Eating for Endurance - Carbo Loading - update

Eating for Endurance – for all those marathon runners, tri-athletes, Iron men and women - and others J

For the past 100 years (and probably longer in a less scientific way) research has looked at the positive impact of eating correctly before and during exercise. Although researchers continue to question the validity of “carbo loading” there is much support for eating carbs to allow you to train or exercise for longer. The picture shows the muscles cells before and after carbo loading. The first picture shows the cells in a light colour with “gaps” and then the second shows the muscle cells darker in colour and packed closely together - all ready for the long run or cycle ride!

For most people a healthy intake of carbs would form about 40-50% of your diet. But for endurance athletes, you will probably have to increase this to 60-70% in addition to the huge increase in calories that are needed in general in order to sustain high quality and regular training. To work this out you need to times your weight in kg by 7-10g for a daily intake for the athletes or ~4g for a normal diet. What happens then is that our bodies are able to convert the “chemical energy” of food into “mechanical energy” of stored carbs (as well as using it to keep warm) – and we mainly store this in our muscles (see pic) with a smaller supply for emergencies in our liver.

Carbo Loading – How to do it.  Commonly, the habit of restricting carbs in the week leading up to an event before consuming loads the day before has been used by many people.  This idea is based on the huge uptake of carbs that we see when we eat breakfast following the “fast” overnight – so long fast = greater uptake?  However, there are many problems with this such as lack of energy and feeling lethargic and lightheaded in the week of training before the event, as well as having a bloated and heavy stomach on the day of the event.  Luckily, there has been much research into the way of maximising stores, so below I detail some of the newer ways of thinking and you can be rest assured that these have been tried and tested by the scientists J

In addition to following your usual training and nutrition plan, try to increase your normal carb intake by 10g per kg of body weight 2 days (48hrs) before an event   - However, this is just a general guideline, and the most current research seems to indicate that a combination of protein and carbohydrates are a better way to be able to recover from exercise and prepare for further training. In particular to time your eating fairly close to after training, and look at combining not only protein into this food stop, but having a combination of glucose and fructose (sugars) for the greatest potential - interestingly, this can be done quite easily with some chocolate milk or flavoured yogurt - happy days :)

The day before your race, you then rest your body and eat as close as you can to your normal diet, but make 100% sure that you are fully hydrated.  However, you could then try another piece of cute research which showed huge improvements in energy stores by increasing (above normal) your carbs by 12.5g per Kg two days before your event.  What I found most fascinating though was the body will take on more carbohydrates into the muscle if you do 3 mins of super intensity exercise (after a warm up) before your meal - so a super-turbo-charged loading mechanism!  Just be warned though – if you already have a great diet and your are “fully loaded” then eating more carbs does not give you more energy – despite what it might say on the bottle...

So for day to day stuff, think about eating 150 – 330g of carbs around 3-4hours before exercise to maximise your energy stores which means you can work out harder.  But beware, that eating 30-60 mins before exercise can cause a different effect where you get the peak of carbs going in too soon and then exercising just as insulin is starting to take effect which can cause you to have low blood sugar.  Not good to feel weak and lightheaded before a race or class! And don't forget to use your low GI foods.   

The added bonus of eating 3-4 hour before exercise is that the body is primed to release more fat into the bloodstream - so maximising your fat burning potential tooJ. Please think about when you eat and try not to be governed by standard meal times. For example, if you want to do a lunch time class, then eat something at around 10am in the morning – a second breakfast if you like. Then eat again at about 3pm before your evening session.  A small tip is that if you have not had time to eat then it is better to eat whist you are exercising rather than the 30 mins beforehand. You could have fruit or energy drink, shake or yogurt (esp. ones with side fruit serving as they have loads of sugar) etc – something to Inc stores without sitting heavy on your stomach

Finally, don’t forget that even if you have eaten well you can still run out of “energy” in a high intensity workout as the ability of the muscle to contract efficiently can be hampered by lactic acid.  So if part of your race involves you running up a hill or overtaking someone then you will need to drop your level of exertion for a few minutes whilst you body catches up with its energy production. It is also then worthwhile knowing how hard you can go in your sprint finish so that you don’t fade at the final few meters. Hydration is key to acting as a buffer to lactic acid, so keep up the fluid intake.

To summarise:

• For long distance endurance runners you will need to increase your carb intake to about 60-70%  carbs. Base your daily calorie intake on 50 cals per Kg of body weight.
• Eat 3-4 hours before exercise for maximum energy stores
•   Don’t eat 30-60 mins before exercise – eat just before you start or during if you have low energy
• Always eat breakfast
• Before an event, eat increased carbs 2 days before the event and then have a normal eating on your rest day the day before the event.
• Always eat following training – this does not have to be immediately if you can face it, but there is some evidence that eating a combination of carbs and protein, within 30 mins increases your energy uptake to the muscle - it may help prevent DOMS but more importantly will allow you to recover quicker and perform better at your next training session 
• Inc in protein is also a must as it forms an important part of the energy cycle for using carbs. Inc protein after exercise helps alleviate DOMS and helps protect female athletes from becoming anaemic.
• For every unit of glucose you pull into the body you also need to take on board 3 units of water – so being well hydrated is essential 
• Sports drinks are often a practical way to replace energy during heavy training sessions and are better than water alone on long or intense training bouts, but they are expensive to use and prior planning can help you deal with replacing glucose
• When training, it makes little difference if the glucose consumed is low or high GI - so go with something you like eating rather than something you feel you should be eating or drinking.