Runners and triathletes who train or race on a low carb diets beware! Like I said in the last post, physiology is physiology! You cannot pick and choose which aspects of physiology you favour and you cannot expect to excel in any sport if you ignore the physiological rules set down by evolution.
We need carbohydrate to function at our maximum potential of speed and endurance. It's easier to get away with bending the rules if you run or race short distance, but if you are running 10km or more during training and racing then "you can run but you can't hide" or should I say "you can run but you won't excel" at least not to your potential.
Steve Prefontaine said "to give anything less than your best is to sacrifice your gift" well "to eat anything less than the best is also a sacrifice of your gift" and without a full fuel tank your aren't going to cover the distance at maximum speed.
Before just about every long distance event (half marathon, marathon, half ironman, ironman and ultras) I've taken part in there have been carb loading parties. Did you ever wonder why? Why not protein parties or fat festivals? The answer is simple, without fuel you cannot move, without appropriate (carbohydrate) fuel you cannot compete.
Carbohydrates are the primary source of fuel we use day to day. It's also the fuel we use when we begin any exercise; it gets us going and the rate with which we can burn it determines our pace and rhythm before we can start to burn our fat stores. A good start is half the battle and fuelling on a low carb diet will set you up for a poor start and an even worse finish.
The key to nutrition when training and racing is not to choose a low carbohydrate diet but a diet of slow releasing carbohydrate (see previous post). This produces energy on a gradual time scale. Avoid sugary foods and simple carbohydrates. Not only are these going to send you on a roller coaster of high and low energy due to their consumption rate, they will also inhibit the growth hormone released after exercise which promotes recovery and repair. As well as spiking your insulin levels that will then affect water levels, which will cause thirst and poor hydration.
In the final kilometres of a long distance race like a marathon, simple carbs can be used to spike you energy and get you to the finish line. However I would not advocate using this method of nutrition on long training runs or cycles due to the inhibition of human growth hormone (HGH) after exercise. Without the release of HGH and endorphins the repair process will be prolonged and your energy levels will take longer to recover. Poor energy and ill repaired muscles will set you up for injury on your next training session or race.
Another mechanism of injury on a low carb diet comes about when all the carbohydrate stores are spent before the body has time to start burning fats. This forces our cells to burn proteins, which will cause muscle, tendon and bone breakdown resulting in muscle tears, tendinitis and stress fractures.
Don't get fooled by thinking that you can shed a few pounds by eliminating carbs from your diet and running an extra few kilometres a week. Although this may be possible on a short-term basis the risk of injury and illness is increased dramatically using such methods.
You will be far stronger and healthier if you choose the correct carbohydrates and correct portion size for you, accompanied by adequate fats and proteins. Reducing your sugar or simple carb intake along with doing some resistance training will benefit you far longer. Long term this will yield far better results than any crash diet plan.