What harm does dehydration have to exercise?

Athletes sweat a lot due to strenuous exercise and lose fluid in the body. While sweating, electrolytes are also lost with sweat. The average sweat amount of 4 hours of long-distance running training can reach 45±0.3 kg. The water requirement of workers with moderate physical ability at room temperature is 2.15 liters per day, and when the ambient temperature is above 20 degrees Celsius, every 55 degrees increase in moisture is required. The required amount of the product is increased by 1 liter.

The effect of water on exercise capacity is obvious, and the reduction of body fluids will significantly reduce long-term endurance exercise capacity. If the athlete does not add water before and during exercise and sweats a lot during exercise, dehydration is prone to occur.

When the body lacks water, it is mainly manifested in the decrease of urine output and body fluids.

Water loss of about 1% of body weight will significantly increase body temperature and heart rate during exercise.

Mild dehydration means that the amount of dehydration accounts for about 2% of the body weight. The main reason is that the extracellular fluid decreases and the body loses its ability to regulate. If the water lost by sweating is not supplemented, the body temperature may continue to rise, leading to a loss of physical strength.

Dehydration accounts for 4% to 6% of body weight, reducing muscle strength and endurance, and at the same time causing heat cramps, which will also affect the energy supply process of anaerobic metabolism in the body.

The effect of dehydration on the cardiovascular system will also cause a decrease in plasma volume and an increase in blood osmolality. Low plasma easily leads to decreased urine output, increased body temperature, increased blood viscosity, and increased risk of heatstroke.

When water loss accounts for more than 6% of body weight, severe heat cramps, heat exhaustion, heatstroke, coma, and even death may occur.

Therefore, it is necessary to prevent or reduce the degree of dehydration, and it is necessary to have the concept that immediate hydration can improve athletic ability.

Perspiration improves the heat dissipation capacity, but the loss of water and electrolytes should be replenished immediately. As athletes lose sweat, electrolytes are also lost with sweat.

How to add water to prevent dehydration?

Replenishment of water lost during exercise should be based on the principle of maintaining balance. The only way to adjust the balance of water and electrolytes in the body is to drink water or beverages. Since body fluids are low osmotic fluids, in contrast, replenishing water during exercise is more important than replenishing electrolytes.

In a hot environment, the amount of dehydration that a normal person does not consciously is 275 milliliters per hour. For athletes of long-term endurance events, the longer the dehydration time is under the thermal environment, the more severe the impact on their athletic ability. Therefore, they should be hydrated before dehydration. Do not drink water until they are thirsty. The body is already dehydrated when thirsty.

In terms of water absorption, the maximum normal rate of gastric emptying is 600 to 800 ml per hour;

The emptying rate of cold or warm water in the stomach is significantly higher than that of body temperature water (37 degrees Celsius). Drinking cold water during exercise has a better effect on lowering body temperature than taking the same amount of water before exercise;

The gastric emptying rate of pure water or low osmotic pressure beverage is higher than that of high osmotic pressure beverages.

Therefore, when exercising vigorously in a hot environment, supplementing water is more important than supplementing carbohydrates and electrolytes. During exercise with a short duration, it is not necessary to supplement electrolytes in beverages, because supplementing electrolytes during exercise will increase the increase caused by exercise. The high degree of penetration. Therefore, for 30-60 minutes of exercise, water can be said to be the most economical and practical replenishment fluid.

What are the techniques for supplementing water during exercise?

(1) Have a planned intake of water, not only during the competition, but also during the training period, and never feel thirsty.

(2) You must start exercising only after getting enough water. Avoid large amounts of alcohol the day before exercise. Take 250~500cc of water 20-40 minutes before exercise. Don’t worry about stopping your exercise because you want to go to the bathroom. There is less urine formation during exercise. By increasing perspiration, you can reduce the rise in body temperature.

(3) When exercising for a long time in hot weather, add 200~300cc of fluid every 15~20 minutes.

(4) The absorption rate of cold drinks (5°C) is faster than that of warm water and hot drinks.

(5) Pure water is absorbed by the human body the fastest. However, commercial sports drinks on the market can not only replenish water but also because they contain carbohydrates, they can replenish energy in the body. However, if used improperly, it will cause vomiting and digestive discomfort, which will adversely affect exercise.

(6) The most ideal water replenishment plan, apart from the need to pay attention to the time and amount of water intake, please carry your own water bottle every day to ensure that you must be able to take in water regularly and quantitatively.

(7) Avoid using salt tablets, because after ingesting, it will cause excessive osmotic pressure (imbalance) in the body, and the water will run from the muscles to the stomach, which is not good for exercise.

(8) Splashing water (splashing water on the skin surface) at the right time during exercise will help supplement the water loss during the body’s evaporation process.

(9) You must adapt to the environment before the competition, especially in high-temperature environments to avoid heatstroke. Note that children take longer than adults to adjust to the new environment.

(10) Wear appropriate clothing to adapt to the weather conditions. The education of the organizers and coaches of the sports preparatory meeting is very important because drinking water is prohibited in certain games and sports venues. The heat generated during the activity is directly proportional to the intensity of the exercise.

So you will find that when you are tired, a lot of heat is lost, and your body temperature drops so that you have to put on a coat. Hypothermia often occurs in continuous competitions (such as marathons).

What are the tips for supplementing water after exercise?

Athletes must completely hydrate after exercise, so as to completely replenish the lost sweat, so as to quickly recover from fatigue and prepare for the next game.

(1) Don’t wait until you are thirsty or have the opportunity to take in water, and you must replenish water in a planned way;

(2) Weight changes before and after exercise can be used to estimate water loss, so as to establish an effective water replenishment strategy.

(3) Ingest a larger amount of water to compensate for the loss of sweat and urine. Generally, it is necessary to ingest 1.5 to 2 times the volume of sweat loss to completely balance the body’s water.

(4) Determine an adequate supply of beverages suitable for taste.

(5) Beverages with better taste are more attractive to athletes than pure water

(6) Beverages containing carbohydrates can promote recovery at the same time. For example, It helps to re-storage liver glycogen in muscles.

(7) Appropriate addition of sodium salt to maintain fluid balance. For example sports drinks, salty foods, or adding salt to meals. When the body fluid is severely insufficient (loss exceeds 2~3% of body weight), high-sodium beverages (50~90mmo/L) can effectively and quickly promote water replenishment.

(8) Ingesting potassium-rich foods after exercise can restore and maintain the potassium concentration, such as bananas. In addition, a glass of orange juice can make up for the calcium and magnesium content of 3 liters of sweat lost.

(9) Drinks containing alcohol and caffeine are not ideal for refilling drinks because they increase urination.

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