Drinking only water when training in the heat: why it may not be enough
Drinking only water may not be enough during long workouts in the heat, because sweat also eliminates sodium and the hydration strategy should be adapted to the duration, intensity and each athlete.
Content developed in collaboration with Crown Sport Nutrition.
When temperature and humidity rise, the body increases sweat production to regulate its temperature. This response allows training to continue, but it also leads to a gradual loss of energy. water and electrolytes, especially sodium.
The sports nutritionist mario king, collaborator of Crown Sport Nutrition, has analyzed one of the common mistakes among endurance athletes: thinking that any session can be covered solely with water, regardless of its duration or environmental conditions.
“Drinking only water can work against you.”
Mario Rey, sports nutritionist
Sweat is not composed solely of water.
The rate of sweating varies greatly among athletes. It also depends on temperature, humidity, exercise intensity, heat acclimatization, body size, and clothing worn.
Through sweat you lose fluid, but you also sodium, chlorine, and smaller amounts of other mineralsTherefore, in prolonged sessions or those performed in high temperatures, simply drinking water may not replace everything the body is eliminating.
A fluid loss of approximately 2% of body weight is associated with increased cardiovascular and thermal stress, and can affect performance in certain contexts, especially during endurance efforts performed in the heat.
In our article on How to adjust nutrition and hydration when training in the heat We also explain why a pattern that works in spring may fall short during the summer months.
When is drinking enough water?
In a short, moderate-intensity session conducted under mild environmental conditions, Water may be enoughespecially if the athlete starts well hydrated and maintains a balanced diet.
The situation changes when the effort exceeds one hour, the intensity increases, it's very hot, or the athlete experiences a high rate of perspiration. In these cases, it may be necessary to combine fluids with electrolytes and, if the duration requires it, with carbohydrates.
The risk does not arise from drinking water normally, but from drink more fluids than you lose during prolonged exertionThis overhydration can dilute the concentration of sodium in the blood and promote exercise-associated hyponatremia.
Exercise-associated hyponatremia is an abnormally low level of sodium in the blood. Overhydration is the main risk factor, although the duration of exertion, sodium loss, and individual response also play a role.
Water, sodium, and carbohydrates perform different functions.
A hydration strategy for endurance must distinguish between three needs: replenish fluids, maintain electrolyte balance, and provide energy.
Water provides fluid replacement. Sodium helps maintain fluid balance and improves fluid retention. Carbohydrates sustain energy availability during prolonged training or competition.
Sodium and glucose work together in the intestinal absorption of water. For this reason, a properly formulated drink can facilitate the replenishment of fluids, electrolytes, and carbohydrates during exercise.
For efforts lasting between one and two and a half hours, references are typically used of 30 to 60 grams of carbohydrates per hourIn trained athletes and tests lasting more than two and a half hours, intake can approach 90 grams per hour through combinations of carbohydrates transportable through different intestinal pathways.
These figures should not be applied automatically. Intensity, duration, digestive tolerance, and total consumption from drinks, gels, and food should be calculated together and tested beforehand in training.
Crown products for different hydration strategies
Crown Sport Nutrition offers several solutions for combining fluids, sodium, and carbohydrates within its product range. These products are not equivalent and should not all be used simultaneously: each addresses a specific need during training or competition.
| Product | What it brings | When might it fit? |
|---|---|---|
| Isodrink & Energy | 26,2g of carbohydrates and 236mg of sodium per 400ml preparation, plus potassium, BCAAs and glutamine. | Training sessions or competitions lasting more than one hour, where the aim is to combine hydration, electrolytes, and a moderate amount of energy. |
| PRO Salt Caps | 310 mg of sodium per capsule, along with potassium, calcium, magnesium, and chlorine. | Long sessions, heat, humidity, or athletes with high sodium losses, always within a previously calculated guideline. |
| Hyper Drink 90 | 90g of carbohydrates in a 1:0,8 ratio of maltodextrin and fructose, with 208mg of sodium per 500ml serving. | Long tests in which a significant portion of the carbohydrates is carried in the jerrycan and digestive tolerance has been trained. |
| Hyper Gel 45 | 45g of carbohydrates in a 1:0,8 ratio and 165mg of sodium in most versions. | Strategies with high carbohydrate intakes that aim to concentrate more energy in each serving. |
The pattern must be tested before competing
There is no single amount of water or sodium that works the same for everyone. Two triathletes competing for the same amount of time can have very different sweat rates and sodium concentrations.
A practical guideline is to monitor weight before and after several training sessions, record fluid intake, and observe how hydration needs change with temperature. For athletes who sweat excessively, have white salt residue on their clothing, or have a history of digestive problems, an individual assessment with a sports nutritionist may be advisable.
The conclusion is not that you should always replace water with a sports drink. The key is deciding. when water is enough and when the effort requires also incorporating sodium and carbohydrates.
This content has been created with the support of AI tools and reviewed by the Triathlon News editorial team.
