What to Eat Before a Race

Your body uses food as an energy source by breaking down macro­nutrients (carbohydrates, proteins, and fats) into smaller molecules — namely glucose, amino acids, and fatty acids. It then uses them to produce adenosine triphosphate (ATP), the body’s primary energy currency.

There are several ways your body turns what you eat into what you do. Known as your metabolic energy systems, these pathways all switch on during physical exercise — but their roles depend on the available energy and specific demands of your chosen activity, explains Mike Thomson, CSCS, USATF, a Life Time running and triathlon coach.

Once you begin intense activity, it takes just thousandths of a second for the adenosine triphosphate-creatine phosphate system, or phosphagen system, to kick in. The ATP stored in the muscles can fuel only about six to 10 seconds of serious effort. This system might engage at the start of a race for quick acceleration, but its utility is short-lived.

The glycolytic system provides energy for high-intensity, short-duration bursts of activity. It can produce ATP rapidly without oxygen, using glucose as fuel. It kicks in for short bursts lasting about 10 to 75 seconds — great for picking up speed to overtake a competitor.

It’s the third energy system — the oxidative system — that is most critical for endurance athletes who need to maintain a relatively moderate intensity for a longer duration. This system uses oxygen to generate ATP. The oxidative system is also called the aerobic system.

“Think of it as the body’s slow-burning furnace,” designed to provide the body with most of its energy, says Thomson. This is the system you want your nutrition plan to stoke. (Learn more about the body’s energy systems at “All About Your Metabolic Energy Systems.”)

Mind Your Gut

Because the body breaks down glucose, fatty acids, and amino acids to produce ATP, it might seem intuitive to fuel and refuel for an endurance event with a balanced blend of carbs, fats, and protein. But not so fast.

“Food as fuel is not the same as nutrition for your health,” says  Ashley Koff, RD, founder of The ­Better Nutrition Program. While con­suming optimal amounts of macro- and micronutrients is imperative for overall wellness, the unique needs of a body under duress can make getting them from certain healthy foods hard to stomach.

During intense or prolonged activity, the body diverts blood to the muscles, lungs, heart, and brain, and away from the digestive tract, which may impair digestion and drastically alter gastrointestinal transit time. And hormonal changes during intense and long-duration exercise can tamp down hunger cues and diminish appetite. As a result, it’s common for endurance athletes to experience nausea, diarrhea, abdominal pain, and vomiting.

But digestive upset is not a foregone conclusion, says Koff. She suggests avoiding high-fiber, high-fat, and high-protein foods and drink — all of which are more filling and as a result more difficult to digest — immediately before or during exercise. And limit these nutrients the day leading up to an event.

Thomson recommends avoiding unfamiliar foods, drinks, and nutritional aids the day of — or even in the week leading up to — your race.

“It’s important to train like you race and race like you train.”

So, what should you consume to fuel your performance?

It’s vital to make sure you’re topped up with fluids, electrolytes, and carbohydrates before you begin your activity.

“Trying to make up for a deficit if you start a bit dehydrated or energy depleted by eating and drinking during the activity itself is definitely leaving it too late,” writes sports scientist Andy Blow, BSc, in an article on his training website, Precision Fuel and Hydration. In other words, you can’t play catch-up during heavy activity.

Follow these tips in the days leading up to your event.

Carbo-Load With Care

We primarily store glycogen in our skeletal muscle and liver. An adult can store about 100 grams of glycogen in their liver and approximately 15 to 25 grams of glycogen per kilogram of muscle mass in their skeletal muscle (total storage varies by muscle mass).

On average, adults can store about 600 grams of total glycogen — and you want those stores to be topped off before race day. Rather than eat as much pasta and bread as possible the night before an event, take a few days to shift your carb-to-fat ratio, Blow advises. Your overall caloric intake likely won’t change; rather, the proportion of your calories from carbs gradually increases while that from fat declines.

This doesn’t have to be drastic. An extra spoonful or two of oatmeal or rice (or other carb-rich foods that you enjoy and tolerate) at each meal can go a long way while sparing your digestive tract from an abrupt change, notes Koff. (Learn more about carbo-loading at “What Is Carbohydrate Loading?“)

Hydrate Holistically

Like carbo-loading, sufficient hydration is a gradual process and involves more than just chugging plain water before toeing the start line. Samantha McKinney, RD, CPT, recommends the following best practices for hydration throughout your training cycle and in the days leading up to your event.

• Aim to drink at least half your body weight in ounces of water per day, plus an additional 16 ounces per hour of exercise.
• Add electrolytes around workouts. Sodium, potassium, chloride, calcium, and magnesium support muscle and nerve function.
• Avoid drinks and electrolyte products with artificial colors, flavors, or sweeteners.
• Limit excess — or avoid ­— caffeine and alcohol.

Plan Your Prerace Meal

It’s paramount to test any preworkout nutritional strategy during your training cycle and to avoid mixing it up the day of your event.

With that important note, here’s what experts suggest for your first race-day meal:

1. One to two hours before your event, consume a meal of easily digestible, low-fiber carbohydrates (70 to 80 percent of the meal’s calories) with low to moderate levels of fat (less than 15 percent of calories) and protein (10 to 12 percent).
2. Additionally, drink 16 ounces of water with electrolytes. (For preworkout food ideas, visit “12 Quick Preworkout and Postworkout Snacks.”)

With ample glycogen and hydration stores, you’ll be set to perform your best when the race starts.

Practice Makes Perfect

It can’t be overemphasized: Make intra-event fueling part of your training. “It’s important to train like you race and race like you train,” Thomson insists.

The number of training sessions needed to ensure a successful approach varies. One study on endurance runners, published in Applied Physiology, Nutrition, and Metabolism, found that two weeks of gut training resulted in improved gastrointestinal symptoms.

Other studies and experts say a gut-training protocol takes four to 10 weeks. “I recommend taking at least a month to adapt to nutrition changes,” says Spar.

During each training session, pay attention to your body’s signals to adjust what, how much, and when you eat. Feeling lightheaded or dizzy can signal dehydration, Spar notes. Craving salt can be an early sign that you’re running low on sodium. Stomach pain and muscle cramps are reliable indications of low electrolytes.

And feeling a lack of energy could be a sign of carbohydrate deficiency. If you crave sugar immediately after a workout, you likely didn’t eat enough carbs before or during your routine.

Learn from your missteps and your successes. Take note of what works for you and rehearse that winning recipe. By race day, you’ll be optimally fueled and ready to go.