Tuesday, May 19, 2009

Eating on the Fly

On the just concluded queen stage 10 (longest stage of 262km) of the ongoing Giro d' Italia (a 21 day cycling stage race otherwise known as the Tour of Italy), the riders in the picture on the left are seen getting their feed bag to get some much needed nourishment so they can do well on this particular stage. 262km in a day? How many of us have ridden that far in a week recently, let alone in a day?

Unless you've been living on another planet, most of you will be aware of the tremendous importance of carbohydrates (CHO) for sporting performance. Much of the published emphasis has been on replenishing CHO stores after training or competition.

There is however, emerging evidence that CHO feeding during exercise offers significant benefits. There is no way the riders can get away with not eating during that stage where they ride 262km. In fact, they have to eat a lot before, during and after the stage. For the rest of us mortals who ride or train much less, eating on the go (while training or exercising) may be just as critical.

Consider the following study where investigators attempt to find out what the impact of eating during a 75 minute training ride at 80% VO2 max on CHO stores in the body and also protein oxidation. In the first trial, the cyclists took 125 grams of glucose while riding, while in the second trial, no glucose was ingested. Sweat and urine metabolites were also analyzed to see how much protein was being oxidized during exercise ( to track to see if your muscle tissue is being broken down to fuel your exercise).

Results showed that feeding on the glucose reduced liver glycogen stores by 12% and muscle glycogen usage by a whopping 16%. The impact on protein utilization was more significant, glucose feeding resulted in a two-thirds drop in protein oxidation.

Hence, it is clear that by ingesting CHO during training, it offers significant benefits to endurance athletes (more so since the athletes studied were not low in CHO stores before the study). Not only does it spare muscle glycogen stores, it also reduces the loss of muscle tissue via protein oxidation.  This may be especially useful for endurance athletes who struggle to maintain muscle mass during periods of high volume training or competition.

So more reason to eat on the go for your next long run or ride.


Int Journal Sport Nutr Exercise Metab Aug 2005; 15(4) : 350-365

1 comment:

  1. Hi.
    I recently went to the doc for shin pain he said it's a muscle strain but I just I don't no when I flex my foot it hurts so bad through the top of my foot up to the side of my shin bone I can't even push my big toedownwafds with out crying.