Sports Nutrition

15 Mar

Sport Nutrition 

There is a lot of noise about Sports Nutrition. The claims are that it will make you go longer, faster, harder, stronger, farther which is all very olympian. Remember that many of these claims come either direct from the makers or from studies funded by the maker. Much of what is claimed is deliberately complicated to confuse and make it difficult for the consumer to understand what is going on. What’s more many of the studies are set up to make sure that the finders product is the one that comes out on top.

So what’s the truth? I’ll try and set it out below as briefly as possible and without getting too scientific. As per normal with me feel free to skip to the end where there will be some conclusions.

Fuel Sources

The human body effectively runs on two main fuel sources. Carbohydrates and Fat. These are both turned into a chemical called ATP which is used to activate the muscles. The bodies preferred fuel source at low intensities is Fat and at high intensities it is carbohydrate (CHO). Fat is stored in adipose tissue and CHO is stored in the muscle themselves and in the liver and the blood stream in lesser quantities. CHO is turned into ATP faster than Fat and the storage sites are nearer to or in the working muscle so that is why it’s used when the going gets fast. At rest the body is predominately burning Fat. As intensities rise the rate of Fat consumption drops and the rate of CHO consumption rises to the point where the body is burning very little Fat and predominately CHO.

Fuel Tank

The ‘average’ human only stores around 2000 calories of CHO, compare this to the 40,000 calories worth of Fat in even the leanest athlete and you can see why being as efficient as possible at using Fat would be beneficial for the endurance athlete  as you simply have much more in the tank. Going at full gas a large or powerful athlete can burn through 1000+ calories of CHO an hour.  This gives the athlete a time of 90mins – 2 hours before they ‘blow up’ and slow down to speeds where they switch back to Fat burning as their primary fuel source. Not so bad for a sprint distance triathlon or short Time Trial or Road Race. It starts to get a bit dicey for a half marathon or standard distance Triathlon. In an event lasting longer than 90 minutes refuelling starts to become increasingly important. At lower intensities you can go for much longer without taking on additional calories though this can place a high metabolic cost on the body.

So we have established that for intense activities lasting longer than 90 minutes it is important to refuel during the event to maintain the rate of CHO consumption and hence the intensity desired by the athlete. A bit like mid-air refuelling for a jet fighter!

This is predominately why sports nutrition will claim to allow you to go longer, faster, harder, stronger, farther. In order to control the effect most studies are done with the athlete in a fasted state having not eaten since the previous evening meal. They also normally involve some form of preliminary pre-exhasution phase to reduce the available CHO stores followed by a time trial effort. They will also often be comparing the sports nutrition product to water. You can see why you might be able to make an claim that ‘SuperSuger allows the athlete to go 45% harder’ in this very controlled case. Be very sceptical of any claim made.

Output

Even at relatively low intensities there is a limit to how much CHO and other fuel that the body can absorb. This is around 1gram per kilo of bodyweight per hour. this can be trained to a higher level and by using a mix of different sugars you can also increase the rate of CHO absorption. As 1 gram of CHO has around 4 calories you can see that you cannot keep up the with rate of consumption at high intensities. If you’re burning 1000 CHO calories an hour and putting in 400 you are only going to gaining some time before you have to slow down. At lower intensities however it is possible to keep going indefinitely. It’s very hard to predict how long this will be as everybody is different and has different metabolisms.

What is Sports Nutrition?

Drinks, Gels and Solids
Drinks are predominately CHO, Gels are CHO but a bit thicker, Solids are often some sort of Grain bar or Jelly Sweet

Mainly it’s CHO in various different forms. These can be Sucrose (table sugar), Glucose, Fructose, Dextrose, Maltodextrin to name but a few. These are transported through the gut by various mechanisms and turned into Glycogen by the liver. This is then moved to the muscles by the blood system. That’s really the long and the short of it. You eat sugar and it’s turned into fuel by the liver. Fructose in large quantities isn’t great and can cause distress to the gastric system. Find out what works for you at your race intensity. Maltodextrin is generally pretty safe.

Companies will add taste to the sugar to make it more palatable, they may add electrolytes (salts) to the product and they may add some additional aids such as caffeine to increase performance. In some cases a small amount of protein is also put in. The jury is still out on protein taken during exercise. It takes quite while to break down but may have an effect on stopping the body using it’s own muscles as fuel sources. It also help aid recovery post exercise.

I quite like High 5 Energy source as a sports drink – however have a good look a the ingredients list. It is effectively 2 sugars, Maltodextrin and Fructose in a 4:1 ratio, sea salt for electrolytes and fruit juices for taste. Cost is around £20 per kilo. You could make a smiler product using bulk powder for well under £5 with a splash of squash for taste.

Have a look at some of the sports chews and bars and the ingredients list. There is very little difference between a pack of Wine Gums and a very expensive Sports Chew. The main difference is that the sports product may be easier to get down and can be packaged more to make it easier to consume. 75p for 250grams of wine gums versus £1.50 for a gel with 25g of CHO!

Don’t be afraid of actually eating FOOD. I know a few people who will eat sandwiches on long rides – wheat flour is basically CHO in another form. Absolutely fine on a longer less intense ride and a welcome relief from sticky sports drinks. I’ve tried eating boiled new potatoes which has worked really well. Kept in a bag with a bit of salt they were great and easy to eat. The professional cycling team Garmin use specially prepared savoury rice balls which apparently the riders love. The humble banana comes with it’s biodegradable wrapper.

Fluid Intake

There is a lot of discussion going on at the moment about how much fluid you should be consuming while exercising. What I’ve taken away from it is that we should be drinking to thirst and not over consuming drinks. The problem with this is that if you are relying on your drink for fuel as well as fluid replacement you may run into trouble. If you are stuck on a rigid refuelling schedule of one bottle containing 75g of CHO and 600ml of fluid per hour you may not be hitting your fluid needs on a hot day or too much on a cold day. If you increase your fluid intake on a hot day you may take on too much CHO and get into problems digesting. If you reduce your fluid intake on a cold day you then run the risk of not consuming enough fuel. There has been some work to show that a drink mixed to 3-4% has the fastest rate of absorption though plain water is not far behind!

if a drink is mixed strong at a rate of over about 6-8% CHO to water it slows down the rate that the fluid is emptied from your stomach and gut. so it again this can cause gastric distress and blasting at high consumption rates. In addition the mix is highly variable during races. If your plan relies on consuming a certain number of calories from on course nutrition it is highly likely you will pick up a bottle containing less or more.

Because of this I would separate your fuel from your fluid for longer races over 90 minutes. My athletes racing 1/2 ironman carry calories with them on the bike and pick up water from the feed stations on the course.

Conclusions and Recommendations

  • Sports nutrition is largely forms of sugar with some nice extras thrown in to make it more palatable. It is possible to make your own very cheaply. if you use a drink mix to around 6% or less for optimum absorption.
  • Use sports nutrition for situations where you need optimum rates of absorption and consumption i.e. racing and some long, hard sessions. Aim for around 1g of CHO per hour per Kg of bodywieght, more if you can absorb it without distress.
  • On long rides or sessions of over 2 hours it’s generally best to eat food and drink water. I just eat sweets! Tangfastic Haribo are rocket fuel! Don’t be afraid to experiment. Sandwiches and bananas are great too.
  • For sessions under 90 minutes you don’t really need to consume any calories at all as long as you eat a good meal afterwards.
  • For long races take calories with you and pick up water to drink, make sure you DRINK TO THIRST
  •  Practise your fuelling plan before you race, don’t leave anything to race day. Different people can tolerate different products.
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