Beat the Heat when Rucking & Tabbing. Nutrition & Hydration for Exertional Heat Stroke Prevention
Updated: 1 day ago
Exertional heat stroke (EHS) is a serious, sometimes fatal risk during weighted rucking in heat and humidity. It can't be nutritionally 'cured' - pacing, acclimatisation and recognising warning signs matter most. If you want to beat the heat and optimise performance, the right fuelling and hydration habits meaningfully lower your risk. In this article we summarise the findings from the 2022 study by Singapore's Lee et al.
As ever, please talk to your doctor, or medical practitioner most familiar with your medical history before implementing any changes in diet, exercise or lifestyle; especially if you are under treatment. Links to relevant studies and resources at Bottom of Page.
DO THIS
Hydrate early: Begin every session properly hydrated. The day before matters more than the 10 minutes beforehand.
Fuel long sessions: For sessions over 90 minutes, take 30 to 90g of carbs per hour (drink mix, gels, chews). Spread it out, large single doses can cause GI upset.
Drink to a plan: Drink to your sweat losses, not as much as possible. Over-drinking risks hyponatraemia, its own medical emergency.
Skip it if unwell: Recently had a cold, fever, or GI bug? Sit this session out or scale back: illness raises EHS risk substantially.
BE CAUTIOUS WITH
Caffeine / pre-workout: Blunts your perception of fatigue and effort, exactly the warning signs you need to feel to slow down or stop.
Beetroot / nitrate supplements: Popular for performance, but may raise core temperature during heat exercise.
Alcohol: Avoid alcohol the night before or day of a big ruck, it worsens gut permeability and dehydration.
Unregulated stimulants: Ephedrine and unregulated stimulant products have been directly linked to fatal EHS cases. Don't use them.
STOP IMMEDIATELY IF YOU EXPERIENCE
Confusion or disorientation
Stopped sweating despite heat
Dizziness or nausea
Loss of coordination
Combativeness or unusual behaviour
If you see this in yourself or others: stop exertion, and cool down (shade, remove pack/layers, water on skin) right away. Don't push through. In Singapore? Call SCDF 995.
BEFORE YOU START YOUR SESSION
Find a training partner.
Understand your hydration needs and plan before the session starts. How much fluid do you need to bring, where can you resupply enroute?
Bring carb-drink/gels for sessions over 90 minutes.
If you or your training partners have been unwell in the last few days, do not proceed - sit the session out. Don’t chase training or event goals at the expense of your health.
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Related Studies
Lee JKW, Tan B, Ogden HB, Chapman S, Sawka MN. Exertional heat stroke: nutritional considerations. Exp Physiol. 2022 Oct;107(10):1122-1135. doi: 10.1113/EP090149. Epub 2022 May 19. PMID: 35521757; PMCID: PMC9790308.
Other
Epstein Y, Charkoudian N, DeGroot DW, House C, Ketko I, Law LYL, Malgoyre A, O'Connor F, Tayari O, Lee JKW. Exertional heat illness: international military-oriented lessons learned and best practices for prevention and management. Front Physiol. 2025 Mar 5;16:1456984. doi: 10.3389/fphys.2025.1456984. PMID: 40110182; PMCID: PMC11920190.
López-Torres, O.; Rodríguez-Longobardo, C.; Escribano-Tabernero, R.; Fernández-Elías, V.E. Hydration, Hyperthermia, Glycogen, and Recovery: Crucial Factors in Exercise Performance— A Systematic Review and Meta-Analysis. Nutrients 2023, 15, 4442. https://doi.org/10.3390/nu15204442
Adrogué HJ, Tucker BM, Madias NE. Diagnosis and Management of Hyponatremia: A Review. JAMA. 2022 Jul 19;328(3):280-291. doi: 10.1001/jama.2022.11176. PMID: 35852524.
Bhasin-Chhabra B, Veitla V, Weinberg S, Koratala A. Demystifying hyponatremia: A clinical guide to evaluation and management. Nutr Clin Pract. 2022 Oct;37(5):1023-1032. doi: 10.1002/ncp.10907. Epub 2022 Aug 29. PMID: 36036229.
Smith JW, Bello ML, Price FG. A Case-Series Observation of Sweat Rate Variability in Endurance-Trained Athletes. Nutrients. 2021 May 26;13(6):1807. doi: 10.3390/nu13061807. PMID: 34073387; PMCID: PMC8226773.
Surapongchai J, Saengsirisuwan V, Rollo I, Randell RK, Nithitsuttibuta K, Sainiyom P, Leow CHW, Lee JKW. Hydration Status, Fluid Intake, Sweat Rate, and Sweat Sodium Concentration in Recreational Tropical Native Runners. Nutrients. 2021 Apr 20;13(4):1374. doi: 10.3390/nu13041374. PMID: 33923890; PMCID: PMC8072971.
Wardenaar, F.C.; Thompsett, D.; Vento, K.A.; Pesek, K.; Bacalzo, D. Athletes’ Self-Assessment of Urine Color Using Two Color Charts to Determine Urine Concentration. Int. J. Environ. Res. Public Health 2021, 18, 4126. https://doi.org/10.3390/ijerph18084126
Ayotte, D., Corcoran, M.P. Individualized hydration plans improve performance outcomes for collegiate athletes engaging in in-season training. J Int Soc Sports Nutr 15, 27 (2018). https://doi.org/10.1186/s12970-018-0230-2
Casa DJ, DeMartini JK, Bergeron MF, Csillan D, Eichner ER, Lopez RM, Ferrara MS, Miller KC, O'Connor F, Sawka MN, Yeargin SW. National Athletic Trainers' Association Position Statement: Exertional Heat Illnesses. J Athl Train. 2015 Sep;50(9):986-1000. doi: 10.4085/1062-6050-50.9.07. Erratum in: J Athl Train. 2017 Apr;52(4):401. PMID: 26381473; PMCID: PMC4639891.
Thomas DT, Erdman KA, Burke LM. American College of Sports Medicine Joint Position Statement. Nutrition and Athletic Performance. Med Sci Sports Exerc. 2016 Mar;48(3):543-68. doi: 10.1249/MSS.0000000000000852. Erratum in: Med Sci Sports Exerc. 2017 Jan;49(1):222. doi: 10.1249/MSS.0000000000001162. PMID: 26891166.
Adan A. Cognitive performance and dehydration. J Am Coll Nutr. 2012 Apr;31(2):71-8. doi: 10.1080/07315724.2012.10720011. PMID: 22855911.
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