Competing in hot and humid conditions places additional stress on the body. Heart rate climbs faster than expected, the same pace begins to feel harder, and fatigue arrives earlier than it would in cooler conditions.

Heat does not just make competition uncomfortable. It changes how your body cools itself, holds onto fluid and salt, handles fueling, and recovers afterward. For professional and elite athletes, these are not minor adjustments. Therefore, they are the difference between performing at your level in the heat and watching your performance decline before the second half even begins.

Why generic advice falls short

Most athletes know hydration matters more in the heat. However, far fewer have a sport-specific, individualized strategy that addresses fluid balance, sodium replacement, fueling, gut tolerance, and recovery as one connected system. Generic advice was not built for athletes performing at the top of their sport in conditions that exceed 90°F (32°C) and 70% humidity.

This article covers what happens to your body in the heat, what the evidence shows about how to manage it, and how to build a practical strategy that holds up under real competition demands.

Key Points

• Heat increases cardiovascular strain, accelerates fluid and sodium losses, and reduces gut tolerance — all of which compound to impair performance
• Sweat rates in the heat range from 0.5 to over 3 L/hour and vary substantially between athletes, making individual sweat testing essential
• Performance typically declines once dehydration exceeds around 2% of body mass, though the threshold varies by athlete, sport, and conditions
• Sodium losses become significant in the heat, particularly for heavy and salty sweaters, and replacement supports blood volume, the drive to drink, and fluid retention
• Carbohydrate intake during competition often needs to be lowered in the heat because gut tolerance drops — smaller, more frequent intake is generally better tolerated
• Heat acclimatization over 10 to 14 days produces meaningful adaptations and should be planned ahead of competition in hot conditions
• Sauna acclimation provides a practical alternative when natural heat exposure is not available
• Athletes coming from cooler climates to compete in hot conditions face an even larger performance cost without acclimatization
• Pre-cooling strategies such as ice slurry can lower core temperature before competition and improve performance in the heat
• Menthol works through perception rather than cooling and has growing evidence in endurance contexts
• Recovery in the heat requires more aggressive fluid and sodium replacement than in cool conditions, alongside standard carbohydrate and protein protocols

How Heat Affects the Body

Cardiovascular strain rises

When you compete in the heat, your body prioritizes cooling. Blood flow shifts toward the skin to release heat, which leaves less blood available for working muscles. As a result, heart rate climbs at any given output, perceived effort rises, and sustaining intensity becomes harder.

The math behind this is unforgiving. Your body operates at roughly 20% efficiency — meaning that for every 100 watts of work you produce, your body also produces 400 watts of heat. In a cool environment, this heat load is manageable. However, in a hot, humid environment, your body has fewer tools to release it, so core temperature climbs faster and cardiovascular strain compounds.

Athletes who normally train in cooler climates feel this faster. Because their bodies are less adapted to managing large heat loads, they overheat sooner, run higher heart rates at the same workload, and reach fatigue earlier than athletes who train regularly in hot conditions.

Cardiovascular drift

A second effect develops across the duration of competition. As exercise continues in the heat, heart rate gradually rises while stroke volume — the amount of blood pumped per beat — decreases. This is called cardiovascular drift, and it affects athletes even when they are well-hydrated.

Two factors drive it. First, blood flow to the skin keeps rising as core temperature climbs. Second, progressive fluid loss through sweat reduces blood volume. As a result, the heart has to beat faster and faster to deliver the same amount of blood to working muscles. Consequently, athletes commonly experience a heart rate that is 10 to 20 beats per minute higher than normal for the same workload across a hot session — even before any meaningful dehydration develops.

Cardiovascular drift is one of the main reasons sustaining intensity in the heat becomes progressively harder, and one of the reasons performance decline shows up later in events rather than from the start.

Sweating accelerates

Sweat losses rise rapidly in the heat. Most athletes lose 1 to 2 L per hour during moderate to hard sessions in cool conditions. However, in the heat, that range can shift to 2 to 3 L per hour or more in elite athletes — and individual values can be higher still.

These losses include both water and sodium. If you do not replace them adequately, blood volume drops, your ability to cool yourself becomes less effective, and the cardiovascular strain you were already managing becomes worse.

Athletes not adapted to heat tend to start with lower sweat rates and higher sweat sodium concentrations than acclimatized athletes. As a result, they retain less heat-clearing capacity early and lose proportionally more sodium per liter of sweat — both of which compound the cardiovascular strain described above.

Gut function declines

One of the most overlooked consequences of heat is reduced gut tolerance. As blood flow shifts toward the skin, less blood is available for the digestive system. As a result, large volumes of fluid or food during competition often become harder to tolerate. Athletes who train without issue at 90 g/h of carbohydrate in cool conditions may struggle at 60 g/h in the heat.

This has direct implications for fueling strategy. Specifically, the carbohydrate target you have been training with is not automatically the right target on a hot competition day.

Glycogen depletion accelerates

Heat stress also shifts the body toward greater carbohydrate use at any given intensity. As a result, athletes burn through muscle glycogen faster in hot conditions than in cool conditions at the same workload. This raises the total carbohydrate demand of a session — even though, as covered above, the gut may tolerate less carbohydrate at the same time.

The combined effect is that fueling becomes both more important and harder to execute. Therefore, smaller, more frequent intakes are the practical answer to this constraint.

Key Takeaway

✔ Heat increases cardiovascular strain, drives cardiovascular drift across competition, accelerates fluid and sodium losses, reduces gut tolerance, and speeds glycogen depletion — and these effects compound. Therefore, addressing one without the others leaves performance on the table.

Why Hydration Matters More in the Heat

Sweat rates are highly individual

Sweat rate varies enormously between athletes. In hot conditions, some athletes lose less than 1 L per hour while others exceed 3 L per hour in the same session. Body size, training status, heat acclimatization, training intensity, and clothing or equipment all influence the rate at which you sweat.

The implication is that generic hydration advice does not work in the heat. For example, an athlete with a 1 L/hour sweat rate and an athlete with a 3 L/hour sweat rate need fundamentally different protocols. Therefore, individual sweat testing — measuring body mass change before and after a session, accounting for fluid intake and urine output — is the foundation of any serious heat hydration strategy.

How much fluid loss matters

The goal during competition is not to replace every milliliter of fluid lost. Instead, it is to limit the deficit to a level that does not meaningfully impair performance.

A commonly cited threshold is that body mass losses exceeding around 2% begin to impair endurance performance and decision-making. The exact threshold varies by athlete, sport, environment, and duration of effort. However, what is consistent is that larger deficits carry larger consequences — a 1% loss may produce mild thirst and minimal performance impact, while a 4 to 5% loss produces severe performance decline and elevates heat illness risk.

For team sports with limited drinking opportunities, the practical implication is that you cannot rely on thirst alone. As a result, athletes who drink to thirst in hot conditions consistently under-replace fluid losses.

Key Takeaway

✔ Sweat rates in the heat vary from under 1 L/hour to over 3 L/hour between athletes. Therefore, individual sweat testing is the foundation of any serious hydration strategy, and the goal is to limit body mass loss to a level that does not meaningfully impair performance.

Sodium and Electrolyte Replacement

Why sodium becomes critical

Sweat is not just water. It contains sodium at concentrations that vary widely between athletes — from roughly 200 mg/L in low sweat sodium athletes to over 1,500 mg/L in high sweat sodium athletes (often identifiable by visible salt residue on skin or kit after training).

When sweat volumes climb in the heat, sodium losses scale with them. For example, a heavy, salty sweater training for two hours in hot conditions can lose 4 to 6 grams of sodium in a single session. As a result, replacing only fluid without addressing sodium leaves you exposed to performance decline, muscle cramping, and in extreme cases hyponatremia (dangerously low blood sodium) from over-drinking plain water.

What sodium does

Sodium plays a central role in performance and hydration:

• Fluid retention — sodium drives the body’s ability to hold onto the fluid you drink
• Blood volume — adequate sodium supports blood volume during prolonged efforts
• The drive to drink — sodium triggers the urge to drink, which is critical when you need to take in fluid actively
• Muscle function — sodium supports the electrical signaling that drives muscle contraction

For sessions exceeding 60 to 90 minutes in the heat, sodium-containing fluids are not optional. Specifically, they are a core part of the hydration strategy. Therefore, sports drinks, oral rehydration solutions, electrolyte tablets in water, and salty foods alongside fluid all serve this purpose.

Individual sweat sodium concentration is best measured through sweat testing — covered in detail in the hydration foundation article.

Key Takeaway

✔ Sodium losses scale with sweat volume and are highly individual. Therefore, for heavy or salty sweaters competing in the heat, deliberate sodium replacement is essential — not a backup plan.

Carbohydrate Intake in the Heat

Why fueling needs adjustment

Heat does not reduce your carbohydrate requirement. If anything, performance in the heat shifts the body toward greater carbohydrate use at any given intensity, accelerating glycogen (your body’s stored carbohydrate) depletion. As a result, the total carbohydrate demand of a hard session in the heat is often higher than the same session in cool conditions.

However, the gut does not always agree with what the muscles need. Reduced blood flow to the digestive system in the heat means that the carbohydrate intake you tolerate in training may not be tolerable in competition. Consequently, this is one of the most common reasons athletes underperform in the heat — they push the same fueling protocol they use in cool conditions and end up with gut problems.

Practical fueling targets

The evidence supports the following approach for competition in the heat:

• 60 to 90 minutes — 30 to 60 g of carbohydrate per hour, ideally from a glucose-fructose combination
• 90 minutes to 2 hours — 45 to 75 g/hour, with attention to gut tolerance
• More than 2 hours in extreme heat — 30 to 60 g/hour is often better tolerated than higher intakes, even though longer sessions in cool conditions might support 60 to 90 g/hour

The form matters too. In the heat, carbohydrate-electrolyte drinks deliver fuel and fluid at the same time and are often better tolerated than gels or solid foods. As a result, smaller, more frequent intakes generally hold up better than large amounts taken in one go.

This is also where the principle of training the gut becomes critical. Gut tolerance is trainable. Therefore, athletes who plan to compete in the heat should rehearse their fueling protocol in hot training conditions — not test it for the first time on competition day.

Key Takeaway

✔ Carbohydrate needs do not drop in the heat, but gut tolerance does. Therefore, smaller, more frequent intakes — typically 30 to 60 g/hour for sessions over 2 hours in extreme heat — are often more practical than the higher targets that work in cool conditions.

Heat Acclimatization: The Strongest Intervention Available

What acclimatization actually changes

No supplement, no cooling strategy, and no fueling protocol matches the effect of proper heat acclimatization. When athletes go through 7 to 14 days of repeated, structured heat exposure, the body responds with measurable changes that affect how it handles heat at every level.

Cardiovascular and core temperature changes

• Blood volume expansion — typically a 5 to 15% increase, which directly reduces cardiovascular strain
• Lower heart rate at any given workload — typically 10 to 20 bpm lower at the same intensity after full acclimatization
• Slower rise in core temperature — for the same effort, body temperature rises less and more slowly
• Lower perceived effort — the same workload feels easier

Sweat and sodium changes

• Earlier sweating — sweating starts at a lower core temperature, releasing heat sooner
• Higher sweat rate — total sweat output increases, supporting better cooling
• Lower sweat sodium concentration — the body becomes better at holding onto sodium through hormone changes involving aldosterone

Why the changes matter together

These changes build on each other. When an athlete arrives in hot conditions fully acclimatized, they have more blood available for working muscles, cool more efficiently, hold onto more sodium, run a lower heart rate, and feel less of the strain — all from the same physical effort. As a result, the combined effect on performance is far larger than any single change on its own.

How long it takes

The bulk of changes develop within the first 7 to 10 days. Specifically, heart rate and core temperature responses adapt fastest, followed by sweat rate, with sweat sodium conservation taking the longest. Therefore, full adaptation needs around 14 days of regular exposure.

For athletes traveling to hot competition environments — European footballers playing summer pre-season tours, northern-climate tennis players at the Australian Open, NFL teams traveling to hot stadiums, motorsport drivers competing in tropical conditions — building this window into the schedule is one of the highest-impact decisions available.

Practical use

Heat acclimatization requires repeated exposure to hot conditions. In practice, this typically combines:

• Daily training sessions of 60 to 90 minutes in the heat at moderate intensity
• Gradual progression of exposure duration and intensity
• Maintained training quality where possible — exposure alone is not enough; the body needs to be working
• Adequate fluid and sodium intake throughout the acclimatization period
• Where natural heat exposure is not available, heat chambers, saunas, or hot-water immersion can produce partial adaptations

Sauna acclimation when natural heat is not available

For athletes living and training in cooler climates, traveling to a hot location for 2 to 3 weeks of natural acclimatization is not always possible. Sauna-based heat acclimation is a well-supported alternative. Specifically, regular post-training sauna sessions can produce many of the same adaptations — blood volume expansion, lower heart rate at a given workload, improved heat tolerance — without requiring relocation.

A practical sauna acclimation protocol looks like this:

• Timing — sauna sessions immediately after training, while core temperature is already raised, produces the strongest adaptation
• Temperature — 80 to 90°C (175 to 195°F) in a traditional dry sauna
• Duration — start with 15 to 20 minutes per session and progress to 30 minutes over the first week
• Frequency — 4 to 5 sessions per week for 2 to 3 weeks
• Fluid and sodium — drink fluids containing sodium during and after each session to replace what is lost
• Caution — sauna sessions should be supervised in the early stages, and athletes with cardiovascular conditions should clear sauna acclimation with a physician first

Hot-water immersion (40°C / 104°F bath for 30 to 40 minutes post-training) can produce similar effects when sauna access is not available. As a result, athletes in cooler climates have viable options for building heat tolerance before traveling to hot competitions.

Maintenance after acclimatization

Once an athlete has acclimatized, the changes need ongoing exposure to hold. After 1 to 2 weeks without heat exposure, the changes begin to fade. As a result, athletes who acclimatize and then return to cool conditions before competition may lose part of the benefit. Therefore, the practical answer is to keep heat exposure going right up to competition where possible — through training in hot conditions, sauna sessions, or arriving at the competition venue with enough time for re-exposure.

Key Takeaway

✔ Heat acclimatization is the single most powerful tool available for performance in hot conditions. Therefore, when athletes go through 7 to 14 days of structured exposure — whether through natural heat or post-training sauna protocols — the body produces changes no supplement or cooling strategy can match.

Pre-Competition Preparation

The 24 to 48 hours before

Heat preparation does not start at warm-up. Hydration status in the days leading into competition directly affects how well your body cools itself when it matters. As a result, daily fluid and sodium intake should be consistent and adequate, and any large fluid debts from training should be addressed before competition.

Carbohydrate availability also matters. Specifically, glycogen stores should be optimized through normal high-carbohydrate intake in the 24 to 48 hours pre-competition, particularly for events lasting longer than 90 minutes.

The hours before competition

The pre-competition meal — typically 3 to 4 hours before start time — should be carbohydrate-rich, easy to digest, and low in fat and fiber. Fat and fiber slow how fast food leaves your stomach, which is the last thing you want before a hot competition where gut tolerance is already going to be reduced.

A smaller carbohydrate-rich snack 60 to 90 minutes before start time tops up your energy without overloading the gut. Furthermore, final fluids in the 30 to 60 minutes before start time bring you to optimal hydration without producing pre-competition urinary urgency.

Pre-cooling

For competition in extreme heat, pre-cooling has meaningful evidence behind it. The mechanism is straightforward: lowering core temperature before competition creates a larger buffer before the body reaches the temperatures that limit performance. As a result, athletes can train or compete harder for longer before heat strain becomes the limiting factor.

The main pre-cooling tools are:

• Ice slurry — drinking a frozen slush of ice and a carbohydrate-electrolyte solution in the 30 to 45 minutes before competition
• Cold water immersion — sitting in cold water (around 15°C / 59°F) for 10 to 20 minutes
• Ice towels and cooling vests — applied during warm-up and during breaks where possible
• Cold drinks — useful as a complement to ice slurry but less effective on their own

These can be combined depending on what is practical in your sport. For example, ice slurry plus an ice towel before warm-up plus a cooling vest during pre-match preparation is a stacked strategy that has been used by elite teams at major tournaments in hot conditions.

Ice slurry in detail

Ice slurry is the most practical and well-supported pre-cooling tool for most sports. Specifically, the slush state means the body uses energy to melt the ice in your gut, creating a heat sink effect that lowers core temperature more effectively than cold drinks alone.

A practical ice slurry protocol:

• Dose — approximately 7.5 g/kg of body weight (so a 75 kg athlete consumes around 560 g, or roughly half a liter)
• Timing — consumed over the 30 to 45 minutes before start time, in 4 to 5 smaller servings rather than all at once
• Composition — water with carbohydrate (6 to 8% solution) and sodium provides fuel and electrolytes alongside the cooling effect
• Gut tolerance — should be rehearsed in training rather than tested on competition day, particularly in athletes who are sensitive to cold liquids
• Combination with menthol — adding menthol to an ice slurry can improve thermal comfort beyond the cooling effect alone

Ice slurry is most effective for endurance and team sports competing in hot conditions. As a result, it has become a standard pre-competition tool for elite marathoners, triathletes, footballers in summer competition, tennis players at hot-weather Grand Slams, and rugby players in summer touring fixtures.

Menthol

Menthol is one of the more interesting heat-specific tools and works through a very different mechanism than ice slurry or cold water immersion. Specifically, menthol does not lower core temperature. Instead, it triggers cold receptors in the mouth and throat that signal coolness to the brain, improving thermal comfort and the perceived effort of competition in the heat.

In practice, menthol can be used as:

• A mouth rinse before or during competition
• Added to cold drinks or ice slurry
• In endurance contexts where thermal sensation is a limiting factor

The evidence base has grown over the past decade, with meaningful effects on running performance, perceived heat strain, and willingness to sustain intensity in hot conditions. As a result, menthol has become a low-cost, low-risk addition to the heat strategy of elite endurance athletes — particularly in events where every margin matters.

Pre-competition timing summary

Key Takeaway

✔ Heat preparation begins 24 to 48 hours before competition, not at warm-up. Therefore, hydration consistency, optimized glycogen stores, easily digestible pre-competition meals, ice slurry pre-cooling, and menthol all contribute to performance in extreme conditions.

Other Heat-Specific Strategies

Caffeine

Some athletes and coaches worry that caffeine raises dehydration risk in the heat and therefore should be avoided. However, current evidence does not support this concern. Specifically, the diuretic effect of caffeine is small and largely offset in athletes who drink it regularly, and the performance benefits of caffeine — improved endurance, reduced perceived effort, sharper mental performance — apply in hot conditions just as they do in cool conditions.

Standard caffeine protocols (3 to 6 mg/kg of body weight, 60 minutes before competition) remain appropriate in the heat. Therefore, heat is not a reason to eliminate caffeine from a competition strategy. The caffeine article in this catalog covers protocols and dosing in more detail.

Glycerol hyperhydration

Glycerol hyperhydration involves drinking glycerol alongside large volumes of fluid before competition to expand total body water and blood volume. The mechanism is well-known, and some evidence supports performance benefits in long, hot events.

However, this is a situational strategy rather than a routine recommendation:

• Effects on performance are inconsistent across studies
• Gut tolerance is variable — some athletes experience bloating, nausea, or headaches
• Effective dosing requires careful protocol design
• Often unnecessary if hydration is already well-managed
• Although WADA removed glycerol from the banned list in 2018, athletes under anti-doping control should check current status before use

Therefore, glycerol may have a role for ultra-endurance athletes, marathoners, and triathletes competing in extreme heat where access to fluid during competition is limited. However, for most professional athletes in most contexts, optimizing routine hydration and acclimatization produces better returns.

What does not work for heat performance

Several commonly marketed approaches lack supporting evidence:

• Magnesium supplements for cramp prevention — covered in detail in the muscle cramps article; not a heat-specific solution
• Potassium supplements (unless deficiency exists) — sodium losses dominate during heat exposure
• BCAAs and glutamine — no specific heat performance evidence
• Most commercial “electrolyte” blends without adequate sodium — many contain too little sodium to matter for athletes with high sweat losses
• Cooling vests during competition in most sports — useful for pre-cooling in some contexts but rarely practical mid-competition

Key Takeaway

✔ Caffeine remains appropriate in the heat. Furthermore, glycerol hyperhydration is a niche tool for specific endurance contexts. However, many other heat-marketed supplements lack supporting evidence and add cost without performance benefit.

Recovery After Competing in the Heat

Why recovery demands rise in the heat

Recovery after competition in hot conditions is more demanding than after the same competition in cool conditions. Specifically, sweat losses are larger, sodium losses are larger, glycogen depletion is greater, core temperature stays raised for longer, and ongoing sweating after the final whistle continues to produce fluid loss.

The standard recovery framework — rehydration, sodium, carbohydrate, protein — still applies. However, the difference in the heat is that the volumes of fluid and sodium are meaningfully higher.

Practical recovery targets

• Fluid replacement — aim for 125 to 150% of estimated losses over the 4 to 6 hours following competition. Drinking the exact amount lost is not enough because ongoing urine production means some of what you drink will be lost before rehydration is complete
• Sodium — include sodium with all recovery fluid. Plain water alone does not stay in your system after heavy sodium losses. Therefore, sports drinks, oral rehydration solutions, or fluid combined with salty foods are all practical options
• Carbohydrate — when the next session or competition is within 24 hours, prioritize rapid glycogen replenishment with 1.0 to 1.2 g/kg/hour in the first 4 hours post-competition
• Protein — 0.3 to 0.4 g/kg of high-quality protein within the first hour post-competition supports muscle repair and adaptation. This target does not change in the heat
• Cooling — active cooling strategies (cold water immersion, ice towels, fans) can speed the return of core temperature to normal and may reduce post-competition fatigue

Key Takeaway

✔ Recovery in the heat requires more aggressive fluid and sodium replacement than recovery in cool conditions. Therefore, standard carbohydrate and protein protocols still apply, but the volumes of fluid and sodium needed alongside them are meaningfully higher.

The Evidence-Based Hierarchy for Performance in the Heat

Not every heat strategy carries the same weight of evidence or the same practical impact. As a result, the athletes who perform best in hot conditions tend to focus on the highest-impact tools first.

Highest impact

• Heat acclimatization (7 to 14 days of structured exposure — natural heat or post-training sauna protocols)
• Individualized hydration plan (built from sweat testing)
• Sodium replacement matched to individual sweat sodium concentration
• Carbohydrate fueling matched to duration, intensity, and gut tolerance
• Pre-cooling (ice slurry, cold water immersion, ice towels)

Moderate impact

• Caffeine (standard protocols, not contraindicated in the heat)
• Menthol (mouth rinse, ice slurry with menthol — improves thermal comfort and perceived effort)
• Active cooling during competition where the sport allows

Situational or niche

• Glycerol hyperhydration for selected ultra-endurance contexts

Not supported for heat performance

• Magnesium supplements for cramp prevention (without deficiency)
• Potassium supplements (without deficiency)
• BCAAs, glutamine, and other amino acid blends
• Most commercial “electrolyte” products without adequate sodium

Key Takeaway

✔ The most effective heat strategy is acclimatization plus individualized hydration plus sodium plus carbohydrate plus pre-cooling. Specifically, this combination consistently outperforms any individual supplement or strategy, and most heat-marketed products do not survive the evidence test.

Common Mistakes Athletes Make in the Heat

Several recurring errors undermine performance in hot conditions, even among experienced professional athletes:

Generic hydration plans

When practitioners apply the same protocol across athletes, conditions, and sessions, they ignore the substantial individual variability in sweat rate and sodium losses. As a result, the same plan will overhydrate one athlete and underhydrate another.

Drinking to thirst alone

Thirst is a late signal in cool conditions and an even later signal in the heat. As a result, athletes who rely on thirst consistently arrive at the second half already meaningfully dehydrated.

Pushing the same carbohydrate intake from cool conditions

Because gut tolerance drops in the heat, the protocol that works at 65°F may produce gut problems at 95°F. Therefore, adjustment is required.

Testing strategies in competition

Pre-cooling, fueling protocols, and hydration plans should be rehearsed in hot training conditions. Specifically, competition day is not the place to test a new approach.

Underestimating sodium needs

Heavy and salty sweaters often need much more sodium than they realize. For example, symptoms like persistent muscle cramping and salt residue on kit are warning signs.

Skipping heat acclimatization

When athletes travel from cooler climates to hot competition environments and skip dedicated acclimatization — including sauna-based alternatives when natural heat exposure is not available — they arrive at a meaningful and entirely avoidable disadvantage. As a result, no supplement, fueling protocol, or pre-cooling strategy makes up for the absence of acclimatization.

Inadequate post-competition recovery

When athletes replace only the fluid lost — without addressing sodium, ongoing losses, and the longer recovery window — they leave themselves underprepared for the next session.

Key Takeaway

✔ The most common heat-related performance errors are generic plans, drinking to thirst, mismatched fueling, untested protocols, and skipping acclimatization. However, each is correctable with deliberate preparation and individualization.

Practical Application: Building Your Heat Strategy

A complete heat strategy spans four phases — preparation, pre-competition, in-competition, and recovery — and each phase builds on the others.

Key Takeaway

✔ A complete heat strategy requires preparation, pre-competition setup, in-competition execution, and aggressive recovery — applied consistently and individualized to your sweat rate, sodium losses, and competition demands.

Conclusion

Heat performance is preparation, not tolerance

Performance in the heat is one of the most evidence-based and immediately actionable areas of sports nutrition. The physiology is well understood, the strategies are well supported, and the difference between athletes who perform in hot conditions and athletes who decline is rarely about innate tolerance. Instead, it is about preparation, individualization, and execution.

The effects compound

Heat increases cardiovascular strain, drives cardiovascular drift across competition, accelerates fluid and sodium losses, and disrupts gut tolerance. Each of these effects can be managed — but only with a strategy that addresses all of them at the same time. Specifically, hydration without fueling falls short. Fueling without sodium falls short. Therefore, none of it works without acclimatization and rehearsal.

Heat is a recurring competitive variable

For professional and elite athletes, heat is not an occasional inconvenience. Instead, it is a recurring competitive variable that affects preseason camps, summer tournaments, international travel, and championship competitions. Therefore, treating heat preparation as a core part of your performance plan — not an afterthought — is what separates athletes who hold up in extreme conditions from those who fade.

Key Takeaway

✔ Performance in the heat depends on heat acclimatization, individualized hydration, deliberate sodium replacement, structured fueling, pre-cooling, and aggressive recovery. The cost of competing in the heat cannot be eliminated, but it can be substantially reduced — and at the elite level, that reduction is what wins competitions.

References

1. Racinais S, Hosokawa Y, Akama T, et al. (2023). IOC consensus statement on recommendations and regulations for sport events in the heat. British Journal of Sports Medicine, 57(1), 8–25.
2. Périard JD, Eijsvogels TMH, Daanen HAM. (2021). Exercise under heat stress: thermoregulation, hydration, performance implications, and mitigation strategies. Physiological Reviews, 101(4), 1873–1979.
3. Sawka MN, Burke LM, Eichner ER, et al. (2007). American College of Sports Medicine position stand. Exercise and fluid replacement. Medicine and Science in Sports and Exercise, 39(2), 377–390.
4. McCubbin AJ, Allanson BA, Caldwell Odgers JN, et al. (2020). Sports Dietitians Australia position statement: Nutrition for exercise in hot environments. International Journal of Sport Nutrition and Exercise Metabolism, 30(1), 83–98.
5. Sawka MN, Cheuvront SN, Kenefick RW. (2015). Hypohydration and human performance: impact of environment and physiological mechanisms. Sports Medicine, 45(Suppl 1), S51–S60.
6. Périard JD, Racinais S, Sawka MN. (2015). Adaptations and mechanisms of human heat acclimation: applications for competitive athletes and sports. Scandinavian Journal of Medicine and Science in Sports, 25(Suppl 1), 20–38.
7. Tyler CJ, Reeve T, Hodges GJ, Cheung SS. (2016). The effects of heat adaptation on physiology, perception, and exercise performance in the heat: a meta-analysis. Sports Medicine, 46(11), 1699–1724.
8. Wingo JE. (2015). Cardiovascular regulation during heat stress: cardiovascular drift, hyperthermia, and the role of skin blood flow. American Journal of Physiology — Regulatory, Integrative and Comparative Physiology, 309(11), R1300–R1308.
9. Baker LB. (2017). Sweating rate and sweat sodium concentration in athletes: a review of methodology and intra/interindividual variability. Sports Medicine, 47(Suppl 1), 111–128.
10. Jentjens RLPG, Underwood K, Achten J, et al. (2006). Exogenous carbohydrate oxidation rates are elevated after combined ingestion of glucose and fructose during exercise in the heat. Journal of Applied Physiology, 100(3), 807–816.
11. Jeukendrup AE. (2017). Training the gut for athletes. Sports Medicine, 47(Suppl 1), 101–110.
12. Mougin L, Horner M, Edwards D, et al. (2025). Heat stress impairs exogenous carbohydrate oxidation during prolonged running when maintaining euhydration. Journal of Applied Physiology, 139(6), 1436–1446.
13. Ross M, Abbiss C, Laursen P, Martin D, Burke L. (2013). Precooling methods and their effects on athletic performance: a systematic review and practical applications. Sports Medicine, 43(3), 207–225.
14. Stevens CJ, Thoseby B, Sculley DV, Callister R, Taylor L, Dascombe BJ. (2016). Running performance and thermal sensation in the heat are improved with menthol mouth rinse but not ice slurry ingestion. Scandinavian Journal of Medicine and Science in Sports, 26(10), 1209–1216.
15. van Rosendal SP, Osborne MA, Fassett RG, Coombes JS. (2010). Guidelines for glycerol use in hyperhydration and rehydration associated with exercise. Sports Medicine, 40(2), 113–139.
16. Scoon GS, Hopkins WG, Mayhew S, Cotter JD. (2007). Effect of post-exercise sauna bathing on the endurance performance of competitive male runners. Journal of Science and Medicine in Sport, 10(4), 259–262.
17. Sekiguchi Y, Adams WA, Hosokawa Y, et al. (2025). Customizing individual heat mitigation strategies to optimize performance in elite athletes. Frontiers in Physiology, 16, 1380645.