The Importance of Hydration While Exercising


One key element of planning that’s important for enhancing performance and physique optimization is a topic that people rarely talk about: and that’s hydration. I know; hydration is neither sexy nor fun to talk about, plus selling water as a performance enhancing supplement isn’t the best business plan. Which is why we hardly hear much about water and how it impacts your performance. However, as Bobby Boucher would tell you; H2O has a major impact on all aspects of fitness.

You all probably know that the majority of our body is made up of water. Water has tons of different functionalities within our cells and body. As much as I would like to speak about the many functions of water and successfully bore everyone to the grave like usual, let’s just focus on how water can influence our performance during our workouts and the outcome of our muscle development. Join me in a cup of high-quality H2O as we dive deeper..

Dehydration and Performance

First off let’s nip this in the bud right away – there’s no benefit to overhydrating yourself (1). If anything, your midsection will feel like a hurricane and you’ll be sprinting to the restroom every 20 minutes – not exactly the best scenario for exercising or competing. There is, however, a plethora of literature based on the negative effects of dehydration, so let’s examine these effects so that we can get a better idea of these consequences.

One review that covers hydration and performance affirms that even mild dehydration will decrease muscle force production by 2%, lower power output by 3%, and endurance performance decreases by a whopping 10% (4). Those stats may not sound huge or concerning, but if you are constantly dehydrated like the majority of people are, then you are missing out on a consistent basis on those few percentages every time you go to the gym to workout.

The fact that dehydration has negative effects on performance that occurs instantly, it can also largely affect long term performance and muscle gains. One study documented the effects of hormones when a person is dehydrated; and this study discovered that dehydrated subjects had an incline in cortisol levels after resistance training as opposed to the hydrated group (3). Which means that the dehydrated group will have higher rates of protein breakdown and will be forced to focus much harder on their diet to overcome this effect and build muscle. This study also discovered that dehydrated people had both higher insulin levels and higher blood glucose levels after their workouts (3). The decrease in cell volume due to lack of water produces cellular insulin resistance which will negatively impact your strength and muscle growth. Many would say that insulin is one of the most anabolic of hormones, so take advantage of monitoring your hydration levels.

Can Sweating Contribute to Dehydration?

Now let’s get into what counts as dehydration and how sweating can affect the status of hydration. Studies have shown that a decrease in as little as 2% body mass due to dehydration is enough to negatively affect performance levels (6). For example, if you normally weigh 180 pounds and you weigh yourself before a workout, any reading under 177 pounds means you will more than likely be decreasing some of the weight on the bar or you’ll be lacking on some key reps during your workout. Assuming that you ignore your dehydrated state and get under the bar anyways.

If it’s one of those hot days in the gym and you’re giving it all that you got, it’s reasonable to assume you’re sweating about 1.5-liters per hour (6). This would be congruent to about 3 pounds of water lost per hour which means that you are down by almost 2% body weight in just one hour. If you’re training outside in the heat, it’s possible to sweat up to 3-liters an hour which would be about 6 pounds an hour worth of water that will be drenched from your body (6). Studies have also discovered that training in any temperature above 60-degrees Fahrenheit can increase cardiovascular strain (2),so if you’re dehydrated and working out at room temperature, you’re making things a lot more difficult on your heart than necessary.

Another caveat to consider is salt. The average person sweats out around a gram of sodium per liter of sweat (6). Sodium is a key component of muscle contraction, especially while being in a fatigued state. Having a sufficient amount of sodium is also necessary for maintaining optimal fluid volume within a cell (6), so normally if you’re low on sodium, there’s a big possibility that you’re also low on water and vice-versa. The need for sodium consumption is understated for athletes – let’s save this conversation for another time – so make sure you’re taking in the efficient amount of sodium around your workouts along with chugging down water.

Keys to Hydration

Fortunately, drinking 1/2 liter of water per hour of exercising is enough to counter further dehydration or lowering of body weight during training (2). In terms of metric measurements, a liter of water is 33 fluid ounces, so half of that would be 16.5 fl oz, or a medium-sized bottle of water. Drinking a quick swig of water is roughly an ounce, give-or-take a little. With that said, it’s easy to see that consuming between 16-33 fl oz during workouts isn’t too hard if you’re consistently taking a sip between sets. Even if you’re not feeling thirsty, it’s a good rule of thumb to take a trip to the water fountain or grab a quick swig from your bottle between sets. This is how you work smarter, and less harder!

So now that you know that being dehydrated can be terrifying, how can you prevent it from occurring before training? One review explains how consuming 500mL (16.9 fl oz) around 2-hours before training is a pretty good place to start (5). The best habit to form is to start sipping on water at least two hours before your workout if you haven’t already been taking in water all day. If you start to get light-headed or nauseous while working out, you’re most likely experiencing more than just dehydration, but you could have symptoms of hyponatremia as well, which occurs when your sodium levels are decreasing. Most sports drinks, such as Gatorade, have sodium in it so it’s definitely a good idea to sip on a sports drink during your training if you think you may have problems with sodium loss. I personally use a pre-workout that has a large amount of sodium and it has made a huge difference in my endurance. There are many intra-workout supplements that have solid electrolyte blends to help maintain sodium levels during intense exercise.

If you train in the morning, gulp on some water before going to bed at night. It’s inevitable that you will have to get up to use the restroom in the middle of the night, but this optimizes hydration before your morning workouts. I normally workout first thing in the morning and I aim to drink between 20-30 fl oz of water an hour before I go to bed along with my protein shake right before bed.


In conclusion, water may not be at all that exciting, but it may be one of the most essential elements for your current performance and your long term gains. Fortunately, it’s a deficit to overcome. All you have to do is keep a bottle of water around you at all times. If you get tired of drinking plain water, don’t hesitate to add some sort of flavoring into it to make it more palatable. Whatever must be done, just do it.


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