Living presupposes three vital pillars: food, sleep, and hydration. For this last point, we need to hydrate our bodies with liquid to optimize proper cellular functioning. It answers to different levels: muscular, cerebral, tendon, bone, visceral, hepatic, pancreatic, visual, blood, etc. Thus, the lack of hydration can foster the onset of various symptoms such as cramps, stress, insomnia, headaches, osteoporosis, muscle wasting, tendonitis, and fatigue. Most of all, not drinking during workouts can cause physical disability and poor performance.
Workout and Effort
By contracting, muscles produce heat (like an engine), which leads to water loss.
During sports activity - notably intense and prolonged - we naturally sweat, and by sweating, we lose water and salt. The salt lost during exercise can be responsible for a complex mechanism that amplifies water loss.
External factors can increase this effect. Indeed, if the surrounding air is hot and the sun is beating down, body temperature rises even further.
Dehydration is one of the main factors responsible for poor performance and can even affect the athlete's health: muscle injuries, cramps, and tendonitis. The heart beats faster, the respiratory rate accelerates, the body temperature rises, heat stroke approaches, and dizziness may develop.
Fact: losing 1% of weight in water during a workout leads to a loss of 10% of physical abilities. And a loss of 2% of weight in water leads to a loss of 20% of physical abilities, and so on.
Water and Body Weight
Water bring no calories, and is very important for the human body. It represents between 60 to 70% of body weight. This corresponds to approximately 45 liters of water for a 70 kg person.
The athlete who trains regularly has a greater volume of water in his body because he has more muscles, containing 73.2% water against 10% fat mass. Where is the water? 60% in our cells and 40% in the tissues in which the cells are bathed: lymph and blood.
Hydrate to Cool
During exercise, muscles demand more energy. Muscles release 70 to 75% of the energy in the form of heat. This heat mainly escapes by a natural transfer to the outside: convection. Water plays a secondary role in cooling the body.
Thus, if doing sports makes us sweat more, it is because of the increase in energy expenditure.The ‘boiler’ works at full speed. It is a sign that your body is working well.
What is Sweat Made of?
The chemical composition of sweat depends on the environmental conditions, the workout intensity, the capacity to acclimate to the heat, and the athlete's physical condition.
Sweat is made up of 99% water and sodium, potassium, calcium, magnesium, zinc, iron, manganese, and vitamin C, but this exact composition may vary. For example, trained and heat-acclimatized athletes excrete less sodium per liter of sweat (115 to 690 mg per liter) than begginer and unacclimatized athletes (920 to 2300 mg per liter).
Thirst, a High-Precision Mechanism
The human body has an effective mechanism to make it understand when to drink. Indeed, when changes in the sodium level or quantity of water in the plasma occur, receptors located in the brain at the level of the hypothalamus, will cause hormonal changes and behavior to avoid serious dehydration.
The kidneys will better retain water and sodium, and the feeling of thirst will be triggered. Contrary to popular belief, the feeling of thirst is very reliable when it is not disturbed by external elements (taking certain medications, illnesses, age).
Even if some people have the ability to regulate their body temperature during prolonged exertion in the heat, even with a lack of water. The human body cannot regulate its water balance instantly, and water and mineral deficits should be quickly corrected. So, it is essential to drink as soon as the effect of thirst is felt, without waiting to avoid dehydration, and medical complications.
Water deficit effects
When we don't drink enough to compensate for water loss, we can become dehydrated. The heart has to work harder and the heat regulation mechanisms are overwhelmed: heart rate increases, blood pressure decreases and the body begins to ‘overheat’.
A slight water deficit of around 1% body weight, i.e., just 0.7 liters for a 70 kg man, is enough to reduce performance by 10%: the athlete may feel tired, have headaches, nausea, heaviness in the legs and shortness of breath. When hydration decreases by 2%, the physical and intellectual performance of the athlete is impaired. More dehydration increases the risk of kidney stones and comas. The danger of heart attack, or exhaustion of the heart also awaits the athlete when he loses 6 to 10% of his initial weight to dehydration.
Heatstroke
When dehydration becomes too significant, blood volume decreases. The different organs, the brain, and the heart no longer receive enough blood. The human body seeks to increase circulation to preserve them: it closes the vessels leading to less essential areas such as the skin.
The body temperature, therefore, continues to rise while the cooling mechanism, perspiration, is no longer effective. The difference between heat produced and heat discharged is too great.
It is heatstroke, and it can be fatal because the brain is unable to withstand temperatures higher than 41°C. But, generally, heatstroke occurs without being in a state of dehydration; it is simply the diffusion of the heat that did not have enough time to be diffused correctly.
Other Dehydration Issues
Cramps
Muscle movement is achieved by the contraction of fibers inside muscle cells. Contraction takes place through the exchange of ions, mainly potassium, sodium, magnesium, and calcium ions. Dehydration can lead to an imbalance of ion exchanges through sweating which causes us to lose a lot of sodium: cramps then appear. This is the most common symptom that warns of poor hydration (in quantity or quality – see below).
Tendinopathies
Dehydration can promote the appearance of tendon problems even if the exact reason is not well known.
Water, the ideal Drink
Mineral Water and Bottled water are of a different kinds:
o Spring water from groundwater bottled at the source.
o Natural mineral water from underground aquifers, closely controlled. Its characteristics are constant. It has health-promoting properties.
o Bottled sparkling water can be either naturally gaseous or enhanced with gas from the source or carbonated with carbon dioxide.
For the sportsman, mineral composition is the most crucial element because it allows you to choose the water according to your needs. However, food remains essential to provide the needed mineral salts for the functioning of the human body.
What Else Besides Water?
Isotonic Drinks
Isotonic drinks contain as much sodium as there is in the cells in our body. Thus, this will facilitate digestion and replace the sodium losses caused by perspiration. An isotonic drink is therefore the first step towards a good drink for effort and performance. Count 500 to 700 mg of sodium per liter of drink.
Energy Drinks
Energy drinks contain carbohydrates and electrolytes. During exercise, they deliver energy to the muscles, help maintain blood sugar levels and reduce the risk of dehydration or hyponatremia. It's a good choice for performance, but not all contain the right amounts of minerals for endurance efforts.
Drinks containing more than 8% carbohydrates such as fruit juices, sodas, and certain sweet drinks (which often contain 10 to 12%) are not recommended during exercise. To dilute these substances, water passes from the blood to the intestines and the very sugary drink “stays in your stomach” because of ionic imbalances. In the same way, avoid table sugar in your drink: a large amount of fructose can render you bloated during exercise (further research is needed, however, since everyone reacts differently). Choose dedicated powdered formulas or make your own mix with glucose, maltodextrin, or similar sugar.
In Conclusion
The main thing is to stay suitably hydrated – and, of course, with healthy drinks. If the athlete can vary the waters he drinks in order to adapt them to the needs of the body, it must be kept in mind that the ‘nutritional’ interest of the waters remains limited and cannot replace food intake.
Finally, some drinks certainly hydrate you, but generate digestive activity, especially when they are sweet (fruit juice, sodas, etc.) or alcoholic (beer, wine, etc.). At least, tea and coffee can sometimes be the enemy of the athlete because they promote demineralization. In short, to stay hydrated, the best drink is still clear water!