Below you'll find an Excel file hosted on this site that contains an in-race nutrition calculator

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It's important to note that individual responses to in-race nutrition will vary.  This calculator is meant as a general means to figure out carb consumption.  In order to have an accurate picture of in-race nutrition, a runner would need to complete a metabolic efficiency profile.  Ideally, a metabolic efficiency profile would be completed very close to race day to get the most accurate represenation.

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You have to "edit" six cells colored in yellow.  For all calculators contained in this spreadsheet to work, you must input information into all six cells.  Please don't attempt to edit anything other than those six yellow cells.

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-You can enter your body weight (in pounds).

-Then choose your gender (Male or Female) using the drop-down arrow.

-Then choose an upcoming race distance using the drop-down arrow.

-You can enter a recent distance using the drop-down arrow.

-You can enter a recent race time (make sure it is in the format of Hours: Min Min : Sec Sec)

-And lastly, enter how many grams of carbohydrates you plan to consume per hour during the race (for example, if you consume 100g carbs in 4 hours, that is 25 g of carbs per hour.

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Find your estimated finish time for a marathon, or half marathon.

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You'll find two sets of data.  One in which a person follows "No Carb Loading Protocol Prior to the Marathon" and one in which a person follows the "Western Australian Carb Loading Protocol" (10.3 g/kg bw carb consumption).  The No Carb Loading calculates based on a 100% glycogen storage estimated value (if you carb load less than 7 g/kg bw, then you are likely in this category).  The WA Carb Loading calculates based on a 190% glycogen storage estimated value (average from the research study).  If you want to know more about the WA protocol see the "Carb Loading" tool.

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Then, look at the blue column "Deficit Carbs (g) / hour".  The value that appears in the same row as your "estimated finish time" is the suggested number of carbs that should be consumed per hour during the race.

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The purple column "ESTIMATED DISTANCE (in miles) TO HIT WALL WITH NO CARB LOAD OR IN-RACE CONSUMPTION" in the same row as your estimated finish time displays the mile at which you will theoretically run out of glycogen storage and "hit the wall" assuming you come in with normal glycogen storage in your leg muscles.

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The orange column "DISTANCE (in miles) TO HIT WALL WITH NO CARB LOAD BUT GLUCOSE CONSUMPTION AT PLANNED RATE" uses your planned carb strategy and displays the mile at which you will theoretically run out of glycogen storage and "hit the wall".

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Two "limits" should be noted.  Per Jentjens 2002, when it's "hot" outside (95 F in lab based study), the oxidation of CHO is about 10% less than in cooler temps.  So the recommended limit of in-race carb consumption in a hot race is 50-60 g carbs/ hour.  The maximal intake of carbs per hour is 90g (source has yet to be found, but from memory) when running.  The 90g limit has been marked in black when the advised deficit of carbs exceeds this value.  These have been shown to be irrespective of body weight.

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If you'd like to know more about how this calculator was made, then scroll below the Excel file for a detailed explanation.

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*Please note that at this time the calculator is not mobile friendly.  I apologize for the inconvenience.