Why is starting hydrated so important? "Once you begin sweating you're generally going to be fighting a losing battle against fluid and electrolyte loss, so starting off properly hydrated can be extremely beneficial," says co-founder of Precision Hydration Andy Blow. "When you're properly hydrated you have a larger reservoir of fluid to draw from over time than if you're dehydrated."


In our Part II of our 3-part series related to Nutrition, Hydration and Gut Health for endurance athletes, we will focus on dynamic topic of hydration, electrolytes and the individualization of fluid balance. If you missed Part I (fuelling guidelines for the endurance athlete) please take some time to review the information as each aspect is optimized when working together. 

Becoming dehydrated during an endurance event can easily derail not only a potential breakthrough performance but it can also turn a functional athlete into a zombie stumbling aimlessly through a race course. Becoming dehydrated is subtle, cumulative and brings on very uncomfortable symptoms that are difficult if not impossible to reverse on the spot. Appropriate rehydration takes hours, sometimes days, due to the slow process of fluid uptake by the cells after severe dehydration kicks in. 

Similar to nutrition & fuelling resources, there is a plethora of information available to athletes about the role of hydration and strategies to manage fluid in-take and electrolyte balance. And, to be consistent in guidelines to athletes - there is no one strategy that works for everyone. With some of the information below (and more through Precision Hydration), we want to help athletes avoid severe dehydration as well as learn how to individualize hydration over the course of ultra endurance events. 

In Part III, we will discuss the role that gut health (and global stress) plays in athletic performance. Optimized gut health is at the root of everything related to energy, wellness and assimilating all hard work you do to become a performer on and off the race course.

Let's begin by discussing "the role of sports drinks" before moving into some guidelines and helpful resources. 



Content by Precision Hydration

Today you can get thousands of different sports drinks containing all manor of things. But what are they actually good for?

Well, your body burns energy when you're exercising because of the work involved in contracting your muscles and it also loses water and electrolytes through sweat. Whilst you have stores of all of these things, all three do need replacing if you exercise reasonably intensively for long enough.

Water, sodium and calories (in different proportions) are the three main things you need to keep the body going during prolonged activity. These are the bottom line ingredients a sports drink has to contain to address your body's needs when you're working hard and sweating. Most other things are just fluff.

There are some drinks containing additives with proven performance benefits, like caffeine, that can be somewhat useful as well, but at the core of it a sports drink is really just a delivery mechanism for water, salt and sugar.

Although the exact composition varies slightly from brand to brand, all of the major 'ades' (Gator and Power) offer a 'one size fits all' solution of approximately 6% carbohydrate and between 400-500mg of sodium per litre, flavoured to make them palatable (palatability matters when it comes to selling beverages).

Interestingly, this 'industry standard' is supposedly quite a bit more sugary and less salty than the very first iterations of Gatorade; perhaps catering more to taste and carbohydrate fuelling needs than maximising their ability to hydrate. This is especially interesting given the direction in which many sports drinks recipes are moving these days.

These drinks are generally termed 'isotonic' because they contain a similar amount of molecules to the body's own fluids (in the region of 285-295 milli-osmoles per kilogram), meaning they're a similar 'thickness' to your blood. As a result, they move across the gut wall into the blood stream at a fairly decent rate.

A good way to think of these industry standard isotonic formulations is that they are designed to be a jack of all trades. They aim to balance the delivery of digestible carbohydrate energy, some electrolytes and fluids to meet all of the main requirements of an exercising body.

To that end they can work pretty well in certain circumstances, for some people. However, this means that they are in fact the masters of no particular function. Despite their apparent versatility, they neither deliver energy nor fluids and electrolytes as effectively as products designed specifically to do one or the other.

They also fail to take into account the fact that calorie, fluid and electrolyte requirements are not synchronised. People's physiology, exercise habits and confounding factors (like the weather) all vary. This means that a single product with a set composition is sadly never going to work for all people, in all scenarios.

So, whilst traditional isotonic sports drinks might work fairly well in small amounts and for shorter activities, where they really start to struggle to deliver is in situations where exercise is prolonged, sweat rates are high and/or individual needs for components like sodium are on the higher side.

That's because, during these longer and sweatier activities, the balance of what your body needs to maintain performance starts to shift away from primarily carbohydrates (as is the case in relatively short, intensive endurance events) towards a greater emphasis on fluids and salts as losses of these finite resources start to mount up over time. This is when serious dehydration or electrolyte depletion becomes more of a threat.

If you're relying entirely on an isotonic drink to replace fluids and electrolytes and you simply increase your intake to meet your escalating needs when your sweat rate is high, gastro-intestinal distress (a.k.a 'gut rot') is often the unfortunate consequence.

That's something that has derailed many endurance athletes to say the least! This 'digestive unhappiness' happens because the stomach and intestines get overwhelmed with the high levels of sugar in the drink. Beyond a certain volume, most people will start to feel sick and bloated which is clearly no good for performance.

To avoid this scenario many athletes learn - often through simple trial and error - to dilute isotonic drinks down with water on hotter days or during longer events, making them hypotonic (i.e. a lower concentration than blood). This does make them easier to consume in large volumes and so helps to solve the fluid replacement issue to a degree, but it has the unwanted side effect of diluting the already minimal levels of electrolytes found in them down to largely insignificant levels.

And this is the reason why a select few modern sports drinks (including the Precision Hydration) have moved on to a hypotonic composition.  These tend to have lower levels of carbohydrate (around a 3% solution, rather than the 6% solution in isotonic drinks) and much higher electrolyte content. 

Whilst the lower level of carbohydrates in the drinks makes them slightly less effective for fuelling, it makes a lot more sense than using isotonic drinks to try to meet all of your needs at once, but not quite fully meeting any of them.

Athletes who drink hypotonic drinks meet the lions share of their fuelling needs through consuming solid or semi solid options like gels, energy bars or 'real' foods instead, depending on the event. In other words, by largely separating your fluid/electrolyte replacement needs from your energy requirements, you can dial both in to your individual physiology rather than finding a 'happy medium'.

If preventing excessive dehydration is the main role of a sports drink, then there's a strong case for looking at the substance it is trying to replace - sweat - to help determine the optimal composition.

The interesting thing about sweat is that how much sodium you lose in it varies dramatically from person to person. Whereas the intracellular electrolytes found in sweat (potassium, calcium and magnesium) tend to be lost in very tiny and consistent amounts in sweat, sodium loss (which is predominant ion in extracellular fluid) can vary 10 fold between individuals. It ranges between around 200mg per litre (32oz) of sweat and 2,000mg/l.

And, although it's so variable between one person and the next, sweat sodium concentration remains pretty stable within an individual, so your own sweat composition can be almost permanently categorised as Low, Moderate, High or Very High.

Coupled with differences in sweat rates (driven by genetics, work rate, environmental temperature and so on) and total sweat volume losses, over time sodium output can vary 30 fold between two athletes doing the same activity.

Because sodium plays such a critical role in fluid balance, nerve impulse transmission and muscular contraction, a truly effective sports drink needs to replace it at a level that takes into account this high level of variance in losses from one person to the next.

In other words, whilst a 'one size fits all' formulation might work for some of the people some of the time, it will never work for all of the people, all of the time. And this is especially true for the 'outliers' - those people whose sweat volume and sweat sodium concentrations are either very high or very low - as their needs are not well catered for by a single formulation of drink that aims to hit the middle of the bell curve.

All of which leads us to the point we're at now with sports drinks starting to become tailored to meet the physiological requirements of the individual athlete. 

Below are a few links to some great articles on the Precision Hydration Blog addressing some of the most common questions and offering further impetus to address your own personalized hydration needs.

You can train as hard as you wish, but if you ignore the fundamental nutrition and hydration habits then you will inevitably reduce adaptations, heighten stress and risk of injury, and also experience fluctuating daily energy. 




Hydration Guidelines:

As detailed in our Nutrition Article (Part I), below are guidelines for hydration. Remember, you're not just fuelling & hydrating for training and racing, you're fuelling & hydrating for performance in everyday life as well. 

For starters, think of hydration in terms of two aspects:

  1. Training & Racing Hydration: Fluids consumed in training
  2. Life Hydration: Fluids consumed outside of training 

Training & Racing Hydration:

  • Sessions less than 60 minutes: drink to thirst with water. No need for sugary sports beverages. Women in high hormone phase or post menopausal will have dampened thirst sensation so utilizing a timer to cue when to hydrate can be beneficial.
  • Sessions over 60 minutes: consume one bottle per hour on average (will vary based on humidity, heat and other factors) or approximately 10-12 ml/kg body weight/hr.
  • Shoot for the higher end range when temperature is above 24 degrees Celsius.   
  • Aim for 3-4% concentration of carbohydrates in solution. 
  • When you consume calories, it is best to consume fluids with little hits, more consistently. Taking in large amounts of calories or fluid at one time may cause GI distress.
  • Sipping every 10-15 minutes.
  • The longer the session, the more important the hydration becomes.
  • Electrolytes balance will be based off your Precision Hydration results. 

Life Hydration - Fluids Consumed Outside of Training:

  • There is no place for sugar-laden drinks in daily life. 
  • Shoot for half of your body weight in fluid ounces.
  • Sip on water throughout the day.
  • If training heavily, add pinch of salt, a splash of maple syrup and a little bit of citrus in your water. The sugars from the maple syrup will help pull sodium into the cells as well as provide some natural minerals. Alternatively, invest in Precision Hydration sachets for ease and customization.


As many of you will learn at the Brite Camp on Fuelling the Hungry & Thirsty Endurance Athlete in Whistler, BC (June 29th to July 1st), Precision Hydration has been championing personalized hydration for years now and it's really starting to catch on. PH offers athletes an Advanced Sweat Test - which tells you exactly how much sodium you lose in your sweat and allows us to build a personalized hydration plan around that data. They also offer a free online Sweat Test  that'll help you get started with refining your hydration strategy through some good ol' fashioned trial and error in training.



No matter how many kilometres you log as an endurance athlete, if you are passionate about going long and performing when it counts, you will do nearly anything to keep your streak going strong. Endurance athletes are often the ones that suffer from unidentified symptoms of gut distress be it seen in the lack of quality sleep, mental or emotional instability, unsettled tummy (aka: bloating or gas) in training and life, difficulty losing weight despite training load, suppressed immune system, re-occurring injuries and poor performance outcomes.  

Taking care of your digestive health and gut functions may be the single most important step you can take to support your endurance practice and help you live your happiest and healthiest days. In Part III, we will discuss the role the gut plays in an endurance athlete's life and the signs and symptoms that signal less than optimal functioning. While we will shed light into practical solutions and options, sometimes it takes a deeper look into how symptoms are showing up in your body, mood or performance. If you feel you are under performing or losing your edge, digestive health might be the key to your next breakthrough.