A sizeable percentage of the human body is water in various forms – 60 per cent on average.
No wonder, water plays multiple, crucial roles in the human body:
- Helps maintain normal physiological parameters such as pH, blood pressure and body temperature
- Acts as a medium for transport of carbon dioxide, oxygen and glucose between the cells
- Has a role in lubricating joints and maintaining the structure of cells and tissues.
The water composition in the body is governed by various factors, including gender, age and hydration levels of the individual. Proper hydration of the body is necessary for the optimal functioning of all the organs. So, it is paramount that the fluids lost from the body — be it due to urination or sweating in hot climates or during exercises — be replenished immediately.
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Dehydration and exercise
During exercises, body fluid is lost in the form of sweat through the sweat glands present in the skin. This is necessary to maintain the body temperature in the normal range.
“During exercise, the body dissipates excess heat through sweating,” says Dr Gagan Kumar Banodhe, department of physiology, AIIMS, Gorakhpur, Uttar Pradesh. “This can lead to dehydration unless [water] is replenished. The dehydration can be severe if a person is performing exercises in a hot and humid climate without proper fluid intake.”
Dehydration is an unpleasant experience to start with. The urine becomes dark yellow, and the person feels dizzy, tired and disoriented. Muscle cramps are a common symptom too besides dry skin, lips and the mouth drying up.
“Dehydration symptoms include mild to severe headache, dizziness, fatigue, nausea, vomiting and heat exhaustion,” says Dr Banodhe.
If dehydration is not managed, it decreases the efficiency of bodily functions significantly, leading to kidney problems and heatstrokes as well. So, a person exercising should have a proper hydration plan in place.
Rehydrate but do not overhydrate
The natural, and largely involuntary, instinct when the body is losing fluid is to drink — a cool, refreshing drink to soothe the dry throat. However, while rehydrating, care must be taken to avoid excessive intake of water. Overhydration is as severe a problem as dehydration.
“Overhydration can lead to hyponatremia (a condition in which the sodium present in the blood gets very low) and the symptoms can be nausea, vomiting, throbbing headache, dizziness, etc.,” says Dr Banodhe.
People follow different hydration plans during exercises. Some take in fluids in a specific volume before and after exercises. Some prefer to take in a specific volume at regular intervals during workouts, while many others consider thirst as a signal for fluid intake. However, thirst is an indicator that the body is already dehydrated.
Common rehydration routines
- Drink when thirsty: It involves the intake of fluid when one feels thirsty.
- Ad libitum drinking: It is the intake of fluid whenever and in whatever volume desired by the individual. There is no specific focus on thirst as an indicator.
- Individualised planned drinking: It involves measuring the sweat rate and then taking in a predetermined volume of fluid.
- No drink: Purposefully drink nothing during exercise.
- Thirst-led drinking: In excess thirst, drink as much as possible.
Drinking when thirsty and ad libitum drinking rehydration practices could help avoid exertional hyponatremia and prevent the exerciser from reaching the level of dehydration that can decrease the exercise performance.
Individualised planned drinking also prevents the person from reaching the level where dehydration can impair performance. It reduces heatstrokes and heat exhaustion, and also decreases dehydration-associated cardiovascular or thermoregulatory strain.
A 2021 review paper by Lawrence E Armstrong, titled Rehydration during Endurance Exercise: Challenges, Research, Options, Methods and published in Nutrients journal, advises individualised hydration plans based on the nature of physical activity, a person’s physiology, rate of sweating and some other factors, including the weather. However, it says that purposefully drinking nothing and purposefully drinking as much as possible during exercises as rehydrating practices should not be recommended by any professional sports-medicine practitioner or sports-nutrition organisation.
Type of rehydration drinks
Rehydrating drinks that you choose should not only make you feel refreshed but also restore the fluid and electrolyte balance in the body.
“Normally, we advise exercise-goers to take sips of water if they feel thirsty during exercise,” says Sheela Krishnaswamy, a registered dietician, nutrition and wellness consultant based in Bengaluru. “If not, an additional 300ml to 500ml of water per day should suffice for a person doing an hour of exercise daily. For example, if a person’s normal water intake is 1,800ml per day, then raising it to 2,100ml per day should be good. Water is a good rehydrating drink. If a person wants something different, then a glass of tender coconut water or thin buttermilk will also do.”
For those who exercise 30 to 60 minutes a day, water alone would suffice as a rehydrating drink because it generally contains traces of commonly found minerals like sodium, potassium, calcium, magnesium, iron, copper, manganese, phosphorous and zinc. However, richer sources of minerals are always better, and they happen to be refreshing too.
A glass of buttermilk, for instance, helps the body stay cool and hydrated. Buttermilk is prepared by mixing a small amount of curd in water. Cumin seeds, mint and salt can be added for flavour and mineral content. Buttermilk has around 90 per cent of water and potassium and sodium that replenish the fluids and electrolytes lost from the body.
Drinking tender coconut water after exercise is also a good option because it is fat-free and low in calories and sugar. Coconut water also has essential electrolytes such as potassium, calcium and magnesium and nutrients such as glucose and amino acids that are essential for the body, making it a good rehydrating drink.
Fresh fruits and vegetables have water content and essential nutrients as well. Moisture-rich fruits and vegetables like watermelon and cucumbers can also be taken to rehydrate oneself.
“Fruits like banana and watermelon can be taken in small quantities and in intervals,” says Dr Banodhe.
Krishnaswamy says fruits can be taken in between mealtimes to satisfy hunger pangs, and vegetables can be had at mealtimes.
Experts advise people to be cautious while incorporating sports drinks into their rehydration routine. Most have high levels of carbohydrates in the form of sugar – such as glucose and sucrose. “Do not go overboard with sports drinks or infused waters or supplemented beverages,” says Krishnaswamy. “Consult a qualified sports dietitian for individual needs and concerns.”
Since fluid requirement varies from person to person, an individualised approach works best.
For that, the first step should be to understand one’s bodily limits and requirements, say experts. Seeking professional advice is the next step in figuring out the right mix to keep dehydration at bay — and your workouts, and your day, happy and in a healthy zone.
Very informative & beautifully summarised.Also I was unaware of the term Overhydration.