Here by the sea and sand

Nothing ever goes as planned

It’s a life giving substance and without it we have 3 to 4 days before we will no longer be around on this planet. It is that important to our survival. On the other hand we can go up to 3 weeks without food, but not water. Our body is largely made up of water and every living cell needs it to function.

We are constantly losing water, through bodily functions such as going to the bathroom, sweating and also breathing. In extreme situations the body can lose 1 to 1.5 liters of sweat per hour. If this amount of water isn’t replenished it can lead to death as blood volume can decrease. A loss of water in the amount of 10% of your body weight is considered a medical emergency and if not reversed can lead to death.


But I’m not writing this to discuss extreme situations but more so how water plays an important role when exercising. Especially when it comes to performance and how we feel mentally when working out.

8oz water
8oz of water is almost a pint of beer

I think it’s a fair assumption to say that 99% of people who show up to exercise are already  dehydrated. Busy day, rushing around, not thinking about drinking water results in the body becoming somewhat dehydrated. Most of us consume drinks that have caffeine which is a diuretic which then causes us to pee out the water we do have. And when this happens and we then start exercising, sweating, we are losing even more water. And this can lead to a direct impact to our performance. And you probably won’t even notice or really understand why you didn’t perform as well as you should have.

A loss of 2% of your body weight through water loss can have a negative impact of up to 25% to your performance. Let’s look at an example:

  • Body weight = 120lbs
  • 2% of 120lbs = 2.4lbs
  • 80z of water  = half a pound

Now, let’s look at the average sweat rate. The average person sweats roughly 27.4 to 47.3 oz per hour when exercising. That’s 1.75lbs to 3lbs of water lost, almost close to the 2.4lbs if you are a ‘light’ sweater or over if you are heavy. Heres another way to look at it. Let’s say the average water bottle is 24oz (I hope you know how much yours holds) and you drink the whole contents during that hour. By this example you are still under the amount a light sweater loses during that hour. If you care about performance that should wake you up.

we need to replenish our fluid loss from sweat

Other performance problems caused by being dehydrated are lack of mental sharpness, cramping, muscles don’t perform as well. This can all add up to having a bad workout and not feeling like you owned the workout. Working out is tough as it should be hard, we all know that but you want to walk away feeling really good, not feeling like you were defeated. A well hydrated athlete will feel sharp, stronger, feeling like they can keep working out. Why? When well hydrated the heart does not have to work as hard to pump blood to provide oxygen and nutrients to the muscles thus providing better performance for the same amount of work being done.

But of course you are drinking water when you exercise so you are ok. I hope so but most of us are not drinking enough before and during exercise and as I stated earlier, most of us are running a water deficit when starting to exercise.


Here are some general guidelines to help ensure you are hydrated before, and during your exercise routine:

  • 2 -3 hours before: drink 17 – 20 ounces of water
  • 20 – 3- minutes before workout: 8 ounces of water
  • 10 – 20 minutes during exercise: 7 – 10 ounces of water
  • Within 30 minutes after workout: 8 ounces of water

Are you doing this? Are you sure? Just like measuring our heart rate to know what percentage of exertion we are exercising at you need to measure to be sure. And I’m pretty sure no one does this. It’s one of those things we really don’t pay attention to. Also, we tend to be light on the water we consume as we are afraid of upsetting our stomach if we drink too much. It’s that whole balance thing. And I don’t think we hear enough about this either. I can talk from experience that I know I don’t drink enough water. I discovered this by measuring out 8oz of water and then drinking it. I compared this to the amount of water I drink when running and and I am way under. Try this to see where you sit. Measure out 8oz of water and put it into your water bottle you tend to use. Now drink it in the same manner you do when you work out? Seems like a lot more?

What can be done to help get the water you need? You need to measure the amount you consume and sweat. How much does your water bottle hold? I hope you know because that’s a good place to start. If you don’t know how much water your water bottle holds measure it.

But how much do you need? Are you a light or heavy sweater? One way to know your requirements is to measure what you lose when working out.

Measure your sweat rate (make sure you are well hydrated before starting):

  • Start with going for a pee. Then weigh yourself without any clothes on (A)
  • After exercise towel yourself dry (be sure to dry your hair also) and measure your weight again without clothes on (B)
  • Subtract your post exercise weight (B) from your pre exercise weight (A)
  • Weight loss (C) = A-B
  • Subtract the weight of the water bottles to get the weight of water consumed (Z)
  • Add the weight of the water (Z) to amount of weight lost (C).
  • Subtract bodily void weight from total weight lost (C) – you can use .6lb for this per bathroom visit

Here’s an example:

1 hour run:

  • Starting weight: 160lbs
  • Ending weight: 158lbs
  • Fluid consumed = 30 ounces
  • 2lbs of weight loss = 32 ounces of sweat
  • Total fluid loss = 32 ounces lost + 30 ounces consumed = 62 ounces total

62 ounces of fluid loss for a one hour event = 62 ounces / hour.

Now, this is one example. There are different variables that come into play, things such as temperature, humidity and sea level. It’s always a good idea to measure your water requirements in different conditions and adjust accordingly.

*NOTE – As with anything, too much of something does not make it better. If you are consuming too much water (hyponatremia) it can cause nausea, headaches, confusion, fatigue, and in extreme cases, coma and death due to diluting your electrolytes. This is rare but it can happen.


Working out is exhausting enough. You wan to be able to push yourself as hard as you can and feel good doing it, not feel like you have been run over by a truck. Everyone is always looking for that something that will give them a boost. Here it is and it’s free, water. Consume proper amounts of water and you just increased your performance levels. Can it get any easier?

Yours in health,






Author: darryl bennett

A certified Canfitpro personal trainer specialist, and a Yondan (4th Degree) black belt in Shorin Ryu Shorin Kan karate, training at Ferraro Karate under Sensei Stephen Ferraro. Also holding a certificate in Plant Based Nutrition from ECornell University. Fitness and health have been a big part of my life, and always will be.

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