Scientific Statement: Carbohydrate Loading

This scientific statement discusses the benefits of carbohydrate loading for Ironman Triathlon and provides nutritional recommendations and key considerations for successful implementation. It also highlights areas for future research, particularly with regards to female athletes.

Running head: SCIENTIFIC STATEMENT: CARBOHYDRATE LOADING
SCIENTIFIC STATEMENT: CARBOHYDRATE LOADING
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1SCIENTIFIC STATEMENT: CARBOHYDRATE LOADING
Executive Summary
The dietary practice of ‘Carbohydrate Loading’ is not new in Sports Nutrition. Carbohydrate
loading is extensively used for the purpose of enhancing an athlete’s glycogen reservoirs, which
are primary fuel for optimal performance during high intensity endurance sports or activities.
However, with regards to the prevalent misuse of this dietary practice, due to lack of awareness
and information by athletes engaged in Ironman Triathlon, there is an immediate requirement for
imparting adequate knowledge and information about the necessary dietary principles, to
athletes. This is due to severe usage of energy pertaining to the high performance requirements
of Ironman Triathlon for which, carbohydrate loading involving increasing the carbohydrate
intake along with balanced intake of lean protein and unsaturated fat sources would be
beneficial.

2SCIENTIFIC STATEMENT: CARBOHYDRATE LOADING
Table of Contents
Introduction..........................................................................................................................3
Discussion............................................................................................................................3
Importance of Carbohydrate Loading in Ironman Triathlon...........................................3
Rationale..........................................................................................................................4
Nutritional Recommendations.........................................................................................5
Carbohydrate Loading Diet Plan (As designed by the Author from FoodWorks)..............6
Key Considerations..........................................................................................................7
Literature Gaps and Future Research..............................................................................8
Conclusion...........................................................................................................................9
References..........................................................................................................................10

3SCIENTIFIC STATEMENT: CARBOHYDRATE LOADING
Introduction
‘Carbohydrate Loading’ is a dietary strategy recommended for athletes, in the days
leading into the start of an endurance event. The enhancement of present stores of glycogen in
one’s muscles forms the crux of execution of carbohydrate loading (Bilku et al., 2014).
The following report is a scientific statement supporting the prepared info-graphic
‘Carbohydrate Loading for Ironman Triathlon’. The report outlines the primary purpose of
carbohydrate loading, situations in sports where it has been shown to enhance performance as a
pre-competition nutritional strategy, a list of nutritional and precautionary procedures. And
lastly, the report highlights areas for future research.
Discussion
Carbohydrate loading is commonly utilized, for the enhancement of one’s energy
sources, prior to the commencement of a sport or athletic activity requiring high intensity
endurance exercise. This is performed through careful modifications of one’s diet, to increase the
muscle glycogen reservoirs (Hackney, 2015).
Importance of Carbohydrate Loading in Ironman Triathlon
Ironman Triathlon is characterized as a series of three types of races, which includes,
firstly a swimming race of 2.4 miles, a bicycle riding event of 112 miles and lastly, a marathon
running event of 26.22 miles (Kopetschny et al., 2018).
With respect to an Ironman Triathlon, athletes exhibit a wide range of metabolic changes,
one of them being high rates of energy expenditure, as per their level of skill and competency.

4SCIENTIFIC STATEMENT: CARBOHYDRATE LOADING
Hence, athletes new to the sport would require a low carbohydrate diet, in order to rely on fat
oxidation for sustained energy supply. Experienced athletes exhibiting high rates of expenditure
require high carbohydrate supplemented diet, along with careful reductions in exercise in order
to mitigate the losses (Maunder, Kildingand & Plews, 2018). For the supply of energy,
Adenosine Tri-phosphate or ATP is of utmost importance. The generation of Adenosine Tri-
phosphate is conducted via the metabolism of carbohydrates (Hardy et al., 2015). Despite the
increased calorie content provided by fat, as compared to its carbohydrate counterpart, its
metabolism by the human body generates energy in the form of ATP at rates which are not
feasible for the athlete to exhibit endurance in high intensity sports. Carbohydrates hence,
continue to remain faster sources of energy, and continuous engagement in strenuous, high
intensity exercise stimulates the preservation of glycogen in the muscles of the human body
(Vole, Noakes & Phinney, 2015). During a situation of low glycogen stores, the metabolism to
generate Adenosine Tri-phosphate is transmitted from carbohydrates to proteins, leading to
gluconeogenic utilization of existing amino acids. Protein metabolism for energy generation,
leads to a a negative nitrogen balance, causing muscle depletion. Hence, the implementation of
carbohydrate loading diet in Ironman Triathlon, would be beneficial to metabolize carbohydrate
as well fat, for a steady supply of energy (Arcega, Contreras & Orey, 2017).
Rationale
As opined by the Australian Institute of Sport, which is a part of the Australian Sports
Commission, carbohydrate is often misinterpreted and misused (Trakman, 2016). Hence, the
rationale behind studying carbohydrate loading is to impart awareness and education, regarding
appropriate selection of food and exercise tapering (Wilson, 2015).

5SCIENTIFIC STATEMENT: CARBOHYDRATE LOADING
Further in the study conducted by Kimber et al, (2002), it was found that the energy
expenditure of male and female athletes engaged in ironman triathlon is far greater as compared
to the intake of energy. According to the results, the energy expenditure in both males and
females were found to be 10, 036 and 8570 calories respectively, while intake was calculated to
be 3940 and 3115 calories respectively. Hence in accordance to the negative energy balance of -
5973 calories in females and -5123 calories in males, the authors feel that the consumption of a
high carbohydrate diet would be beneficial in reducing such nutritional and performance
discrepancies in ironman triathlon athletes.
The athletes’ level of competency is positively associated with high rates of energy
expenditure, as uncovered by the review performed by Maunder, Kildingand and Plews (2018).
The authors also stated that ironman triathlon athletes exhibit a range of various metabolic
changes, and hence modifying the carbohydrate and exercise routine as per their competence
would be a beneficial method leading to improved performance. While a low carbohydrate diet
associated with oxidization of fat would be beneficial for novice athletes, a tapered exercise plan,
followed by external supplementation of carbohydrate would yield advantageous effects on
professional ironman triathlon athletes.
Nutritional Recommendations
For the execution of carbohydrate loading, it is essential to perform the required
amendments to one’s diet, through careful and calculated incorporation of carbohydrate-rich
food sources, four to seven days preceding the high intensity or endurance event (Burke, van
Loon & Hawley, 2016). As stated by the Australian Institute of Sport, an athlete weighing 70
kilograms and participating in an Ironman Triathlon, must consume a diet of 14-18 mega joules,
consisting of 9 kilograms of carbohydrate per kilogram of body weight. This would amount to a

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total carbohydrate intake of 630 grams, a protein intake of 125 grams and fat intake of 60 grams
per day (Mckay et al., 2018). The protein intake should include consumption of low fat or lean
sources, such as vegetarian sources like beans and lentils, or lean meats like 60 grams of egg
whites or 100 grams of fish per day, or even low fat milk proteins such as 1 cup of low fat
yoghurt or soy milk, required for muscle repair. (Bean, 2017). The athlete may then proceed to
incorporation of carbohydrate rich food sources, preferably lighter and easily assimilated items
such as 100-200 grams of fruits, 0.5-1 liter sweetened drinks, sweeteners like honey or jam and
soluble fiber sources such as 60 grams of bagels and 60 grams of oats per day. The ingestion of
high fiber carbohydrates is to be regulated, in order to prevent the possible occurrence of
gastrointestinal discomfort. With progress of a carbohydrate loading diet, Ironman Triathlon
athletes must considering increasing their water intake to an additional 1 to 2 liters, which will
aid in beneficial weight and glycogen gain, since optimum glycogen storage and utilization
requires additional water retention (Raman et al., 2014).
Carbohydrate Loading Diet Plan (As designed by the Author from
FoodWorks)
Day Meal Food Quantity
13-Nov-18 Breakfast Oat bran 3 cups
Fruit salad,fresh,
+apple+banana+berries
1 cup (diced)
Juice,100% juice,lemon,home
squeezed
250 mL (1
glass)
Snack Muffin,apple,homemade 50g (1,
medium)
Honey 1 teaspoon
Gatorade 02 Perform Fierce Grape 500 mL (2
glasses)
Lunch Sandwich,other,fresh 100g (4 slices)
Bulla Fruit'n Yogurt Wildberry
97% Fat Free
250g (1 cup)
Juice,100% juice,orange,home 375 mL (1 large

7SCIENTIFIC STATEMENT: CARBOHYDRATE LOADING
squeezed glass/1 can)
Snack Smoothie,juice based,+berries 250 mL (1
glass)
Muesli bar,other 50g (1 bar)
Dinner Pasta dish,homemade,in
commercial sauce,cream based
sauce,with chicken & vegetables
250g (1 cup)
Bread rolls,with topping,spinach &
fetta
100g (2 rolls)
Juice,100% juice,fruit & vegetable
blend,commercial,
+apple+carrot+mango+orange+pine
apple+passionfruit
250 mL (1
glass)
Supper Bagel,from white flour,toasted 75g (1 large)
Fruit salad,fresh & dried
fruit,homemade
2 cups (diced)
Key Considerations
 For a successful carbohydrate loading diet, an athlete must engage in adequate rest, in
order to prevent depletion of carbohydrate sources, before the commencement of the
Ironman Triathlon event. Athletes must gradually engage in reduction of their exercise
and training time, engaging in only 20 minutes of physical activity prior to two days
before the event, followed by complete rest on the day before the same (Anderson et al.,
2016).
 Often there is a discrepancy between the amount of carbohydrates required as compared
to actual amount ingested by the athlete, due to lack of adequate knowledge and
awareness regarding appropriate sources of carbohydrates. Hence, athletes must take
active participation in formulating their diet plan, with the aid of a qualified sports
nutritionist, in order to successfully achieve the beneficial impacts of the carbohydrate
loading diet (Trakman et al., 2016).
 Consumption of foods high in insoluble fiber and bulky foods, may cause constipation,
bloating and gastric discomfort. Hence, athletes must carefully select the foods to be

8SCIENTIFIC STATEMENT: CARBOHYDRATE LOADING
consumed, and incorporate items which are quicker sources of carbohydrates, such as
fruits, sweeteners, liquids and oats (Close et al., 2016).
 Weight gain is inevitable in the process of following a carbohydrate loading diet, which
is indicative of the increased storage of glycogen in one’s muscles (Ørtenblad & Nielsen,
2015).
 It is common of some athletes to engage in excessive food consumption or faulty
selection of foods, as an excuse to fulfill carbohydrate loading. Hence, athletes must be
adequately informed regarding the salient features of the diet, and the possible negative
consequences due to misconduct of the same (Wilson, 2015).
 It is imperative for Ironman Triathlon athletes to consume adequate electrolytes to
prevent muscle spasms, with an intake of beverages containing 30-50 mmol of sodium
per liter (Volek et al., 2015).
Literature Gaps and Future Research
As stated by the Nestle Nutrition Institute, there is a considerable lack of information
about carbohydrate loading diet for female athletes. A majority of research has been performed
utilizing male athletes (Close et al., 2016). Female athletes may require an increased
consumption of carbohydrate rich foods as compared to males, due to decreased intake of energy
(Devries, 2016). An additional concerning factor lacking research is the association between the
female menstrual cycle and intake of carbohydrate loading diet. Female athletes may exhibit
decreased response to carbohydrate loading, in comparison to male athletes, during the
occurrence of menstruation or follicular phase (Nindi et al., 2016). Despite limited evidence
advocating the efficiency of carbohydrate loading during two weeks preceding the event of

9SCIENTIFIC STATEMENT: CARBOHYDRATE LOADING
female menstruation, there is still requirement of conducting research, with respect to utilization
of female athletes and sportspersons as subjects. (Heikura et al., 2017).
Conclusion
Hence, it can be concluded that, carbohydrate loading is an efficient way to enhance an
athlete’s reservoirs of energy, with respect to performance during a high intensity and high
endurance sports or activity such as Ironman Triathlon. However, the execution of such a diet
would require careful selection and planning of foods and subsequent reduction in exercise,
which athletes must adhere to, with respect to guidance from qualified professionals. Despite its
proven efficiency, there is still a dearth of evidence regarding the effects of carbohydrate loading
on female athletes, and hence, future research must be directed at achieving the same.

10SCIENTIFIC STATEMENT: CARBOHYDRATE LOADING
References
Amer, M. A., Smith, M. D., Herbison, G. P., Plank, L. D., & McCall, J. L. (2017). Network
meta‐analysis of the effect of preoperative carbohydrate loading on recovery after
elective surgery. British Journal of Surgery, 104(3), 187-197.
Anderson, L., Orme, P., Di Michele, R., Close, G. L., Morgans, R., Drust, B., & Morton, J. P.
(2016). Quantification of training load during one-, two-and three-game week schedules
in professional soccer players from the English Premier League: implications for
carbohydrate periodisation. Journal of sports sciences, 34(13), 1250-1259.
Arcega, R., Contreras, D., &Orey, J. (2017). Carbohydrate (CHO) loading does improve
endurance performance.
Bean, A. (2017). The complete guide to sports nutrition. Bloomsbury Publishing.
Bilku, D. K., Dennison, A. R., Hall, T. C., Metcalfe, M. S., &Garcea, G. (2014). Role of
preoperative carbohydrate loading: a systematic review. The Annals of The Royal College
of Surgeons of England, 96(1), 15-22.
Burke, L. M., van Loon, L. J., & Hawley, J. A. (2016). Postexercise muscle glycogen resynthesis
in humans. Journal of applied physiology, 122(5), 1055-1067.
Close, G. L., Hamilton, D. L., Philp, A., Burke, L. M., & Morton, J. P. (2016). New strategies in
sport nutrition to increase exercise performance. Free Radical Biology and Medicine, 98,
144-158.

11SCIENTIFIC STATEMENT: CARBOHYDRATE LOADING
Devries, M. C. (2016). Sex‐based differences in endurance exercise muscle metabolism: impact
on exercise and nutritional strategies to optimize health and performance in
women. Experimental physiology, 101(2), 243-249.
Hackney, A. C. (2015). Human Performance Enhancement in Sports and Exercise: Nutritional
Factors-“Carbohydrate Loading”. RevistaUniversitaria de la EducaciónFísica y el
Deporte, (2), 28-31.
Hardy, K., Brand-Miller, J., Brown, K. D., Thomas, M. G., & Copeland, L. (2015). The
importance of dietary carbohydrate in human evolution. The Quarterly review of
biology, 90(3), 251-268.
Heikura, I. A., Stellingwerff, T., Mero, A. A., Uusitalo, A. L. T., & Burke, L. M. (2017). A
mismatch between athlete practice and current sports nutrition guidelines among elite
female and male middle-and long-distance athletes. International journal of sport
nutrition and exercise metabolism, 27(4), 351-360.
Kimber, N. E., Ross, J. J., Mason, S. L., & Speedy, D. B. (2002). Energy balance during an
ironman triathlon in male and female triathletes. International journal of sport nutrition
and exercise metabolism, 12(1), 47-62.
Kopetschny, H., Rowlands, D., Popovich, D., & Thomson, J. (2018). Long-Distance Triathletes’
Intentions to Manipulate Energy and Macronutrient Intake Over a Training
Macrocycle. International journal of sport nutrition and exercise metabolism, 20(XX), 1-
7.

12SCIENTIFIC STATEMENT: CARBOHYDRATE LOADING
Maunder, E., Kilding, A. E., & Plews, D. J. (2018). Substrate Metabolism During Ironman
Triathlon: Different Horses on the Same Courses. Sports Medicine, 1-8.
McKay, A. K., Pyne, D. B., Peeling, P., Sharma, A. P., Ross, M. L., & Burke, L. M. (2018). The
impact of chronic carbohydrate manipulation on mucosal immunity in elite endurance
athletes. Journal of sports sciences, 1-7.
Nindl, B. C., Jones, B. H., Van Arsdale, S. J., Kelly, K., & Kraemer, W. J. (2016). Operational
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Ørtenblad, N., & Nielsen, J. (2015). Muscle glycogen and cell function–Location, location,
location. Scandinavian journal of medicine & science in sports, 25, 34-40.
Raman, A., Macdermid, P. W., Mündel, T., Mann, M., &Stannard, S. R. (2014). The effects of
carbohydrate loading 48 hours before a simulated squash match. International journal of
sport nutrition and exercise metabolism, 24(2), 157-165.
Trakman, G., Forsyth, A., Devlin, B., &Belski, R. (2016). A systematic review of athletes’ and
coaches’ nutrition knowledge and reflections on the quality of current nutrition
knowledge measures. Nutrients, 8(9), 570.
Volek, J. S., Noakes, T., &Phinney, S. D. (2015). Rethinking fat as a fuel for endurance
exercise. European journal of sport science, 15(1), 13-20.

13SCIENTIFIC STATEMENT: CARBOHYDRATE LOADING
Wilson, P. B. (2015). Misrepresentation of carbohydrate for exercise:‘It is time to bust the myth
of physical inactivity and obesity: you cannot outrun a bad diet’. Br J Sports Med,
bjsports-2015.
For infographic:
Hackney, A. C. (2015). Human Performance Enhancement in Sports and Exercise:
Nutritional Factors-“Carbohydrate Loading”. RevistaUniversitaria de la
EducaciónFísica y el Deporte, (2), 28-31.
Kopetschny, H., Rowlands, D., Popovich, D., & Thomson, J. (2018). Long-Distance
Triathletes’ Intentions to Manipulate Energy and Macronutrient Intake Over a
Training Macrocycle. International journal of sport nutrition and exercise
metabolism, 20(XX), 1-7.
McKay, A. K., Pyne, D. B., Peeling, P., Sharma, A. P., Ross, M. L., & Burke, L. M. (2018).
The impact of chronic carbohydrate manipulation on mucosal immunity in elite
endurance athletes. Journal of sports sciences, 1-7.
Raman, A., Macdermid, P. W., Mündel, T., Mann, M., &Stannard, S. R. (2014). The effects
of carbohydrate loading 48 hours before a simulated squash match. International
journal of sport nutrition and exercise metabolism, 24(2), 157-165.