How much should endurance athletes drink ?

Your hydration strategy could be the missing tool in the toolbox in your approach to maximining your performance. Hydration gets overlooked fare too often, but now its time you should be really placing the deserved attention on your own personal hydration plan to prevent dehydration, and allow your body to utilize the fuels your putting into your body during training/competition allowing you to work harder for longer.

Hydration & Your Performance

Getting your hydration right is vital as an athlete if you want to be able to compete at your best.

Unfortunately, this aspect of the diet and comp day fuelling plans, can be over showed by focusing on other fuels, such as carbohydrates & supplements extra.

As an athlete depending on the conditions & environment when training/competing in moderate prolonged exercise sweat rates can be as high from 1-2.5 litres per hour. With this dehydration can set in resulting in earlier onset fatigue. Reducing your performance.

What the research shows

 Serval studies using an incremental and constant load exercise protocols have shown the impact of dehydration and or hyperthermia (high body temperature) on VO2max and over all endurance performance. During these studies when athletes were dehydrated by 4% of there body mass (ie 3.2kg loss in an 80kg athlete) their work capacity was reduced from 9-12%. However on the flip side during these incremental exercise studies when the loss in body mass was minimized by regular fluid ingestion throughout there was no significant fall in VO2max. Meaning that maintaining a hydrated state while training/competing can allow you to maintain that higher performance.

Takeaway message form the research

 What we can currently take away from the research is dehydration levels resulting in a 3-4% drop in body mass, often the case during endurance events, promotes hyperthermia (high body temperature) impairing submaximal and maximal endurance exercise capacity. These impairments are associated with a significantly reduced VO2max and a greater reliance on muscle glycogen and cellular metabolism. Meaning your potentialy going to burn through more of your muscles precious fuel source and have to deal with more by-products placeing a higher demand on your body for the same given exercise intensity (if you were in a hydrated state). In the cold similar dehydration will have a smaller effect on exercise performance.

Dehydrations impact on your Muscles, Brain & Heart

We know that dehydration as little as 2% in total body weight will start to have a negative impact on performance.

But what’s really going on under the hood.

 Hydration and your Heart

 A key feature of dehydration is a progressive fall in cardiac out put and cardiovascular strain seen during prolonged exercise in temperate / hot conditions. With the decline in cardiac out put heart rate rises continuously (upwards 30 beats/min), whereas stroke volume declines by as much as 30%, limiting the filling of the heart.

This results in the heart trying to work harder to keep up with the demand being placed on the body, but its capacity to carry out the work required is greatly reduced, ultimately resulting in decreased cardiovascular performance.

Hydration and your Muscles  

 As we exercise in a dehydrated state our cardiac out put is greatly reduced having a knock-on effect to our working muscles. Less oxygen is being delivered to our skeletal muscles while the oxygen reserve is too small to compensate for this lack of supply. Hence dehydration & hyperthermia result in a large fall in active muscle blood supple during prolonged exercise reducing the capacity to generate motion and hence performance out put will suffer.

Hydration and your Brain

 The onset of dehydration (> 3% in body mass) during prolonged exercise in temperate/hot conditions, leads to cerebrovascular (blood flow in the brain) instability by speeding up the decline in cerebral blood flow.

So, in summary, exercising in the heat inducing severe body hyperthermia compromises cerebral perfusion (blood flow to the brain) during submaximal and maximal endurance exercise. The development of dehydration intensifies the strain leading to a fall cerebral blood flow.

Moral of the story, you need to drink your water if you want to perform at your best.

So how much and what should you drink ?

Theres two things that you can do that will help you nail down your optimal hydration strategy, first how much volume of fluids you need and second whether to pick water or a sports drink. So let me get right to them.

1) Sweat test your self

 Assessing your own hydration is a crucial part for you as an athlete, and this needs to be done on a regular basis, because we need to account for the changes in weather, and conditions your training / competing in.

 How to sweat test your self

1. Weight your self immediately before you begin your training. In your training gear clothes, shoes extra.
2. Reframe from eating or drinking during your training session. If you do need to drink, make sure to record how much fluids you consumed during the training.
3. Weight yourself immediately post training. Again, in all your training gear.

The volume of sweat lost will be reflected in your weight loss (i.e. down 1kg  post training = 1 litre of body water lost), therefore you would need to drink 1 litre throughout that session to insure optimal hydration.

 If you did consume fluids during training, add that amount to the to the calculated volume lost. I.e. down 0.5 kg in weigh, consumed 500ml. Therefore, you would need to consume 1 litre of fluids for that type of training.

 If in doubt

Stick to these general hydrations recommendations and they’ll keep you out of trouble.

 Pre training

Current recommendation from the American college of sports medicine is to consume 5-10 ml/per kg of body weight in water 2-4 hours pre exercise for optimal hydration.

 Daily

A good starting point when it comes to getting in the volume if water you need to stay hydrated is 30 – 45 ml per kg of body weight per day.

 Pee colour

You can assess your pee colour first thing and throughout the day, aiming to keep it clear with a slight tinge of yellow (note supplements can change you pee colour).

2) Lastly Water or a Sports drink?

This is a question I get asked a lot by athletes. Should I bring a sports drink with me or just stick to water during my training.

 Well it depends on a few factors.

 The intensity of the training session, the duration of the training session, weather your training low or high carbohydrate availability, the conditions (temperature, terrain) and weather you want to really maximise your performance in that training session.

 So, you need to ask yourself the following questions.

 Just to note you need to go through theses questions for your different types of training sessions. For example, you answers will be quite different when comparing a strength based session compared to a interval running training session.

Questions

1. Is the training session going to be intense (7+ on an RPE scale)?
2. Will the training session be longer than 60minutes?
3. Is my training sessions focus on all out maximal physical performance?

Answered No

 If you answered no to all questions, then for you water is most likely to be the better choice for your fluids for your training session.

Note; if you in a training low phase (low carbohydrate intake) then water is what you need to stick to when training.

 Answered Yes

If you answered yes to the all the question or yes to question 2 & 3, well then, a sport (carb based) drink then is most likely the best option for you training hydration.

Note; if you in a training high phase (high carbohydrate intake) then a carb-based fluid is what you need to stick to when training. The Ideal drink should be a 10% carb solution of a 2:1 glucose/fructose mix.

The only exception of sports drink when in a training low phase is when your goal is to train your gut.

 "Thanks  for checking us out and having a look at our blog. And please do remember that I’m here to help you in any way I can so don’t be shy and get in touch with any of your questions, Id be more than happy to help you."

Don’t forget to download our E-book on the Food exercise and the Gut. This is an essential guide to solving any GI issues you may have during your training while also preventing any  GI episodes from happening when you are competing next.

Grab the eBook

Here are the main areas that I cover in this eBook that can help you take your performance to the next level.

1. Finally, understand what’s happening to your Gut when competing.
2. How to optimal train your gut to absorb more carbs
3. How to fuel for correctly for your training.
4. Know what supplements can help and not waste your time and money.
5. How to build an insurance policy preventing GI upset from happening to you

References

Trangmar, S. and González-Alonso, J., 2019. Heat, Hydration and the Human Brain, Heart and Skeletal Muscles. Sports Medicine, 49(S1), pp.69-85.

Kenefick, R., 2018. Drinking Strategies: Planned Drinking Versus Drinking to Thirst. Sports Medicine, 48(S1), pp.31-37.

Corcoran, M. and Ayotte, D., 2019. INDIVIDUALIZED HYDRATION PLANS FOR ULTRADISTANCE ENDURANCE ATHLETES. ACSMʼs Health & Fitness Journal, 23(4), pp.27-31.

Cheuvront, S., 2020. Hydration Assessment Of Athletes. [online] Gatorade Sports Science Institute. Available at: <https://www.gssiweb.org/sports-science-exchange/article/sse-97-hydration-assessment-of-athletes> [Accessed 27 June 2020].

Kostelnik, S., Davy, K., Hedrick, V., Thomas, D. and Davy, B., 2020. The Validity of Urine Color as a Hydration Biomarker within the General Adult Population and Athletes: A Systematic Review. Journal of the American College of Nutrition, pp.1-8.