Because hydration is only one piece of the ‘what exactly should I throw down the hatch when I’m training and racing?!’ puzzle faced by endurance athletes, we get a lot of questions about how to use our products as part of an overall fuelling strategy.

Until now, we’ve been answering those questions on a one on one basis, which has been a great way to understand lots of different ways our athletes are fuelling up. 

However, I thought it was time to address some of the basics in a blog post. What follows is supposed to be a fairly simplistic overview of our take on how to meet both your hydration and nutritional needs during endurance exercise. It's based on a combination of recent peer reviewed science and a healthy dose of personal experience.

What does your body need during endurance exercise?

No matter what kind of activity you’re doing, whenever you're exercising hard for several hours at a time your body loses water and sodium in sweat. It also burns calories, mostly in the form of carbohydrates stored in your muscles and liver.

Water, salt and calories are therefore essentially the main ‘costs’ of doing an endurance event.

The nuts and bolts of any sensible nutrition plan should therefore be largely based on replacing varying proportions of each of these three items to enable you to sustain your performance.

When it comes to fuelling, I find it helpful to break activities down into three broad categories...

  1. ‘Short’ activities (less than about 90 minutes)
  2. ‘Medium to Long’ activities (about 90 minutes to 4 hours)
  3. ‘Ultra’ activities (4 hours+)

Image credit: Asoggetti via Unsplash (copyright free).

Each of these categories demands a different approach when it comes to hydration and energy replenishment...

Short activities (<90 minutes)

Before you start

Make sure you begin whatever you’re doing topped up with fluids, electrolytes and carbohydrates. Trying to make up for a deficit if you start a bit dehydrated or energy depleted by eating and drinking during the activity itself is definitely leaving it too late.

From a hydration perspective this is relatively simple. Drink 500ml (16oz) of PH 1500 the night before your event and another 500ml about 90 minutes before you start, aiming to finish your drink no less than 45 minutes before go-time.

I wrote a blog diving into the science behind our advice on starting hydrated, if you want to understand this in more detail.

Remember, one of the main benefits of preloading before shorter activities is that it should reduce (or even remove) the need to drink much during your activity...

Whilst you're sweating

If you start most shorter activities well fuelled and properly hydrated, there's usually little to be gained from taking in large amounts of anything - be that water, electrolytes or calories - during the activity itself.

Your body has what it needs to last this long in reserve (even at a relatively high intensity) and you can simply refuel and rehydrate afterwards to replenish stores for next time.

This doesn’t mean you categorically shouldn’t consume anything during exercise lasting less than 90 min. You should absolutely still listen to your body and eat or drink if you feel you really need to (and it's also a bright idea to eat and drink something if you're training again very soon afterwards so you don't start the next bout of activity really depleted), but it’s worth understanding that the impact that nutritional intake is going to have on your performance during the race or session itself is probably quite negligible.

A slight exception to this rule might be if you are competing at the elite end of the spectrum in very high intensity aerobic events. There is some evidence that ingesting small amounts of a carb based drink (or even just rinsing it your mouth) can be beneficial to your performance in those circumstances.

Essentially the ‘mouth rinse effect’ is thought to be because receptors in the mouth shout to the brain ‘SUGAR IS COMING!’ (even if you just spit the drink out) and your brain then allows your body to work harder than it otherwise would - presuming more energy is on the way - tricking you into putting out a stronger performance than might otherwise be possible. For a decent summary of the idea see this post from Asker Jeukendrup.

Image credit: Mali Maedar via Pexels (copyright free).

This (along with keeping topped up for subsequent sessions or events) is one of the reasons why we still sometimes recommend having a bottle of our all-natural Precision Fuel & Hydration drinks to sip at during shorter events when this is convenient.

Medium to Long activities (90 minutes - 4 hours)

It’s during medium to long sessions that fluid intake and carbohydrate fuelling in particular starts to have more of an impact on performance.

There's a whole heap of research out there on the effects of carbohydrate ingestion on performance during longer periods of aerobic exercise. A 2013 paper called ‘The use of carbohydrates during exercise as an ergogenic aid' gives a decent overview if you want to dig into some of the technical details without doing your own PhD on the subject!

The bottom line from all that research and the current consensus is that taking in around 60g of carbohydrate per hour is optimal for most endurance athletes doing 2 to 4 hour activities. Think more like 40g/hr if you’re a smaller person and not working at a high intensity, but maybe as high as 90g/hr if you're bigger and going really hard at it. This carbohydrate can come from a range of sources including drinks, bars, gels and ‘real’ foods (if their composition allows for easy consumption and digestion).

Before you start

Again, it's important to make sure you begin whatever you’re doing well hydrated and fuelled. Trying to make up for a deficit is definitely leaving it too late.

I wrote a blog diving into the science behind our advice on starting hydrated, if you want to understand this in more detail, but in summary:

  • Drink ~500ml of PH 1500 the night before your event.
  • ~Drink 500ml of PH 1500 around 90 minutes before you start (finishing ~45 minutes before you begin)
  • Don’t just drink lots of water or 'low strength electrolytes' in the build-up to an event. You can end up diluting your body’s sodium levels before you start sweating.

Whilst you're sweating

About 90 minutes to two hours is usually the threshold at which sweat losses can become significant, so fluid needs must be considered along with fuelling at this point too.  

If you’re using our PH packets as your primary source of fluids, the important thing you need to know is that they contain around 17g of carbs per 500ml (16oz) bottle. This makes the drinks hypotonic (i.e. a lower concentration than your blood), so they’re easily absorbed by the gut. But, unlike isotonic drinks, they don’t deliver all of the carbs you’re likely to need during your activity.

It’s also crucial to remember that our effervescent tablets and Electrolyte capsules contain close to zero calories, so these won’t contribute to your energy intake at all. 

Example scenarios

If you use the PH packets and drink about 500ml (16oz) per hour in cooler conditions, on average you'll be getting 17g/hr of carbs from your drink, so will need to take in an additional ~43 grams of carb/hr to hit the 60g carb/hr target.

PF 30 Gels contain 30g of carbs, as does 1 packet of PF 30 Chews (each chew is 15g, and there are 2 chews per packet), so 1.5 servings would meet the mark. Taking half of a PF 90 Gel would also deliver the needed 45g of carb.

If you prefer your carbs a bit more 'old school', then 8 Bassets Jelly Babies contains 42g, so this could do the trick. Or, if you want to go 100% natural you could go for about 1.5 bananas, as they tend to contain around 25-30g of carbs per fruit. Though what you’d do with the leftover half, I’m not exactly sure...

Image credit: Charles Deluvio via Unsplash (copyright free).

In hotter conditions, where your fluid intake is likely to go up towards 1 litre per hour (32oz/hr) then you’ll now be getting up to 34g of carbs from your Precision Hydration drinks, so you'll be able to reduce the amount you eat accordingly. This would mean just taking in around 1 energy gel, half an energy bar, 4 jelly babies or 1 banana.

Alternatively, the Carb & Electrolyte Drink Mix provides 60g of carbohydrate and 1,000mg of sodium per litre.

We do know a few athletes who have very high sweat rates and can also absorb as much as 1.5 litres per hour of Precision Hydration drink when they're racing or training, usually in very hot conditions. These guys are already getting 51g of carbs from their drinks alone, so only need a relatively small amount from other sources to meet their fuelling needs.

These examples highlight that your fueling and hydration intake need to be tweaked in proportion to one another based on sweat loss and fluid absorption.

Bear in mind that if you don’t decrease your calorie intake from solid or semi solid foods at times when fluid intake is very high it can be a recipe for GI distress and this is a major reason why traditional isotonic sports drinks (i.e. those with a lot of carbs in, making them a similar concentration to your blood) can be very difficult to live with in longer and hotter events. That's because your need for fluid starts to be proportionally greater than they can comfortably deliver via your water bottle without overdosing you on sugar. 

In my own experience, using more highly processed ‘simple’ sports nutrition products like the PF 30 Gels or PF 90 Gels along with Precision Hydration drinks tends to work best because they reduce the amount of effort your body needs to put into chewing them, digesting them and getting the sugars into your blood stream.

These kind of events are also not quite long enough for you to get really sick of sweeter products and flavours, so it’s usually possible to get to the end without suffering the kind of nausea that so often occurs when you rely too heavily on sugar as you main source of calories during longer events.

'Ultra' activities (4 hours+)

Before you start

As with shorter activities it's crucial to make sure you begin an ultra distance event or session well hydrated and fuelled. In fact, as you'll be out there for a lot longer, some would argue its even more important. Making sure you get it right before you start is what you'd call 'free money' in the ultra-distance game!

We make a big deal about preloading with higher strength sodium drinks before these events and it would be almost criminal if you prepared to tackle an ultra distance race without reading our blog about how to start hydrated. If you're truly strapped for time though (we won't hold it against you), you won't go too far wrong if you follow these guidelines...

  • Drink 500ml of PH 1500 the night before the event
  • Drink 500ml of PH 1500 around 90 minutes before you start (finishing ~45 minutes before you begin)
  • DON’T just drink lots of water in the build-up to an event. You can end up diluting your body’s sodium levels before you start, increasing the risk of hyponatremia.

Whilst you're sweating

The required rate of fluid and carbohydrate ingestion for ultras is not dramatically different to what you should be aiming for during medium/long events. You’re still limited by the absorption rates in the gut for carbs and fluids, so the ~60g/hr and ~1l/hour maximums still apply. But, there are some notable differences to how we’d generally advise approaching fuelling for longer events.

First - because you're going to be out there for much longer, there's a lot to be said for introducing more variety into your energy and fluid intake so that you don’t become sick of the taste of any one thing.

Second - because you'll be going at a lower intensity than you would for shorter events, chewing and digesting more ‘real’ solid foods becomes a lot easier. This opens up a much wider range of possibilities for your race day menu. It also tends to keep your stomach a lot happier than asking it to process nothing but syrupy, sugary goo for hours on end.

Third - sodium intake (along with appropriate amounts of fluid) becomes far more important during ultra distance events because the risk of hyponatremia increases along with total sweat losses. So, its more important than ever to be getting an appropriate level of electrolytes in with your drinks. Of course this is not likely to be a problem if you’re using the right strength Precision Fuel & Hydration drink for you, or if you're supplementing fluid intake with the right amount of SweatSalt capsules, but it's definitely worth make sure you have a solid understanding of this. If you haven't already, take our free Online Sweat Test or check out our Sweat Test if you want to make sure you’re getting this bit right.

Image credit: Hans Reniers via Unsplash (copyright free).

Its also worth taking a look at our blog about how much dehydration you can tolerate before your performance is affected. Its a golden question for athletes and we've taken a look a the most recent research so you don't have to..

Finally - listening to your body becomes a critical component of staying properly fuelled and hydrated during ultra distance events. That's because the longer the event goes on, the harder it gets to predict how your body’s internal chemistry is going to react to the pace, temperature, environment, foods and drinks thrown at it during a long day out.

As a result, you need to be well tuned in to the subtle signals your body uses to tell you when it's getting out of whack and needs something specific to get it back on track. Look out for a craving for salty foods as this can be an early warning sign that you’re getting a bit low on sodium. If that is the case, eating something salty like salted nuts, pretzels or taking some extra SweatSalt capsules can be a good idea to keep everything balanced.

Example scenarios

Some examples of the foods and drinks I’ve successfully used for fueling during ultra endurance events are...

  • PF 60 Energy Drink Mix = 60g carb per litre
  • PF 30 Gel = 30g carb
  • PF 30 Chew = 30g carb (2 x 15g chews)
  • PF 90 Gel = 90g carb
  • Boiled new potatoes with butter and salt (DW Canoe race) = ~5g carb per potato.
  • Mini croissant with cheese and ham (NZ Coast to Coast race) = ~ 15g carb each.
  • Pizza slices (TransAlpine trail run) = ~35g carb per slice.
  • Marzipan balls (DW Canoe race) = ~10g per ball.
  • Flat Coke (Most long races, in the later stages!) = ~ 52g carb per 500ml/16oz.
  • Malt loaf with butter (Many long bike training sessions) = ~15g carb per slice.

In most of these cases I used these ‘real food’ alternatives in combination with plenty of the typical pre-packed fueling products and our hydration products to hit the kind of carb per hour figure I needed to achieve.

Fueling for ultra events always requires a lot of creative trial and error to figure out exactly what works for you. It's such an important part of these events that it's worth dedicating some time to getting things right.

When you start experimenting, make sure you’re staying close to the guidelines of ~60g of carbs per hour (across all of your foods and drinks), with enough fluid to stop you getting thirsty and a sufficient amount of sodium to offset what you losing in your sweat.

As an aside - because its something we do get asked about a lot these days - the idea of training to be 'fat-adapted' and fuelling lower intensity efforts from existing fat reserves i.e. the Low Carb High Fat (LCHF) approach is definitely gaining more popularity at the moment. Whilst it's definitely way too early to write this off as a 'fad' it's interesting to highlight the findings of a recent (2016) study into the competition eating practices of a group of elite ultra marathon runners.

After analysing the intakes of these guys before and during a race, they found that...

  1. they tended to choose to eat around 70g of carbs per hour during their long races (with minimal protein and fat intake) on average.
  2. that most (93%) of their calories came from pre-packaged sports nutrition products
  3. that in the words of the researchers "all of the athletes practiced fuelling strategies that maximise CHO [Carbohydrate] intake and are congruent with contemporary evidence-based recommendations."

Anyway, once you’ve tried some of this stuff out in the real world, don’t hesitate to get in touch with us if you’ve still got any specific questions and we’ll always do our best to get back to you with more nuanced answers. Whilst we certainly don’t know it all, we’ve had a few successes and failures in this space as a team, so we should be able to draw on some relevant past experience in most cases, and might well be able to help.

Further reading