Role of nutrition for Triathlon training

Nutrition plays a key role in the life of a triathlete.  For a triathlete eating the right food at the right time means they are able to train harder, recover faster, adapt better and ultimately help them to perform to the best of their ability.  Nutrition plays four key roles in the life of a triathlete:

Fuel:  Triathletes have a heavy training load which means they need plenty of calories to perform all their training at the desired intensity, recover afterwards and stay healthy.

Health:  For a triathlete staying free from illness and injury is a constant battle due to the heavy training load.  Getting the nutrition right around training allows the body to fight off illness and prevents injury.

Function:  The food we eat provides the body with the nutrients it needs to repair itself and function effectively day to day.  Food provides the building blocks of the body and allows the body to make sure that everything works in the way it should.

Performance:  Eat for energy, health and function and you will maximise your training.  Nothing improves performance like training.  When race day comes eating the right foods will push a triathlete beyond their normal performance.  Get it wrong and they will go slower.

Improve your performance - Learn to cook

Seems so simple doesn't it.  Learn to cook and your performance will improve.  Well your health certainly will improve and with that comes a better ability to train and a greater chance of your body recovering between training sessions.  You learn to cook and the quality of your diet improves exponentially, and the quality of what you eat is key.

When you eat food there are a series of responses which go on in the body.  Your body produces heat in response to the digestion of the food you eat, scientists like to call this diet induced thermogenesis.  This takes energy to do and is an important part of your body functioning properly.  Depending on what you eat you will get an increase in the amount of sugar in your blood and the amount of fat too.  Too much sugar in your blood (called hyperglycamia) leads to "stress" on your body, similarly with an increase in fat (lipids in science language) in your blood, especially some of the saturated fatty acids.

Two newer areas which have been researched are the postprandial (after eating) response of your bodies antioxidant system and the inflammatory system.  You generally want your bodies antioxidant system to be in good working order and preferably not have too much inflammation. 

So lets take a look at these four areas and see how they are affected by processed food versus "homemade" foods:

Diet Induced Thermogenesis:  A lovely recent study by Barr and Wright from Pomona College in the USA looked at the effect of eating a processed cheese sandwhich on white bread versus cheddar cheese on whole grain bread.  There was a 50% increase in diet induced thermogenesis due to the "homemade" sandwhich compared to the processed food.  Now I now what your thinking.  Cheese and Bread doesn't sound too healthy or even homemade, but if even this small change can have such a big effect imagine what a proper homecooked meal would do.

Postprandial glycamic and lipid responses:  Generally processed food is full of processed carbohydrates and bad saturated fats.  These lead to spikes in blood glucose and lipids which lead to your body becoming over stressed.  If you cook food yourself it will generally be lower glycamic index and contain reasonable amounts of fibre which slows absorption and lowers the peak response in blood sugars and lipids.  There are also some nice ways to help your body cope with these postprandial responses, and they are called herbs and spices.  Cinnamon is particuarly effective in helping your body cope with nutrients you eat.  Hlebowicz et al. (2007) showed that just adding 6g of cinnamon to a rice pudding meal will reduce the post prandial glucose response .

Postprandial antioxidant status:  This is key to general health, as these support your immune system and will help you recover from the stress of training.  A lower glycamic index meal will have a greater response to your bodies antioxidant status, whereas high glycamic index meals will have only a small effect on the bodies antioxidant status.  We also know that fruits are particuarly good at increasing your bodies antioxidant capacity after you eat them.   

Postprandial inflammation:  This is quite a new area but is quite interesting.  There has been a large increase in research suggesting that diet can contribute to low grade inflammation which in turn can be linked to many chronic diseases such as diabetes.  From a sport performance perspective if you have a constant low grade inflammation you will not recover properly and are more likely to get ill.  Certain foods seem to cause large inflammatory responses such as alcohol, added sugars, other refined carbohydrates and saturated fats (sounds like a processed meal!!!).  Foods which decrease the inflammatory response to food include fruit, vegetables, milk, nuts, wholegrains and fish (sounds like homemade meal).  Arya et al. compared the postprandial inflammatory response to kangaroo meat versus a more processed meat called wagyu (the research was done in Australia!!!).  Various inflammatory markers such as IL-6, TNF-alpha and C-Reactive Protein were measured.  The wagyu meat showed significant increases in these inflammatory markers, whereas the kangaroo meat only showed a slight increase in these markers.  Therefore, buying good quality meat and other foods is key.  

So hopefully you are convinced that learning to cook will help your performance, it will certainly help your recovery and if you can do that you can train harder.  Saying you can't cook is not an excuse, saying you have no time to cook is not an excuse.  You don't have to cook gourmet food which takes hours.  Keep it simple.

Individualisation of nutrition

Have you ever heard someone say if I look at a carbohydrate I get fat, or similarly that they can eat anything and not put on weight.  I bet you have.  This fascinates me, how the same people can eat essentially the same diet and have such as different response to it.  The idea of an individualised diet is key.  I think sometimes nutrition can be set up as a one size fits all approach, this worries me and if you don't listen to how your body reacts to food you are missing a trick. 

Lets try and put some science into this.  The first peice of evidence I want to look at is the idea of predicting energy expenditure whether it be from heart rate, accelerometry or some other form.  You tend to get a graph which looks something like figure 1.

Figure 1 - Predicted energy expenditure

Now, science likes graphs like that in figure 1 because there seems to be a positive and pretty good correlation between the actual energy expenditure and the predicted energy expenditure.  This means you can get a nice equation which predicts energy expenditure from something simple like heart rate.  You can then use this to calculate how many calories you burned during exercise and subsequently how many calories you need to eat.

However, not everyone sits nicely on the line.  At an actual energy expenditure of 200 kcal per hour one indivdiual has a predicted energy expenditure of 100 kcal/hour and another 300 kcal/hour.  This means that over one hour of exercise the prediction has over estimated or underestimated energy expenditure by 100 kcal.  Now this might not seem a lot, but for an endurance athlete doing lots of training this could add up.  You could either end up putting on weight if your energy expenditure is over extimated or maybe not train properly if your energy expenditure is under estimated.

What about how you react to different nutrients.  A recent study by Pittas et al. 2006 looked at how healthy men and women reacted to either a high glycemic load diet (basically a high carbohydrate diet) versus a low glycemic load diet.  What was interesting was that one group of individuals lost more weight on a high glycemic load diet and another group lost more on the low glycemic load diet.  The difference between the group was how the hormone insulin responds to a carbohydrate load (called an Oral Glucose Tolerance Test (OGTT)).  If there was a high insulin response in the OGTT then the individuals tended to lose more weight on a low glycemic load, if there was a low insulin response then individuals tended to lose more weight on the high glycemic load diet.

So if everyone has the same diet they are going to respond differently and therefore what you eat should be individual to you.  General guidelines are a great starting place but don't forget to listen to your body

How important is nutrition to triathlon performance?

This is often a question I get asked, how important is nutrition?  Why should I bother doing this?  These are valid questions and it is good that they are asked.  So why is nutrition important to triathlon performance.  Lets try and answer this in a scientific way.

About 10 years ago a scientific review was published looking at all the ways in which 40 km time trial performance can be improved from training through various nutrition techniques to aerodynamic changes.  The results of this were quite fascinating.  They showed that aerodyanmic changes to your bike position could make between 1 and 7 min difference to 40 km time trial performance in a novice athlete.  Training could improve your 40 km time trial time by anything up to 10 minutes and nutrition interventions such as carbohydrate and caffeine intake can make between a 30 and 90 second difference to time trial performance.  So nutrition interventions improve performance but not by as much as aerodynamics or training.

But I think the authors missed a trick, they forgot to factor in the effect of nutrition on training.  Eating the right things at the right time and you can massively improve your recovery for the next training session.  For a triathlete this is likely to come quite soon. 

More and more research is also showing that eating the right things can maximise the adaptation to training.  Eating can indeed make you fitter.

Of course the reverse is also true, some foods will slow your recovery and some will blunt adaptation.

So ultimately get your nutrition right and performance is improved, get it wrong and boy will you know about it.
  

Introduction

So if you are reading this welcome to my blog and thankyou for having a look at what this blog is all about.  This blog is simply all about Sports Nutrition.  Having worked in the field for many years I have often looked on the internet and thought how confusing it must be for the general public.  There is so much mis-information about not only sports nutrition but general nutrition too.  It is a minefield. 

The general philosophy of this blog will be to provide sports nutrition information based on SCIENTIFIC evidence.  There will be no fads, no gimmicks, no porducts to sell, no quackery.  Just simple evidence based information with a practical spin and my opinion on some of this science.

So to start the scientific theme lets put this into a scientific abstract

Aim:  To porvide the reader with a practical spin on scientific evidence.  To take the reader from scientific journal to their kitchen.  The main interest will be around endurance sport and Triathlon in particular, but I might chuck some nutrition for strength athletes in now and again.

Methods:  Commentaries, reviews of areas, thoughts and murmerings, recipies, myth busting, the list could be endless

Results:  A greater understanding of how nutrition can impact on your performance.

Conclusion:  Improved performance with appropriate nutrition.