Marathon Nutrition:  What you need along the way.

One typical brisk and bright Sunday morning in October of 1992 a college housemate woke me out of a deep post-party slumber.  “Jared, you bike a little,” he said, “let’s go for a ride!”  Mounting my rarely ridden Dave Scott edition Centurion road bike, we pedaled off.  To my surprise, we rode through Minneapolis, along the river roads and up to St. Paul, while watching a stream of amazing runners make their way through the bright autumn colors up Summit Avenue and down to the capital. 

That was how I discovered the Twin Cities Marathon.  On that day I made a promise to myself that I would do the marathon the following year. 

About 9 months later I went out for a late-night run and decided to go farther than my usual three miles.  Feeling good at about mile four, I remembered my marathon promise.  The next morning I registered for my first-ever running race - The Twin Cities Marathon.

I needed a training plan. I hadn’t yet begun my Exercise Physiology studies at the University of MN, so I did some reading and talked to a few runners in my hometown of Green Bay.  About 2 months later I was on the starting line.  I quickly settled into my typical 6:50min/mile pace and cruised through the miles.  At mile 19, I soared over the Franklin Bridge on pace for a 2:50-2:55 marathon.  Not more than a mile later I started feeling dizzy and unfocused. My legs were dead, and all I wanted was pizza. I had hit the wall, or bonked. Whatever you want to call it, I was running impaired.  My finish time was 3 hours and 17 minutes.  I fell 20 minutes off the pace I had set over the first 19 miles.

The truth is, I made simply one mistake.  I drank only the beverage I was used to - water.  Had I consumed the sports beverage available, I would have maintained optimal energy levels the entire marathon.  Once you bonk, it’s nearly impossible to come back.  With less sugar going to your brain, you feel too goofy to realize how to recover from this funk.  I sure wish I had read about specific nutrition for running a marathon.  Now, however, after over a decade of endurance racing, college coursework in Nutrition and Exercise Physiology, and tons of personal research on the topic, I have generated some very simple and basic theories about marathon nutrition. 

Presently, there is an abundance of endurance performance nutrition products on the market.  We can choose from thousands of drinks, gels, energy bars, etc…  It can all get a bit confusing.  The current problem is not that there aren’t enough nutritional options available, but that there are too many. 

Each body has a certain amount of calories it can absorb when exercising at marathon intensities.  The highly adapted gut might be able to consume 250 calories an hour, while the inexperienced stomach absorbs around 200 cal/hour.  Any food not absorbed will either just sit in your upset stomach, or pass through your intestines in the form of waste.  Unwanted calories might lead to time spent in the “port-a-johns” late in the marathon.  I dedicate the remainder of this column to understanding the nutrition demands during a marathon.

Tools to help you determine your Marathon Nutrition Plan

·        Learn your sweat rate:  Your goal is to drink the perfect amount of fluid, resulting in neither weight loss nor weight gain.  In the heat you sweat and drink more. If it is cooler, you sweat and drink less.  To determine sweat rate, just weigh in before a workout and weigh out after a workout.  Then, account for fluid consumed during the workout and add this into the total weight loss.  Let’s do the math for a hypothetical 60-minute run in the heat.

Determining weight loss:

Pre-workout weight                  158 lbs

Total weight loss                        4lbs

 Determining sweat loss:

Weight loss                               4lbs

                        Total weight loss in sweat          6lbs

Knowing your sweat rate under different climate and intensity situations will establish how many calories you can consume through fluid intake.

·        Drink only sports beverages:  The combination of carbohydrates and electrolytes in a sports beverage has been proven to enhance endurance performance.  Water alone will dilute the blood sugar and electrolyte concentration in the blood, and can lead to cramping, a sloshy stomach, low blood sugar, and eventually hyponatremia, a potentially health-threatening condition marked by poor electrolyte and fluid balance.  Practice using sports beverages in training.

·        Determine calorie content in sports beverages:  A typical sports beverage has 50 calories per 8oz serving.  You usually get about 4oz of fluid (25 calories) when handed a cup at the aid station during a marathon.  How much you should drink at each aid station depends on your sweat rate.

·        Ensure adequate caloric intake:  Marathoners burn anywhere from 600-1000 calories an hour, depending on pace and efficiency.  A typical runner has about 2500 calories of stored carbohydrates to use for maintaining marathon pace.  This would get a runner through 2.5 to 3.5 hours of running if drinking only water.  If a runner consumed around 25 calories (4oz of fluid) at every aid station he/she would consume anywhere from 150 to 250 calories in an hour depending on their pace.  After 3 hours of running, 150 calories an hour would give an extra 450 calories of available carbohydrates to help maintain pace through the end of the race. 

·        Consider energy gel supplementation: On colder days when sweat rate is lower, an athlete does not drink as much sports beverage.  In this case, supplementation with energy gels might be necessary.  A typical gel has 90-100 calories.  These gels can upset a stomach, so make sure you practice and learn your tolerance.  I suggest taking only half a gel at a time, and aim for consuming one whole gel in an hour.  This amount of gel, along with a sports beverage, will keep your calories topped off.  On hotter days, an athlete is often better off sticking to a sports beverage alone and skipping the energy gels.

·        Eat well on race morning:  A good breakfast would be 400-800 kcal of oatmeal or your favorite healthy cereal made with water or soymilk, with protein powder mixed in, about 2-2.5 hrs before the start.  Stay away from lactose-based milk, as it may not digest completely.  Drink about 12-16 oz of a highly concentrated carbohydrate sports drink (15% carbs) during the 90 minutes before the race, and another 8oz of normally concentrated sports drink (6-7% carbs) within 30 minutes of race start.  This formula will top off energy, electrolytes, and hydration stores.

·        Eat well the night before:  The typical noodle or rice dinner with a protein source like chicken or tofu will work really well.  The goal is to top of carbohydrate stores, consume a balance of protein and fat to help settle the stomach, slow down digestion, and provide muscle recovery during and after the race.

Marathon nutrition doesn’t have to be complicated. By taking a few simple steps, you can increase your chances of success in your next big race!

Date modified: 8/23/2005