Every runner on the planet has heard of carbohydrate loading, and most major marathons sponsor pre-race carbohydrate loading dinners the evening before their race.
A word to the wise- don't get carried away! Some runners think loading gives them a license to eat as much as the last 72 hours, while others focus more on desserts and cookies. In other words, fat loading.
According to the Australian Institute of Sport, if you do it correctly, carbohydrate loading can improve run performance by 2%-3%. That may not sound like much, but 3% translates to 5 minutes for a 3 hour marathoner and 7 minutes for a 4 hour runner. That's not bad!
What's the trick to maximizing the benefits of loading carbohydrates? Over the years physiologists have found modest success with different protocols. Here are 2 of the best.
As you taper your distance, do one last hard but short effort about 72 hours before your race. I like 4 x 800s.
Immediately following your workout, begin your focus on carbohydrates. This study in the European J of Applied Physiology found that glycogen loaded muscles will stay that way for up to 5 days as long as you rest and maintain a high carbohydrate intake. While its ok to start that early, I prefer 3 days.
Research has shown that muscles will stock more if you spread out your intake over 4 hours rather than eating 1 large meal following a hard workout. It makes sense to me that you continue this "carbohydrate grazing" technique following each of your short taper workouts.
A common problem associated with 3 days of carbohydrate loading is the disruption in your normal eating pattern. Your trying to stuff yourself when you aren't very hungry. Your reduced training load along with the extra fiber in many carbohydrate foods leaves you with no appetite.
More research out of Australia has uncovered an effective strategy that may work as well or even better (see Tip #5: The Taper). They found ample super compensation in athletes that performed 1 very hard 3 minute exercise bout followed by just 24 hours of carb. loading (pponline.com). Do this 2 days before your race and rest the day before.
Since it takes 10 hours or more for any one meal to break down and reach the muscles (drmirkin.com)it makes sense that what you eat 2 days before may be more important than that big pre race pasta party.
I always try to get a sufficient amount of fiber the day before, snacking on foods like popcorn or whole grain fig newtons. Stick mainly with high carbohydrate foods, but stay with food groups you are used to. For me, that's oatmeal, cereal, pasta, bread, fruit, and vegetables.
Since muscle glycogen is heavy and retains water, maintain a sufficient intake of fluids and keep an eye on the scale. You know you are ready when you are a couple of pounds heavy.