Hydration & Exercise: How to Nail It for Maximum Performance

Nov 21, 2023 | fitness

There are plenty of myths and misconceptions about the best way to stay hydrated during a workout. In fact, calculating how much water to drink (and when) can feel as challenging as a half-marathon!

We all know that hydration and health go hand-in-hand, but truthfully, many people still struggle to drink eight glasses a day

Why is it so critical to drink enough water during a workout? Even mild dehydration can undermine your athletic performance. You might not even feel thirsty, leaving you pondering why you’re having such an ‘off day’.

The bottom line: if you’re not hydrated enough, there’s no way you’ll be hitting your full potential during training. So, what’s the best approach for optimal hydration?

As an exercise scientist, I’m here to demystify this topic and break it down for you.

In this article, I’ll unpack:

  • The science of hydration & exercise
  • Why it’s vital to performance and recovery
  • How much to drink before, during and after exercise
  • The pros & cons of sports drinks

and many more burning questions about drinking water for sports & exercise.

Ready to quench your thirst for knowledge? Let’s dive in!

Hydration & Exercise: Why Is It Important?

Staying hydrated isn’t just about cooling down or quenching thirst – it’s 100% essential to perform at your best. If you’re starting your workout dehydrated, you’re already selling yourself short!

Once you start breaking a sweat, your body loses fluids rapidly, especially if you’re exercising in hot weather. Dehydration, the loss of essential fluid and salts we need to function, can occur in just 30 minutes.

Dehydration is the number one enemy of exercise performance. Without enough water, the body can’t keep up with the demands of physical activity, so your stamina, strength, and coordination all take a hit. Definitely not ideal for training, let alone race day!

All of this can happen before you even realise you’re thirsty – and it only gets worse from there.

The adverse effects of dehydration can include:

Especially when exercising outdoors in hot weather, drinking enough water is critical to avoiding dangerous heat-related illnesses. High intensity exercise is also a common culprit in dehydration, including indoor workouts like spin or RPM classes where you may not take a break to rehydrate.

At best, dehydration is an obstacle to reaching your true performance potential. At worst, failing to drink enough water during exercise can be dangerous or even life-threatening!

Let’s take a look at why your body needs water during physical activity – keep reading to learn all about it.

The Science Behind Hydration & Exercise Performance

Failing to drink enough water has immediate and long-term effects on your performance, as well as your overall health.

If you’re keen for some science, here are four ways hydration is essential to exercise performance:

1. Supports Energy Metabolism

Water is critical to the body’s metabolic process, where the carbs, proteins, and fats we eat are turned into energy. Not drinking enough water can zap our energy, leaving you feeling tired and not performing at your best. If you’re dehydrated during exercise, you can expect muscle fatigue to set in more quickly, as well as reduced power and stamina – increasing ‘perceived exertion’.

2. Transports Nutrients & Oxygen

Water is what transports critical nutrients and oxygen around the body. If you’re well-hydrated during training, the heart can efficiently pump oxygen and nutrients around the body, keeping those hardworking muscles well-supplied. On the other hand, if your performance isn’t up to scratch, your hydration levels might be the culprit.

3. Regulates Temperature

We all expect to get hot and sweaty during a good workout, but how often do you stop and think about why? Sweat may have an ‘ick factor’, but it’s essential to prevent us from overheating during exercise. As we break a sweat, the moisture on our skin evaporates to cool us down a bit.

If we’re not hydrated enough, the body can’t regulate temperature properly, leaving us vulnerable to heat-related illnesses like heat exhaustion or heat stroke. A lack of sweating is a major warning sign for heat stroke!

4. Lubricates Joints

Proper hydration is a great way to reduce the risk of exercise-related injury. Water helps to lubricate the joints, which reduces friction, making movement more comfortable and less stressful on the body. If you don’t hydrate properly, your body takes more wear and tear during a workout, increasing your risk of joint pain and reducing long-term performance.

Why Hydration is Critical to Exercise Recovery

Struggling to bounce back after a workout? Neglecting your water intake could be the cause! There’s a good reason hydration and post-workout recovery go hand in hand – and failing to rehydrate can leave you feeling sore for longer.

Exercise naturally leads to muscle breakdown and the build-up of waste products in the body. During recovery, your body needs water to flush out the waste and transport nutrients for muscle repair to the cells that need them.

If you don’t drink enough water after a workout, recovery is slowed, causing longer-lasting muscle soreness and fatigue. Plus, you’ll want to see all your hard work pay off – and no matter what your goal is, hydration will help you reap the benefits.

Training for muscle growth? Rehydrate to help your muscle cells get the nutrients they need. Keen to boost your metabolism and burn fat all day? Water is an essential part of that metabolic process, so don’t forget to top up!

For extended exercise, dehydration can also throw your electrolytes out of whack. Replenishing fluids and minerals lost after intense exercise (like when recovering from a marathon) restores a healthy electrolyte balance, supporting muscle function and repair.

In a nutshell, staying hydrated isn’t just about performance – it’s essential to exercise recovery and muscle repair. To find out how much you need to drink and when, keep reading below.

How Much Water to Drink for Your Workout

For optimal performance and recovery, it’s super important to stay hydrated before, during, and after physical activity. In other words, keep that water bottle handy!

Here’s how much water you need to drink at each stage of exercise:

Pre-Workout Hydration

Pre-hydration is often overlooked, but it’s vital to exercise performance. When preparing for a big event, like a marathon or half-marathon, start working on your hydration the day before the race. 

For most exercise sessions, the recommendation is 200-400mL of fluid 15 minutes before starting. It’s not an exact science, so it’s important to work out what suits your body and training style.

It’s a good idea to check your hydration first. The colour of your urine is a good indicator. If you are well hydrated, it will be a pale yellow; the darker your urine, the more dehydrated you are.

Another great test for those who frequently do endurance or intense workouts is to jump on the scales and weigh yourself – this will help you calculate your post-workout fluid loss.

Hydration During Exercise

How much you need to drink during a workout will depend on the temperature, your age, exercise intensity, how much you sweat, and the length of your workout.

Generally, for workouts less than an hour, you should aim for approximately 200-300mL every 15 to 20 minutes. For workouts longer than an hour, such as a long run, start including a drink with salt or carbohydrate, such as a sports drink.

Water is vital for any physical activity, but it goes without saying that you’ll sweat more heavily in hot weather or during intense exercise. Watch for signs of dehydration, like muscle fatigue, flushed skin, loss of coordination, and weakness.

Post-Workout Rehydration

Now that you have smashed that sesh, jump back on those scales and weigh yourself. This means you can calculate your fluid loss during the workout.

The American College of Sports Medicine says you should aim to replace fluids within 2 hours, drinking approximately 600mL for every kilo lost. Any more than a 3% body weight change can mean significant dehydration.

Another rule of thumb is to drink 600mL for every 30 minutes that you run. For those who had a tough training session or a long endurance run, you’ll most likely need to replace electrolytes with something like Gatorade or coconut water.

Avoid guzzling your water, as you can overdo it and throw your electrolytes out of balance. Stick to the urine and weight test to work out your fluid strategy. Drinking excessive amounts of water during or after exercise can lead to a dangerous condition called hyponatremia, so don’t overdo it.

Do I Need a Sports Drink for my Workout?

Sports drinks are really only required for sessions lasting over 90 minutes, during extreme heat and humidity, or on race day where performance is critical. Under these circumstances, we lose about one teaspoon of sodium every 2 hours.

Electrolyte or isotonic drinks such as Gatorade contain sugars and minerals that water doesn’t have, and they’re designed to replenish these levels as quickly as possible. During prolonged, intense exercise, the fast-absorbing carbohydrates help maintain energy levels.

For regular exercise, there’s no need to guzzle a sports drink – in fact, the hidden calories in these beverages mean you may be cancelling out your calorie burn. A 600mL sports drink contains about 670 KJ, the equivalent of 9 sugar cubes!

Water is generally sufficient for a routine workout unless you’re training extremely hard. When you do need some extra hydration, you are better off ditching the high-sugar Gatorade and replacing it with coconut water. 

Coconut Water for Post-Exercise Hydration

Coconut water is a great substitute for a pre- or post-workout drink, as it’s rich in electrolytes, potassium and magnesium. Better still, it’s natural, free from refined sugars, oils and additives – which can’t be said for sports drinks. 

Note that coconut water is high in potassium and contains minimal sodium, so it should not be your sole means of replacing sweat losses. For heavy exercise, like an endurance run or marathon, make sure you add a little extra salt to your meals afterwards. Too much coconut water can also trigger diarrhoea, you have been warned! 

Top Hydration FAQs for Sports & Exercise

Should I only drink water once I’m thirsty?

Thirst isn’t always a reliable indicator of your hydration levels, especially during intense workouts. By the time you feel thirsty, chances are you’re already mildly dehydrated! Proactive hydration before, during and after exercise is best to stay on top of your water intake.

Is it possible to drink too much water while exercising?

Drinking too much water can lead to hyponatremia, but it is rare, especially during routine training. Also known as water intoxication or overhydration, it’s more of a risk with endurance events like marathons, where athletes drink excessive water and don’t replace electrolytes.

Simply put, hyponatremia isn’t really about ‘too much water’; it’s about balancing water intake with electrolytes. Replenishing these minerals is recommended for long, intense physical activity (over 90 minutes).

Under normal circumstances, you’re not likely to be overhydrated, but drinking water during exercise can cause stomach discomfort for some people. Keep in mind that dehydration can also cause nausea, but don’t push yourself to guzzle large amounts of water if you’re feeling ill.

Can I drink coffee before working out?

Caffeine can be a great workout booster to enhance performance, stamina and calorie burn. Studies suggest 3-6mg of caffeine per kg of body weight is ideal (about 2-3 cups of coffee for a 70kg individual). However, caffeine is a diuretic and can contribute to dehydration, so it’s important not to overdo it.

Start with a small dose and increase gradually, as everyone’s caffeine sensitivity will be different, and higher doses (above 9mg/kg) increase the risk of side effects. Make sure hydration is a priority when using caffeine to enhance your workout.

Key Takeaways

Hydration is crucial to exercise performance and recovery, whether it’s a routine training session or a big race day. The correct balance of fluids and electrolytes makes all the difference, helping your body do what it does best.

Water should be your go-to choice to rehydrate, but for intense or prolonged activities, it’s important to replenish electrolytes as well. Coconut water is my recommendation to replenish lost fluids and minerals without a lot of refined sugars.

Whether you’re opting for water, a sports drink or a natural alternative, don’t wait until you feel thirsty to start hydrating! Even better, monitor the colour of your urine to track your hydration levels. Weighing yourself before and after exercise also helps determine your fluid loss – the most accurate guide for post-workout fluid replacement.

Keep these tips in mind when planning your pre- or post-workout hydration strategy. Don’t wait for your body’s thirst cues, but always listen to them and make hydration a top priority.

By drinking enough water, you give your body the strength and stamina it needs to keep crushing those workouts!


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