Sports Nutrition: One Size Does Not Fit all – Theory vs. Real Life

Triathlon is a demanding sport, of your time, energy, focus and money. I have been involved in the sport both as a competitor and as a nutritionist for well over 14 years. One thing that always amazes me is the time and effort people go to with their training and equipment selection but they often forget to focus on their ‘fuel’.

Nutrition should really be seen as another discipline in triathlon, as should sleep, so really there are 5 disciplines! It is vital for a good performance but it is also necessary to keep the body going year after year with heavy training loads and is especially important for good recovery between sessions and on race day!

The internet is now full of information for you to read about sports nutrition, some of the information is cutting edge research and other info is tried and tested plans and some is just nutritional folklore. Most information can be useful if you know how to interpret it, but therein is the problem. People are often looking for the ‘quick fix’, that 3% more power output or cutting 10 minutes off their PB that they are willing to try anything. With new information there needs to be a period of time where one practices new nutrition strategies and see’s if this latest change works for them, if their digestive system can handle it.

Research in sports nutrition at the moment is amazing. Some of the great minds in sports science are focused on endurance sport specifically and this is a great help for those competing in triathlon. Researchers are testing the bounds of performance and how to fuel the body so as to get the optimum performance. But the question still remains, can these new ideas be translated into real life racing plans and who will this work for?

For years we have been told (and been telling people) to ingest about 1 gram per kilo of body weight per hour or thereabouts (obviously a wee bit lower if you run above the 100 kg mark). In fact in my clinical practice I still start with this formula just to see how their digestive system handles it. More recent research tells us that we should all (no matter size or sex) be trying to ingest up to 90 grams hour for optimum performance if possible. The second part of the research says that to ingest over 60 grams and to get closer to 90, the carbohydrates ingested need to be from MULTIPLE sources not just a single source of carbs.

So what does that mean? First I would like to point out that the large majority of triathletes weigh between 60 and 90 kilos so these new guidelines are not that different from the old ideas (unless you are a tiny pixie or a 110kg guy). Let me explain further.

Research in the last decade has focused on the fact that our intestines max out on glucose absorption at 60gm/hour, so to get around this you must ingest multiple carbohydrates as this way you are absorbing through multiple pathways (like you have different doors in your intestines for different carbs to go through) and thus can potentially ingest more carb per hour. This means taking in glucose and fructose or sucrose or maltodextrin etc. at the same time. This is pretty phenomenal research and has really changed the way we should be thinking about fuelling during endurance events, to a point!

Many sports products (gels and drinks) have adjusted their formulas because of this research and you will often find multiple carb sources in products these days. Let’s be clear though, if you are going to try and ingest this amount of carbohydrate per hour you will potentially need to ingest more water as well. Sports drinks are made in what is known as a 6-8% solution, this means they contain 6 to 8 grams of carbohydrate per 100 ml of fluid as this is known to be an amount that does not inhibit gastric emptying. When ingesting a carbohydrate gel, you are ingesting a very concentrated source of carb and need to dilute it to a lower concentration in your stomach with the ingestion of water. Once the amount of carbohydrate sitting in the stomach goes above about 9% the rate at which fluid (and fuel) will leave your digestive tract becomes much slower.

So if you are attempting to go by the new guidelines and ingest up to 90 grams hour of multiple carb sources that means you also need to be ingesting more fluid per hour. There appears to be a better absorption with a higher concentration of carb if there are multiple sources available but you still need to consider your individual digestive capacity and tolerance. As Professor Asker Jeukendrup, one of the most knowledgeable endurance sports Nutritionists in the world says (see article link below) ‘Ingesting a carbohydrate solution that is very concentrated and/or has a high osmolality is likely to cause gastrointestinal discomfort.’

Now I don’t know about you, but for many people this is a volume that is very hard to consume. In fact if a very small person who does not have a high sweat rate, this could potentially cause a few problems. Over hydration is a serious issue in endurance sport, (hyponatraemia) and can land you in the medical tent or hospital for a few days. Most athletes I know struggle to ingest above the 1 litre mark and above this feel uncomfortable and also complain about how much they will need to pee.

Everyone has a different digestive sensitivity to racing. Some people it appears can eat almost anything and get away with it while others suffer terrible digestive issues that can lead to problems such as: vomiting, sloshy stomach, diarrhoea, stomach cramps and what many refer to as a stomach plug, none of which is fun and all of which can be experienced by someone while racing.

You must remember that your ability to absorb carbohydrates and fluids goes down if you…..

Are dehydrated, as you race harder ( intensity goes up), if the outside temperature is hot , the duration of exercise gets longer, if you over ingest carbohydrate without enough fluid to take the carbohydrate through at a good osmolality.

Are you getting my point? I think to get through an Ironman without any digestive trouble is a miracle (or at least half a miracle) and you should thank the triathlon GODS every time you pull this off.

Just because a Professional triathlete says that they consume a ‘set’ amount of carb from a certain brand doesn’t mean that your digestive system can do the same thing, sometimes it can and sometimes it won’t and more often than not it NEVER will. You see we are all different, whether you are a Pro or an age grouper it simply comes down to your own body, its physiology and its limits of digestive capacity while racing.

You need to approach your fuelling in triathlon, or any sport with trial and error, practice, change and then some more trial and error. If you perchance come upon a formula that works for you, personally I would say STAY WITH IT, if it’s not broken, don’t mess with it no matter what others may tell you, marketing may say or your training buddy may be doing. Don’t get me wrong it’s great to discuss nutrition tactics with training buddies, what else are you going to talk about on 100+km rides?

So to put an end to my story, please be aware that we are all different and you may be fine on 60 grams an hour while racing and someone else may be great on 90. Sports nutrition is not a one size fits all and you need to consider your size, digestive ability, sex, sweat rate, power output, ambient temperature during a race and probably 10 other things I can’t think of. If all else fails just remember the more expensive your bike, the better your digestive system will be!