
This would be an interesting test to run on myself. Should not be terribly hard.
