Hydration in endurance sports: a Q&A with Andy Blow | EP#191

​​​​​Hydration in endurance sports: a Q&A with Andy Blow | EP#191

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About Andy Blow

• Andy is the founder of Precision Hydration and a former elite triathlete. 
• He now races swim run events. 

Q: How to rehydrate when you're doing evening workouts?

Q: How to approach pre-loading for races?

Q: Do I need to drink more if I don't have any issues?

Question from Pat - I drink 500ml of carb drink every 2 hours, and rarely have anything other than clear pee. If I try to drink 500ml every hour, as recommended, I end up peeing all day. I pee regularly anyway, every couple of hours. Is there a benefit to forcing down more fluid?

8:55 -

• No! If what you're doing works for you, stick with it.
• That's a relatively small amount of fluid consumption for an endurance athlete, but it's not unheard of. 
• I would expect Pat to be someone with a relatively low sweat rate. 
  
  If you don't seem to require as much fluid as the average, stick with what you know. 

Q: Is sports drink osmolality important, and how should it be considered when selecting a sports drink?

Question from Michael (Canada) - I've heard people recommending that the ​key role f fluid suggested to replace fluids lost, rather than act as a vehicle for carbs and electrolyte, so having an isotonic rather than hypotonic solution might be the best from that perspective?
​
The theory would be that hypertonic solution would draw fluid into the gut which would cause GI distress potentially, and not be as effective at hydrating the athlete?

10:09 - 

• Osmolality is the amount of stuff that's dissolved into a solution, so the more stuff you put into a drinks bottle other than water, the higher the osmolality goes. 
• It's important because the relationship between the osmolality of the fluid you're drinking, and the osmolality of your blood, dictates to a certain extent how effective that drink will be at delivering fluids, electrolytes and carbohydrates into your system. 
• You can split sports drinks into three broad categories:
• HyPERtonic sports drinks, which are heavy on nutrients or calories. They have a lot of solute in them and would typically be good at delivering energy quickly. However they are less effective at rehydration.
  
  Flat coke is an example of this type. It's 10% carbs, people drink it when they feel their blood sugar is low and it's effective at getting energy back in the system, but not good for rehydration.
• Isotonic drinks, which are a similar osmolality to blood. The typical drinks here are classic sports drinks like Gatoraid, Lucozade and Powerade. They contain 6-7% carb, a little bit of electrolyte, and lots of water.
  
  These are the jack of all trade sports drinks, designed to replace, some energy, some electrolytes and some fluids. They are good for athletes doing short and fast, or intermittent sports and need a little bit of a top up.
  
  These can go wrong for endurance athletes doing long hot races, because if you try to get all your fluid needs from a syrupy carbohydrate mix, it can cause GI issues and make you feel sick and bloated. 
  
  A study in Switzerland took a load of commercially available isotonic sports drinks and measured the actual osmolality of them, and most were actually slightly hypertonic, not isotonic. 
  
  As a quirk of product labelling, in order to classify a drink as isotonic it technically doesn't have to be fully isotonic, so they can stray into being a little bit strong. 
  
  They contain a lot of sugar so if you're consuming a large amount of them, that's what causes GI issues because you can't absorb it fast enough, and that's what makes you feel a bit sick. 
  
  Watering down an isotonic drink often makes them more palatable in hotter and longer events. 
• HyPOtonic drinks have the least amount of solute. 
  
  These are often primary recommendation for longer and hotter events because the primary role of your drink in those events is to rehydrate you, not necessarily give you energy. 
  
  A good hypotonic drink either has a small amount of carbs (2-3%), or some have no calories but relatively high amounts of electrolytes to replace what you're losing in your sweat. 
  
  This optimises the absorption in the gut and hydrates you a lot better than either drinking plain water, or drinking something with a lot of calories. 
  
  The downside of those is that you need to eat more calories if your energy demands are high - but this is the strategy that seems to work best with athletes once they're experienced at doing long distance. 
• When we talk about more solid food, it forms a bolus in your stomach and gets digested more slowly.
• I'm not sure on the exact rate of absorption of gels versus liquids but from practical experience, the longer and slower events get the more athletes seem to thrive on a combination of hypotonic drinks and solid foods. 
• As events get towards shorter and faster, but might still be going on for several hours, some athletes tend to gravitate more towards hypotonic drinks and gels and get on okay. 
• A lot of it comes down to personal preference and ability to tolerate what you're putting in, but also practice in training. 
  
  There's a lot of evidence that the gut is relatively trainable, if you start to experiment with different types of food and drinks and get the body used to it you can get better results. 

• The role of electrolyte replacement in fluid balance for athletes is still contested, and is fairly open for debate. 
  
  The reason for this is we need to replace them in approximate proportion to losses. 
• At some point electrolyte depletion and sodium loss because a problem for the body. 
  
  If you add sodium with drinks, you can maintain much better blood volume than if you just drink water alone, or just drinking a carb solution. 
  
  The idea of replacing fluids if we're sweating heaving for hours is to maintain blood volume. Blood is very salty so it makes sense to have an element of electrolyte in there. 
• The disagreement comes from some peoples requirements being very high, and others being negligible, so therefore there's not enough research on the individualisation to come up with strong guidelines. 
• We talk about having three levers to pull when it comes to the nutrition programme: your body needs calories, water and salt. 
  
  The proportion of those vary based on your output, the temperature, and from person to person. 
  
  Having a handle on what level of calories you can absorb and utilise, the amount of fluid you're using or that you can absorb, and whether you are a low, medium or high salt loss person you can then tweak them in training and competition. 
  
  You can then discover what the best ratio for you is.
• I personally learnt that my requirements for salt and fluid were very high, but I could race for fairly long distances on a low carbohydrate intake. 
  
  I always had to skew my intake more heavily towards a hydration focus instead of calories. 

Q: Proper hydration for children and teenagers

Question from Brent (Texas) - They do triathlons than range from 20 minutes to an hour or so. Do you have any recommendations for hydration strategies for younger teenagers, ages 11-15, for longer races that last up to an hour. 

22:18 - 

• I'm a Dad of two kids myself, and I'm fascinated by what they eat and drink. 
  
  Kids are generally quite good at being intuitive about what they need. They don't overthink it and just respond to their instincts. 
• Although up to an hour in Texas heat is a considerable amount of exercise, while kids are growing and developing trying to educate them on this is largely unnecessary and could be counter-productive.
• I would say the principle thing is making sure they've got drinks available, usually water, and making sure they can access them in an easy way and they'll sort themselves out. 
  
  If they're thirsty, they will definitely drink, if they're not the won't. 
• They should be left to their own devices unless past experience with certain individuals shows anything different. 
• There might be some things you can do such an encouraging kids that they should maybe drink more in the build up, and making sure they have drinks available during and after. 
• For a one hour race, thermoregulation of core temperature may be more important, particularly if you're pre-loaded with hydration. 
  
  There's evidence to show it can really impact your RPE and how you feel. 
  
  You see in the Tour de France on the mountain climbs, spectators often given the riders drinks and they pour it over their heads because they know it helps them cool down. 

Q: Carrying Precision Hydration products during long distance racing

Question from Dom (Luxembourg) - Doing a long distance triathlon I use Precision Hydration products (PH1500). My other fluid is gels dissolved in water, and is my fuel. If all fluids should be Precision Hydration, or half being Precision Hydration and half water, what is the easiest way to carry powder to mix it on the course with the supplied water? 

25:58 - 

• I would not usually recommend athletes drink exclusively one thing during competition. 
• If I'm doing a long race I use the PH1500 myself, but I'll always have a bottle of water available because as you get deeper into the race, your tastebuds start to tell you if you want something salty or water. 
• In a really long race, flavour fatigue can be quite off-putting after a while. 
• I know some athletes do mix drinks en route, but I'm not a big fan of it. 
  
  We recommend a product we have called sweat salts, which are capsules in a blister pack and they have 250mg of sodium in them. 
  ​
  If you start your bike with your bottles filled with your preferred drink mix, once you start running out you can get water bottles from an aid station and supplement with sweat salts capsules. 
  
  You need to take it in an appropriate ratio. E.g. if you're trying to get 1500mg/litre you'd take three sweat salt capsules for every half litre of water that you drank. 
  
  That feels like a more efficient way of doing it rather than trying to mix products on the course which can slow you down. 
• Having water in some of your bottles is a good safety net if you drink too much gel/it's unusually hot and you start to feel bloated or sick.  

Q: How to manage gastric discomfort on the run?

Q: Where do you stand on the drink to thirst tactic that Tim Noakes advocates?

Question from Cathy (Memphis) - ​I collapsed doing an ultra in extreme heat and ended up on a drip in hospital last year. A friend recommended the book Waterlogged by Tim Noakes. Having read it, I wondered if I was overdoing it with hydration, and not listening to my body.

36:12 - 

• The book Waterlogged by Tim Noakes definitely shook up the sports science and nutrition world a few years ago. 
• Time Noakes was the doctor and researcher behind uncovering the growing incidence of hyponatremia in sport.
  
  Athletes have got in trouble, and some have even died from over-drinking and diluting their bodies sodium levels. 
• He implicates the sports drinks industry in the book for advocating a 'more is better' approach to hydration. 
• 100 years ago athletes were recommended not to drink too much, but in the 90's it was common for coaches and sports scientists to recommend athletes drink a lot.
  
  Ultimately this led to an epidemic of hyponatremia. 
• Cathy intimates she may have been overdoing it with the drinking, and I would say in longer events an element of drinking to thirst is important. 
  
  Listen to your body, because you don't want to keep piling fluids in when you don't feel you're needing or absorbing them. 
• The view that Noakes takes in the book is quite extreme, and he advocates only drinking to thirst and only drinking water. 
  
  Based on experience I've had with athletes this isn't an adequate enough plan. 
• I prefer a blended approach where you have a hydration strategy and an outline plan, based on trial and error and research you've done on your own body. 
  
  Then on the day, you also do rely to an extent on instinct and thirst and it helps to prevent you from overdoing it. 

Q: Do potassium and magnesium need to be considered too, as well as sodium?

Question from Devon (Texas) - I hear sodium mentioned a lot when it comes to hydration, but what about the other electrolytes like potassium and magnesium - are these important ingredients to look for in a sports drink?

39:32 - 

• Sodium is mentioned a lot from a hydration perspective because your sweat comes from extra cellular fluid in the body, and the predominant electrolyte in extra cellular fluid is sodium so it's one we see the largest amount of in sweat. 
  
  Sodium accounts for about 90% of the electrolyte component of most peoples sweat. 
• Potassium is an important electrolyte in the body, and is the predominant intra-cellular electrolyte. 
  
  Although we need to replace some of it because we do lose small amounts in sweat, predominantly that comes from the diet. 
• Most sports drinks, if they're composed well, will have a higher proportion of sodium and might have a small proportion of things like calcium, magnesium and potassium. 
• The evidence behind the replenishment of those to replace what is lost in sweat is weak, but there also seems to be little downside to replacing some of them as well which is why they end up in most sports drinks. 

Q: How should hydration change with age?

Question from Steve (Richmond) - Im a 50-something triathlete and my own performances have inevitably declined with age. With age I find myself having to answer the call of nature more often and it made me think about how much I drink when I change and race. Should I be changing how much fluids I take on as I get older?

40:57 - 

• The evidence around this is that hydration is more of a challenge for a few reasons. 
• Thirst instinct is more blunted with age, so if you're relying on this then they are less trustworthy so it may be easier to become dehydrated before you know to correct it. 
• At the same time, you can get a weaker bladder which means you pee more and leads to loosing more fluid. 
• As you get older you also tend to lose muscle mass and in your muscle cells if where your body stores a lot of water so you have less of a reservoir on board when you start. 
• We usually recommend for older athletes maybe using a slightly stronger electrolyte drink when they are racing and training, especially if they're sweating a lot. 
  
  This will help them to absorb and retain more of what they drink. 
• Also paying particular attention to pre-loading so they're starting well topped up. 

Q: Could cramps in a race be hydration related?

Question from Raj (Leicester) - I recently did my first Ironman 70.3 and got terrible cramps on the bike at 70km, to the point where when I got off to start running my upper legs were locking with severe cramp. I take salt tabs on the bike but this is the second time on a long distance ride that I've had these problems. I don't get them when training but I have been training hard and rode right on point speed wise in the race. Could this be hydration related?

43:03 - 

• As we've discussed above, cramps is such a tricky one to diagnose. 
• The electrolyte theory of muscle cramping is not strongly supported by lots of great scientific evidence but it has masses of anecdotal and circumstantial evidence behind it.
  
  It's often a good place to start looking if cramps are happening later on in endurance events.
• The downside of trying to manipulate your hydration plan to see if it helps is relatively small, but the upside can be massive. 
• If he's taking three salt tabs across a whole 70.3 bike ride, that's a relatively small dose of electrolytes. 
  
  A typical salt tab might have 150-200mg of sodium in it, so he may be taking 600mg of sodium over 2-3 hours. That's a really small amount. 
• One place we'd start would be tweaking up the amount of sodium and fluid he's able to take on during the bike. 
• Another place to look would be intensity. We know if you ask muscles to do things they're not trained to do they can complain and cramp as a result.
  
  We'd want to make sure he does enough race intensity rides on his race bike. 

Q: Can you mix salt tablets into other energy drinks?

Question from Corey (Boulder) - I usually drink a carb-rich energy drink mix on the bike during half and full Ironman events, but I want to get more electrolytes in to set me up for a good run leg as my next race is a hot and humid one. Can I just mix salt tabs in with the energy powder mix so it's all in one bottle?

46:25 -

• People love the idea of combining all their nutrition, hydration and electrolyte needs into these home brew, one bottle mixes. 
  
  Generally I try to advocate against it.
• Partly because of osmolality - the more stuff you dump in the higher this gets and the more challenging it becomes for your gut to deal with it. 
• The other reason is that you want to be able to pull the three levers we discussed independently - calories, fluid and salt. 
  
  If Corey feels like he's low on energy and needs more carbs, but his main source then has extra salt and all his fluid, he's just going to have to drink way more and you can potentially run into stomach issues. 
• People do some very specific things with nutrition plans like this and find that they work for them, and if they do that's fine - performance is the best test. 
• But approaching this from a theoretical view I'd suggest having salt tabs as an additional and washing them down with the drinks. 
  
  You can then dial up and down the amount you're taking per hour based on how you feel. 

Q: Thoughts on new energy mixes with highly concentrated carbohydrates?

Question from Mikael - The new energy mixes we see that are highly concentrated carbohydrates (e.g. Maurten) - do you have experiences of those from yourself or with athletes? How do they work and how do they fit in with a race plan?

48:35 -

• Things like the Maurten ones are a hydrogel where they start off as a liquid in the bottle, and then with stomach acid they combine into a gel so you can allegedly absorb more carbohydrate via the drink per hour or serving without causing GI distress. 
• The scientific evidence behind them isn't really there yet - a couple of studies have been published, one being fairly positive and one inconclusive, about how much carbohydrate they make available in the bloodstream. 
• On a practical note I've had a play around with them myself and I was surprised at how palatable they were given the high concentrations of carbohydrate. 
  
  I found it very hard to make a strong judgement on whether they were better than having a drink and taking a gel, other than with the convenience factor of it all being in one bottle. 
• They are being used by a lot of athletes and there's some good performances linked to them, but whether that can be attributed to those specific products is a lot less clear. 

Q: When to pre-hydrate and what to use?

Question from Mirian (Bordeaux) - I read somewhere that you can pre-hydrate before a race. How many days before a race should I do that and what should I drink?

50:19 -

• The classic thing that I would do, and see so many athletes do is get worried and start drinking way too much in the days building up to a race. 
  
  This can actually be quite negative because it causes you to see more as your body equalises the amount of fluid it has on board. 
• You definitely don't want to go into a race dehydrated so it's important to make sure you have a normal, adequate level of fluid consumption in the days leading up. 
• We recommend starting to pre-hydrate the night before and the morning of the race. 
  
  If you take on much fluid before that you're just going to pee it out. 
• Usually we recommend a strong electrolyte drink, something like the PH1500, 500ml the night before and another 5-600ml the morning of the race about 60-90 minutes before. 
  
  This means you can absorb it, pee out any extra and hit the line in shape. 

Q: What is the biggest mistake that athletes make when it comes to hydration on race day?

Question from John (Dublin) - I feel like I made my fair share of mistakes during the course of my racing career, whether it's dropping cups at aid stations, forgetting to fill my bottles up or heading out on a long training ride without money or food. What do you think?

52:01 - 

• Hydration mistakes on race day fall into two extreme categories:
• Following an overly rigid plan despite what your body is telling you. 
  
  This can lead to overconsumption. I did this when I raced, particularly when it was hot. 
• On the flip side, going into a race with absolutely no plan, that can be just as disastrous! 
• The best performances tend to come from an idea and working within some well thought through guard rails, and then listening to your body on the day and adapting it as you go. 
• With training, a lot of it comes down to being organised. 
  
  Athletes are more likely to show up less well-prepared. 
• If you're training in the evening and aren't drinking adequately in the day, that's a problem. 
• You need to show up to sessions well hydrated, and if you're doing two sessions a day you need to ensure your hydration recovery is on point. 

Q: Using coconut water as an electrolyte?

Question from Pete (Halifax) - I'm training for my first Ironman 70.3 and I'm still trying to get a handle on what to eat and drink during the race. A lady in my training group went a whole season using just coconut water to fuel races. Is this something you'd recommend? I'm not convinced it offers enough to sustain me.

54:58 - 

• Coconut water alone is quite an extreme strategy. 
• Anything that's over simplified and quite extreme I would always be wary of when it comes to nutrition and hydration advice. 
• You need some water, some calories and some salts or electrolytes. 
  
  Figuring out the ratio and recipe of those given your individual outputs and the length of the race and environment is the key thing to do. 
• Coconut water has been marketed as a sports drink, but the composition is really odd for a sports drink - it's really high in potassium and really low in sodium. 
  
  This means it makes no sense for replacing sweat losses. 
  
  It does have a bit of sugar, but I don't know exactly how much - I would suspect it's low on calories so is unlikely to give a huge amount of carbohydrate to sustain you. 
• Splitting those three things out and figure out how many calories you'll need - the typical range for most guys is 50-80g or carb per hour. 
  
  How much fluid - 500-750ml per hour in not too extreme conditions is a good start. 
  
  Sodium could be anywhere from 200-1200/1500mg sodium per hour. 
• They are the three variables so figuring that out, and then working out what kind of nutritional drinks can help you meet those numbers and trialing that out. 
• In nutrition you do often see really extreme things - e.g. ketogenic diet, just eating meat etc. People get dogmatic about really extreme views and can usually pull out examples where it's worked for one individual. 
  
  It's often a lot more nuanced and individual than that, and a lot less simple to implement. 
• If there was a silver bullet that could really help, it would be used, it wouldn't be an 'extreme'. 

Q: Using different units for sodium

Question from Mikael - You mentioned 200-1500mg sodium per hour but often the units we use are per litre of fluid - how much sodium to put in the bottle. How would you use these different units - would you generally stick to per hour, or per litre? 

59:30 -

• Generally I prefer to talk in the per litre range because it's important that there's a ratio of sodium to fluid. 
• One of the dangers of using salt tablets is that you can increase the amount of mg of sodium you take quite dramatically but if you don't also take adequate fluids you end up with a mismatch of concentration in the gut which can make you feel quite sick. 
• Generally if I'm talking about 200-1500mg, you could say 200-1500mg per litre but the absolute net amount of sodium will vary with the volume of fluid that you intake. 
  
  1500mg/litre would be up towards the upper end of what is wise to use as a strong electrolyte mix. 
  
  Whereas 200mg is on the very light and weak end. 
  
  Playing around with the amount you drink at those specific ratios. 
• If you think you're somewhere who will require a lot of sodium, taking a more concentration solution is probably a good idea rather than upping the amount of sodium randomly and guestimating the fluid. 

News from Precision Hydration

1:01:41 -

• We're keeping busy thanks to it being the hotter part of the year in the Northern hemisphere!
• We're in the early phases of looking at new product developments. 
  
  We won't be able to announce them for a few months but we're in the process of expanding the range which is exciting. 
• We've grown our team at PHHQ and if anyone has got questions, we now have a full time team answering athletes questions on nutrition and hydration and related subjects. 
• They can get hold of James and the guys at hello@precisionhydration.com or message us through any of our social media platforms. 
• If you want to try the products, go to the website and use the promo code at the top of this episode for great discounts! 

Links, resources and contact

Links and resources mentioned

• On Precision Hydration's website
• On Twitter: @andybl0w
• Precision Hydration on Twitter: @thesweatexperts
• Precision Hydration on Instagram: @precisionhydration
• Precision Hydration on Facebook: Precision Hydration Facebook