Hydration for cyclists: How much fluid and electrolytes do we need?

Given Singapore’s hot and humid weather, how much should we be drinking when we go out for a ride? It is important to note that the higher the loss of fluids, the more important it is to have sufficient water intake. On a bike ride of medium intensity or more, your body cannot absorb water as fast as it loses it. 



The reason why you need to hydrate enough is to maintain enough blood volume to keep your muscles working properly and produce sweat to stay cool. If you lose too much water, your blood becomes too thick to do either, and your performance will be affected. 

Dehydration can be detrimental if you lose as little as 2% of your body’s water content (1.4kg water weight for a 70kg cyclist). 


According to triathlete coach Colin O’Shea , he recommends consuming at least 750ml of liquid when competing in races that are over 2 hours in duration.

“Each athlete will have different sweat rates and will also lose varying amounts of sodium whilst exercising. My recommendation is for athletes to test work out their own bespoke numbers for sweat rate and sodium loss so they can accurately calculate their own bespoke nutrition strategy.”


“One way to calculate your sweat rate is to weigh yourself before and after your ride. Your weight difference divided by the number of hours you spent on the bike will be how much liquid you lose per hour.”


You should always make it a point to check your hydration status, and one way you can do so is the urine colour test.


Source: britishcycling.org.uk


What are electrolytes and why do they matter?


Electrolytes are minerals which are lost in sweat and which need to be replaced as exercise progresses. The electrolytes that you need to replenish are…

1. Sodium (and chloride): Maintain normal blood pressure, support muscle and nerve function

2. Magnesium: Aids healthy cell function

3. Potassium & Phosphate: Help to regulate energy and pH balance 

4. Calcium: Aids in muscle contraction 


Without sufficient replenishment of electrolytes and water, your physical function can be compromised. Resulting symptoms can include muscle fatigue, dizziness, and nausea. 

Mr Derrick Ong, a registered Dietitian from Eat Right suggests that “the key electrolyte to replace is sodium which is crucial for many bodily metabolic functions. How much to replace is dependant on a number of factors including individual sweat rate, amount of sodium in one’s sweat, as well as the environmental conditions of riding (temperature, humidity).”



“As a general rule of thumb, carbohydrate-electrolyte drinks e.g. isotonic drinks should be taken from the 2nd hour of exercise onwards, while electrolyte tablets can be considered for prolonged riding durations (more than 4 hours).”

Derrick further states that the temperature of the drink is also extremely important in hot, humid climates like Singapore in order to lower body core temperatures and prevent heat exhaustion.


Myth: “If I have cramps,  I need to take more electrolytes.” 

Nope. Recent research shows that dehydration is not the main reason for cramping, rather it is more likely due to fatigue and overexertion for your fitness level. So it’s your body’s way of telling you to back off the intensity. 


Where can you get electrolytes from? 

There are so many options to choose from, ranging from electrolyte drinks, electrolyte powder mixes, tablets… However do watch out on your intake as the sugar content in some drinks can be very high.  I also find these commercial electrolyte drinks to be quite costly. Why not try making one yourself!

Here is a homemade electrolyte drink recipe:


600ml water + Juice from 1 orange + 1/4 tsp of salt (or just a pinch if you’re lazy to find a measuring spoon). Another alternative is to substitute the orange with lemon & a sweetener (sugar/honey). 

Coconut water + 1/4 tsp of salt is another great electrolyte drink too! Coconut water contains all the electrolytes listed above, but slightly low in sodium content. 

If you would like a more in-depth explanation for hydration pre, during and after sports, do refer to the America College of Sports Medicine (ACSM) guideline


Esther Koh
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