Archive for February, 2012

Metabolic efficiency for endurance athletes, tapping into the fat..

This article is the first of a 4 part series, which will aim to give advice regarding nutrition and it’s impact upon performance and recovery. The 4 articles will cover the following topics:

  1. Metabolic efficiency for endurance athletes.
  2. Planning your weekly eating to enhance training and recovery.
  3. Sports event nutrition, what to eat on the day.
  4. Hydration strategy for sports events.

We operate a sports science testing facility in St Helens, Merseyside and have a particular interest in metabolic efficiency for endurance sports. Over the past 24 months we have completed endless hours of testing. We believe that metabolic efficiency is one of the key factors for success in endurance sports and we also believe that training alone is not sufficient to unlock potential. This series of articles will discuss the link between training and nutrition and how they can be manipulated to make you a better athlete.

Nutrition Part 1: Metabolic efficiency

During endurance events there are 2 main fuel sources, these are fat and carbohydrate stored within the body. Protein is used in small quantities but generally only supplies 2-4% of the overall energy demand, with the remaining 96-98% coming from fat and carbohydrate.

It is important to note that even during the latter stages of an event, our use of protein for energy does not increase. Muscle tissue may become damaged and there will be significant protein break down, but this is not being used for energy.

Fat is available in relatively large quantities within the body. A 70kg person with 15% body fat equates to 10.5kg of body fat (70 x 15%). In terms of stored calories, 10.5kg of body fat provides 94,500 stored calories (10.5kg = 10,500g with 9kcal per gram).

When moving at moderate speeds you will burn 500-750 calories per hour, so with 94,500 stores calories of fat, our 70kg / 15% body fat person should be able to run non-stop for 100 miles without any issue whatsoever!

Of course, it isn’t that simple. Competing in endurance events leads to muscle tissue damage and this is one of the main causes of slowing down. When we discuss carbohydrate and fat usage, we are simply discussing the manner in which we create energy. If your legs are physically damaged and unable to function, the ability to create energy becomes irrelevant. To compete for several hours, your body must be physically conditioned to the repetitive movement and impact. Combined with this, you must be capable of using fat as a fuel source.

What’s the catch with using fat?

Fat is a very poor standard fuel, it requires a lot of oxygen to break down each gram and is therefore very ‘uneconomical’. If you were to use fat as your main fuel source, it’s likely you would be moving very slowly.

By contrast carbohydrate is a much better fuel source. When you are moving quickly or working at higher intensities, a high percentage of your energy will come from your carbohydrate stores.

Why not just use carbohydrate for the full event?

Whilst our fat stores are relatively large, our carbohydrate stores are relatively limited and there’s not enough to last the length of most endurance events.

Throughout the event, your carbohydrate stores will be dropping continuously, leading to a ‘switch’ in energy provision from carbohydrate to fat. In the opening miles of any endurance event as your carbohydrate stores are full, 75% of your energy may come from carbohydrate and only 25% from fat. At the mid-way point as your stores run a little low, usage may change to the extent that only 50% of energy is supplied by carbohydrate. This figure may continue to decrease all the way to the finish as your carbohydrate stores progressively empty.

By contrast, whilst only 25% of your energy requirements may be provided by fat at the start of the event, this figure will continue to increase to counteract the reduction in carbohydrate usage. Ultimately fat becomes the major energy source in the second half of the event.

The problem can be summarised as follows:

1. Carbohydrate is limited and runs out quickly

2. As you run out of carbohydrate, you are forced to use fat as an alternative

3. As our bodies are not good at using fat, we slow down as a consequence

To resolve this problem there are 2 things we can do:

1. Keep stuffing carbohydrate rich foods into our bodies whilst we exercise and make sure the carbohydrate tanks don’t drop too low. The problem with this plan is that we can’t absorb enough carbohydrate to account for the usage (but it will slow down the ‘switch’).

2. We can teach our bodies to use fat more economically. If our bodies learn to love fat, we can use it with greater ease and save our precious carbohydrate stores.

Love the fat!

To enhance your endurance, your muscles need to ‘love the fat’ and your muscles must be more effective at using this calorie rich substance, which has had a fair bit of bad press.

Things to consider:

1. If you don’t practice burning fat you’ll never become good at it.

2. To burn fat you need to complete long duration and low intensity exercise.

3. If you give yourself carbohydrates, your body will gladly accept and always prefers to use them.

4. When your body is using fat, it’s likely that you will not feel great and you will feel as though you are travelling slow / under-performing (at least in the short term).

Things to do:

1. Long, low intensity, steady exercise sessions lasting several hours.

2. Eat low carbohydrate foods prior to exercising and choose low GI carbohydrates*.

3. Consider training in the morning before eating any breakfast.

4. During exercise avoid sports drinks and gels, which provide high amounts of instant carbohydrates.

5. Be wary of becoming psychologically attached to nutrition products i.e. ‘If I don’t take 3 gels per hour, I feel dreadful’.

6. Accept that you will feel ‘tired’, it doesn’t mean that you are ‘unfit’, you are doing this for a specific reason and the benefits will come later. You will notice a change over time as you body learns how to use fat more effectively, the pace and energy levels will rise.

7. Take some emergency food just in case you really need it. If you have been exercising for 1 hour or more and feel that you need some carbohydrates for energy, that’s fine. By this time your body will be using fat to the extent that a small amount of carbohydrate will not be enough to reverse the process.

*GI refers to glycaemic index. Foods are rated on how quickly they enter the blood stream. Low GI foods enter slowly and ‘drip feed’ the body, whilst high GI enter quickly and can cause sugar spikes in the blood stream.

Other things to consider:

1. Some research has shown that training in a ‘low carbohydrate state’ can suppress immune system function due to low ‘glutamine’ levels. Our advice is that you should only train in a low carbohydrate state for a limited time and at a low intensity. Longer or high intensity sessions should be done with supplemented carbohydrates to avoid negative effects upon immune system. You can also opt to take zero calorie electrolyte drinks to assist hydration, some of these come with added glutamine to prevent immune suppression.

Examples of training sessions are to run easy for 45-60 minutes or ride 1-2 hours before breakfast, without taking any other supplemental carbohydrate. The intensity should be low and consistent, avoiding spikes in intensity. If you are training in the evening, avoid food for 3-4 hours beforehand and at lunch choose low carbohydrate, higher fat and protein foods. If you are doing sessions reaching several hours, then you should supplement with carbohydrates. For breakfast prior to such long sessions avoid high GI carbohydrates. Higher intensity sessions such as track running or interval training should also be supplemented with carbohydrate before and during to ensure high quality training.

2. If your general daily diet is high in carbohydrate, in particular the high GI variety, you should change this pattern. Our belief is that changing your training techniques will have minimal impact if your general diet is conflicting. As endurance athletes we believe that it is necessary to eat a high amount of carbohydrates such as potatoes, bread, cereals, pasta, rice and specific sports products. Eating such a high percentage of carbohydrates can alter your metabolism and reduce your ability to use fat as a fuel source.

Your diet should be balanced and consist of an split between 3 main sources which are good carbohydrates (40%), good proteins (30%) and good fats (30%). During harder training sessions you can supplement with quick carbohydrates and sports products.

Table 1

Good carbohydrates Quick carbohydrates
MuesliAllbran

Fruit n fibre

Porridge oats/oat cakes

Bulgar wheat

Quiona

Brown/wild/basmati rice

Wholemeal pasta

Wholegrain bread

Sweet potato

Vegetables

Fruit

Sports drinksSports gels

Cereal bars

Jelly sweets

Jaffa cakes/fig rolls

Pancakes/breads

Cornflakes/rice krispies/honey nut cornflakes

White bread or rolls

White rice, pasta and noodles

General potatoes, boiled/mashed/new/baked

Rice cakes

Milk chocolate

Table 2

Good proteins: Good fats:
TurkeyChicken

Lean beef and lamb

White fish

Tinned tuna/salmon

Oily fish (e.g. salmon, mackerel, fresh tuna)

Eggs

Cheese

Milk

Plain yoghurts

Oily fish (other e.g. mackerel, sardines, herring, trout, pilchards) tinned varieties are ok.Olive oil/nut oils

Nuts and seeds

Avocado

Flaxseed/linseed

Butter

Full fat dairy products
Cheese

Plain dark chocolate

Table 1 & 2 shows examples of each main source. Planning your weekly diet to enhance performance and recovery will be the focal topic for part 2 of this series

 

4 Comments

Building the team..

The planning for Montane Lakeland 50 & 100 is a long and complicated process. There are hundreds of details we need to take into account and changes from the 2011 event which need to be made. last year there were approximately 140 people helping over the weekend to ensure competitors finished safely and enjoyed the experience. All of the volunteers and staff involved in last year’s event played a large part in the success and to them all we are indebted.

Volunteering for 2012

This year the event will be bigger and better than ever and we are looking for willing volunteers who can help over the weekend for various tasks. We are seeking people who are enthusiastic, energetic and can donate their weekend. in turn, we’ll provide food, clothing, a lot of laughter and a free entry into next year’s event. Everyone who was part of the team last year found the whole experience pretty uplifting, many of them are returning and this year the experience will be even better.

CP Teams

Even though there are 6 months to go to the start of the event, of the 14 checkpoints on the course, we already have 12 of them staffed. We are currently putting teams together for the remaining 2 checkpoints. If you are part of a group or company who would like to support the event, staff a checkpoint and be associated with the event, we’d be interested to hear from you. Your responsibility would we to provide 6-8 bodies and we’d do the rest.

Interested?

Email: organiser@lakeland100.com

Hope to see you there..!

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