Metabolic efficiency for endurance athletes, tapping into 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
MuesliAllbranFruit n fibre Porridge oats/oat cakes Bulgar wheat Quiona Brown/wild/basmati rice Wholemeal pasta Wholegrain bread Sweet potato Vegetables Fruit	Sports drinksSports gelsCereal bars Jelly sweets Jaffa cakes/fig rolls Pancakes/breads Sugar Cereals 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:
TurkeyChickenLean beef and lamb White fish Tinned tuna/salmon Oily fish (e.g. salmon, mackerel, fresh tuna) Eggs Milk Plain yoghurts	Oily fish (other e.g. mackerel, sardines, herring, trout, pilchards) tinned varieties are ok.Olive oil/nut oilsNuts and seeds Avocado Flaxseed/linseed

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.

Winter Time Trial Series, Race 4

It was a ‘fresh’ morning but luckily no ice on the roads for the finale of the winter series. There was only 11 riders attended the final event on what was possibly the toughest course (you decide). The 12 miles route was a real road riding test with some twisty roads, sharp corners and a big climb to be done twice. On top of that, the roads were wet and dirty so caution was the order of the day. We had one retiree as Daniel Burdekin missed a route sign and lost momentum! Results are below:

Marc Laithwaite 35:50
Richard Carey 37:03
Steve Hilton 38:09
Pete Murray 38:29
Paul Owens 39:34
Mathew Burdekin 40:36
Ian Hampson 41:31
Tracey Hampson 44:28
Alfie Shaw 46:02
Mark Fenn 48:10

The summer series starts from beginning of April with 2 time trials every month through to (and including) August. These will take place on a Thursday evening and will include courses similar to those used for the winter series.

For club members, we will be riding ‘open’ time trial events from March onwards, click the TES cycle racing tab at the top of this page for more info.

See you there..

Amateur club runners, what is the main barrier to going faster?

It is of course the million dollar question, particularly when you consider the fact that pretty much every runner of every ability level wants to go faster in races. As a coach and sports scientist I’ve thought about this long and hard and reached a conclusion. Here we go..

Physiology of endurance running

Endurance running is an aerobic discipline, this means that all the things relating to aerobic energy production are important. Those things include a good set of heart and lungs, a decent supply of red blood cells to carry oxygen and muscles which are adapted to aerobic activity (in particular the slow twitch fibres). All of the above have an impact upon the amount of oxygen which can be supplied and utilised by the muscles to create energy. If you can use more oxygen, you can generate more aerobic energy and therefore run faster. The maximum amount of oxygen you can use to create energy is your VO2 Peak, or VO2 Max as its more commonly referred to.

What kind of training develops the aerobic energy system?

Aerobic running (longer running at slow to moderate paces) develops the aerobic system, so based on this fact, running lots of miles at a steady pace will help to improve your endurance running. If that’s the case, why do most club runners fall into the category of running lots of steady miles and yet seemingly never getting any faster? An important thing to take into account at this point is that aerobic energy production is exactly that.. its energy production. We need energy to run fast, but your ability to run fast is determined by a complex list of ingredients and providing energy is only one part of it.

What makes some fast and others not so fast?

I’m not just referring to 10k or half marathon, I’m talking about 100/200m on the running track. At my local training group on Monday evening, all of the runners could be deemed to be ‘aerobically fit’ as most run regularly and most run for an hour plus. Last week we completed a set of 200m fast repeats on the track, running for such a short distance is deemed ‘anaerobic’ due to it’s short nature. Strangely, the quickest 10k runners were the quickest 200m runners in the group and the slowest 10k runners were the slowest 200m runners (aside from a few odd ones!), so is that just coincidence?

If longer distance 10k running is an ‘aerobic activity’ and shorter distance 200m running is an ‘anaerobic activity’, then the above really shouldn’t happen, the fastest 10k runners shouldn’t necessarily be the fastest 200m runners as the requirements are totally different. There are 2 important things to consider:

1. Yet again, we are slipping into the habit of discussing only ‘energy production’. Aerobic and anaerobic are 2 separate ways to produce energy within the body, but there is far more to running quickly than simply producing energy.
2. What I see every Monday is the simple fact that fast runners are fast runners. When coaching distance runners, whether the track repetitions are 200m / 400m / 800m / 1 mile, the same runners are at the front and the same ones are at the back.

What are the other ingredients?

We’ve posted previously in our footstrikescience blog regarding some of the other ingredients and the major 3 are as follows:

1. Core – a chassis which holds firm every time your foot strikes the ground and resists collapse or buckling. If your chassis collapses, the energy is lost…
2. Contact – as your foot hits the ground, elastic energy is stored in tendons allows us to bounce. Your tendon structure and ‘tension’ has a large impact upon how much force you can produce.
3. Co-ordination – the ability of the nervous system to ‘fire your muscles’ and make your limbs move both quickly and smoothly, allowing you to run fast and make it look easy…

Can you run fast?

It’s a simple question but the one most overlooked. If you are hoping to race 10k events this year and you are capable of running for more than an hour, then you need to identify the main barrier that is preventing you reaching your target time. The likely answer is that you are simply not a fast enough runner, you cannot run quick and that’s the thing which you’ll need to change. A lot of amateur athletes have a great cardiovascular system but never convert it to fast times and there’s little point having a great engine when you’re trying to drive on square wheels..

Well.. it worked for him so why not me?

Many coaching models for endurance athletes are historically written the same way. We start with a ‘base’ phase which includes mileage and ‘time on feet’. As the season draws closer we gradually increase the intensity and the sessions get faster, peaking at the right time for the right race. As we mentioned earlier, there are several ingredients required for successful endurance running and perhaps one of the essential requirements is that you just have to be fast? Perhaps an essential element is owning the basic, raw ability to run quick.

It’s easy to identify that pretty much all elite long distance runners have the ability to run fast over short distances, they own that basic, raw ability. Once, you have that ability, applying a training schedule which enhances endurance would allow those runners to maintain fast running for longer periods of time. For those runners who are gifted with natural speed, the classic ‘base phase’ and subsequent progressions would work perfectly. What if you never had that speed in the first place?

Our training schedules are largely based upon ‘what the professionals do’. If that’s how the Olympic champion trains for the marathon, then surely we can all learn from that? The issue with that theory is that they have that one vital ingredient, the ability to run fast, and you probably don’t. That’s possibly the single most important factor which makes all the difference. In such a case, people who can’t run fast following the standard schedule as outlined above, would simply learn to maintain slower speed for longer.

In conclusion, I firmly believe that raw, basic speed (determined by the 3C’s above) is something naturally found in all elite runners and standard training schedules allow them to develop endurance and therefore maintain speed for longer periods of time. We are not elite runners and we do not have such basic speed yet follow the same training schedules as the champions, believing it to be the best way forwards.

Does any of this make sense?

Do you identify with the above? Any nervous alarm bells ringing?? If so, you’re probably wondering where we go from here.. simple, you need to learn how to run fast.

I know at this point you’re probably thinking ‘intervals’.. I’ll run some mile repeats at the track next week!! Stop right there.. If you would like to learn how to run fast you need to take it right back to basics and shock the system. Start with 50-100m and run quickly, do this regularly. Learn how to run smooth (coordination), with force (contact) and with perfect technique (core). If you start with mile repeats you’ll simply run round at your usual slow speeds and get nowhere. If you want to undo all your good work, you could run the next day for 90 minutes and shuffle your way round, that should do it.

If the above makes perfect sense then your quickest way forwards is to make radical changes to your training, work on your main limiting factor and focus on the simple ability to run quickly. If you’ve been running for several years and you are continually failing to make progress, what have you got to lose? Do you really think that breaking from your usual routine will see you running slower?

Don’t worry about training, go and learn how to run again..

Marc Laithwaite
www.theendurancecoach.com
www.theendurancestore.com