Marathon Nutrition Tips Based on How You Run

“I’m training for a marathon so I can eat whatever I want.” Have you said those words or heard them before? Sure, you’re likely burning some major calories, but shoving down a half-dozen breakfast tacos after every run is likely the wrong strategy for successfully getting across the finish line. 

How you fuel your body during 19 weeks of training will have a strong impact on how you feel getting to, and across, the finish line. Food is energy and you need energy to successfully run 13.1 or 26.2 miles.  Nutritionist Michael Florida from Life Nutrition sat with our runners after a recent long run to discuss nutrition strategies.  

Do you run anaerobically or aerobically?

How you plan your nutritional strategy varies from person to person based on your body composition, condition and how your energy is supplied, aerobically or anaerobically. During aerobic exercise there is enough oxygen intake to sustain your current level without additional energy. When in an anaerobic state, oxygen is not sufficient and your muscles break down sugar (carbs) for fuel.

If you have a well-developed aerobic engine (a product of years of endurance training), you are able to train predominantly in an aerobic zone. This allows you to primarily utilize your own fat or healthy fats from food to fuel your body. More often than not, many novice runners tend to unknowingly train all anaerobically which leads them to be very glucose dependent (which can cause sugar cravings after your run).

Once you understand the unique demands of your body and the way you’re training, you can create a customized fueling strategy for the three phases of fueling: pre-run, intra-run and post-run.

Pre-run fueling

We hear it all the time “When I wake up in the morning, I’m not hungry”.  When you wake up, your cortisol (a stress hormone) is typically at its highest levels, which stimulates a response from your sympathetic (“flight or fight”) nervous system.  When this happens, your non-essential bodily functions shutdown, including digestion (and therefore hunger).  Despite not feeling hungry, your body still requires fuel to function.  Therefore, as a rule of thumb, target fueling approximately 30 minutes before training.  When it comes to what to eat, the specific fuel source(s) will depend on the extent to which your exercise is fueled by your aerobic vs. anaerobic system.  Both systems will power your training, but the extent to which you rely on one system relative to the other will be highly dependent on the individual and will influence your optimal pre-run nutrition.  For example, if you’re primarily aerobic during your run, a healthy fat source will be effective at fueling that activity.  Conversely, if you primarily run anaerobically, eating a high carb snack will be the most beneficial.

Intra-run fueling

Much like not being hungry first thing when you wake up, it’s also common to not crave fuel during exercise. 

Similarly, your body is in motion and blood is being directed to the muscles to ensure oxygen and nutrients are supplied to those working muscles.  As a result, nonessential functions, once again, take a back seat.  But, as with when you wake up, your lack of hunger during activity is just a poor signal.

When it comes to fueling during runs, a general strategy (though this will vary depending on the individual) is to start fueling approximately 45 mins (or 5-6 miles whichever comes first) into a run and then consume additional fuel every 25-35 mins thereafter.

The three most common types of on-the-run fuel are:

  • Gels – many gels are maltodextrin-based which (chemically speaking) are polysaccharides that, when it hits your stomach, break down into monosaccharides and can commonly cause gastric dumping, sending you sprinting for the porta-potty. There are more natural alternatives (such as Huma gels) which have a lower glycemic load and tend to digest easier.  But, ultimately, the only way to know what your body can effectively tolerate is for you to experiment with it.

  • Liquids — Liquid fuel sources (namely sports drinks like Gatorade or Powerade) are very common in endurance training and racing. While effective for providing a quick form of glucose and electrolytes, it’s important to remember that liquid fuel is not a form of hydration.  If you’re using liquid forms of fuel, you need to balance it with water to ensure you’re maintaining your hydration levels and able to absorb the liquid fuel effectively.

  • Solids – While the ultra-running community has fully embraced eating solid foods during long bouts of activity, it is far less common among the road-racing community. That said, for individuals who have a difficult time tolerating gels or liquids, solid foods like fig newtons or peanut butter and jelly sandwiches can be highly effective fuel sources on-the-run. 

Post-run fueling

When it comes to fueling after your run, you should be focused on both the timing and the composition of the fuel.  You should try to introduce fuel within 30 minutes of exercise.  It is typically within this window that your heart rate is still elevated and can most rapidly replenish nutrients and minerals to the depleted muscles.

Looking for a 2-3:1 carb:protein ratio, on average, will ensure replacing depleted glycogen stores while simultaneously initiating the process of rebuilding damaged muscle fibers.  Stick to quality sources of carbohydrates and faster-uptake sources of protein (whey vs casein) to ensure that it’s a fuel combination that can rapidly uptake and repair.

Hydration In conjunction with fueling, hydration is critical to your body operating efficiently and effectively.  Find a consistent hydration level that you can sustain over time to meet the needs of your body.  On average, aim for 50% of your body weight in fluid ounces of water.  So, for example, if you weigh 200 pounds, aim for 100 fluid ounces of water per day.  In our tropical Houston climate, on a day when you’re running outside and sweating profusely, you are losing more water (than average) and you might need more than 50% of your body weight to offset the water lost during exercise. 

After establishing your baseline hydration needs, it’s also important to avoid drastically increasing your water intake in the days immediately preceding your race.  This can lead to your body purging the excess fluid and the sodium and electrolytes along with it (a perfect recipe for cramps and/or bonking). 

In summary, thoughtful, deliberate and quality fueling is important to practice consistently.  If you’re going to spend 19 weeks training for a race, maximize every effort by fueling properly for it before, during and after to promote growth and progress from session to session and over time.  Fuel for the specific nature and intensity of your training and start to fuel your body based on its unique performance. 

If you have questions you can contact us at RacePace or Michael Florida at Life Nutrition.

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