EXSC 310 Research Study1_HT

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The Effects of a Pre-exercise High-Carbohydrate Diet versus a Pre-
Exercise High-Fat Diet on Workout Performance
Hope Templeman
EXSC 310-001
November 16, 2015

THE EFFECTS OF A PRE-EXERICSE HIH-CARB VS. HIGH-FAT DIET ON WORKOUT PERFORMANCE
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Table of Contents
Introduction………………………………………………………………………………….3
Statement of Problem…………………………………………………………………...........4
Importance of This Study……………………………………………………………………4
Review of Related Literature………………………………………………………………...4
Research Procedures…………………………………………………………………………9
Analysis of Data…………………………………………………………………………….10
Summary, Findings and Conclusions……………………………………………………….12
Recommendations for Future Studies………………………………………………………13
Bibliography………………………………………………………………………………...14
Appendix…………………………………………………………………………………...16

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Introduction
Exercise, whether aerobic or anaerobic, requires energy which comes from the two primary
substrates (fuel sources): carbohydrates and fats. These two fuels work simultaneously in providing the
energy needed to carry out certain endurance and anaerobic exercises, however, one source may be more
prominently used than the other depending on the type, intensity, and duration of the exercise as well as
the fitness level of the individual. For instance, the primary substrate used in high-intensity, sprint
exercises is carbohydrates while the primary substrate is fat for moderate- to –low intensity endurance
exercises. This is because glucose, the usable form of carbohydrates, is the main source of energy in our
body and is used up more quickly, especially in high-intensity, anaerobic exercises. The two anaerobic
systems in the body are the ATP-PCr and glycolytic systems, with glucose being the primary fuel
source. In these two systems, glucose is used up very quickly, usually within the 5 to 10 minutes,
because fat requires more oxygen and time to actually burn. Therefore, the primary cause of exhaustion
during anaerobic-type exercises is the fast depletion of carbohydrates in the blood, muscles, and liver.
In contrast, during endurance exercises such as running a marathon or other steady-state exercises, more
free fatty acids (FFAs), the usable form of fat, are being burned while less glucose is being burned,
resulting in more sustained energy at the desired intensity and for longer periods of time because there is
an endless supply of energy in the form of fat not carbohydrates. However, both substrates are essential
for any type of exercise, only the ratio (amount) of carbs versus fats should be changed in relation to
aerobic or anaerobic exercises. For instance, a high-carb, low-fat diet will very quickly lead to fatigue
and exhaustion due to the limited amount of glycogen able to be stored in the muscle and liver. Also,
after the glycogen is used up there is only a short supply of free fatty acids available to burn so energy
will continue to diminish to the point of exhaustion. Consequently, a high-fat, low-carb diet may be
more beneficial because free fatty acids may help conserve carbohydrate stores, therefore, improving
exercise performance and sustaining energy for longer periods of time.

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Statement of Problem
The purpose of this study was to compare and contrast the effects of a pre-exercise high-carbohydrate
diet (70% of diet) for three days versus a pre-exercise high-fat diet (55% of diet) for three days on
overall workout performance, including both aerobic and anaerobic exercises.
Importance of This Study
This study was important, in that, it showed the effects that certain substrates can have on both aerobic
(with oxygen) and anaerobic (without oxygen) exercise performance. It is important to understand what
fuel sources can benefit a person the most, depending on both the duration and intensity of the exercise
as well as an individual’s fitness level. The two most important substrates, carbohydrates and fats, were
used in this study and were consumed at least three to four hours prior to exercise. This study was also
important in that it demonstrated the certain effects that a pre-workout meal, whether high-carb or high-
fat, will have on overall workout performance.
Review of Related Literature
Studies show that the main substrate, having the most significant influence on our daily energy intake
and exercise performance is that of carbohydrates. Also, studies show that glycogen is an extremely
important source for aerobic exercises (marathons, running, biking, etc.) and, therefore, a high-
carbohydrate diet should be consumed at least 3 to 4 hours prior to aerobic or anaerobic exercise to
increase muscle and liver glycogen concentrations during exercise. However, glycogen stores will be
depleted very rapidly during anaerobic exercises such as sprinting and explosive exercises, thereby
inhibiting performance and leading to fatigue.
It is the primary fuel source for sprint or explosive exercises, also known as anaerobic exercises, because
it is used first and is used up very quickly usually within the first 5 to 10 minutes of exercise (from the

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ATP-PCr system to the Glycolytic system). One important study was done showing the effects of a
high-carb meal on cyclists

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Research Procedures
For this study, a longitudinal research method was performed over the course of one week. This
longitudinal study included 6 participants, consisting of a mixture of 3 males and 3 females whose ages
ranged from 19 to 21 years. Two out of the three males were of average fitness level while the third
male had a highly active fitness level. All three females were of average fitness levels. The study took
place in the Lahaye Student Union located on Liberty University’s campus, where treadmills and
ellipticals were the main equipment used. All 6 participants were picked randomly on campus and varied
in age and fitness level. The same 6 participants took part in the entire one week study for best results.
The participants were told to eat a high-carb diet (at least 70% carbs), low-fat diet for three days, eating
bigger meals 3 to 4 hours prior to a 30 to 60 minute steady-state workout on the treadmill. After three
days of a high-carb diet, participants were then told to eat a high-fat diet (at least 50% fat) for three days
at least 4 hours prior to working out, due to the slower digestion of fat. All participants were cautioned
only to eat bigger high-carb or high-fat meals 3 to 4 hours prior to working out to prevent indigestion
and other GI tract issues that may impair exercise performance.
For the first three days on a high-carb diet, all participants were told to run on the treadmill at a steady
pace up to an hour, depending on fitness level and/or time to exhaustion, on at least a 5.0 speed or
higher. For instance, the fit participants averaged a constant speed of 7.0 for 30-minutes straight,
whereas, participants who were of average fitness levels held a constant speed of 5.0 for 20-minutes.
For the next three days on a high-fat diet, participants were challenged to run on the treadmill at a
minimum speed of 5.5 or higher for a longer period of time (an hour or more) to feel the most effects
that burning fat, not carbs, can have on workout performance. At the end of each workout, I had the
participants cool-down for 10 minutes on the elliptical at a low intensity to help facilitate active pH
recovery, thereby clearing the lactic acid in 30 to 60 minutes, which is about half the time it takes to
clear lactic acid in passive recovery.

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Analysis of Data
The data in the line graph above shows the results over the period of 6 days, including the first three
days of a high-carbohydrate diet and the next three days of a high-fat diet. The speed (s) indicates, on
average, how fast all 6 participants ran on the treadmill each day over at least a period of 60 minutes or
less. Average speed the participants ran on the first day was 5.0 for all 6 participants which explain why
all 6 lines on the chart start on speed 5.0 for day 1. Day 6 reveals a large improvement in speed for all 6
participants after consuming high amounts of fat for 3 days, with largest improvements in speed made
by the 3 participants with a dark blue line, dark green line, and light green line. Average speed by all
participants after the 6 day study was increased by at least 1.0 to 2.0 speeds more than the beginning.
Between day 1 and day 3, most participants increased in speed significantly from as low as 5.0 speed to
as high as 7.5 speed, however, by day 3 of a high-carb diet participants either decreased in speed or
stayed at the same speed but with much less energy. Results from the graph reveal that days 4 through 6
show increases in speed for all participants which was sustained for much longer (45 minutes or more)
than the first 3 days (30 minutes or less).
0
1
2
3
4
5
6
7
8
Day 1 Day 2 Day 3 Day 4 Day 5 Day 6
Speed
Effects of a Pre-Workout High-Carb Versus
High-Fat Diet on Exercise Performance(6
Days)
Seth
Manny
Jonathan
Kolleen
Me
Hannah

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This chart shows results of
0
1
2
3
4
5
6
Category 1 Category 2 Category 3 Category 4
High-Carb Diet (3 Days)
Series 1 Series 2 Series 3
0
1
2
3
4
5
6
Category 1 Category 2 Category 3 Category 4
High-Fat Diet (3 Days)
Series 1 Series 2 Series 3

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Summary, Findings, and Conclusions
Based on the results, overall, it is evident that a high-fat diet is more beneficial in sustaining
energy for longer periods of time for moderate intensity steady-state endurance exercises than a high-
carb diet. Also, results proved that a high-carb diet is very beneficial in providing immediate energy and
is good for sprinting or other anaerobic-type exercises. On day 1 of eating a high-carb diet, all
participants (unfit and fit alike) ran at a constant speed of 5.0 for 30 minutes and cooled down for 10
minutes on the elliptical at a speed of 4.0. Also, time to exhaustion, noted for each participant, was right
at the 10 to 15 minute mark on the first day. The next 2 days the participants ran at a pace set according
to fitness level, the average unfit participants remained in the 5.0 to 5.5 speed range for 45 minutes and
the active fit participants remained in the 7.0 to 7.5 speed range for 45 minutes. Time to exhaustion for
those 2 days was not noted until the 15 to 20 minute mark, when participants started to slow down pace
and breathing rate increased. At the end of the first 3 days of eating only a high-carb diet, participants
claimed they felt less energetic, weaker, tired, worn out and unable to sustain a constant pace for long
periods of time. After 3 days of eating a high-fat diet, participants felt more energetic and were able to
sustain a higher intensity for a longer period of time. Time to exhaustion for those 3 days did not occur
until about the 20 to 25 minute mark for all participants. Also, the unfit participants significantly
improved overall fitness by the end of the study as they were able to increase intensity from 5.0 speed to
at least 6.0 to 6.5 speed by the end of the week. The fit participants had little to no actual increase in
speed overall but reported feeling the difference in energy levels between the first 3 days and the last 3
days. They claimed that the high-carb diet (especially the first day) gave them a large amount of energy
which helped them achieve a higher running speed but only lasted up to 15 minutes (time to exhaustion)
because glycogen stores were depleted early on making it more difficult to sustain a high speed. In
contrast, fit participants claimed that the 3 day high-fat diet was beneficially in helping them to sustain a
high speed (7.0 or higher) for at least 30 minutes or more, further proving that a high-fat diet ingested 3

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to 4 hours prior to exercise is beneficial in sustaining energy because there is endless energy in the form
of fat and free fatty acid (FFA) protect glycogen stores from being used up right away.
Participants were warned prior to the study not to consume large amounts of fat of carbs any later than 3
hours before working out but a couple of the participants broke that rule and ate a large high-fat, high-
protein meal less than an hour before running. The two participants who made this mistake were told to
go ahead and run at the usual pace on the treadmill and results were as follows: one participant who ate a
large high-fat meal less than an hour prior to running, reported feeling ill only 5 to 10 minutes into the
workout. The other participant who ate both a high-fat and high-protein meal just an hour before
running, reported feeling ill and not being able to keep going only 5 minutes into the workout. Both
cases proved that eating a large meal right before a moderate to high intensity workout is detrimental to
performance as it causes GI tract and stomach problems to occur. All other participants followed exact
instructions prior to working out and results were conclusive for all 6 days of the study. On average,
results are based on a constant speed for 45 minutes following a cool down for 10 minutes on the
elliptical to prevent the buildup of lactic acid. This study was effective in showing the impact certain
substrates have on workout performance and how essential the two most important fuel sources,
carbohydrates and fats, are on both aerobic and anaerobic performance. A high-carb diet is proves
essential for short-term, high intensity workouts such as sprinting and explosive exercises. A high-fat
diet proves to be essential for long-term, low to moderate intensity workouts such as bicycling,
marathon training, running, and other endurance exercises. In conclusion, exercise, whether it is aerobic
or anaerobic, requires energy and that energy is found in three fuel sources, two of which are the most
beneficial in supplying energy during exercise: carbohydrates and fats. Eating a high-fat or a high-carb
meal prior to working out can make all the difference in an individual’s overall workout performance
and should always be consumed 3 to 4 hours prior to working out to avoid indigestion and GI tract
problems, therefore, allowing 85% of blood to circulate to the active muscles.

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Recommendations for Future Studies
This study was only based on evaluating the effects of a pre-exercise high-carb diet for 3 days and a pre-
exercise high-fat diet for 3 days on workout performance. Future research studies should examine the
effects of a high-fat diet and a high-carb diet for longer than 3 days and should include a wider variety of
participants of all fitness levels. Future studies should look at evaluating the effects

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Bibliography
1. Romero, Melissa. Running a Marathon? Load Up on Fat. Washington Magazine, Inc. 2015.
2. Erlenbusch M., Haub M., Munoz K., MacConnie S., and Stillwell B. “Effect of High-Fat or High-
Carbohydrate Diets on Endurance Exercise: A Meta-Analysis.” International Journal of Sport
Nutrition and Exercise Metabolism.15:1-14, 2005.
3. Rowlands D.S. & Hopkins W.G. “Effects of high-fat and high-carbohydrate diets on metabolism and
performance in cycling”. ScienceDirect.51 (6):678-690, 2002.
4. Murakami, Ikuma et al. “Significant Effect of a Pre-Exercise High-Fat Meal after a 3-Day High-
Carbohydrate Diet on Endurance Performance.” Nutrients 4.7 (2012): 625–637.PMC. Web. 9 Nov.
2015.
5. Agriculture and Consumer Protection. “The Role of Carbohydrates in Exercise and Physical
Performance.” Food and Agriculture Organization of the United Nations.n.d. Web. 8 Nov. 2015.
6. Whitley H., Humphreys S.M., Campbell I.T., Keegan M.A., Jayanetti T.D., Sperry D.A., MacLaren
P., Reilly T., and Frayn K.N. “Metabolic and Performance Responses During Endurance Exercise
after High-Fat and High-Carbohydrate Meals.” Journal of Applied Physiology.85 (2): 418-424,
1998. Web. 8 Nov. 2015.
7. Helge J.W. & Kiens B. “Effect of High-Fat Diets on Exercise Performance.” Proceedings of the
Nutrition Society. 57:73-75, 1998.
8. Jeukendrup, A.E. “High-carbohydrate versus high-fats in endurance sports.” Researchgate.net. Jan.
2003.Web. 8 Nov. 2015.
9. Coyle E.F., Coggan A.R., Hemmert M.K., Lowe R.C., and Walters T.J. “Substrate usage during
prolonged exercise following a preexercise meal.” Journal of Applied Physiology.59 (2): 429-433,
1985. Web 8 Nov 2015.

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10. Achten J., Halson S.L., Moseley L., Rayson M.P., Casey A., and Jeukendrup A.E. “Higher Dietary
Carbohydrate Content During Intensified Running Training Results in Better Maintenance of
Performance and Mood State.” Journal of Applied Physiology.96 (4): 1331-40, April 2004. Web. 8
Nov. 2015

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Appendix A

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