Carb Loading Methods Calculators
Below you'll find an Excel file hosted on this site that contains several different carbohydrate loading calculators
The following are different carbohydrate loading methods. The goal of a carbohydrate loading method is to achieve an outcome known as "glycogen supercompensation". The hope is that by performing one of these methods, that you'll enable your body to store more glycogen that can be then used on race day. Per a review article by Hawley et al. (1997), the increase in storage of glycogen in the muscles plays a more pivotal role in endurance events lasting longer than 90 minutes. So if your event is to last less than 90 minutes, then you're unlikely to see any performance gains by carrying out one of these methods. If the event lasts longer than 90 minutes, then having an increased amount of glycogen present has been shown to increase performance. Ideally, it will help you stave off the glycogen depletion wall. The benefits in events longer than 90 min, but less than a marathon (like most runner's half-marathons) the benefit is less measurable by means of glycogen depletion. So the following calculators will inform you a "theoretical marathon limit", but not a half marathon time.
The following calculators have been made to assist you in carrying out one of these methods.
-Western Australian Method
For both males and females, my recommended carbohydrate loading procedure is the Western Australian Method (WA). Carrying out this method may not be for everyone, so I've included a few other options and show the differences between their methods and their "theoretical results" to the WA method. It's important to note, the WA, Sherman, and Goforth methods were all research based studies based on men alone. The Tarnopolsky and James methods included women. I state this because my recommended method for both genders is the WA method even though the research was only based on men. As I explain below the calculators, I do believe that this leap of faith is justified.
Something very important to note, the consumption of this number of carbs requires a significant portion coming from a liquid carb source. If you attempted to consume this amount of carbs from a purely solid source (like the classic spaghetti dinner), then you're likely to end up with a very sore stomach. Instead, plan to consume nearly 80% of all the carbs listed in a liquid form as this will aid in absorption and leave you without the stomach problems. My preferred source of liquid carbs is Maurten Drink Mix 320 at the moment. It is soluble at 4.6g carbs per ounce instead of 2g carbs per ounce like many other products. Thus, it dramatically reduces the water burden of attempting a primarily liquid carb loading plan. If you'd like more information about Maurten, see below the calculator.
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.
-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 your normal caloric intake in kcals (or calories).
If you'd like to know more about each individual calculator, then scroll below the Excel file for a detailed explanation. In addition, I've written a long blog post covering many of the important findings regarding carbohydrate loading for the purpose of racing (Glycogen Supercompensation (AKA Carb Loading for a Race)).
*Please note that at this time the calculator is not mobile friendly. I apologize for the inconvenience.
Credit goes mostly to the Sedlock 2008 paper "The latest on carbohydrate loading: a practical approach" which compiled most of this research.
Western Australian Carb Loading Procedure (My recommended method for both genders)
The Western Australian carbohydrate loading procedure comes from the Fairchild et al. 2002 paper. In the original paper, the authors concluded a 1-day carb loading procedure with 10.3 grams/kilogram body weight of carbohydrates consumed could yield an average gain of 190% of normal glycogen storage. A drawback to the original research was the need for a glycogen depletion (GD) exercise the morning of the carb procedure. The GD exercise was a 5 min warm-up, then 150 seconds of cycling at 130% VO2peak (really really fast), and then 30 seconds of all-out sprint. Not necessarily a desirable workout to be carried out the day prior to your big race.
However, a follow-up research article (Bussau et al. 2002) showed that the GD exercise was unnecessary for the glycogen supercompensation to occur. Additionally, no statistically significant increase was seen in glycogen storage when increasing the WA protocol from 1 day to 3 days. This follow-up article cemented this protocol into a 1 day carb consumption with no need for any intense exercise proceeding the big race. In my mind, a win-win. It's important to note, the subjects of this research were all men who trained about 11 hours per week with a VO2peak of 59 (around a 1:20 half marathon or 2:47 marathon).
In order to carry out the WA protocol, do the following:
-On the day prior to the event, consume 10.3 grams of carbohydrates per kilogram body weight.
-80% of those carbs should be in liquid form in order to aid in absorption.
-The protein (g) and fat (g) values are suggested based on a 90% carb, 7.5% protein, and 2.5% fat diet on that single day.
-In theory, you would be able to store 190% of normal glycogen storage.
-In theory, if glycogen depletion were the only limiting factor (it isn't), then the time listed is the fastest you could run without taking in any nutrition during the race (in theory). That is not necessarily how fast you can run the event, rather it is meant to show whether the need for in-race nutrition may still be necessary given your goal time. This value is calculated by the following method:
((60/(vV02mph*(((Carb storage (kcal) / Estimated Calories burned (kcal))*100)+5)/100)))*26.2)/1440 = Time to glycogen depletion
Something that may become immediately evident is the sheer amount of carbohydrates and calories needed to carry out the WA method. This may be a significant increase for most females. But as will be noted in the Tarnoplosky and James methods, a significant increase in caloric intake and carb intake (by ratio to body weight) is a critical step to yield glycogen supercompensation in females. But with that being said, this method isn't for everyone. Not everyone wants to attempt to consume several hundred grams of carbohydrates the day prior to the event. So below are a few other options.
The Sherman method consists of 3 days of a "normal diet" followed by 3 days of a "high carb" diet. The normal diet was 50% carbs (protein and fat not specified) and the high carb diet was 70% carbs (protein and fat not specified). This method does not require a glycogen depletion workout. Instead, it was conducted with the following exercise protocol:
Low intensity pace (73% VO2max) for 90 min on Day 6, 40 min on Day 5, 40 min on Day 4, 20 min on Day 3, 20 min on Day 2, rest on the day prior to the event, and then Day 0 was the event.
The Goforth Method examined two possible protocols simultaneously. This method was done either with or without a glycogen depletion (GD) exercise. The GD exercise was 90 min at 65% VO2peak followed by 1 min run:1 min rest at 120% VO2peak for five intervals. This was conducted 7 days prior to the event. For the remaining days between the GD exercise and event day, the participants were limited to 20 min at 65% VO2peak per day.
During days 6 through 4 proceeding the event, the participants (men) consumed an 80% carb, 10% protein, and 10% fat diet. This equated to 9 grams of carbs per kilogram body weight in these men. During days 3 through 1 proceeding the event, the men consumed a 56% carbs, 26% protein, and 18% fat diet. This equated to 6.5 grams of carbs per kilogram body weight in these men.
The men who did the GD exercise saw their glycogen storage increase 147%. The men who did not do the GD exercise saw their glycogen storage increase 124%. The theoretical times needed to ensure in-race nutrition would not be necessary are shown for these two possible methods (with and without GD). It's important to note, these pale in comparison to the WA method which showed a 190% increase in storage in two separate papers.
This method was done with liquid carbs in part. The men consumed 315 g of liquid carbs per day during the 1st phase (80% carb) and 210 g of liquid carbs per day during the second phase (56% carbs). This would be about 44-48% of the total carbs consumed in these men.
Research Based on Women
Most of the research conducted to date in the glycogen supercompensation realm has been based on data from men. But several research articles (Tarnopolsky 1995, Walker 2000, Andrews 2003, Nicklas 1989, McLay 2007, and Paul 2001) have shown that men and women do not necessarily react the same to similar carb loading methods. What may indeed matter more than the composition of the diet is the total caloric intake and the total grams of carbohydrates per kilogram body weight.
Tarnopolsky aimed to test just that in the 2001 paper. Men and women consumed one of three diets for five days.
Normal diet (Men was 3000 calories and 6.1 g carb per kilogram body weight and Women was 2000 calories and 5.1 g carb per kg/bw)
High Carb (Men was 3000 calories and 7.9 g carb/kg bw and Women 2000 calories and 6.4 g carb/kg bw)
High Carb/High Calorie (Men was 4000 calories and 10.5 g carb/kg bw and Women 2711 calories and 8.8 g carb/kg bw).
The content of the normal diet was 58% C, 28% P, and 14% F. The High carb and the High Carb/High calorie were 75% C, 15% P, and 10% F. Lastly, the FFM (free fat mass) relative to carb consumption was equivalent in all three diets between genders (6.8 vs 6.6, 8.8 vs 8.3, and 11.7 vs 11.3).
The method also required a glycogen depletion exercise to occur on the 5th day proceeding the event. It was 60 min at 65% VO2peak followed by a 2:1 run to rest at 85% VO2peak. The remaining days were at 65% VO2peak at 60, 45, 30, and 0 min proceeding the event.
The result was men increased glycogen storage by 138% over normal and women by 117%. Not the same, but one of the higher reported values for females at the time. The value shown shows the in-theory marathon time that would not require in-race nutrition.
This study does reinforce that a high carb diet alone (75/15/15) was not enough to make a significant increase in glycogen storage in females, but was able to make a nominal increase in males. Males had a 123% increase whereas females had a 113% increase. This was likely due to the disparity in grams of carbs per kilogram body weight, but as the author posits this would require a siginficant portion of dietary calories comes from carbs to hit a value near 10 g carbs/kg bw.
To note, the males in this study had at least a 55 VO2peak (average was 63) and the females had at least a 45 VO2peak (average was 53). A 45 VO2peak estimates a HM at 1:40 and M at 3:28, and a 53 VO2peak estimates a HM at 1:27 and M at 3:01. Just to give you an idea as to the test subjects in this study.
The James 2001 article represents an important piece to the puzzle. In this study, men and women both consumed about 10 g carbs per kilogram body weight (10.5 g/kg bw in males and 9.9 g/kg bw in females). The participants went through a glycogen depletion exercise of 61% VO2peak for 90 min on day 4 prior to the event. The next three days were spent in the carb loading procedure, but no exercise was done.
Both the males and females were able to significantly increase their glycogen storage to about 182% normal. The females were tested 6 days prior to mensuration and separately 6 days post mensuration. All of these women were on oral contraceptives for at least the last two years and showed no hormonal changes between the two timeframes. This is important to note because according to Marieb et al. 1998 females when not on oral contraceptives showed a greater ability to store additional glycogen during the luteal phase.
Because the males and females showed a similar response when on a similar diet (as expressed as g carbs/kg bw), then it leads me to believe that females may elicit the same response from the Western Australian method as did men. This would eliminate the need for three days (as the James method uses) and the need for a GD exercise (as the James method uses).
Maurten Drink Mix 320 Advantages as a Liquid Carb Source for Carb Loading
As soon as I became aware of Maurten Drink Mix 320, the real possible avenue of it's use became clear to me. Normally, a carb based liquid product requires a 2 g carb per 1 oz water absorption rate. But Maurten Drink Mix 320 is unique given it is absorbable at 4.6 g carb per 1 oz water. When doing a massive carb loading strategy, this is a HUGE win.
Let's say you follow a 10g/kg bw protocol. Let's say you weigh 75 kilograms. That means you'd need to consume 750 g carb to complete the protocol. If you follow the 80% from liquid source, then that's 600 g carbs. If you did a 2:1 ratio like almost all liquid carb sources require, then you'd need to consume 300oz of water on that day. That's 2.3 gallons of water. It can be done, but man is it tough.
Whereas, let's use Maurten instead. At 4.6 g carb per ounce water, that means 600g carb would need 130 oz water. That's still a ton of water, but it's only 1 gallon comparatively. That's a huge win.
But I couldn't be sure whether this was practical and whether Maurten's product had actually been used for carb loading. Their website didn't have anything beyond in-race nutrition really mentioned. So I reached out to Maurten's Sports Nutritionist whom is partially responsible for the carb loading procedure of some of the top athletes they work with (including the Swedish Marathon Champion). He was nice enough to confirm my ideas on the product as well as confirm they do indeed follow a similar protocol in their elite athletes. As the sports nutritionist pointed out, what's probably most important more than anything when following the protocol is the sheer amount of carbs per kilogram body weight. The liquid source doesn't have to be 80% for it to work. It helps it become a feasible protocol for most. But many of their athletes daily diet is already 7-8 g carb per kilogram body weight and during peak season/high volume can be much higher. So he agreed the 10g/kg bw amount is a good number to try and hit, but that it doesn't have to be solely liquid carbs if you don't want it to be (but from a bulk standpoint can make it easier).
Other calculations in this file
Total kcal burned = Body Weight (in kg) * Distance of race (in km)
*(Humphrey 2013) This is a general value and a specific value would require physiological testing.
Leg Muscle Mass: Males = Body Weight (in kg) * 21%; Females = Body Weight (in kg) *20%
*21% and 20% represent averages for males and females respectively with ranges of 14-27% and 18-22% respectively (Rapoport 2010). Again this illustrates the "average" or generalness of this calculation
CHO Storage in Legs = Leg Muscle Mass * 80
VO2peak = *formula not shown due to proprietary nature, from Jack Daniels
vVO2 (m/s) = 2.8859+0.0686*(VO2peak-29)
vVO2 (mph) = vVO2 (in m/s) *2.23694
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Humphrey, L. [Hanson's Coaching Services]. (2013, Nov 23). Calculating Caloric Needs for Marathon- Updated 11/22/2013 . [Video File]. https://www.youtube.com/watch?v=TTQt3pjeqKg