Understanding a few key fueling concepts can be the difference between having a great marathon and not even making it to the finish.
Everybody is different, so it’s important how to customize an individual fueling plan to ensure race-day success. It can take months of preparation to properly prepare for a marathon, and failing to understand a couple key nutrition tips is often what prevents someone from reaching their true potential. Taking a little time to research, plan, test, and fine-tune your nutrition throughout all your training will significantly improve your marathon-day success.
This article will give you a starting point which you should adjust as necessary based on these six variables: body size, athletic background, total duration, pace, conditions, and training habits.
Consider a 150-pound, trained athlete whose goal is to finish a marathon in 3.5 hours in 65 degrees. This athlete has a background of 2-5 years racing in endurance sports.
This athlete should consume 150 calories per hour (525 calories) and 53-ounces of water. A balance of all five electrolytes should be consumed with a target of 400mg sodium per hour. Again, it’s important to practice and implement this nutrition plan during your long training days.
courtesy Nils Nilsen photography
Body size: Larger athletes require more caloric fuel than smaller athletes. There is no rule of thumb here because other variables need to be considered. However, for a trained athlete, 1-calorie per hour per pound is a good starting point. If you’re a 200-pound athlete, you should consider 200 calories per hour. This general rule should be adjusted considering the following variables.
Athletic background: Aerobic training brings about physiological adaptations that take a number of years to develop. An athlete with a long history of endurance training has developed increased vascularization, more mitochondria and is more efficient at burning fat than an athlete who has no endurance training background. Your body has to go through the process of adapting to stress in order become more metabolically efficient at longer distances. The goal is to train your body to spare glycogen, burn fat more efficiently and use fewer calories per hour.
Total duration: While you only have around 2 hours of stored glycogen (fuel), you have days worth of stored fat as fuel. Again, the goal is to train your body to spare glycogen, burn fat more efficiently and use fewer calories per hour.
Your body prefers glycogen, which is then converted to glucose as its fuel for racing. This means if your race lasts two hours, you can just consume water. On the other hand, if you race takes four hours, you must consume enough fuel to cover the two additional hours worth of effort. If you race ten hours, you’ll need enough fuel to cover a minimum of eight hours of exercise.
Pace/Effort: How hard you plan to race determines which fuel you should use. The ONLY calories that need to bereplaced during the event are glycogen calories. Fat calories do not need to be replaced. If you plan to run your marathon at a fast past, which requires more effort, you’ll require more glycogen and will need to increase your calorie intake per hour. If you plan to run at a slower pace, which requires less effort, you’ll rely on more fat as fuel and you can therefore consume fewer calories per hour.
Conditions: Whether the race day temperature is cold or hot does not affect the amount of calories you should consume, however, it does affect the amount of fluid and electrolytes you should consume. In a hot race, total fluid consumption is critical to success and you should drink no less than 12 ounces of water for every 100 calories. In cooler conditions the total fluid can be reduced to as little as 6 ounces for every 100 calories. The endurance fueling article reviews this in detail.
Training habits: Athletes who’ve trained many months or years with few calories are able to also race with fewer calories. If much of your long distance training has been done with very few calories you will have systematically improved your metabolic efficiency. This means you’ve successfully shifted your body’s reliance to burning fat over burning glycogen. Details on this can be found in the low carbohydrate training article.
Summary: How you fuel for a marathon is greatly affected by your athletic background and other key variables. Understanding these variables allows you to fine tune your unique fueling plan to ensure success on your next marathon. During your marathon, consume the appropriate amount of calories and fluids based on your training and you can be assured success.