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March 17, 2015

Fueling for Endurance Events

Written by Ashley Benson

Guest Blog Post from Heather Tanner

Heather Tanner is a 3-time Olympic Trial marathon qualifier, 2004 USA World Half Marathon Team Member and decorated NCAA Cross Country and Track & Field Athlete during her time at the University of North Carolina and Stanford University. Tanner is currently preparing for the 2016 Olympic Marathon Trials and offers her advice on fueling for the marathon to runcoach and movecoach trainees.

There are many things to worry about in the final days leading up to a marathon. Like mapping out a race strategy in line with your fitness so that you don’t end up becoming intimately acquainted with the “wall”. Like taking care of the not so little things such as sleep, nutrition and stress management to ensure that you can get to the starting line healthy. Point is, fueling strategy really shouldn’t be one of those worrisome things. As long as you practice your fueling method in the long runs leading up to the race and have figured out a way to ensure regular carbohydrate replenishment during the race, you will be ok on this front.

During my first marathon experience (Columbus Marathon, 2003), I was a novice on many fronts and broke some major cardinal marathon rules (most importantly: don’t start a marathon injured, ever!). I had no idea what I was doing on the fueling front either and recall being alone at the expo the day before, trying to decide what type of fluids to try (water or maybe that new, strange-tasting Accelerade?) and how many gels I might need (is 1 or 2 enough?). As was inevitable, my hip injury helped me avoid hitting the wall, by slowing me down in the form of 8 stretching breaks. Not pleasant, for the record. Let’s just say fueling probably would have gotten the better of me had something else not have gotten there first.

Fortunately, I’ve had the opportunity to learn from some amazing runners over the last 10+ years and have since followed a few simple yet important guidelines in order to avoid the “bonk”:

1.) Take fluids as EARLY as possible – Do not pass the early water stations by. I typically try to take fluid at every station available, sometimes both water and the race-provided electrolyte beverage. This often means fluid consumption at least every 2 miles. You may only successfully take in a couple of ounces per cup, depending on your speed and your ability to coordinate moving and drinking at the same time, so it’s better to focus on frequency of water stops.

2.) Take your gels SLOWLY – Your digestive system can only absorb about 1-1.5 grams of carbohydrate per minute. An average gel contains 20-22 grams of carbohydrate. The quick math here means that your body can’t keep up with you very well if you down the whole gel in one second. In addition, gel consumption becomes even slower if you do not consume it with adequate fluids. I may take a gel every 4-6 miles during the course of the marathon (4-5 gels in total), but I take each one in slowly.

Note: Magdalena Lewy-Boulet, US Olympian and VP of R&D for Gu, told me about me this slow Gu consumption method after she had a successful marathon in cold “frozen Gu” weather (CIM, 2001 – 2nd: 2:37:57). Her Gu had formed into a cold, solid state and she was only able to consume small amounts at a time as it thawed. Despite this, Magda felt properly fueled.

Logistically, slow gel consumption can present some challenges. I prefer to hold onto the packet and take a small amount every minute or so, i.e. “sipping” on the gel. It can become a sticky mess, and the only helpful thing I can offer here is that this is all less annoying if you are wearing gloves. If you prefer other types of fuel, there are options that are already conveniently partitioned into smaller caloric chunks. Think Sport Beans or Clif shot blocks. Always intersperse gel consumption at or near water stations and practice this slow fuel consumption method in training.

3.) Ingest electrolyte-based drinks, not just water - This is another fairly obvious one, but not always followed. Research has supported evolution of sports drinks over recent years and many are purportedly optimal for electrolyte replenishment during the marathon. If you have the choice, it’s best to use beverages backed by science and your own experience. Osmo, UCAN, GuBrew and Nuun are some good newer beverage options with solid science to support their use. The more common beverage choices serve their purpose for most of us too though (Gatorage, Powerade, etc.).

    The same slow carbohydrate absorption rule may apply for your electrolyte drink, but remember that these drinks are often significantly diluted, which can be a good thing. If the race-provided drink tastes too concentrated, try to balance it out with more water consumption at the next station. This may help your digestive system to absorb the carbohydrates more easily.
    Also, if you are at all at risk for hyponatremia, or essentially over-hydrating, counterbalancing your fluid intake with an appropriate volume of electrolytes is even more important. The risk threshold for hyponatremia is known to apply to those who consume approximately 8 oz of fluid (any type) every 20 minutes (a lot!) and this risk is even higher if that fluid is water alone. Don’t over drink.

    4.) Adapt your strategy for weather conditions – Heat and/or humidity will of course greatly increase your rate of sweating and will necessitate increased fluid consumption. Stay on top of that early. Potentially equally damaging in a different way, extremely cold conditions may interfere with your desire to consume fluids. You could then be at risk for dehydration and subsequent muscle cramping if you do not drink according to your normal plan, despite your perceived lack of thirst.

    5) Don’t worry if something goes wrong – If you miss a water station, or an untrained child volunteer throws the cup all over your shirt at mile 16, do not panic. It will be ok as long as you’re following rule #1. Make it up for it at the next stop by grabbing both water and electrolyte drinks.

    I try to remember these themes as I race, but do so in an unscientific way because, in most cases, there are many other elements you cannot control over the course of 26.2 miles. You don’t want to create an overly specific fueling plan in case it becomes difficult to execute. One missed water station and you could find yourself in an unnecessary tailspin of distraction. Based on your individual body composition, it is certainly possible to estimate the precise amount of carbohydrate, electrolyte and fluid you should consume over the course of a marathon. It is extremely difficult to make that precision happen in real life, particularly if you are not fortunate enough to have the luxury of elite water bottles placed at regular intervals over the course. Fortunately, by keeping these general guidelines in mind, you can still get pretty close to optimal fueling and feel good come mile 26!

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