Race Strategy – Fluids and Carbohydrates

Strategic Questions

Ask yourself these questions: Are you training for an event that will last longer than 60 minutes? What sources of energy will you rely on to complete the race?  What sources of fluids will you rely on to complete the race?  Do you plan on needing to consume electrolytes during the race? What are you doing to prevent bonking and seeing spots? What are you doing during your 14-week training season to determine what you can eat and what you can drink during the race without getting sick to your stomach? Early in your training season is the time to experiment with sources of fluids for adequate hydration, as well as sources of carbohydrates for adequate energy.



When discussing race-day strategic consumption of carbohydrate and fluids, we begin with the assumption that we have  balanced nutrition and adequate hydration as a lifestyle. As part of our lifestyle, in this discussion we assume you have good nutrition and hydration for it’s only then that your coaches can give you examples of useful strategic plans for race day.

Energy Stores in Muscles, Liver and Blood

A flat half marathon is going to take most people nearly two hours and up to about three hours for some. But the human body stores only enough energy in the muscles and liver and blood for up to about 90 minutes of work, assuming you do everything right. Therefore for most people, unless they supplement with additional carbs and fluids during the race, will bonk (run out of energy) the last 30 minutes or hour or two after the race starts.

Calculations and Assumptions

A woman who weights 130lbs and runs a half marathon in 2:30. She will burn approx 1,290 calories, or about 516 calories per hour, or approx 98 calories per mile. With proper training and race-week strategy, she will start the race with reserves in her muscles and liver of about 1,000 calories. Calculation: this woman will need to consume 290 calories during the half marathon, else she bonks.


What sources of carbohydrate should she consume during the half marathon? How much water should she drink? What about electrolytes? Should she start experimenting early in the season and treat each long-distance Saturday workout as a dress rehearsal for race day?


Through effective training for Race to Robie Creek with BOISE RunWalk’s 14-week training program, this lady has arrived at the starting line with a proven plan and the confidence that she will have lots of fun running uphill 8 miles and downhill 5 miles during Robie Creek. This lady has a plan that will work for her. Is she using GU for her source of carbohydrate? Or is she using Shot Blocks? Is she drinking sports drink as a source of fluids and electrolytes? Is she eating chicken sandwiches and pretzels every other mile during her race? Whatever she has decided, she arrived at her decision by experimentation, treating each Saturday morning as a dress rehearsal for race day. Yes, she made some mistakes along the 14-weeks especially early on, and things sometimes got to be a little messy. But by mid to late season, she was fine-tuning her decisions as to the sources of carbohydrate, fluids and electrolyte. And BOISE RunWalk was very helpful, by providing an example chart showing carbohydrate and fluids consumption for three difference race finish times. See example chart above (note: W=water, PA=sports drink PowerAde, G=Gu).








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