JUNE 2012

Now that the Network coordinator, Rob Cocking is sending out regular information about coaching courses there is no point in me repeating the information, therefore I intend to look at other points that may be of benefit to coaches

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Don’t forget UCoach on the uka and England Athletics website.


When Ron Hill won the Commonwealth marathon in 1970 he attributed his win to a large extent on carbohydrate loading following a period of carbohydrate depletion, thereby increasing the levels of muscle glycogen in time for the race. Lots of runners followed his example, with various degrees of effect, and not always beneficial. Little has been said about this form of performance boosting until Tim Noakes MD. 2003 edition of his book, ‘Lore of Running’, added some detailed research into this hypothesis.

The risk of hypoglycaemia should be the greatest worry of any long distance runner, brought about when liver glycogen levels run low and upset blood insulin balance, reducing the glycogen supply to the brain and central nervous system, bringing on a lack of ability to focus, sudden weakness that demands slowing down or stopping, and with persistence it could eventually lead to collapsing.

Glycogen is a direct result of the ingestion of the fructose element of carbohydrate, and therefore when levels run low the body compensates by trying to reduce it’s workload or shut down the areas of consumption

By depleting the body of carbohydrate (CH) while still training, as in the carbo loading ‘diet’, an athlete is putting his body at risk of hypoglycaemia, a risk which must be balanced against the resulting carbo boost to the muscle glycogen levels just prior to the race. The following end-to-end graphs illustrate the principle of depletion, loading, racing and recovery.

CH overload

CH depletion CH loading

Risk of hypoglycaemia

Risk of hypoglycaemia

Normal muscle glycogen

Liver glycogen


6 days 3 days race day 1 hr. 2 hrs. 3 hrs. 4 hrs

The point at which the mind of an unloaded athlete switches off

and performance deteriorates rapidly (hitting the wall)

In addition to the risk of hypoglycaemia, there is also a small risk of raising your LDL level of cholesterol.

Club marathon runner will normally set a pace that they hope will just get them to the finish, at which point they are generally knackered, which means that they set off with good intentions and are probably running at about 80-85% of their VO2max, but in many cases their pace drops off towards the end of the run, a phenomena that is often attributed to a variety of reasons, usually associated with tiredness of the muscles and a desire to get it over with, (loss of motivation or concentration). Therefore it is worth considering the effects of the energy supply system to see if any improvement can be made that will result in a better performance.

Initially the depletion in the level of liver glycogen up in the first hour or so will have no detrimental effect on performance, being backed up by muscle glycogen; but once the stores in the liver run down then a greater demand is placed upon that stored in the muscles (and supplied by the liver), hence this will eventually fall off rapidly until it reaches a point where common sense will tell most people to stop or reduce their pace dramatically.

It can be seen from the graph that by raising the level of CH before the race so that when the point at which normal muscle CH levels would begin to dive they are in fact still high; this can be further enhanced by taking more CH during the run, meaning that the athlete should not loose pace, or alternatively he/she could be operating at a higher pace from the onset.

Simple performance line graph

CH loading before the race but no top up during the race

No CH loading before the race, but CH top up during the race

CH loading before the race, plus top up during the race.

The latter would appear to be the better option.

When should the last ingestion of CH take place?

This is tricky because a lot can depend upon the athletes’ rate of digestion and absorption, as ingested CH also raises blood glucose and insulin concentration (an exercise inhibitor) within the first 30-60 minutes, which in itself depletes muscle glycogen storage and therefore reduce your race pace quicker than anticipated. This is especially evident when simple/refined carbohydrates are taken.

However, complex carbohydrates with their lower glycemic index (GI) will take longer to be absorbed and therefore lowers the ultimate risk of reaching a point of hypoglycaemia

From this it can be concluded that starchy foods with a low GI are the best carbohydrate to consume when preparing for a marathon, and contrary to popular belief, these do not include the simple CH of bread, potatoes or cornflakes.

Complex CH/ low glycemic index foods

Pasta, rice, couscous, oat muesli, lentils, yoghouts, dairy and most milk products, most green vegetables, apples, cherries and beans.

Simple CH/high glycemic index foods

Sugars, honey, jams, low fat ice cream, power bars, bananas, nuts, raisins, most drinks, potatoes, bread except wholemeal rye, most cereals.

It is believed that by eating these high CH/low GI foods 45 min - 4 hours before a run the food will stay in the gut for a steady release of energy, which, when added to a topping up of CH during the run, will increase the performance of most long distance runners.

Tim Noakes points out that this not always applicable to all athletes, quoting Gert Thys who dropped out of two runs at about the 30-35km mark, until the problem was solved by experimenting with his carbohydrate intake, allowing him to run a 2:06:30 marathon.

Running at a slower pace from the onset, say up to 60% VO2max will burn fat as a fuel, thereby saving some of the glycogen store for later. Experiments have shown that not everybody has the same metabolic system, and whilst most of us are carbohydrate burners, some are fat burners and would not benefit from ‘carbo loading’, but would be better off ‘fat loading,’ for about ten days, which sounds like the Doctor Atkins diet.

How much carbohydrate is an overload?

Approximately 1-1.5 kg, depending upon your build.

How much carbohydrate during the run?

40-80 grms/hour. That equates to 1 x 500ml bottle of Lucozade Energy or 2 bottles of Powerade. CH can be taken in any form, liquid or solid.

The solution is to try these ideas on long training runs, measuring the pace, heart rate, feeling of exhaustion and testing to see if there are any energy reserves left by finishing off with a final mile at a higher pace than the rest of the run.

Reference has been made to some of the material in Tim Noakes book, ‘Lore of Running’ but is only scratching the surface of over 900 pages of useful information.

Tony Lett Level 4 coach with 18 years experience of coaching marathon runners, including a Commonwealth Bronze me