Page 36 - 2009 AMA Summer

drinks and gels, sweets, bananas and plen- ty of water, most avoid total collapse.
Bonking
Bonking is a condition familiar to most peo- ple that have attempted endurance sports. It is a feeling of dizziness and overall weakness – perhaps blurred vision or faintness – that occurs when insufficient glucose is delivered to your brain. You get fuddled and clumsy. If this happens on a race track, it’s pretty unpleasant. If it happens while you’re trying to negotiate a tricky descent on a mountain bike or concentrate on navigation in adverse
mountain weather it’s potentially dangerous. It can turn a normally sure-footed, clear- thinking individual into an accident waiting to happen. Fortunately it’s easily avoided and simple to fix ... just put some fuel in. By con- tinually topping up your blood sugar levels you can stay sharp and avoid ever having to rely on your glycogen stores. As long as they stay intact, you will never bonk! Of course refuelling isn’t a cure for exhaustion; even the finest athletes have their limit. Nor is it a sub- stitute for training, but it helps.
Glycaemic Index
The Glycaemic Index (GI) ranks foods accord- ing to the effect they have on levels of glucose in the blood (blood sugar). The system was originally developed to help diabetics control their blood sugar levels. It was adapted by sports scientists then by the mainstream diet industry, and most nutritionists subscribe to it as an important part of healthy eating. Many food manufacturers now provide GI informa- tion on packaging. The higher the GI number, the faster and bigger the sugar hit. Pure glu- cose has a GI of 100.
GI is not simply a reflection of which foods contain the most glucose or sugar. GI is related to the accessibility of the sugar, and this can be affected by all sorts of factors, including fat and fibre content and methods of preparation. High GI foods (those scor- ing 80–100) include sports drinks, sweets such as jelly babies, no surprises there – but also cornflakes and potato. Gram for gram, a baked potato will give you a con- siderably more abrupt rush than the same weight of honey, and rice cakes, crackers, most bread and couscous all score higher than table sugar. This is great if you want a sudden boost that will take effect right away, but not so great if you want the effect to last. Glucose never stays in the blood- stream very long because cells that need it extract it right away and burn it off immedi- ately. Any excess will be converted to glycogen for storage. Either way, the sugar hit is over as quickly as it began, often leav- ing you feeling worse as the sudden rush will confuse your body into suspending the mobilisation of stored reserves of glycogen and fat. You can use high GI foods to top up your blood sugar during exercise, and to
34 ARMY MOUNTAINEER