How often have you headed to a race or a long training session and thought, ‘Man I’m hungry?” How often have you had a bite (or more) from an energy bar, taken a sip (or more) from an energy drink, or eaten a meal just an hour or less beforehand? Big mistake! Fuelling this soon before prolonged exercise is actually counterproductive and will hurt your performance.
In the sometimes confusing world of sports supplementation and fuelling, 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.
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.
During sleep, your liver-stored glycogen maintains proper blood glucose level; you hardly expend any calories of your muscle glycogen. You might wake up feeling hungry, 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. It is advised that a pre-workout/race meal should be something that is easily digested, high in complex carbohydrate, with a minimum of fiber, simple sugar, and fat.
You want the carbohydrates to be easily dissolved into the bloodstream, but steer clear of fibre because that 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, 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 all agree that the pre-race meal should be eaten 3-4 hours prior to the event. Three hours allows enough time for your body to fully process the meal and it’s approximately the digestion time necessary to avoid intestinal distress.
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.
- 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 normalise. 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 utilisation. The combination of accelerated glycogen depletion and disruption of your primary long-distance fuel availability can devastate your performance.
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, 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:
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 90-minute mark, you don’t want to do anything that will accelerate muscle glycogen utilisation.
By Liam Bromilow.
