Protein requirement: endurance vs. strength

Giselle

Hondra wrote:

> Where I can find more information and studies abot the fact that an endurance athlete needs more
> proteins than a strength one ? I guess therefore that all Lemon PW studes are very flawed (??)
>
Summary of studies listed below:

PMID: 12380246 gender, age not specified 1.6-1.7 g/kg/d PMID: 12012556 gender, age, type of athlete
not specified. 1.2-2.0g/kg/d PMID: 11023001: gender not specified: 1.6-1.8 g/kg/d PMID: 10466184:
1.5g/kg/d safe upper limit may need revision PMID: 8700446 gender not specified. 1.7-1.8 g/kg/d
PMID: 8897314 gender, type of athlete not specified, 1.2-1.7 g/kg/d PMID: 1474076 (males): 1.41
g.kg-1.day-1 balanced nitrogen, 2.4 g/kg/d overkill PMID: 1763249: needs may be increased 50 to 100%
in excess of RDA PMID: 1844991: gender not specified 1.5-2.0 g/kg/d PMID: 1895363 gender not
specified: 1.2-1.7 g/kg/d PMID: 1844991 gender not specified,:1.5-2.0 g/kg/d PMID: 6390614 gender
not specified: 1.8 to 2.0 g/kg/d

Eur J Appl Physiol. 2002 Dec;88(3):288-93. Epub 2002 Oct 30. Protein intake and nitrogen balance in
male non-active adolescents and soccer players. Boisseau N, Le Creff C, Loyens M, Poortmans JR.
Laboratoire d'Analyse de la Performance Motrice Humaine (LAPMH), Faculte des Sciences du Sport,
Universite de Poitiers, 4 allee Jean Monnet, 86000 Poitiers, France.
nathalie.boisseau@univ-poitiers.fr

Recommendations for the requirements for protein intake amount usually to .8-1.0 g x kg(-1) body
mass x day(-1) in adolescents without any reference to the undertaking of acute exercise or to the
training status. The present investigation intended to determine the nitrogen balance and protein
intake in 8 healthy male non-active adolescents and 11 adolescent soccer players, both groups aged
about 15 years. An assessment of nutrient intake was obtained by analysing 7 day food records
collected by a questionnaire. Nitrogen excretion rate was determined and nitrogen balance was
calculated from the mean daily protein intake and the urinary excretion. The results showed that the
nutritional status of the two groups was similar. Nevertheless, we found that their diets were quite
inappropriate in terms of the intakes of carbohydrate, some minerals (zinc, calcium, magnesium),
vitamins (A, B6, D) and fibre. A positive nitrogen balance was observed from a mean protein intake
of 1.57 g x kg(-1) body mass x day(-1) in these adolescents, whether they were non-active or
athletes. Thus, the present investigation indicated that the growth and development in non-active
adolescents and in adolescent soccer-players give rise to a need for a higher protein intake than is
usually recommended. However, the higher protein requirements did not seem to be related only to the
increased energy expenditure imposed by the exercise training in the soccer-player group.

PMID: 12458373 [PubMed - indexed for MEDLINE]

Nutr Clin Care. 2002 Jul-Aug;5(4):191-6. What are the dietary protein requirements of physically
active individuals? New evidence on the effects of exercise on protein utilization during
post-exercise recovery. Fielding RA, Parkington J.

Human Physiology Laboratory, Department of Health Sciences, Boston University, Sargent College of
Health and Rehabilitation Sciences, 635 Commonwealth Avenue, Boston, MA 02215, USA. fielding@bu.edu

Exercise and physical activity increase energy expenditure up to 10-fold. This brief review will
focus on the effect of exercise on protein requirements. Evidence has accumulated that amino acids
are oxidized as substrates during prolonged submaximal exercise. In addition, studies have
determined that both endurance and resistance training exercise increase skeletal muscle protein
synthesis and breakdown in the post-exercise recovery period. Studies using nitrogen balance have
further confirmed that protein requirements for individuals engaged in regular exercise are
increased. The current recommended intakes of protein for strength and endurance athletes are 1.6 to
1.7 g/kg and
1.2 to 1.4 g/kg per day, respectively. Presently, most athletes consume an adequate amount of
protein in their diet. The timing and nutritional content of the post-exercise meal, although
often overlooked, are known to have synergistic effects on protein accretion after exercise. New
evidence suggests that individuals engaging in strenuous activity consume a meal rich in amino
acids and carbohydrate soon after the exercise bout or training session.

Publication Types: Review Review, Tutorial

PMID: 12380246 [PubMed - indexed for MEDLINE]

Arch Latinoam Nutr. 2001 Dec;51(4):321-31. [Nutrition in the sport practice: adaptation of the food
guide pyramid to the characteristics of athletes diet] [Article in Spanish] Gonzalez-Gross M,
Gutierrez A, Mesa JL, Ruiz-Ruiz J, Castillo MJ.

Universidad de Granada, Granada-Espana, Rheinische Friedrich-Wilhelm Universitaet, Bonn, Germany.

In spite of all the advances in sport nutrition and the importance of an adequate food intake in
order to improve sport performance, both recreational and professional athletes forget frequently to
include planning an optimum diet and fluid intake in their global strategy for performance.
Physiological and metabolic adaptations produced as a consequence of physical exercise lead to the
necessity of increasing caloric (in accordance to energy output) and protein (based on the trophic
needs of the organism) intake. Likewise, paying major attention to vitamin and mineral intake,
specifically B vitamins and zinc and chromium, is required, in order to optimize carbohydrate
metabolism, the ultimate limiting factor for sport performance. During the training phase, 60% of
calories should come from carbohydrates, protein intake should be 1.2-2
g/kg/day and athletes should follow the recommendations of the food guide pyramid. During the pre-,
per- and post-competition phase the healthy aspect of the diet passes to a second level, in order
to obtain good sport performance and to guarantee a fast and effective recovery. Again,
carbohydrates with a high or medium glycaemic index and water are the nutrients which have to be
calculated more thoroughly. In conclusion, athletes have to follow a diet that is adequate to
their higher energy output and to their higher metabolic turnover. The food guide pyramid is a
graphic expression which facilitates the comprehension and following of a healthy diet. In the
present article, the authors introduce the pyramid adapted to the characteristics of sports
nutrition, with easy-to-follow practical recommendations regarding the kind and amounts of
foodstuffs that should be consumed in order to cover nutrient needs of people who exercise
regularly.

Publication Types: Review Review, Tutorial

PMID: 12012556 [PubMed - indexed for MEDLINE]

Proc Nutr Soc. 2002 Feb;61(1):87-96. The athlete's diet: nutritional goals and dietary strategies.
Maughan R. University Medical School, Aberdeen, UK. r.maughan@abdn.ac.uk

When talented, motivated and highly trained athletes meet for competition the margin between victory
and defeat is usually small. When everything else is equal, nutrition can make the difference
between winning and losing. Although the primary concern of many athletes is to supplement the diet
with protein, vitamins and minerals, and a range of more exotic compounds, key dietary issues are
often neglected. Athletes must establish their nutritional goals, and must also be able to translate
them into dietary strategies that will meet these goals. Athletes are often concerned with dietary
manipulations in the period around competition, but the main role of nutrition may be to support
consistent intensive training which will lead to improved performance. Meeting energy demand and
maintaining body mass and body fat at appropriate levels are key goals. An adequate intake of
carbohydrate is crucial for maintaining muscle glycogen stores during hard training, but the types
of food and the timing of intake are also important. Protein ingestion may stimulate muscle protein
synthesis in the post-exercise period, promoting the process of adaptation in the muscles.
Restoration of fluid and electrolyte balance after exercise is essential. If energy intake is high
and a varied diet is consumed, supplementation of the diet with vitamins and minerals is not
warranted, unless a specific deficiency is identified. Specific strategies before competition may be
necessary, but this requirement depends on the demands of the sport. Generally, it is important to
ensure high pre-competition glycogen stores and to maintain fluid balance. There is limited evidence
to support the use of dietary supplements, but some, including perhaps creatine and caffeine, may be
beneficial.

Publication Types:
Lectures

PMID: 12002799 [PubMed - indexed for MEDLINE]

Can J Appl Physiol. 2001;26 Suppl:S130-40. Protein and amino acid requirements of adults: current
controversies. Millward DJ.

Centre for Nutrition & Food Safety, School of Biomedical and Life Sciences, University of Surrey,
Guildford, Surrey, United Kingdom.

Protein intakes vary widely but costs and benefits of such variation is a long standing unresolved
issue. The wide range of reported values for the minimum protein intake for N equilibrium in adults,
i.e. 0.39 to 1.09 g/kg is best explained by an Adaptive Metabolic Demands model in which metabolic
demands include amino acid oxidation at a rate varying with habitual protein intake and which
changes slowly with dietary change. Thus within the reported data the true minimum requirement
intake, the lowest values in the range at intakes approaching the Obligatory Nitrogen Loss, allows
only fully adapted subjects to achieve N equilibrium. The higher values reflect incomplete
adaptation. (13)C-1 leucine tracer balance studies of this model show (a) a fall with age in
apparent protein requirements, (b) better than predicted efficiency of wheat protein utilization,
and (c) controversially, lower lysine requirements than other workers, consistent with new evidence
of de novo synthesis of lysine from urea salvaged by large bowel microflora. The main implication of
the requirements model for athletes on high protein diets is increased exercise induced amino acid
oxidation and risk of loss of body N when such high intakes are not maintained.

Publication Types: Review Review, Tutorial

PMID: 11897889 [PubMed - indexed for MEDLINE]

Can J Diet Pract Res. 2000 Winter;61(4):176-192. Position of Dietitians of Canada, the American
Dietetic Association, and the American College of Sports Medicine: Nutrition and Athletic
Performance. [No authors listed]

It is the position of Dietitians of Canada, the American Dietetic Association, and the American
College of Sports Medicine that physical activity, athletic performance, and recovery from exercise
are enhanced by optimal nutrition. These organizations recommend appropriate selection of food and
fluids, timing of intake, and supplement choices for optimal health and exercise performance. This
position paper reviews the current scientific data related to athletes' energy needs, assessment of
body composition, strategies for weight change, athletes' nutrient and fluid needs, special
nutrient needs during training, the use of supplements and nutritional ergogenic aids, and
nutrition recommendations for vegetarian athletes. During times of high physical activity, energy
and macronutrient needs - especially carbohydrate and protein intake - must be met in order to
maintain body weight, replenish glycogen stores, and provide adequate protein for building and
repairing tissue. Fat intake should be adequate to provide essential fatty acids and fat-soluble
vitamins, as well as to help provide adequate energy for weight maintenance. Overall, diets should
provide moderate amounts of energy from fat (20-25% of energy); there appears to be no health or
performance benefit to consuming a diet containing less than 15% of energy from fat. Body weight
and composition can affect exercise performance, but should not be used as the sole criterion for
sports performance; daily weigh-ins are discouraged. Consuming adequate food and fluid before,
during, and after exercise can help maintain blood glucose levels during exercise, maximize
exercise performance, and improve recovery time. Athletes should be well hydrated before beginning
exercise; they should also drink enough fluid during and after exercise to balance fluid losses.
Consumption of sport drinks containing carbohydrates and electrolytes during exercise will provide
fuel for the muscles, help maintain blood glucose levels and the thirst mechanism, and decrease the
risk of dehydration or hyponatremia. Athletes will not need vitamin-and-mineral supplements if
adequate energy to maintain body weight is consumed from a variety of foods. However, supplements
may be required by athletes who restrict energy intake, have severe weight-loss practices,
eliminate one or more food groups from their diet, or consume high-carbohydrate diets with low
micronutrient density. Nutritional ergogenic aids should be used with caution, and only after
careful evaluation of the product for safety, for efficacy, for potency, and to determine whether
or not it is a banned or illegal substance. Nutrition advice, by a qualified nutrition expert,
should be provided only after the athlete's health, diet, supplement and drug use, and energy
requirements have been carefully reviewed.

PMID: 11551367 [PubMed - as supplied by publisher]

J Am Diet Assoc. 2000 Dec;100(12):1543-56. Position of the American Dietetic Association, Dietitians
of Canada, and the American College of Sports Medicine: Nutrition and athletic performance. [No
authors listed]

It is the position of the American Dietetic Association, Dietitians of Canada, and the American
College of Sports Medicine that physical activity, athletic performance, and recovery from exercise
are enhanced by optimal nutrition. These organizations recommend appropriate selection of food and
fluids, timing of intake, and supplement choices for optimal health and exercise performance. This
position paper reviews the current scientific data related to the energy needs of athletes,
assessment of body composition, strategies for weight change, the nutrient and fluid needs of
athletes, special nutrient needs during training, the use of supplements and nutritional ergogenic
aids, and the nutrition recommendations for vegetarian athletes. During times of high physical
activity, energy and macronutrient needs--especially carbohydrate and protein intake--must be met in
order to maintain body weight, replenish glycogen stores, and provide adequate protein for building
and repair of tissue. Fat intake should be adequate to provide the essential fatty acids and
fat-soluble vitamins, as well as to help provide adequate energy for weight maintenance. Overall,
diets should provide moderate amounts of energy from fat (20% to 25% of energy); however, there
appears to be no health or performance benefit to consuming a diet containing less than 15% of
energy from fat. Body weight and composition can affect exercise performance, but should not be used
as the sole criterion for sports performance; daily weigh-ins are discouraged. Consuming adequate
food and fluid before, during, and after exercise can help maintain blood glucose during exercise,
maximize exercise performance, and improve recovery time. Athletes should be well-hydrated before
beginning to exercise; athletes should also drink enough fluid during and after exercise to balance
fluid losses. Consumption of sport drinks containing carbohydrates and electrolytes during exercise
will provide fuel for the muscles, help maintain blood glucose and the thirst mechanism, and
decrease the risk of dehydration or hyponatremia. Athletes will not need vitamin and mineral
supplements if adequate energy to maintain body weight is consumed from a variety of foods. However,
supplements may be required by athletes who restrict energy intake, use severe weight-loss
practices, eliminate one or more food groups from their diet, or consume high-carbohydrate diets
with low micronutrient density. Nutritional ergogenic aids should be used with caution, and only
after careful evaluation of the product for safety, efficacy, potency, and whether or not it is a
banned or illegal substance. Nutrition advice, by a qualified nutrition expert, should only be
provided after carefully reviewing the athlete's health, diet, supplement and drug use, and energy
requirements.

Publication Types:
Guideline

PMID: 11145214 [PubMed - indexed for MEDLINE]

Med Sci Sports Exerc. 2000 Dec;32(12):2130-45. Erratum in: Med Sci Sports Exerc 2001
Jan;33(1):following table of contents.

Joint Position Statement: nutrition and athletic performance. American College of Sports Medicine,
American Dietetic Association, and Dietitians of Canada.

American College of Sports Medicine; American Dietetic Association; Dietitians of Canada.

It is the position of the American Dietetic Association, Dietitians of Canada, and the American
College of Sports Medicine that physical activity, athletic performance, and recovery from exercise
are enhanced by optimal nutrition. These organizations recommend appropriate selection of food and
fluids, timing of intake, and supplement choices for optimal health and exercise performance. This
position paper reviews the current scientific data related to the energy needs of athletes,
assessment of body composition, strategies for weight change, the nutrient and fluid needs of
athletes, special nutrient needs during training, the use of supplements and nutritional ergogenic
aids, and the nutrition recommendations for vegetarian athletes. During times of high physical
activity, energy and macronutrient needs-especially carbohydrate and protein intake-must be met in
order to maintain body weight, replenish glycogen stores, and provide adequate protein for building
and repair of tissue. Fat intake should be adequate to provide the essential fatty acids and
fat-soluble vitamins, as well as to help provide adequate energy for weight maintenance. Overall,
diets should provide moderate amounts of energy from fat (20% to 25% of energy); however, there
appears to be no health or performance benefit to consuming a diet containing less than 15% of
energy from fat. Body weight and composition can affect exercise performance, but should not be used
as the sole criterion for sports performance; daily weigh-ins are discouraged. Consuming adequate
food and fluid before, during, and after exercise can help maintain blood glucose during exercise,
maximize exercise performance, and improve recovery time. Athletes should be well-hydrated before
beginning to exercise; athletes should also drink enough fluid during and after exercise to balance
fluid losses. Consumption of sport drinks containing carbohydrates and electrolytes during exercise
will provide fuel for the muscles, help maintain blood glucose and the thirst mechanism, and
decrease the risk of dehydration or hyponatremia. Athletes will not need vitamin and mineral
supplements if adequate energy to maintain body weight is consumed from a variety of foods. However,
supplements may be required by athletes who restrict energy intake, use severe weight-loss
practices, eliminate one or more food groups from their diet, or consume high-carbohydrate diets
with low micronutrient density. Nutritional ergogenic aids should be used with caution, and only
after careful evaluation of the product for safety, efficacy, potency, and whether or not it is a
banned or illegal substance. Nutrition advice, by a qualified nutrition expert, should only be
provided after carefully reviewing the athlete's health, diet, supplement and drug use, and energy
requirements.

Publication Types:
Guideline

PMID: 11128862 [PubMed - indexed for MEDLINE]

J Sci Med Sport. 2000 Sep;3(3):287-98. Gender differences in metabolism; nutrition and supplements.
Tarnopolsky MA. McMaster University, Department of Medicine, (Neurology and Rehabilitation),
McMaster University Medical Centre, Hamilton, Ontario, Canada.

For many decades researchers did not consider that there were any differences between the genders
in the metabolic response to exercise. As a result, nutritional recommendations and exercise
training prescriptions have not considered the potential for gender specific responses. More
recently, we and others have demonstrated that females oxidize proportionately more lipid and less
carbohydrate during endurance exercise as compared to males. The oxidation of amino acids is
similarly lower in females as compared to males during exercise.These gender differences are
partially mediated by a higher estrogen concentration in females. Specific areas where there are
gender differences in nutritional/supplement recommendations include carbohydrate (CHO) nutrition,
protein requirements and creatine (CRM) supplementation. We have shown that females do not
carbohydrate load in response to an increase in dietary carbohydrate when expressed as a percentage
of total energy intake (i.e., 55-75%), however if they consume >8 g CHOxkg(-1)xd(-1), they show
similar increases as compared to males. Top sport male and female athletes require somewhat more
dietary protein as compared to sedentary persons. The maximal increase is approximately 100% for
elite male athletes and approximately 50-60% for elite female athletes. Fortunately, most athletes
habitually consume this level of protein intake. We have recently demonstrated that females show a
lesser increase in lean body mass following acute CRM loading as compared to males. Females also
did not show reductions in protein breakdown in response to CRM loading, whereas males did. In the
future I expect that there will be further research from which gender specific
nutritional/supplement recommendations can be made.

Publication Types: Review Review, Tutorial

PMID: 11101268 [PubMed - indexed for MEDLINE]

Immunol Cell Biol. 2000 Oct;78(5):554-61. Special feature for the Olympics: effects of exercise on
the immune system: modification of immune responses to exercise by carbohydrate, glutamine and
anti-oxidant supplements. Gleeson M, Bishop NC.

School of Sport and Exercise Sciences, University of Birmingham, Edgbaston, Birmingham, England.
m.gleeson@bham.ac.uk

Immunosuppression in athletes involved in heavy training is undoubtedly multifactorial in origin.
Training and competitive surroundings may increase the athlete's exposure to pathogens and provide
optimal conditions for pathogen transmission. Heavy prolonged exertion is associated with numerous
hormonal and biochemical changes, many of which potentially have detrimental effects on immune
function. Furthermore, improper nutrition can compound the negative influence of heavy exertion on
immunocompetence. An athlete exercising in a carbohydrate-depleted state experiences larger
increases in circulating stress hormones and a greater perturbation of several immune function
indices. The poor nutritional status of some athletes may predispose them to immunosuppression. For
example, dietary deficiencies of protein and specific micronutrients have long been associated with
immune dysfunction. Although it is impossible to counter the effects of all of the factors that
contribute to exercise-induced immunosuppression, it has been shown to be possible to minimize the
effects of many factors. Athletes can help themselves by eating a well-balanced diet that includes
adequate protein and carbohydrate, sufficient to meet their energy requirements. This will ensure a
more than adequate intake of trace elements without the need for special supplements. Consuming
carbohydrate (but not glutamine or other amino acids) during exercise attenuates rises in stress
hormones, such as cortisol, and appears to limit the degree of exercise-induced immunosuppression,
at least for non-fatiguing bouts of exercise. Evidence that high doses of anti-oxidant vitamins can
prevent exercise-induced immunosuppression is also lacking.

Publication Types: Review Review, Tutorial

PMID: 11050539 [PubMed - indexed for MEDLINE]

J Am Coll Nutr. 2000 Oct;19(5 Suppl):513S-521S. Beyond the zone: protein needs of active
individuals. Lemon PW. Exercise Nutrition Research Laboratory, The University of Western Ontario,
London, Canada. plemon@julian.uwo.ca

There has been debate among athletes and nutritionists regarding dietary protein needs for
centuries. Although contrary to traditional belief, recent scientific information collected on
physically active individuals tends to indicate that regular exercise increases daily protein
requirements; however, the precise details remain to be worked out. Based on laboratory measures,
daily protein requirements are increased by perhaps as much as 100% vs. recommendations for
sedentary individuals (1.6-1.8 vs. 0.8 g/kg). Yet even these intakes are much less than those
reported by most athletes. This may mean that actual requirements are below what is needed to
optimize athletic performance, and so the debate continues. Numerous interacting factors including
energy intake, carbohydrate availability, exercise intensity, duration and type, dietary protein
quality, training history, gender, age, timing of nutrient intake and the like make this topic
extremely complex. Many questions remain to be resolved. At the present time, substantial data
indicate that the current recommended protein intake should be adjusted upward for those who are
physically active, especially in populations whose needs are elevated for other reasons, e.g.,
growing individuals, dieters, vegetarians, individuals with muscle disease-induced weakness and the
elderly. For these latter groups, specific supplementation may be appropriate, but for most North
Americans who consume a varied diet, including complete protein foods (meat, eggs, fish and dairy
products), and sufficient energy the increased protein needs induced by a regular exercise program
can be met in one's diet.

Publication Types: Review Review, Tutorial

PMID: 11023001 [PubMed - indexed for MEDLINE]

Proc Nutr Soc. 1999 May;58(2):403-13. Optimal intakes of protein in the human diet. Millward DJ.

Centre for Nutrition and Food Safety, School of Biological Sciences, University of Surrey,
Guildford, UK. d.millward@surrey.ac.uk

For protein, progress is slow in defining quantifiable indicators of adequacy other than balance and
growth. As far as current requirements are concerned, only in the case of infants and children is
there any case for revision, and this change is to lower values. Such intakes would appear to be
safe when consumed as milk formula. In pregnancy, notwithstanding the concern that deficiency may
influence programming of disease in later life, there is little evidence of any increased need, and
some evidence that increased intakes would pose a risk. For the elderly there is no evidence of an
increased requirement or of benefit from increased intakes, except possibly for bone health. For
adults, while we now know much more about metabolic adaptation to varying intakes, there would
appear to be no case for a change in current recommendations. As far as risks and benefits of high
intakes are concerned, there is now only a weak case for risk for renal function. For bone health
the established views of risk of high protein intakes are not supported by newly-emerging data, with
benefit indicated in the elderly. There is also circumstantial evidence for benefit on blood
pressure and stroke mortality. With athletes there is little evidence of benefit of increased
intakes in terms of performance, with older literature suggesting an adverse influence. Thus, given
that a safe upper limit is currently defined as twice the reference nutrient intake, and that for
individuals with high energy requirements this value (1.5 g/kg per d) is easily exceeded, there is a
case for revising the definition of a safe upper limit.

Publication Types: Review Review, Tutorial

PMID: 10466184 [PubMed - indexed for MEDLINE]

[not directly relevant, but interesting:] J Nutr. 1998 Dec;128(12 Suppl):2686S-2690S. The
nutritional requirements of exercising dogs. Hill RC. Department of Small Animal Clinical Sciences,
College of Veterinary Medicine, University of Florida, Gainesville, FL 32610, USA.

The nutrient requirements of canine athletes are unique. Dogs have a greater capacity for fat
oxidation than humans both at rest and during exercise. In dogs undertaking endurance exercise, such
as sled dogs, high fat (>50% of energy) diets increase stamina and maximize energy production, and
high protein (>30% of energy) diets prevent training-induced anemia. Nutrient requirements differ,
however, for sprint racing dogs, such as greyhounds. Greyhounds run faster when fed moderately
increased dietary fat but run more slowly when dietary protein is increased. Sled dogs have similar
energy requirements to other breeds at rest in a thermoneutral environment ( approximately 550W0.75
kJ/d where W is body weight in kg) but may require as much as 4200W0.75 kJ/d during a race. The
energy requirement of greyhounds in training, however, is only approximately 600W0.75 kJ/d. There is
little information, however, concerning the vitamin, mineral or other nutrient requirements of
athletic dogs; most sled dogs and greyhounds are fed "homemade" recipes. These recipes usually
include raw meat and represent a health risk. More studies are required to improve the health and
performance of working and racing dogs.

Publication Types: Review Review, Tutorial

PMID: 9868242 [PubMed - indexed for MEDLINE]

Nutr Rev. 1996 Apr;54(4 Pt 2):S169-75. Is increased dietary protein necessary or beneficial for
individuals with a physically active lifestyle? Lemon PW. Kent State University, USA.

For most of the 20th century, scientists have believed that protein needs are not altered by
physical exercise. In contrast, athletes are typically convinced that additional dietary protein can
significantly enhance exercise performance. Until recently, the opinion of the athletes has been
largely unsubstantiated in the scientific literature. However, since the 1970s, an increasing number
of studies have appeared that indicate dietary protein needs are elevated in individuals who are
regularly physically active. Together, these data suggest that the RDA for those who engage in
regular endurance exercise should be about
1.2-1.4 g protein/kg body mass/d (150-175% of the current RDA) and 1.7-1.8 g protein/kg body mass/d
(212-225% of the current RDA) for strength exercisers. Fortunately, the typical North American
diet contains protein near these quantities, so most individuals who decide to begin an exercise
program will obtain sufficient protein as long as their diet is mixed and they are careful to
consume adequate energy. Populations at greatest risk for consuming insufficient protein include
any group that restricts energy intake (those on diets) or high quality protein sources
(vegetarians) as well as any group that has a requirement higher than normal due to another
existing condition (growing individuals). Future studies should focus on these groups. Moreover,
few exercise performance measures have been made, so any negative effect of insufficient dietary
protein on athletic success needs to be determined. Supplementation of several individual amino
acids may be beneficial for physically active individuals, but considerable potential risk is also
present. Intake of large quantities of individual amino acids is not recommended until much more
information is available.

Publication Types: Review Review, Tutorial

PMID: 8700446 [PubMed - indexed for MEDLINE]

J Sports Sci. 1995 Summer;13 Spec No:S1-10. Macronutrients and performance. Williams C.

Department of Physical Education, Sports Science and Recreation Management, Loughborough University
of Technology, UK.

Athletes should eat a well-balanced diet made up of a wide variety of foods in sufficient quantity
to cover their daily energy expenditures. Carbohydrate-containing foods should provide approximately
60-70% of their daily energy intake, protein approximately 12-15%, with the remainder being provided
by fat. The higher carbohydrate intakes, however, are only recommended during preparation for, and
immediate recovery from, heavy training and competition. Adopting nutritional strategies to increase
muscle and liver glycogen stores before, during and after exercise can improve performance. The
protein requirements of most athletes are fulfilled when their daily intake is between
2.2 and 1.7 g per kg body mass. This amount of protein is provided by a diet which covers the
athlete's daily energy expenditure. Although fat metabolism contributes to energy production
during exercise, and the amount increases with endurance training, there is no evidence to suggest
that athletes should increase their fat intake as a means of improving their performance.

Publication Types: Review Review, Tutorial

PMID: 8897314 [PubMed - indexed for MEDLINE]

Schweiz Z Med Traumatol. 1994;(3):35-42. [Energy and nutritional intake in young weight lifters
before and after nutritional counseling] [Article in German] Bauer S, Jakob E, Berg A, Keul J.
Medizinische Universitatsklinik Freiburg, Abteilung Sport- und Leistungsmedizin, Hugstetterstrasse.

A well-balanced diet is an essential component for the development and maintenance of physical
performance. Several studies on the dietary status of power athletes have shown, that there are
still problems to realize the nutritional recommendations. The purpose of the present study was to
analyse the energy- and nutrient intake of 11 young weight lifters aged 14 to 17 years before and
after an intensive nutritional counselling (NC). Dietary status was evaluated by 7-day-protocols
filled out by the young athletes 4 weeks before and 4 weeks after the NC. Before the NC the athletes
(x: age 15, height 174 cm, weight 69.5 kg, BMI 22.2 kg/m2) had a mean energy intake of 179.7 kJ/kg
body weight (11.2 MJ/day). The energy percentage of carbohydrate:fatrotein was
2:1:1. The protein consumption was 1.6 g/kg of body weight and the fluid intake was 1.7 l/day. The
athletes did not meet the recommendation for niacin, folic acid, vitamin E, magnesium,
calcium, iodine and zinc. After the NC the athletes had a significant higher energy
percentage of carbohydrate and lower energy percentage of fat. In addition a significantly
higher intake of fluid, dietary fiber, vitamins and minerals was observed. This study
revealed that the young weight lifters without NC fall short of nutritional recommendations.
With the intensive nutritional counselling an improvement of the nutrient intake could be
reached. Additional nutritional counselling for the athletes and an intensive teamwork with
the coach and parents of the athletes seem necessary to develop and stabilize a good
nutritional behavior.

PMID: 7921793 [PubMed - indexed for MEDLINE]

Clin Pharm. 1993 Dec;12(12):900-8. Efficacy of nutritional supplements used by athletes. Beltz SD,
Doering PL. Department of Pharmacy, Shands Hospital, Gainesville, FL.

Findings on the efficacy of nutritional supplements used by athletes are reviewed. Many athletes
have turned away from anabolic steroids and toward nutritional supplements in the hope of gaining a
competitive edge without threatening their health. Athletes may require slightly more protein than
sedentary people do to maintain positive nitrogen balance, but it is dubious whether extra dietary
protein will help someone to achieve athletic goals. Purified amino acids have become a popular if
expensive form of protein supplementation; there is no scientific evidence, however, to support
their use. Excessive protein supplementation can lead to dehydration, gout, liver and kidney damage,
calcium loss, and gastrointestinal effects. Supplementation with vitamins and minerals in excess of
recommended daily allowances appears to have no effect on muscle mass or athletic performance. Other
substances touted as having ergogenic properties are carnitine, cobamamide, growth hormone
releasers, octacosanol, and ginseng; again, there is no reliable scientific evidence to support
claims that products containing these compounds have ergogenic potential, and heavy supplementation
may lead to adverse effects. Nutritional supplements are promoted through unsubstantiated claims by
magazine advertisements, health food stores, coaches, and other sources. The FDA considers
nutritional supplements to be foodstuffs, not drugs, and therefore has not required that they be
proved safe and effective. Dosage guidelines are inadequate, and quality control is poor. The FDA
has begun to revise regulations governing labeling and health claims for these products. There is
little if any evidence that nutritional supplements have ergogenic effects in athletes consuming a
balanced diet, and some products have the potential for harm.

Publication Types: Review Review, Tutorial

PMID: 8137607 [PubMed - indexed for MEDLINE]

J Appl Physiol. 1993 Nov;75(5):2134-41. Gender differences in leucine kinetics and nitrogen balance
in endurance athletes. Phillips SM, Atkinson SA, Tarnopolsky MA, MacDougall JD. Department of
Pediatrics, McMaster University, Hamilton, Ontario, Canada.

The current Canadian Recommended Nutrient Intake (RNI) for protein (0.86
g.kg-1.day-1) makes no allowance for an effect of habitual physical activity. In addition,
Tarnopolsky et al. (J. Appl. Physiol. 68: 302-308, 1990) showed that males may catabolize more
protein than females consequent to endurance exercise. We examined nitrogen (N) balance and
leucine kinetics during submaximal endurance exercise to determine the adequacy of the current
Canadian RNI for protein for male and female endurance athletes. Athletes were matched for equal
training volume, competitive status, and conditioning and were fed diets isoenergetic with their
habitual intake, containing protein at the Canadian RNI. Subjects were adapted to the diet for 10
days before completing a 3-day measurement of N balance. N balance showed that the RNI was
inadequate for females (-15.9 +/- 6.0 mg.kg-1.day-1) and males (-26.3 +/- 11.0 mg.kg-1.day-1).
Leucine kinetics during exercise were determined for each subject on day 3 of the N balance
experiment by use of a primed continuous infusion of L-[1-13C]leucine and the reciprocal pool
model. Exercise resulted in a significant (P < 0.01) increase in leucine oxidation for both
groups. Males oxidized a greater amount of leucine during the infusion than females (P < .01).
Leucine flux also increased significantly (P < 0.01) during exercise in both groups. We conclude
that the current Canadian RNI for protein is inadequate for those who chronically engage in
endurance exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

PMID: 8307870 [PubMed - indexed for MEDLINE]

Am Fam Physician. 1993 Jun;47(8):1757-64. Comment in: Am Fam Physician. 1994 Mar;49(4):759, 764.
Nutrition and athletes. Holt WS Jr.

Department of Family Medicine, Indiana University School of Medicine, Indianapolis.

Athletes differ from nonathletes in their nutritional requirements. Proper determination of
nutritional needs in athletes requires knowledge of the athlete's body-fat composition and daily
caloric expenditure. A balanced diet for athletes consists of 60 percent of calories from
carbohydrates, 15 percent from protein and 25 percent from fat. Other important considerations
include adequate intake of minerals and fluids.

Publication Types: Review Review, Tutorial

PMID: 8498285 [PubMed - indexed for MEDLINE]

J Appl Physiol. 1992 Nov;73(5):1986-95. Evaluation of protein requirements for trained strength
athletes. Tarnopolsky MA, Atkinson SA, MacDougall JD, Chesley A, Phillips S, Schwarcz HP. Department
of Pediatrics, McMaster University, Hamilton, Ontario, Canada.

Leucine kinetic and nitrogen balance (NBAL) methods were used to determine the dietary protein
requirements of strength athletes (SA) compared with sedentary subjects (S). Individual subjects
were randomly assigned to one of three protein intakes: low protein (LP) = 0.86 g
protein.kg-1.day-1, moderate protein (MP) =
1.40 g protein.kg-1.day-1, or high protein (HP) = 2.40 g protein.kg-1.day-1 for 13 days for each
dietary treatment. NBAL was measured and whole body protein synthesis (WBPS) and leucine oxidation
were determined from L-[1-13C]leucine turnover. NBAL data were used to determine that the protein
intake for zero NBAL for S was 0.69 g.kg-1.day-1 and for SA was 1.41 g.kg-1.day-1. A suggested
recommended intake for S was 0.89 g.kg-1.day-1 and for SA was 1.76 g.kg-1.day-1. For SA, the LP
diet did not provide adequate protein and resulted in an accommodated state (decreased WBPS vs. MP
and HP), and the MP diet resulted in a state of adaptation [increase in WBPS (vs. LP) and no
change in leucine oxidation (vs. LP)]. The HP diet did not result in increased WBPS compared with
the MP diet, but leucine oxidation did increase significantly, indicating a nutrient overload. For
S the LP diet provided adequate protein, and increasing protein intake did not increase WBPS. On
the HP diet leucine oxidation increased for S. These results indicated that the MP and HP diets
were nutrient overloads for S. There were no effects of varying protein intake on indexes of lean
body mass (creatinine excretion, body density) for either group. In summary, protein requirements
for athletes performing strength training are greater than for sedentary individuals and are above
current Canadian and US recommended daily protein intake requirements for young healthy males.

Publication Types: Clinical Trial Randomized Controlled Trial

PMID: 1474076 [PubMed - indexed for MEDLINE]

Int J Sports Med. 1992 Oct;13 Suppl 1:S100-6. Nutritional aspects of health and performance at
lowland and altitude. Brouns F. Nutrition Research Center, University of Limburg, Maastricht,
Netherlands.

One of the most important nutritional goals amongst athletes is to maintain adequate energy and
fluid balance, since these are subject to relatively rapid changes and are directly related to
performance and health. This may especially be the case when exercise intensity is high.
Furthermore, when due to exercise and environmental stress food and fluid intake become depressed.
In such conditions there may be a dramatic increase in the utilization of carbohydrate (CHO), fluid,
and in some instances protein. These increased requirements may then not be covered. Insufficient
replacement of CHO may lead to hypoglycemia, altered protein metabolism, central fatigue and
exhaustion. Large sweat losses may pose a risk to health by inducing severe dehydration, impaired
blood circulation and heat transfer, leading to heat exhaustion and collapse. Inadequate CHO and
protein intake leads to a negative nitrogen balance, which over the long term will lead to a loss of
muscle mass. In the scope of this presentation we will refer to the most important nutritional
factors which are known to affect performance over a short term, at sea level and altitude.

Publication Types: Review Review, Tutorial

PMID: 1483743 [PubMed - indexed for MEDLINE]

Sports Med. 1991 Nov;12(5):313-25. Protein intake and athletic performance. Lemon PW, Proctor DN.

Applied Physiology Research Laboratory, School of Biomedical Sciences, Kent State University, Ohio.

For most of the current century, exercise/nutritional scientists have generally accepted the
belief that exercise has little effect on protein/amino acid requirements. However, during the
same time period many athletes (especially strength athletes) have routinely consumed diets high
in protein. In recent years, the results of a number of investigations involving both strength and
endurance athletes indicate that, in fact, exercise does increase protein/amino acid need. For
endurance athletes, regular exercise may increase protein need by 50 to 100%. For strength
athletes, the data are less clear; however, protein intakes in excess of sedentary needs may
enhance muscle development. Despite these observations increased protein intake may not improve
athletic performance because many athletes routinely consume 150 to 200% of sedentary protein
requirements. Assuming total energy intake is sufficient to cover the high expenditures caused by
daily training, a diet containing 12 to 15% of its energy from protein should be adequate for both
types of athletes.

Publication Types: Review Review, Academic

PMID: 1763249 [PubMed - indexed for MEDLINE]

Int J Sport Nutr. 1991 Jun;1(2):127-45. Protein and amino acid needs of the strength
athlete. Lemon PW.

Applied Physiology Research Laboratory, Kent State University, OH 44242.

The debate regarding optimal protein/amino acid needs of strength athletes is an old one. Recent
evidence indicates that actual requirements are higher than those of more sedentary individuals,
although this is not widely recognized. Some data even suggest that high protein/amino acid diets
can enhance the development of muscle mass and strength when combined with heavy resistance exercise
training. Novices may have higher needs than experienced strength athletes, and substantial
interindividual variability exists. Perhaps the most important single factor determining absolute
protein/amino acid need is the adequacy of energy intake. Present data indicate that strength
athletes should consume approximately 12-15% of their daily total energy intake as protein, or about
1.5-2.0 g protein/kg.d-1 (approximately 188-250% of the U.S. recommended dietary allowance).
Although routinely consumed by many strength athletes, higher protein intakes have not been shown to
be consistently effective and may even be associated with some health risks.

Publication Types: Review Review, Tutorial

PMID: 1844991 [PubMed - indexed for MEDLINE]

J Sports Sci. 1991 Summer;9 Spec No:53-70. Effect of exercise on protein requirements. Lemon
PW. Applied Physiology Research Laboratory, School of Biomedical Sciences, Kent State
University, OH 44242.

The effect(s) of exercise on dietary protein requirements has (have) been a controversial topic for
many years. Although most expert committees on nutrition have not provided an additional allowance
of protein for active individuals, a considerable amount of experimental evidence has accumulated
during the past 15 years which indicates that regular exercise does in fact increase protein needs.
Part of the confusion is due to methodological difficulties and inadequate control of several
interacting factors including: diet composition, total energy intake, exercise intensity, duration
and training, ambient temperature, gender, and perhaps even age. Although definitive dietary
recommendations for various athletic groups must await future study, the weight of current evidence
suggests that strength or speed athletes should consume about 1.2-1.7 g protein/kg body weight.d-1
(approximately 100-212% of current recommendations) and endurance athletes about 1.2-1.4 g/kg.d-1
(approximately 100-175% of current recommendations). These quantities of protein can be obtained
from a diet which consists of 12-15% energy from protein, unless total energy intake is
insufficient. There is no evidence that protein intakes in this range will cause any adverse
effects. Future studies with large sample sizes, adequate controls, and performance as well as
physiological/biochemical measures are necessary to fine tune these recommendations.

Publication Types: Review Review, Tutorial

PMID: 1895363 [PubMed - indexed for MEDLINE]

Semin Adolesc Med. 1987 Sep;3(3):177-83. Eating for competing. Mirkin G. Department of Pediatrics,
Georgetown University School of Medicine, Washington,
D.C.

Many adolescent athletes take nutritional supplements in the hope that such supplements will make
them better athletes. Protein supplements will not build muscles unless the athlete is not ingesting
adequate amounts of protein in food. Vitamins and mineral supplements will not improve performance
unless the athlete suffers from a deficiency. No nutritional supplement contains any ingredient that
cannot be obtained from food. However, following the scientific principles outlined in this article,
on what and when to eat foods and drink fluids, can improve athletic performance.

PMID: 3685660 [PubMed - indexed for MEDLINE]

Sports Med. 1984 Nov-Dec;1(6):474-84. The importance of protein for athletes. Lemon PW, Yarasheski
KE, Dolny DG.

Although it is generally believed that carbohydrate and fat are the only sources of energy during
physical activity, recent experimental results suggest that there are also significant alterations
in protein metabolism during exercise. Depending on several factors, including intensity, duration
and type of exercise, as well as prior diet, training, environment and perhaps even gender or age,
these changes may be quite large. Generally, exercise promotes: a decrease in protein synthesis
(production) unless the exercise duration is prolonged (greater than 4h) when increases occur;
either an increase or no change in protein catabolism (breakdown); and an increase in amino acid
oxidation. In addition, significant subcellular damage to skeletal muscle has been shown following
exercise. Taken together, these observations suggest that the protein requirements of active
individuals are greater than those of inactive individuals. Although the underlying reasons are
different, this statement applies to both endurance and strength/power athletes. At present, it is
not possible to precisely determine protein requirements. However, because deficiencies in total
protein or in specific amino acids may occur, we suggest that athletes consume 1.8 to 2.0 g of
protein/kg of bodyweight/day. This is approximately twice the recommended requirement for sedentary
individuals. For some athletes this may require supplementation; however, these quantities of
protein can be easily obtained in a diet where 12 to 15% of the total energy is from protein.
Although the effect of exercise on protein metabolism has been studied for many years, numerous
questions remain. Hopefully, with the recent renewed interest in this area of study, most of these
answers will soon be available.

Publication Types:
Review

PMID: 6390614 [PubMed - indexed for MEDLINE]

Sports Med. 1984 Sep-Oct;1(5):350-89. Nutrition and sports performance. Brotherhood JR.

During the past 20 years there have been great developments in the scientific understanding of the
role of nutrition in health and physical performance. Epidemiological and physiological studies have
provided evidence that certain forms of dietary behaviour may be linked with an increased risk of
developing disorders such as high blood pressure, coronary artery disease and some cancers. This has
resulted in dietary recommendations that are intended to reduce the incidence of these disorders in
the community. The science of nutrition in relation to sports performance has progressed from
empirical studies investigating the effects of dietary manipulations, such as restriction and
supplementation, to the direct investigation of the physiological basis of the specific nutritional
demands of hard physical exercise. This review is based on the premise that it is "what comes out'
rather than "what goes in', which provides the clues to ideal nutrition for athletic performance.
Various aspects of the physical demands of athletic exercise are viewed as stresses that induce
specific biochemical, and hence nutritional, strains in the athlete. Training is the predominant
demand in the athletic lifestyle. This is characterised by acute bouts of high power output. During
one hour of hard training an athlete may expend 30% of his or her total 24-hour energy output. These
high power outputs have important implications for energy substrate and water requirements.
Carbohydrate, specifically muscle glycogen, is an obligatory fuel for the high power outputs
demanded by athletic sports. Muscle glycogen is a limiting factor in hard exercise because it is
held in limited amounts, utilised rapidly by intense exercise, and fatigue occurs when it is
depleted to low levels in the active muscles. Liver glycogen may also be exhausted by hard exercise
and low blood glucose contributes to fatigue. High sweat rates are demanded during severe exercise
and large water deficits commensurate with energy expenditure are incurred during extended periods
of hard training and competition. Salt, potassium, and magnesium are lost in nutritionally
significant amounts in the sweat, but vitamins and trace elements are not. Adaptive mechanisms
protect athletes against electrolyte depletion. Iron loss in sweat may contribute to the iron
deficiency seen in some endurance runners. Protein is degraded and amino acids are oxidised during
physical exercise. Protein is also retained during muscle building training. Recent investigations
indicate that the minimal protein requirements of athletes may be substantially higher than those
for sedentary persons.(ABSTRACT TRUNCATED AT 400 WORDS)

Publication Types:
Review

PMID: 6390609 [PubMed - indexed for MEDLINE]

Clin Sports Med. 1984 Jul;3(3):595-604. Protein nutrition for the athlete. Dohm GL.

Endurance exercise results in a protein catabolic state characterized by decreased protein
synthesis, increased amino acid oxidation, and increased conversion of amino acids to glucose. The
adaptive response to performance of strength exercise, on the other hand, results in an anabolic
state in hypertrophying muscles, and the accretion of protein is the result of increased protein
synthesis. Because of changes in protein metabolism there is an increased dietary requirement for
protein in both endurance and strength exercise. However, the normal dietary intake of protein is
adequate for athletes as long as the energy intake is sufficient to maintain body weight. There is
little scientific evidence that consumption of large protein supplements will have any beneficial
effect on muscle hypertrophy, muscular strength, or physical performance.

PMID: 6571233 [PubMed - indexed for MEDLINE]