All You Need To Know About Hydration

Everyone knows that it is important to stay hydrated during exercise but what how much exactly do you need to drink? It boils down to how much water you are excreting. Let’s explore further, know more about hydration.

So why is hydration important?

Our body is made up of 70% water, translating into an important component for survival and body function. It is also responsible for vital chemical reaction within the body such as healing of tissues and muscle recovery. Thus without enough hydration, these processes would be slowed down and your body will not be able to function at its 100% efficiency.

Our body loses water constantly through breathing but mainly through urine and sweat. When we lose water, we also lose body salts, mostly sodium and chloride. The loss of these body salts result in an imbalance in electrolytes which can also lead to symptoms such as cramps and dizziness thus would also need to be replenish and is especially important when it comes to maximum athlete performance. This is also the key difference between plain water and sports drink.

​In terms of performance, a 1% to 2% loss in water with respect to our bodyweight can impair performance by around 10 to 25%. If you are well hydrated, you will feel stronger, able to exercise longer and more efficiently. The heart does not have to work as hard to pump blood around the body and oxygen and nutrients can be transported more efficiently to the muscles that you are working on.

So how do I know if I’m well hydrated?

It is common to hear people saying to drink when you are thirsty. However, it is far from being a good gauge for hydration. In fact, when you are thirsty, you are already dehydrated.

The simplest sign would be from your urine color. The darker it is, the more dehydrated you are. Though do take note that some supplements do affect urine color such as Vitamin B where your urine may turn fluorescent yellow or lime green.

​Another way to check if you are well hydrated is to weigh yourself before and after your training session to see how much weight is reduced. 1kg of weight loss equates to around 1L of fluid thus aim to restore back to your original weight after exercising.

So how can I gauge how much water to drink during daily?

​First of all, before we can gauge how much water to drink during an exercise, we must be well hydrated to begin with. The theory is simple. If your body doesn’t have enough water to begin with, it will start to preserve the fluid within your body, resulting in less sweat. This in terms leads to a poorer body function efficiency and performance (eg. Body unable to regulate body temperature, less oxygen and nutrients transported to muscles).

For general hydration along the day, although it is commonly recommended to have at least 8 glasses of water, this amount can differ greatly across different individual based simply by their weight. A more accurate general hydration guideline would be 0.5 to 1 ounce of water per pound of body weight. If a person weighs 65kg, that would be around 145lbs thus he/she should be drinking between 72.5 to 145 ounces of water daily. That is about 2.1L to 4.3L a day.

(1 ounce ≈ 30ml | 1kg ≈ 2.2lb)

Putting back into the context of 8 glasses of water, which equates to roughly 2.2L, it is definitely insufficient for a person who weighs more than 75kg. 

How about during exercise?

It is safe to assume that the more intense an exercise session is, as well as the warmer the environment that your session is carried out, the more you will sweat. Thus as mentioned previously, it is best to drink back whatever water weight that you may have loss during exercise. However, that should not be done purely after the exercise session, but also during your session to maximize your performance.

An average person sweats around 0.8 to 1.4L per hour during exercising. That equates to 0.8 to 1.4L of water that you have to replenish during your exercise. Just for your information, the highest sweat record in an hour of exercise is 3.7.

Thus, a recommended amount and frequency to hydrate yourself would be about 200ml to 350ml of water every 15 minutes. That is roughly about 3 to 5 mouthful of water so pace yourself. If you are sweating heavily, especially if you’re working out in a very hot weather, it is definitely recommended to go on the higher side of the range of your water intake so do take note.

On a side note, if you want a more precise and reliable hydration rate based on your body and activity level, here’s what you can do.

1. First, make sure that you are already well hydrated. (Eg. Clear urine color)

2. Weigh yourself before you work out, preferably with as little clothes possible for a more accurate reading.

3. Go for a 30 minutes work out session without any hydration and at an intensity that you would usually work out.

4. Weigh yourself again after the session, under the same condition as you weight yourself before, and see how much weight you have loss.

5. Take the weight loss in grams and divide by 2. That is the amount of water that you should be drinking every 15 minutes of your workout.

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Do note that a more accurate reading can be achieve with a longer initial exercise duration without hydration due to the fact that your body temperature and heartrate might remain higher for a longer period of time resulting in a more consistent sweat rate as a mechanism to regulate body temperature. However, it is advisable not to go longer than 60 minutes without hydration for this test.

Is it dangerous to over-drink?

Over drinking can lead to hyponatremia, where blood becomes excessively diluted from too much water and sodium levels drop to dangerously low level, resulting in nausea, headaches, confusion fatigue and in extreme cases, coma and death. Although it takes quite a lot of water to get to this point, it is good to be aware of it.

What are sports drink?

As mentioned in the article, when you lose body fluid, you also lose salt. This is where sports drink comes in. Besides containing salt to rebalance your electrolytes loss from the body fluid, various types of sports drink also contain different concentration of carbohydrates to replenish your glycogen storage.

There are 3 types of sports drink that ranges in ascending order, the various concentration of carbohydrates – Hypotonic, Isotonic and Hypertonic.

Conclusion

​How much to drink is based on your bodyweight and how much you excrete your body fluid. The general hydration guideline would be 0.5 to 1 ounce of water per pound of body weight on a daily basis and 200ml to 350ml of water every 15 minutes during period of exercising.