preview-9781439844571_A23985364

Dietary Protein and
Resistance Exercise
Edited by
Lonnie Michael Lowery, PhD
Jose Antonio, PhD

Dietary Protein and
Resistance Exercise

Dietary Protein and
Resistance Exercise
Edited by
Lonnie Michael Lowery, PhD
Jose Antonio, PhD
Boca Raton London New York
CRC Press is an imprint of the
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Contents
Preface......................................................................................................................vii
Acknowledgments.....................................................................................................ix
Editor Biographies.....................................................................................................xi
Contributors............................................................................................................ xiii
Contributor Biographies...........................................................................................xv
Chapter 1
Dietary Protein and Strength Exercise: Historical Perspectives..........1
Peter W. R. Lemon
Chapter 2 Protein Metabolism: Synthesis and Breakdown on a Cellular Level.... 17
Layne E. Norton, Gabriel J. Wilson, and Jacob M. Wilson
Chapter 3 The Safety Debate Regarding Dietary Protein in Strength Athletes.... 41
Lonnie M. Lowery
Chapter 4
Chapter 5
Dietary Protein Efficacy: Dose and Peri-Exercise Timing.................69
Joshua A. Cotter and David Barr
Dietary Protein Efficacy: Dietary Protein Types................................95
Bill Campbell
Chapter 6 Weight Control with Dietary Protein................................................ 115
Ronald Mendel
Chapter 7 Protein, Resistance Training, and Women........................................ 135
Dawn Anderson and Christin Seher
Chapter 8 Protein’s Effects on Rehabilitation and the Sarcopenia of Aging.... 153
Troy Smurawa
Chapter 9 Nitrogenous Compounds and Supplements...................................... 177
Jamie Landis, Tim N. Ziegenfuss, and Hector L. Lopez
v

vi
Contents
Chapter 10 Case Studies and Sports Application................................................ 201
Michael T. Nelson, Jonathan N. Mike, and David Barr

Preface
According to Dr. Carl Sagan, scientific debates are often settled not by better arguments
but by better instruments and research. You hold in your hands a research
compendium that is hoped will update and clarify the issues surrounding purposeful
protein intakes and resistance trainers—especially strength athletes. Whether this
book, being a central resource, will reduce the controversy is anyone’s guess. The
discussions and debates surrounding dietary protein in sport, particularly for this
population, are decades old. They are, in many respects, only recently being settled.
But why is there controversy or even interest? It may have begun long ago with
athletes insisting on steak as a pregame meal. Or perhaps Rocky Balboa’s ingestion
of raw eggs helped ignite athlete interest. The active carbohydrate research, and concerns
over dietary fats, from the 1970s through the 1990s sometimes put scientists
and practitioners at odds with these “steak-and-egg” focused athletes. During those
years, evidence-based practice was not yet in full force and a counterculture to overzealous
athletes seemed to crop up.
As time moved on, many scientists started to slowly change their conclusions on
purposeful, even ample, protein intakes for athletes. Stable isotope methodologies
partly replaced nitrogen balance techniques. A direct look at resistance trainers suggested
they differed from other populations. The timing—the windows of opportunity—that
surround an exercise bout were acknowledged as important. Different
protein types were recognized as possessing different physiological effects that
might be used to an athlete’s advantage.
And yet, as of the writing of this book, introductory college textbooks use dissuasive
language regarding dietary protein, sometimes referencing one another’s statements
as sources of evidence. Practitioners and health educators continue to counsel
athletes that their interest in amino acid building blocks is misguided, unnecessary,
and even dangerous (see Chapter 3). There appears to be a gap or disconnect between
scientists and the practitioners and educators of at least some sports nutrition groups.
On the opposite end of the spectrum, however, dietary supplement companies
and the food industry are spending large sums of money to reach resistance trainers,
often with overly positive and even exaggerated marketing messages. Images of
anabolic hormone-using athletes on the covers of magazines or in advertisements
imply that the protein product they hold is the reason for their dramatic physiques.
This not only misleads many athletes and laypersons, but it also serves to confuse
them considering the oppositional messages that many practitioners provide. What
can be done?
Educating the public, including both practitioners and strength athletes, on what
current science is finding on this population is our best approach. Belief, dogma, or
even long-embraced professional opinions need to be replaced with a willingness
to change our conclusions in the light of new scientific evidence. This is not easy.
With hundreds of new studies appearing daily in the National Library of Medicine’s
PubMed database, it is clear that many bodies of nutritional literature are evolving.
vii

viii
Preface
A central resource on the various protein–athlete topics would be invaluable. That
is what this book is meant to be. It reviews the science-related history of protein and
strength athletes; it analyzes the mechanisms being elucidated on what proteins do
in muscle cells; and it offers information on protein efficacy for performance, recovery,
and body composition. This book also explores various populations that employ
resistance training and dietary protein as interventions. Timing, type, and safety
data regarding liberal protein diets and related supplements are included. Finally, the
book features sidebars, practical examples, and case studies translating the science
into a practical understanding of various protein-related topics.
Jose Antonio and I hope you enjoy learning from this much needed, central
resource on dietary protein and resistance training. As you read, we encourage you
to form your own conclusions. Remain curious, but employ a high standard, weighing
the evidence. The result is a pursuit of truth that can only serve to enhance your
performance or your practice.
Yours in Health,
Lonnie Lowery

Acknowledgments
First, I would like to thank my wife, Kelly Lowery, and son, Logan, for tolerating
my countless hours in coffee shops during the preparation of this book, and during
my research and writing in general. You are very precious to me. Second, I thank
the impressive list of authors in this book; these mentors, friends, and colleagues
have my sincere gratitude for their effort, their expertise, and their willingness to
perform and review objective research on this sometimes contentious topic.
Lonnie Lowery
This book is dedicated to all the trailblazers who embraced the science of sports
supplements in the face of dogmatic opposition from traditional academics. Thank
God for those individuals who are willing to think independently.
Jose Antonio
PHOTO CREDITS AND EDITORIAL
ASSISTANCE ACKNOWLEDGMENTS
The editors would also like to thank Chelsea Anibas, Phil Stevens, Sherry Hudak,
Laura Hemlepp, Mike Walker, Robert Fortney, Jim Heron, and Jon Mike for their
assistance regarding a number of the photos in this book. Also, special thanks to Eric
Bernstein for his assistance in editing and contributing.
ix

Editor Biographies
Lonnie M. Lowery, PhD, RD, has been a professor of nutrition and exercise physiology
of 11 years, currently at Winona State University, and is president of Nutrition,
Exercise and Wellness Associates Ltd. With formal training in both exercise physiology
and nutrition from Kent State University, San Diego State University, and the
Cleveland Clinic, he has published in academic and research settings on various
sports nutrition topics such as dietary proteins, fats, antioxidants, dietary supplements,
and overtraining. Dr. Lowery has also served as an educational, scientific,
and product development consultant for a number of large dietary supplement
companies such as Met Rx, Bodyonics-Pinnacle, and Biotest Laboratories. As an
award-winning mentor and educator, he has written hundreds of lay articles for the
strength and fitness communities (across essentially all major fitness magazines and
several Web sites, notably T-Nation.com) and cohosts www.IronRadio.org, a free
educational and consumer advocacy podcast on iTunes that reaches more than 8000
listeners each month.
Jose Antonio, PhD, is the chief executive officer and cofounder of the International
Society of Sports Nutrition (www.theissn.org); furthermore, he is a Fellow of the
American College of Sports Medicine and National Strength and Conditioning
Association (NSCA). He was the 2005 recipient of the NSCA Research Achievement
Award and the 2009 NSCA Educator of the Year; moreover, he has published
13 books and over 50 peer-reviewed scientific publications. Dr. Antonio is the editorin-chief
of Sports Nutrition Insider, the first and only trade publication dedicated to
the sports nutrition industry, and Inside Fitness magazine, and has contributed to
Ironman, Muscular Development, Muscle and Fitness, and Fitness Rx Men/Women.
He is the sports science advisor to VPX/Redline and a cofounder of Javalution. Dr.
Antonio completed a PhD and postdoctoral research fellowship at the University of
Texas Southwestern Medical Center in Dallas, Texas. He is an assistant professor at
Nova Southeastern University in Fort Lauderdale, Florida.
xi

Contributors
Dawn Anderson
Winona State University
Winona, Minnesota
David Barr
National Strength and Conditioning
Association
Colorado Springs, Colorado
Bill Campbell
University of South Florida
Tampa, Florida
Joshua A. Cotter
University of California, Irvine
Irvine, California
Jamie Landis
Lakeland Community College
Kirtland, Ohio
Peter W. R. Lemon
University of Western Ontario
London, Ontario, Canada
Hector L. Lopez
The Center for Applied Health Sciences
Stow, Ohio
Ronald Mendel
University of Mount Union
Alliance, Ohio
Jonathan N. Mike
University of New Mexico
Albuquerque, New Mexico
Michael T. Nelson
University of Minnesota
Minneapolis, Minnesota
Layne E. Norton
University of Illinois at
Urbana-Champaign
Urbana, Illinois
Christin Seher
Kent State University
Kent, Ohio
Troy Smurawa
Akron Children’s Hospital Sports
Medicine Center
Akron, Ohio
and
North Eastern Ohio Universities
College of Medicine (NEOUCOM)
Rootstown, Ohio
Gabriel J. Wilson
University of Illinois at
Urbana-Champaign
Urbana, Illinois
Jacob M. Wilson
University of Tampa
Tampa, Florida
Tim N. Ziegenfuss
The Center for Applied Health Sciences
Stow, Ohio
xiii

Contributor Biographies
CHAPTER 1
Peter W. R. Lemon, PhD, FACSM, completed his undergraduate education at
McMaster University and his graduate studies at the Universities of Windsor and
Wisconsin–Madison. From 1979 to 1997, he was on the faculty at Ohio’s Kent
State University working in the Applied Physiology Research Laboratory, most
recently as the laboratory director. In January 1998, Dr. Lemon became the first
recipient of the Weider Research Chair in Exercise Nutrition at the University of
Western Ontario.
CHAPTER 2
Layne E. Norton, PhD, completed his undergraduate degree in biochemistry at
Eckerd College in 2004 and his PhD in nutritional sciences at the University of
Illinois in 2010. He founded BioLayne LLC, is currently on the Scivation scientific
advisory board, and is a columnist for lay fitness magazines and Internet publications.
Dr. Norton’s published research involves leucine metabolism, muscle protein
synthesis, and related topics.
Gabriel J. Wilson received his BS in kinesiology at California State Eastbay, his
MS in sport psychology–motor learning at California State Eastbay, and currently
is a doctoral student in the Division of Nutritional Sciences, University of Illinois,
Urbana. His research involves an emphasis on optimal protein requirements for muscle
growth.
Jacob M. Wilson, PhD, studied exercise nutrition at California State University
(CSU) Hayward, where he received his BS. He then received a master of science,
also at CSU, with an emphasis in both sports psychology and exercise physiology,
and he completed doctoral work at Florida State University, working in its skeletal
muscle laboratory. Dr. Wilson has published research in more than 40 peerreviewed
manuscripts, book chapters, and abstracts. He is currently on the faculty at
the University of Tampa, Florida.
CHAPTER 3
Lonnie M. Lowery, PhD, RD. See Editor Biographies.
CHAPTER 4
Joshua A. Cotter, PhD, CSCS, NSCA-CPT, is a postdoctoral fellow in the
Department of Orthopaedic Surgery at University of California, Irvine. His
xv

xvi
Contributor Biographies
postdoctoral research involves the utilization of exercise countermeasures for preventing
the physiological changes related to microgravity and disuse as well as
understanding the biology of the myogenic satellite cell. He completed his graduate
studies from the Ohio State University with concentrations in muscle physiology
and biomechanics while performing his research at the Ohio State University Sports
Biomechanics Laboratory. Dr. Cotter’s research and professional interests are related
to the overarching theme of muscle mass regulation.
David Barr, CSCS, CISSN, USATF, is the education content Web manger with
the National Strength and Conditioning Association (NSCA). Barr is a performance
specialist whose research experience includes work for NASA at the Johnson Space
Center, as well as clinical research on the effect of protein intake on muscle growth.
He has authorship in five books and more than 50 Web-based publications on applied
training and supplement science. He is a certified sports nutritionist (CISSN) through
the International Society of Sports Nutrition (ISSN), and a certified track and field
coach through USA Track & Field.
CHAPTER 5
Bill Campbell, PhD, CSCS, FISSN, is an assistant professor at the University of
South Florida where he directs the Exercise & Performance Nutrition Laboratory.
Dr. Campbell earned his PhD in exercise, nutrition, and preventive health from
Baylor University, and has published over 100 scientific abstracts and papers related
to sports nutrition and enhancement of sports performance. He is a paid consultant
to professional sports team organizations and sports entertainment corporations. He
has lectured on various topics related to sports nutrition and exercise performance to
audiences spanning five different nations and four continents. He is also the coeditor
of the National Strength and Conditioning Association’s (NSCA) forthcoming
textbook on sports nutrition. In addition, he is a fellow of the International Society of
Sports Nutrition and a certified strength and conditioning specialist.
CHAPTER 6
Ronald Mendel, PhD, received his doctorate from Kent State University in exercise
physiology, where his dissertation focused in part on creatine monohydrate. He
is currently program director of the Exercise Science Department at Mount Union
College, Alliance, Ohio, where he has won teaching awards. His research foci are
interactions between exercise and nutrition or dietary supplements. Dr. Mendel’s
publications include the effects of creatine on thermoregulation in heat and creatine
and muscle volume.
CHAPTER 7
Dawn Anderson, PhD, CISSN, CSCS, received her BS in mathematics and speech
from the University of Minnesota–Morris, her MS in exercise physiology from Iowa
State University, and her PhD in human bioenergetics from Ball State University.

Contributor Biographies
xvii
Dr. Anderson is currently involved in research projects in the area of sports nutrition
and exercise physiology.
Christin Seher, MS, RD, is a doctoral student and teaching fellow at Kent State
University in Ohio, an adjunct faculty member at Youngstown State University, and
founder of Strategic Health Solutions, LLC. She graduated with her MS in dietetics
from the University of Akron and her BS in psychology from Marietta College.
CHAPTER 8
Troy Smurawa, MD, is an attending physician of the Akron Children’s Hospital
Sports Medicine Center and an assistant professor of pediatrics at NEOUCOM. He is
a team physician for the University of Akron and Hudson High School. Dr. Smurawa
is certified by the American Board of Pediatrics in both pediatrics and sports medicine.
He is a graduate of the University of Wisconsin and a graduate of the University
of Texas Health Science Center Medical School. He completed his residency at the
University of Wisconsin and a fellowship in Sports Medicine at Akron Children’s
Hospital. Dr. Smurawa is a competitive runner and triathlete, and has completed
over 25 marathons and 5 Ironman Triathlons. He is a team physician for the USA
Triathlon World Championships teams. He is certified by USA Triathlon as a multisport
coach, and coaches runners and multisport athletes. He has served on the
sports medicine staff of Disney’s Wide World of Sports complex, the USA Triathlon
National Training Center, and the Orlando Devil Rays. Dr. Smurawa is an active
member of the American Academy of Pediatrics, the American Medical Society for
Sports Medicine, and the North American Society for Pediatric Exercise Medicine.
He is a member and clinical adviser for the American Medical Athletic Association.
CHAPTER 9
Jamie Landis, PhD, MD, CSCS, received a BS in biology from Ferris State
University, an MS in endocrine physiology, and a PhD in neuroscience, both from
Bowling Green State University. His MD was earned at the Medical University of
Ohio, and was followed by an internship in medicine at Michigan State University
and a residency appointment at the Mayo Clinic. He is a certified strength and conditioning
specialist (CSCS) and volunteers his time as a youth weightlifting and football
coach. Dr. Landis does not currently practice medicine, instead combining his
depth of knowledge with his passion for teaching. He is currently a professor of biology
at Lakeland Community College (Kirtland, Ohio), where he received the 2006
College Excellence in Teaching Award.
Tim N. Ziegenfuss, PhD, is a world-renowned sports nutrition and exercise scientist
with graduate degrees from Purdue (MS) and Kent State University (PhD).
He is the cofounder of the Center for Applied Health Sciences, and past president
of the International Society of Sports Nutrition. His client list includes current and
former Olympic track and field athletes; professional mixed martial arts fighters;
NFL, MLB, NHL, high school, and NCAA athletes; firefighters; police; Department

xviii
Contributor Biographies
of Homeland Security personnel; and the U.S. military including the Army, Navy
Seals, and Secret Service. Dr. Ziegenfuss has published over 600 articles in mainstream
magazines, 35 scientific papers, 5 book chapters, and has made numerous
interviews and appearances in top 25 national print, radio, and TV media.
Hector L. Lopez, MD, CSCS, is recognized for applying his diverse background
in nutrition, exercise science, sports and musculoskeletal medicine, endocrinology
and metabolism to improving not only the health and quality of life in his patients
but also athletic performance in recreational and elite athletes. He received his training
at the Northwestern University Feinberg School of Medicine–Rehabilitation
Institute of Chicago. He is a certified strength and conditioning specialist (CSCS)
through the National Strength and Conditioning Association (NSCA), and holds a
master’s degree in nutritional biochemistry with a concentration in exercise physiology
from Northwestern University. His clinical and research interests include spine,
sports, and orthopedic medicine; electrodiagnostic medicine; interventional spine
and pain management; optimal aging and sarcopenia; and nutritional interventions
to improve human performance and rehabilitation outcomes of injured patients. An
active researcher, speaker, and author, he has presented nationally and published
articles and scientific abstracts on various topics related to nutrition, stroke, orthopedic
injuries, chronic pain disorders, athletic performance, optimal aging, and
physician-based exercise prescription. Dr. Lopez is also the chief medical officer of
the Center for Applied Health Sciences; a consultant to professional athletes; and
a product developer, researcher, and writer for the nutritional supplement industry.
CHAPTER 10
Mike T. Nelson, PhD, earned a PhD from the University of Minnesota in exercise
science concentrated in the area of metabolism. He has published research in peerreviewed
journals in addition to serving as a journal reviewer himself. His background
includes an MS in mechanical engineering from Michigan Technological
University and a BA in natural science from St. Scholastica. He is a certified strength
and conditioning specialist (CSCS) by the National Strength and Conditioning
Association (NSCA) and founding member of the Movement, LLC. Dr. Nelson is a
dynamic keynote speaker and coach to people focused on increasing performance
with less joint pain. He has presented at American College of Sports Medicine,
the International Society of Nutrition, and others. He has done consulting work for
sports supplement companies and also the military’s elite research division Defense
Advanced Research Projects Agency (DARPA).
Jonathan N. Mike, PhD (Candidate), CSCS, USAW, NSCA-CPT, studied exercise
physiology and strength and conditioning at the University of New Mexico,
Department of Health, Exercise, and Sport Sciences, Albuquerque. He has an active
history as a strength coach in the American Society of Exercise Physiologists (ASEP)
and in the National Strength and Conditioning Association (NSCA), and recently
became a member of the NSCA-CPT Exam Developing Committee. He is also a
contributor and guest host for the Iron Radio podcast (www.ironradio.org) where he

Contributor Biographies
xix
often takes a consumer advocacy stance on behalf of resistance trainers. His research
and professional interests include strength and power performance, exercise metabolism
and sports nutrition, resistance training and exercise endocrinology, neuromuscular
physiology, and ergogenic aids. He continues to train and compete in the sport
strong man.
David Barr, CSCS, CISSN, USATF. See biographies for Chapter 4.

1
Dietary Protein and
Strength Exercise
Historical Perspectives
Peter W. R. Lemon
CONTENTS
1.1 Introduction.......................................................................................................1
1.2 Dietary Protein Research Studies: Early Years.................................................2
1.3 Experimental Techniques Used to Assess Protein Requirements.....................4
1.4 Timing of Protein and Amino Acid Intake versus Quantity of Intake.............7
1.5 Protein Type......................................................................................................9
1.6 Optimal Protein and Amino Acid Dose.......................................................... 10
1.7 Summary......................................................................................................... 11
References................................................................................................................ 12
1.1 INTRODUCTION
Strength training and bodybuilding have enjoyed a very, very long and fascinating
history, beginning perhaps as early as the 6th century b.c. in Greece when Milo
reportedly strengthened his musculature by regularly carrying a calf as it grew
into a bull (Todd, 1985). Apparently even very early man understood that muscles
grow bigger and stronger when a greater than normal load is placed on them progressively.
Over the years since then, references to the use of strength training to
improve function (often within a combative context) and health is a theme common
to the literature. The diet of these early strength athletes is less clear, but protein,
carbohydrate, and even alcohol intake may have all been substantial, as Greek legend
Milo allegedly consumed as much as 20 pounds (~9 kg) of meat, 20 pounds (~9
kg) of bread, and 18 pints (~10.6 L) of wine daily (Harris, 1964). Regardless of the
accuracy of this dietary detail, this information or other similar anecdotes may be
the origin of the age-old idea that large quantities of dietary protein are needed to
maximize muscle growth.
Apparently over the centuries since those ancient days, the use of strength training
and bodybuilding waxed and waned in many cultures, and with the amazing
feats of the circus strongmen (19th and 20th centuries), such behavior became almost
freakish. Most of the early literature records mention men only, but there is evidence
1

2 Dietary Protein and Resistance Exercise
that some women engaged in strength training as early as the 4th century a.d. Rome
(Todd, 1995). Of course, the use of strength training by modern American girls and
women was insignificant until the exponential growth of participation in sporting
activities by females occurred following the 1972 adoption of Title 9 of the U.S.
Education Amendments Law, which required equal access and funding, regardless
of gender, for all education programs and activities receiving federal financial
assistance. Interestingly, even as strength exercise training techniques became more
refined, this type of training was perceived by many to be very inappropriate for athletes
because it was thought to make one uncoordinated or “muscle bound.” In fact,
even as recently as the middle of the 20th century, strength training was dismissed
by all but a small minority of mainstream North American athletes. Fortunately, this
myth was eventually disproven as university scientists began to study the effects of
strength training objectively, and strength training proponents like brothers, Ben and
Joe Weider, as well as Bob Hoffman and Angelo Sicilianio (aka Charles Atlas) very
successfully marketed strength training techniques and its associated health benefits
to the general public (Todd, 1994). Although slowly at first, by the 1950s and 1960s
strength training was being utilized in some sports, and into the 1970s and thereafter
it became commonplace for virtually all athletes in all sports.
Although documentation of the critical nature of diet on muscle growth would not
occur until the last few decades of the 20th century, many of these early strongmen
promoted eating large quantities of raw foods, including milk and eggs, as well as
meat and eventually protein powders when the nutritional supplement industry got
going in the 1940s and 1950s. The rationale for such dietary practices was seldom
clear, but obviously these athletes were able to build muscle so their opinions carried
considerable influence.
1.2 DIETARY PROTEIN RESEARCH STUDIES: EARLY YEARS
By the latter part of the 18th century, the French chemist and biologist Lavoisier
had figured out that chemical energy released from catabolized organic compounds
fueled muscle contraction and by the mid-1800s experts of the time such as the
German biochemist von Liebig believed that protein was the main fuel for exercise
(Kleiber, 1975). However, this idea was challenged successfully in the 1860s,
when two students using urinary nitrogen excretion measures on themselves while
climbing a peak in the Alps demonstrated that the major fuel for muscle contraction
must come from substrates free of nitrogen (Fick & Wislicenus, 1866). As a result,
considerable study designed to determine the fuel source for exercise ensued and
by the 1930s it had become clear that carbohydrate was the main fuel for exercise,
especially intense exercise, that fat use increased with exercise duration because
carbohydrate stores were quite limited, and that protein use for exercise fuel was, in
fact, minimal (Carpenter, 1931; Gemmill, 1942). Unfortunately, this later point led
to the oversweeping generalization that dietary protein was not important for exercising
individuals, which resulted in little interest and study of protein metabolism
with exercise over the next 30 years or so (Lemon & Nagle, 1981). Consequently,
an appreciation of the central role that dietary protein and its component amino
acids play in the overall metabolic response to exercise would have to wait until

Dietary Protein and Strength Exercise
3
newer methodologies, including metabolic tracers to measure protein turnover and
molecular techniques to access gene signaling, came into use in the later part of the
20th century.
Specifically in the 1970s, interest in the potential role of protein as an exercise
fuel was rekindled due to observations that nitrogen production tended to increase
with prolonged strenuous exercise (Décombaz et al., 1979; Haralambie & Berg,
1976; Refsum & Strömme, 1974). Moreover, even these studies underestimated the
actual protein used because nitrogen excretion via perspiration, which is now known
to be substantial, was not quantified in the studies of this era (Cerny, 1975; Lemon
& Mullin, 1980) and also because a considerable amount of urinary nitrogen excretion
occurs hours after prolonged, intense exercise due to delays in urine output
caused by the exercise-induced decrease in kidney blood flow (Dolny & Lemon,
1988; Lemon et al., 1983).
Moreover as the limited carbohydrate availability during starvation was known
to increase protein oxidation and because prolonged, strenuous exercise can exhaust
body carbohydrate stores it was reasonable to suggest that, in an analogous manner,
carbohydrate availability to the exercising muscle might be an important determinant
of exercise protein use. This hypothesis was confirmed with the observation
that nitrogen excretion increased more than twofold when exercise was initiated with
low versus high body carbohydrate stores (Lemon & Mullin, 1980). Under these
conditions, sweat nitrogen losses were significant (Figure 1.1). Shortly thereafter,
data from studies using metabolic tracers demonstrated that some amino acids are
oxidized during exercise (Lemon et al., 1982, 1985; White & Brooks, 1981) and
that this oxidation increased as carbohydrate stores become reduced, perhaps due to
Sweat Urea Nitrogen (mg.h –1 )
1800
1600
1400
1200
1000
800
600
20
0
c
SEM
Unlike letters P < 0.05
b
a
Rest EX-CHO L EX-CHO D
FIGURE 1.1 Exercise (1 h @ 61% VO 2 max) preceded by carbohydrate depletion increases
(P < 0.05) sweat nitrogen excretion (and presumably exercise protein use) significantly relative
to the same exercise completed under carbohydrate-loaded conditions. Resting sweat
nitrogen excretion rate is shown for comparison. CHO L = carbohydrate loaded; CHO D = carbohydrate
depleted; EX = exercise. (Adapted from Lemon PWR, JP Mullin, 1980, J Appl
Physiol 48: 624–629.)

4 Dietary Protein and Resistance Exercise
associated significant increases in the active form of the branched-chain 2-oxoacid
dehydrogenase (BC) complex in muscle (Wangenmakers et al., 1991). However even
so, the total quantity of protein used to fuel muscle with exercise is likely no more
than 10% of the total exercise energy expended (Lemon, 1998). So, as it turns out,
carbohydrate and fat are the major sources of energy for exercise (Karelis et al.,
2010; Yeo et al., 2011) and, therefore, from a relative standpoint, protein utilization
for fuel during exercise is insignificant. Importantly, however, this does not mean
that protein intake for athletes is trivial because protein and its component amino
acids serve many other roles, for example, building blocks for critical structural and
functional proteins and likely also as signalers of key steps in protein metabolism
(Deldicque et al., 2005; Hawley et al., 2011; Koopman, 2007).
1.3 EXPERIMENTAL TECHNIQUES USED TO
ASSESS PROTEIN REQUIREMENTS
Classically, nitrogen balance (difference between nitrogen intake and excretion)
has been the method of choice for assessments of protein requirements (Food and
Nutrition Board, 2005). Nitrogen is used as a proxy for protein because it reflects
protein use (most proteins contain 16% nitrogen so multiplying measured nitrogen
by 6.25 gives the equivalent protein) and it is easily quantified. Experimentally, if
dietary protein intake is manipulated slightly above and below the protein requirement,
the daily protein requirement can be estimated using linear regression techniques
as the protein intake where one attains balance. Then to be certain to cover
individual variability in the population of interest, the dietary recommendation is
set at two standard deviations above the mean requirement, that is, mean intake that
elicits balance plus the amount of protein equal to two standard deviations for the
sample studied. Statistically, this recommendation should cover 97% to 98% of the
population. Moreover because this quantity of protein above the requirement is only
needed by those in the population exceeding the mean requirement, realistically
many individuals will meet their requirement at ~67% of the recommendation.
The nitrogen balance technique has also been used to assess dietary protein
requirements in both endurance and strength athletes and the evidence suggests that
protein intake recommendations should be ~1.2 to 1.8 g•kg –1 •d –1 (~50% to 100%
greater than for sedentary individuals) (Lemon et al., 1992; Tarnopolsky et al., 1988).
Consistent with this recommendation are the observations (Figure 1.2) that measured
rates of protein synthesis in strength athletes during training were greater when protein
intake was 1.4 versus 0.9 g•kg –1 •d –1 (Tarnopolsky et al., 1992). Of equal interest
was the observation that an intake of 2.4 g•kg –1 •d –1 did not increase the protein synthetic
rate any more, suggesting that even this intake exceeds the intake necessary
for maximal muscle growth. However, study participants were allowed to consume
their protein at any time throughout the day so intake timing may have been suboptimal
(see importance of timing of protein intake in Section 1.4). Regardless, there is
good evidence that only small quantities of protein or amino acid (especially indispensable
amino acids; <10 g) and carbohydrate (~35 g) ingested shortly before, during,
or following strength exercise enhance muscle protein balance, that is, stimulate