How many times have you had a bite (or more) from an energy bar, taken a swig (or more) from an energy drink, or eaten a meal just an hour or two before starting a lengthy workout or taking your position at the starting line of a long distance race? Big mistake! Eating this soon before prolonged exercise is actually counterproductive and will hurt your performance. In the sometimes confusing world of sports supplementation and fueling, pre-exercise food/fuel consumption generates arguably the greatest confusion, and many athletes have paid a hefty performance price for their misinformation. But really, there's no insider secret regarding what to do for a pre-workout/race meal, just some effective strategies and guidelines. You need to know what to eat, how much, and most importantly, when. You also need to know a bit about glycogen storage, depletion, and resupply, and how to use that knowledge at the practical level. This article supplies all of the information you need, and I've also included some suggested meals, equally appropriate for workouts as well as competition.
The goal of pre-exercise calorie consumption
Assuming that your workout or race starts in the morning, the purpose of your pre-race meal is to top off liver glycogen stores, which your body has expended during your night of sleep. Muscle glycogen, the first fuel recruited when exercise commences, remains intact overnight. If you had a proper recovery meal after your last workout, you’ll have a full load of muscle glycogen on board, which constitutes about 80% of your total glycogen stores. If you didn’t re-supply with complex carbs and protein after your last workout, there’s nothing you can do about it now; in fact, you’ll only hurt yourself by trying. To repeat: during sleep, your liver-stored glycogen maintains proper blood glucose level; you expend nary a calorie of your muscle glycogen. You might wake up feeling hungry, and I’ll discuss that issue later, but you’ll have a full supply of muscle-stored glycogen, your body’s first used and main energy source. Your stomach might be saying, “I’m hungry,” but your muscles are saying, “Hey, we’re good to go!”
With only your liver-stored glycogen to top off, you want a light pre-race nutrition meal. Sports nutrition expert Bill Misner, Ph.D., advises that a pre-workout/race meal should be “an easily digested, high complex carbohydrate meal of between 200-400 calories with a minimum of fiber, simple sugar, and fat.” That’s hardly what most folks would call a meal, but in terms of pre-exercise fueling, it’s meal enough. According to Dr. Misner, fat slows digestion and has no positive influence on fuels metabolized during an event. He further states that a meal high in fiber may “create the call for an unscheduled and undesirable bathroom break in the middle or near the end of the event.”
Complex carbohydrates & protein
One study found that athletes who drank a meal consisting of both carbohydrates and a small amount of protein had better performances than when they consumed only an all-carbohydrate sports drink.
If you do feel the need for solid food instead of a liquid fuel meal, choose high starch foods such as skinless potatoes, bananas, rice, pasta, plain bagels, low fat active culture yogurt, tapioca, and low fiber hot cereals.
The key - Allow three hours or more!
Equally as important as what you eat is when you eat your pre-exercise meal. Authorities such as Dr. Misner, Dr. Michael Colgan, and Dr. David Costill all agree that the pre-race meal should be eaten 3-4 hours prior to the event. Dr. Misner suggests the athlete “leave three hours minimum to digest foods eaten at breakfast. After breakfast, drink 10-12 ounces of fluid each hour up to 30 minutes prior to the start (24-30 ounces total fluid intake).”
Three hours allows enough time for your body to fully process the meal. Colgan says it’s the digestion time necessary to avoid intestinal distress. Costill’s landmark study [Costill DL. Carbohydrates for exercise. Dietary demand for optimal performance. Int J Sports 1988;9:1-18] shows that complex carbohydrates taken 3-4 hours prior to exercise raise blood glucose and improve performance. But it’s Misner’s argument that has proved most compelling to me.
Dr. Misner's rationale - It's all in the timing
If you consume high glycemic carbohydrates such as simple sugars (or even the preferred complex carbohydrates such as starches and maltodextrins) within three hours of exercise, you can expect the following, with possible negative effects on performance:
• Rapidly elevated blood sugar causes excess insulin release, leading to hypoglycemia, an abnormally low level of glucose in the blood.
• High insulin levels inhibit lipid mobilization during aerobic exercise, which means reduced fats-to-fuels conversion. Our ability to utilize stored fatty acids as energy largely determines our performance, which is why we can continue to exercise when our caloric intake falls far below our energy expenditure. We want to enhance, not impede, our stored fat utilization pathways.
• A high insulin level will induce blood sugar into muscle cells, which increases the rate of carbohydrate metabolism, hence rapid carbohydrate fuel depletion. In simple terms: high insulin means faster muscle glycogen depletion.
You must complete your pre-workout/race fueling three or more hours prior to the start to allow adequate time for insulin and blood glucose to normalize. After three hours, hormonal balance is restored, and you won’t be at risk for increased glycogen depletion. Eating within three hours of a training session or race promotes faster release/depletion of both liver and muscle glycogen and inhibits fat utilization. The combination of accelerated glycogen depletion and disruption of your primary long-distance fuel availability can devastate your performance.
But I'm hungry!
Recall that I mentioned earlier that muscle glycogen, the main fuel recruited for the first 60-90 minutes of exercise, remains unaffected by a nightlong fast. When you awaken in the morning, you haven’t lost your primary fuel supply, and can’t add to it by eating within an hour or two of exercise. That’s absolutely correct, and believe it or not, being hungry before an event won't inhibit performance.
However, hard-training athletes often do wake up very hungry and feel they need to eat something before their workout or race. This is especially true for half and full iron-distance triathletes, who start very early in the morning in the water, swimming for up to an hour or more where consuming food is not possible.
What to do? Try either of the following suggestions to help with this problem:
• Just start anyway, realizing that hunger is not a performance inhibitor, and begin fueling shortly after you start, when you get into a comfortable rhythm. The hunger sensation will diminish almost as soon as you begin to exercise, and you’ll actually be benefiting, not hurting, your performance by following this procedure. You can safely use Sustained Energy, Perpetuem, HEED, or Hammer Gel, or any combination thereof, as soon as you want after exercise commences.
• If you feel that you absolutely must eat, consume 100-200 calories about five minutes before start time. By the time these calories are digested and blood sugar levels are elevated, you’ll be well into your workout or race, and glycogen depletion will not be negatively affected. In this regard, good choices are one or two servings of Hammer Gel or a generous drink from a premixed bottle of Sustained Energy or Perpetuem. This strategy is especially appropriate for triathletes who will hit the water first and not have a chance to replenish calories right away. Small amounts of nutrient-dense fuels, such as those named above, go a long way to stanching hunger pangs.
Are there any exceptions to the three-hour rule?
When you’re engaged in training sessions or races in the 90-minute range or shorter (personally, I prefer an hour limit), fasting three hours prior to the start is not necessary. Consuming some easily digested calories an hour or two prior to the start will not negatively affect performance, and may actually enhance it. Here’s why:
As we’ve discussed earlier, when you consume calories sooner than three hours prior to the start of a workout or race, you accelerate the rate at which your body burns its finite amounts of muscle glycogen stores. In events lasting longer than 60-90 minutes, refraining from calorie consumption for the three-hour period prior to the start is crucial because you want to preserve your glycogen stores, not accelerate their depletion. Muscle glycogen is the first fuel that the body will use when exercise commences, and your body only has a limited supply of this premium fuel. If your workout or race goes beyond the 60-90 minute mark, you don't want to do anything that will accelerate muscle glycogen utilization.