Marathon: Race Day Nutrition and Hydration Strategies

When there is 1 week to go until race day, it is important to make sure you have your hydration and fuel strategy thought out.   Fuel is key to a successful marathon experience, as we want to make sure we are adequately hydrated and can sustain running the 13.1 or 26.2 distance with enough calories, carbohydrates and blood glucose levels.  Most races begin early, 7 AM is a typical start time, you must know what time your race starts, or corral begins, especially if the marathon and half marathon have different start times.   

   Ideally you will want to eat a breakfast about 2 to 3 hours before start time.   If you have GI or digestive issues, maybe eating 3-4 hours before the start is better to give you more time to digest.  Keep your breakfast calorie range between 500- 800 kcal, which is a wide range, some runners can eat a meal on race day and some a have smaller capacity tolerance.   If 500 kcal seems like too much, break it down and spread out by eating a little every hour, within the 3-4 hour window.  A good rule to follow is 3 g/ carbohydrate per kg body weight within 3 hour window, 2g carb/ kg body weight within 2 hour window.     Most important is to know what foods you tolerate and can easily digest, do not try anything new on race day.  Aim for eating mostly carbohydrate rich, easily digestible breakfast the morning of race day, this is primarily to replace the liver glycogen stores that are used for the brain while we sleep.  (See last blog for more info) At this point the carbs you intake are not going to make it into your muscle glycogen, those are already stored from past 3-4 days, but you still need to make sure your topping off your glycogen stores. 

Some good examples of race day friendly breakfast ideas include  Toast with honey, bagel with peanut butter or fruit spread, oatmeal with mix in of protein, stay away from adding fruit especially fiber like berries.  Bananas with peanut butter, a protein bar (with sufficient carbohydrates),  and at least 8 oz. -12. Oz water every hour.  Avoid excessive fiber, protein and fat as these slow digestion and may cause stomach and GI upset.   Hopefully in your training, you have had time to get to know what foods work well for you.  


There is a lot of great research out there that concludes caffeine can enhance athletic performance, especially in endurance sports as it can lower the perceived rate of exertion.  I would strongly encourage you to NOT TRY ANYTHING NEW ON RACE DAY.  If you are a runner who typically runs in the morning and coffee or tea is part of your pre run routine and does not negatively affect you, you may consider having a small cup the morning of race day.  However, if you do not typically run with caffeine in your system, I would strongly encourage you to avoid it.  Caffeine will increase heart rate, GI motility, and is also a diuretic.  In addition to being nervous, anxious, or excited, adding caffeine may multiply these emotions, and remember there are long lines to the porta potties near the start of the race.   


1- 2 Hours Pre Race 

Focus on fluid intake and continue to supplement in some carbohydrates. Aim for drinking 8 –12 oz every hour, try sipping on water and a sports drink.   One of the biggest influences on your race will be the weather.  If it is hot or humid you are going to need to take in more fluids, also if it is cooler temperatures, do not forget to stay hydrated.  

Aid Stations 

Most races will offer water/ sports drink every 3-5 miles.  The best strategy to prepare is to study the course and know where and when the water stations will be.  If you think the aid stations are too far apart, or it’s a warmer  forecast, make sure you bring water with you.  The best strategy is study the race course ahead of time and plan out  your water/hydration accordingly.  A typical paper cup  will hold 5 – 6 oz water, but you might only  get between 3 –5 oz if you drink while running.  The stomach can empty 6- 7oz water in 15 min, so remember drinking too much or too fast may negatively affect you.  Try to make sure you take in both water and sports drinks to make sure you are getting electrolytes.  If you consume 1 water and 1 sports drink every aid station you will get about  10- 12 oz fluid oz. Or if you alternate every aid station take 1 water then the next sports drink.  Try to plan which stations ahead of time by studying the course. 


Carbohydrate Intake 

You may reference the last post about carbohydrates but during a run, you will be burning a tremendous amount of fuel, and endurance sport studies suggest intaking about 40- 60 g carb/hr  of high intensity activity.   I would recommend for every hour of running you anticipate, try to consume between  40- 60 g carbohydrates, so if you anticipate running 2 hours about 100 carbohydrates, 3 hours around 150 grams etc.  


Some good examples include: 

  • Bananas 20- 30 g/ whole, half banana 10-15, g. carbohydrates 
  • Gel / GU packet 20-30 g 
  • Gatorade  12 fluid oz has 22 g carbohydrates, 6 fluid oz 11 grams  
  • Energy Bar- 20-30, be careful with these  as they have a lot of protein 
  • Candy-  starburst 6 pieces have 24 g carbs,  
  • Jelly Belly Sport Beans  25 grams carbohydrates for one packet 
  • Honey Stinger  Chews- 23 g carbs for 6 pieces 
  • Honey Stinger Waffle- 1 waffle  19 g. carbohydrates 
  • Fruit Slices Oranges or apples- about ½ a fruit will be 10-15 grams of carbohydrates 
  • Beer- While I do not recommend this mid-race you will likely see spectators handing out beers and if you decide to make their day and chug one it will give you about 10-20 g carbohydrates.  


For your upcoming marathon or half marathon, the best strategy is to calculate approx how long you will be running and  mapout your fuel strategy by studying the course and lok at the race map. You may need a little less or a little more water/ fluids  depending on speed, course conditions, weather and humidity.  

Good luck preparing for your upcoming race.  



WRITTEN BY: Angela Dirnbeck PT, DPT, CMPT 

Angela, Physical Therapist at Chesterfield, MO ApexNetwork Physical Therapy, working on a patient.BIO:  Angela is a Physical Therapist and clinic manager at the Chesterfield ApexNetwork location in Chesterfield, MO.  She  graduated in 2013 with her Doctor of Physical Therapy from Des Moines University.   She has extensive training in manual therapy and a certification  from the North American Institute of Orthopedic Manual Therapy (NAIOMT) and has been with ApexNetwork for almost 10 years and enjoys treating a variety of orthopedic and musculoskeletal injuries, including runners and endurance athletes.   Angela has a comprehensive understanding of injury prevention and treatment being a distance runner herself for > 20 years.  She competed as an NCAA D1 athlete in cross country and track for the University of Dayton.  Following  undergraduate competition she began running half marathon and full marathon distances, completing 4  marathons, 2 of which were the Boston Marathon.  Over her years of practice, she has incorporated a lot of her experience and knowledge into treatment and patient care and has helped many patients and athletes rehabilitate and  teach biomechanics for greater awareness of  injury prevention and return to sport.