Physical Performance Rndicators and A ModeB for lntegrati ... · PDF fileof studies that have assessed the protein requirements of athletes ... Certainly athletes can benefit from

CASE STUDIES lnternationaljournal of Sport Nutrition, 1991, 1, 192-204

blutritioan Assessmenat of Athletes: A ModeB for lntegrat i~g Nutrition

and Physical Performance Rndicators

Jean StorBie Rush University and$$ Associates

Athletes, like all people, have special nutritional needs based on their age, lifestyle, health status, level o f physical activity, physical conditioning, and type of sport. The diets o f many athletes are inadequate due to overly restrictive eating habits, nutrition misinformation, dietary fads, andlor obsession with weight and food. There is a growing need for sports nutrition counseling and education to help athletes improve their eating habits. However, before attempting to develop intervention strategies, sports nutritionists should assess the metabolic changes that take place during exercise and how these changes affect nutrition status. In addition, it is important to consider how psychosocial factors may influence an athlete's eating habits and hislher ability to make positive changes. A two-pronged model is introduced that can be used as a guide for the practitioner in interpreting relevant data and integrating physiological and psychological considerations for the design of individualized nutrition care plans for athletes.

Like all people, athletes have special nutritional needs. Endurance athletes, for instance, often have increased needs for B-complex vitamins, iron, zinc, and calories due to the physical demands o f training and competition (4). A review of studies that have assessed the protein requirements o f athletes suggests that the requirements for both strength and endurance athletes are often higher than normal and that the recornended dietary dlowalnces (RDA) may not be adequate for athletes (18). And while their needs may be greater, many athletes fail to meet even the WDA due to hectic schedules and poor food choices (8) . For example, a study o f adolescent female gymnasts revealed that they consumed an average of 300 cdories less than their energy requirement, and of them consumed diets that provided less than two-thirds of the RDA for several vitamins and minerds (12). Numerous studies have shown that the diets o f many athletes are inadequate due to overly restrictive eating habits and nutrition misinformation (3, 7, 12, 20, 22).

Jean Storlie is with the Department o f Clinical Nutrition at Rush University, Chicago, and with JS Associates, 522 Mahogany Way, Vernona, WI 53593.

Nutrition Assessment of Athletes / 193

Certainly athletes can benefit from nutrition education and counseling, and there is a growing need for practitioners to provide this care. In addition to a thorough understanding of nutrition, sports nutritionists must understand metabolic changes (15) that occur during exercise and the effect of these changes. Furthermore, they need practical skills in counseling and education to help motivate athletes to modify their food choices and eating habits. The foundation of an effective nutrition care plan for active individuals is an assessment of physical, biochemical, and nutritional status as well as relevant psychosocial factors (13). The assessment process should integrate nutrition and physical performance indicators to determine physiological needs and compare these needs to food intake. In addition, other factors influencing the athlete's eating habits (e.g., level of motivation, social pressures, beliefs, competitive goals, work and school schedules) should be considered before attempting to counsel for change.

Figure 1 depicts a conceptual framework for conducting a nutrition assessment of athletes. The model suggests a two-pronged approach: (a) assessment of nutrition needs during training and (b) assessment of nutrition needs immediately preceding, during, and following competition. Note that nutrition conditioning during training as well as nutrition practices surrounding the event will support competitive performance. This model will focus on conceptual rather than opera- tional issues.

It is the role of the practitioner to apply the elements of this assessment process that are pertinent to the populations and individuals being assessed. In some cases the reader will be referred to other sources that more fully address the collection of data and selection of assessment protocols. It is important to realize that this model promotes a comprehensive approach to nutrition assessment of athletes; in any given practice setting, some of the data presented in the model may be unavailable or irrelevant.

Weight Analysis

11 Eating and Lifestyle. Patterns I I Pimess and Iaboratory Tests I

Figure 1 - Flowchart for the nutrition assessment of athletes.

Nutrition Assessment

The nutrition assessment process involves the interpretation of objective and subjective data that will help the practitioner understand the multifaceted issues that affect an individual athlete's nutrition needs (see Figure 1). Using the results of a thorough assessment, sports nutritionists can work with athletes to establish goals, identify and rank areas for change, and use baseline data to monitor progress.

Weight Analysis

Caloric requirements will depend on whether an athlete needs to lose, maintain, or gain weight as well as on histher average daily energy expenditure. Therefore it is useful to initiate the nutrition assessment process with a thorough evaluation of weight related factors that can affect an athlete's performance and personal goals. Table 1 outlines the factors to consider in assessing weight control needs.

The first step in the weight analysis is to determine the athlete's optimal body weight using three methods: personal goal weight, a heighttweight formula, and percent body-fat prediction. The athlete's personal goal weight lends insight into histher motivation and body image. Collection of anthropometric data will allow the practitioner to calculate ideal body weight and determine how the athlete's current weight deviates from the predicted ideal. A number of sources discuss in detail the various protocols for anthropometric assessment (13, 14). Calculation of ideal body weight using both heighttweight and percent body fat is recommended, since each has clinical limitations. For instance, the height/ weight formulas do not factor lean body mass into the ideal weight prediction. On the other hand, since the percent body-fat prediction is based on lean body mass, deviations from normal lean body mass will give misleading results. To

Table 1

Weight Analysis

Assessment activity Relevant information

Determine optimal Anthropometric measures (height, weight, ratio of lean:fat weight) body weight Personal goal weight

Ideal weight prediction (height based, 04 body fat) Identify optimal targets for age and specific competitive goals

(weight, % body fat) Calculate calorie Basal metabolism (13) expenditure Average daily exercise calories

Seasonal variations in training Differences in training vs. competition

Identify weight Weight fluctuations (short- and long-term history, frequency, history % change)

Cause of fluctuations (age, lifestyle, sport, illness, other) Pathogenic weight behaviors (2)


Table 2

Assessment of ldeal Weight Using Three Methods

Case 1 Case 2 Case 3

Age Sex Height (in.) Weight (Ibs) Percent body fat Ideal weight prediction

Personal goal Height-baseda Based on % body fat (14)

45 yrs Male 74 237 27.5%

195 190 202-209~

19 yrs Female 62 102 1 1 010

98 110 103-10P

41 yrs Female 66 160 46%

1 40 130 105-1 1 2d

aCalculated using rule-of-thumb method: Women, 100 Ibs. for 5 ft, +5 Ibs for every inch over 5 ft. Men, 106 Ibs for 5 ft, +6 Ibs for every inch over 5 ft. (11, p. 507) bldeal weight calculated using 15-1896 as the desired percent body fat, Cu~ing 12-15% as the desired percent body fat; dusing 18-23% as the desired percent body fat.

illustrate this problem, Table 2 presents three cases in which all three methods result in different ideal weight predictions; the discrepancies reveal pertinent insights.

Case 1 is a large-framed male who is moderately overweight due to lifestyle factors. Since the height based formula has not accounted for his above-average lean body mass, it underpredicts his ideal weight. Therefore the percent body- fat prediction is the most appropriate ideal weight for him. Case 2 is a gymnast who reveals symptoms of a distorted body image and could be suffering from amenorrhea and an eating disorder. She needs referral to experts in these areas and further counseling on a realistic weight goal. Case 3 is a sedentary yo-yo dieter whose muscle tissue is wasted due to her chronic dieting and inactivity. In her case the percent body-fat prediction is grossly inaccurate because her lean body mass is abnormally low. From a motivational viewpoint, the personal goal weight is the most realistic weight, but she also needs a muscle development program to improve her body composition.

Unfortunately there is no concrete set of guidelines for determining which formula is the most appropriate in any given situation; a sports nutritionist needs to consider all three predictors and use professional judgment. It is often useful to incorporate this decision into the counseling process by presenting all three numbers to the athlete, helping himiher interpret the calculations, and negotiating a target body weight. This approach integrates professional judgment with the individual's motivation, which will address specific competitive goals. However, when there are eating disorders this approach may not be appropriate.

The final step in determining an optimal body weight is to adjust the ideal weight predictions for any age- or sport-specific targets. In addition, it is also worth considering how the target weight goal may fluctuate during on- and off- season months. For example, oflcial weight classifications for wrestling and

body building will influence the weight goals of coaches and athletes involved in those sports. In many cases wrestlers lose weight rapidly to compete in a particu- lar weight class, which adversely affects their performance (1). Ideally the sports nutritionist, coach, and athlete should jointly determine a proper and reasonably consistent weight classification, using a valid technique such as the approach suggested by Tipton (21). While performance is affected by percent body fat, it is difficult to predict with precision the optimal weight for specific athletic and health goals. Table 3 summarizes the guidelines that are generally accepted. Although these reference levels can help the sports nutritionist assess individual needs, it is important to keep in mind that the figures are not exact.

Once the athlete's ideal body weight has been determined, it is possible to calculate the caloric requirement to maintain the desirable weight, adding or subtracting 500-1,000 calories a day for a weight change of 1-2 lbs a week. Marcus suggests two methods commonly used by dietitians in clinical settings to determine the caloric requirements of their patients based on formulas for esti- mating basal energy and activity calories (13). Although these techniques are appropriate for inactive populations, the adjustments for activity levels are imprecise. Through an interview with the athlete, it is possible to determine his/ her training routines (e.g., type of activity, frequency, intensity, and duration) and to calculate the average daily expenditure from physical activity, based on a normal week of training and using an energy expenditure table. Through this approach, the average daily activity level in addition to desired weight changes can be factored into the recommended calorie intake. Also, seasonal variations in daily energy expenditure due to changes in training schedule should be calculated and appropriate adjustments made. Energy expenditure during training may differ from energy expenditure during competition; these variations should also be considered.

Table 3

Guidelines for Acceptable Percent Body Fat Levels

Male (010) Female (010)

Essential (1 4) Recommended for athletic

performance (23) Recommended for health

and fitness Average American adults (14)

17-30 yrs 31-68 yrs

Excess (23)

=Males: longdistance runners, wrestlers, gymnasts, basketball players, soccer players, swimmers, body-builders, football backs, tennis players; Females: gymnasts, ballet dancers, long-distance runners. b~a les : baseball players, football linemen, weightlifters, weight men in track and field; Fe- males: other athletes.


During the process of analyzing weight related factors, sports nutritionists should identify their clients' short- and long-term weight histories. Drastic fluctuations in weight and the causes should be noted. Weight loss due to illness or injury, frequent weight changes, starvation diets, or any unexplained weight loss could hamper performance and cause health problems. These weight fluctuations can be identified from a medical record, an interview, or a questionnaire. The tendency for athletes to engage in pathogenic weight behaviors in order to achieve unrealistic weight goals is a growing concern in the sports medicine community (9, 17, 23). Obsession with exercise and diet, preoccupation with weight and appearance, and bizarre eating habits should be further investigated to rule out the possibility of eating disorders.

Eating and Lifestyle Patterns

As Figure 1 suggests, the second step in a nutrition assessment is the analysis of eating and lifestyle patterns. To develop a picture of the athlete's strengths and weaknesses, the sports nutritionist should perform the following assessment activities:

Analyze nutrient intake using a valid method that is practical for the given practice setting (5, 13). Evaluate eating habits through an interview or questionnaire.

* Identify use and abuse of dietary supplements and how they affect health and performance. Evaluate lifestyle routines that affect the athlete's level of stress and time to select, purchase, and prepare food.

Table 4 outlines factors to consider within each stage of the assessment process. The methods for collecting data on eating and lifestyle patterns will vary in different practice settings, and the techniques employed will depend on the purpose of the assessment (e.g., screening, clinical evaluation, research), skill of the practitioner, tools available (e.g., computerized dietary analysis), and depth of interaction with the athlete (e.g., individual or group sessions, number and frequency of contacts). Dwyer discusses the complexities of assessing dietary intake and reviews the pro's and con's of the 24-hour recall, food record, and food frequency questionnaires for assessing nutrient intake (5). Since measure- ment of diet is imprecise, it is worthwhile to use more than one method to collect dietary information, such as food record, interview, and diet history questionnaire. If an interview or questionnaire is used, it should be tailored to the lifestyle of the athletic population served. For many athletes who train 10-20 hours a week, travel to competitive events, and maintain full-time school and/or work commitments, time constraints affect food choices. Collecting information on eating and lifestyle routines will help the sports nutritionist identify individual characteristics that influence an athlete's eating habits and his/her ability to make changes.

Fitness and Laboratory Tests

In some practice settings, for example sports medicine clinics or fitness centers, it will be possible to access fitness data and/or medical records that can yield useful information. Sports nutritionists should have a basic understanding of

Table 4

Eating and Lifestyle Patterns

Assessment activity Relevant information

Analyze nutrient intake (5) 24-hr recall Food record (3 day, 7 day) Food frequency questionnaire

Evaluate eating habitsa Meal and snacking patterns (no, of meals and snacks, frequency and timing, and type of foods selected)

Food choices (likes and dislikes, intolerances and allergies)

Food purchasing routines (shopping, dining out)

Cooking techniques Alcohol intake Vitamins and minerals Protein supplements Sports beverages Ergogenic aids (e.g., bee pollen) Sleep schedule Work-out schedule (time of day, length

of time) Work andlor school routines Other time demands (travel, volunteer work,

family commitments)

Identify use and abuse of dietary supplementsa

Evaluate lifestyle routinesa

aUse an interview or questionnaire to collect this data.

exercise physiology, the accepted testing protocols, and population norms. With this knowledge they can review the results of fitness assessments, interpret the data, and relate it to the nutrition assessment.

If available, the information in medical records such as blood tests, diag- noses, or histories will shed light on special problems or concerns that are related to nutrition status. The pertinence of medical data will depend largely on the age, sex, and health status of the athlete. For example, female athletes could have special concerns such as amenorrhea, pregnancy, or lactation that will affect nutrition status. Older athletes could be at cardiovascular risk, in which case medical data will be beneficial to the nutrition intervention process. Table 5 summarizes the data that can be gleaned from fitness and laboratory tests.

Psychosocial Influences

The final step (see Figure 1) in conducting a nutrition assessment consists of considering how psychosocial factors influence the eating habits and overall lifestyle of an athlete. While psychological assessment is beyond the scope of most sports nutrition practices, an awareness of the relevant issues is helpful. A wide range of psychological issues could be uncovered during nutrition assessment


Table 5

Physical Fitness and Laboratory Tests

Testlassessment Relevant information I I

Fitness assessment Heart rate Blood pressure Aerobic capacity Strength Flexibility Percent body fat

Blood tests Cholesterol (total, HDL, LDL) Triglycerides Glucose Iron status (hemoglobinlhematocrit, serum irona, ferritinb) Plasma electrolytes

Medical assessment Current health status Medical history Cardiovascular risk status Orthopedic problems Recent and past injuries Gynecological problems

Note. Appropriateness of some of these tests will depend on the athlete's age and sex. In many practice settings some of this information will not be available. aSerum iron can be evaluated in women; b~erritin can be evaluated if anemia is suspected.

and counseling; the factors likely to emerge in working with athletes are summa- rized in Table 6.

Social influences can be both positive and negative. Parents may have a vicarious interest in a child's athletic performance borne out of their own past failures. This could pressure a young athlete into experiencing competitive anxieties, obsessions with exercise, and even eating disorders. On the other hand, parents can be supportive and encourage their children's participation in sports. A healthy mentoring relationship with a coach can motivate an athlete's performance, but some coaches badger athletes to the point of rebellion. Family members, friends, peers, coaches, and celebrities are all role models; athletes learn both good and bad practices from these people.

Athletes who are prone to pathogenic weight behaviors appear to be partic- ularly vulnerable to disturbances in body image, fear of failure, and a high need for control and perfection (9,23). Major incongruencies between athletic aspirations and abilities, body image and ideal weight, or perceptions of self versus others' perceptions are indicators of potential psychological problems. When exercise and competition become allconsurning, work, school, and other activities are affected and the athlete's lifestyle can become narrow and unbalanced. Although it is diicult to make an accurate assessment of psychosocial influences, a sports nutritionist should be alert to these potentid problems and be prepared to make referrals to qualified professionals.

Table 6

Psychosocial Influences - -

Dimension Factors to consider

Social influences Family members Friends Teammates Coaches Celebrities

Self-concept

Competitive goals and commitment

Attitudes and philosophy toward life

Forms of support Sources of conflictlfriction Vicarious interests Expectationslpressures Role modeling

Body image Self-efficacy Self-confidence Fears of failure, fears of competition Locus of control Realistic aspirations (athletic talent, self-discipline) Prioritylimportance Competitive anxieties Balanced vs. imbalanced approach Aspirations (career, school, other areas) Tendency to be driven or single-minded Need for power and control Stress patternsflife satisfaction

Determining Nutrition Needs During Training

While eating before competition is important, nutrition habits during training are more critical than any dietary manipulations surrounding competition (16). The basic functions of food are to (a) supply energy, (b) provide nutrients to regulate metabolic processes, and (c) provide nutrients to support growth, maintenance, and repair of body tissue. While the food supplied for competition should fulfill the first two functions, all three of these needs must be met during training. Most athletes will simply need a normal, well-balanced diet; however, the physiological demands of training can increase nutrition needs in specific situations. Once the physiological demands of training have been identified, it is possible to identify which nutrients might be at risk. Figure 1 illustrates how the nutrient needs during training result from the physiological demands and in turn affect performance during competition.

Table 7 summarizes the nutrients that could be affected by specific physiological demands during exercise. For example, endurance athletes who train 1-2 hours a day may need 500-600 grams of carbohydrate (i.e., 2,000-2,400 calories from carbohydrates) in the daily diet to replace muscle glycogen stores and maintain a quality training program (23). Even athletes who engage in prolonged periods of intermittent anaerobic activity (e.g., downhill skiing, soccer, ice


Table 7

Physiological Demands of Exercise and Possible Nutrient Needs

Physiological demand Possible nutrient needs

Aerobic energy production for endurance exercise

Prolonged anaerobic workouta Hockey Soccer Downhill skiing

Musculoskeletal stress Muscle development programs Injury-prone sports

Thermoregulatory stress Endurance sports Environmental conditions Long or frequent air travel

Weight loss Wrestling Body building Gymnastics Ballet

Immune system Frequent injuries or illness Overtraining ~atigue'

lncreased calories lncreased carbohydrates lncreased protein lncreased B-complex vitamins lncreased water and electrolytes

lncreased carbohydrate lncreased Bcomplex vitamins lncreased water

lncreased protein lncreased carbohydratesb Adequate caloriesC lncreased vitamin C lncreased iron and zinc lncreased vitamins B6 and B~~~ lncreased calciume

lncreased water lncreased electrolytes

Decreased calories lncreased nutrient density of foods lncreased water

lncreased protein lncreased vitamin C lncreased water and electrolytes lncreased iron and zinc lncreased Bcomplex vitamins

anaerobic sports do not typically deplete carbohydrate stores, intermittent anaerobic workouts that last for several hours could deplete muscle glycogen through anaerobic glycolysis; b~arbohydrates will spare protein; CCaloric requirements must be adequate to spare protein and promote proper healing, but could decrease due to inactivity during injury rehabilitation; d~ssociated with protein metabolism; % bone injuries; f ~ u e to the hectic schedules that some athletes must keep to handle long workouts, travel, jobs, andlor school schedules, they may not get enough sleep and relaxation.

202 l Storlie

hockey) may experience fatigue and performance decreases induced by muscle glycogen depletion, suggesting that a high carbohydrate diet may enhance their training program (23). The nutrients involved in the growth and repair of muscle tissue will be affected by strength training programs (10) and involvement in injury-prone sports. Thermoregulatory stress is probably the most common nutrition problem in sports, and it is often exaggerated by environmental factors such as hot or cold weather, altitude, or airplane travel. Nutrition needs also will be affected by conditioning programs that result in frequent or rapid weight loss, chronic injuries, andlor overtraining responses.

Nutrient needs that have been identified using this approach should be confirmed by objective and subjective data collected in the nutrition assessment; however, this framework can be used for detecting potential problems. First, if the RDA is not being met by the athlete's current diet, corrective action should be taken to ensure the minimum nutrient requirements for good health. In addition, any special nutrient needs due to exercise-induced stress, growth spurts, illness, pregnancy, lactation, or other health risks should be addressed.

Determining Nutrition Needs During Competition

The topic of preevent nutrition has gained a great deal of attention as athletes explore ways to achieve a competitive advantage through last-minute dietary manipulations. Although there is no nutritional quick fix that will override ge- netic predispositions and the quality of physical training, a few basic nutrition practices are worth considering (16). But before making specific recommenda- tions, sports nutritionists should consider the physiological demands of the competitive event. For example, events lasting less than 60-90 minutes will not deplete carbohydrate stores; therefore carbohydrate loading is not appropriate. As Figure 1 suggests, nutrition support during competition is similar to the approach used during training-the relationship between physiological demands and nutrient needs sets the course for nutrition care. In distinguishing the nutrition support provided during training from that provided during competition, this model views the training demands as those that occur over time (i.e., reflect the athlete's daily and weekly routines). On the other hand, the competitive nutrition support focuses on preparation for, maintenance during, and recovery from a specific competitive event or set of consecutive events.

In many cases the same demands will exist during competition that are present during training, but to a greater or lesser degree because the intensity and possibly the duration of exercise during competition is different. For example, an athlete training for a marathon may not run 26 miles on a regular basis in preparation for the race, so fluid, electrolyte, and carbohydrate needs will be greater before, during, and after the race than during training. On the other hand, another athlete may run an average of 8-10 miles a day but only compete in 10-kilometer races.

The competitive schedule of an athlete will also have a significant impact on how nutrition is approached. For instance, professional baseball players might play 21 days in a row before they have a day off. While baseball does not impose many significant nutritional risks, the lifestyle of the professional player introduces certain concerns. The games are frequently held during evening hours with players reporting to the park at 1 p.m. and finishing their game at 10 or 11


p.m. Sometimes the team is required to catch a flight the same night to play an out-of-town game the next day. Frequent air travel and skipped meals could lead to dehydration, carbohydrate depletion, and other nutrient inadequacies (19).

Foster et al. (6) found that the performance of soccer players was favorably influenced by carbohydrate supplementation in the interval between matches. Possibly, other athletes who engage in all-day competition (e.g., hockey, gym- nastic, and racquetball tournaments) similarly suffer from depleted carbohydrate stores, and a proper nutrition regimen could enhance performance especially at the end of the day.

Although the most common nutrition needs during competition are fluids, electrolytes, carbohydrates, and calories, other demands specific to the competitive situation should be considered. Competition in injury-prone sports such as skiing, hockey, and football could affect an athlete's immune system and protein status if the injuries are frequent and severe in a given season. Nutrition needs before, during, and after competition will vary from sport to sport and athlete to athlete, so it is best to assess these needs individually.

Care PlanlSummary

The assessment process should reveal the discrepancies between the athlete's nutrition needs and nutrient intake, that is, identify specific problems that require intervention. A nutrition care plan will evolve from a comprehensive list of problems, which should include (a) normal nutrition needs, (b) additional nutrition needs resulting from training and competitive schedules, and (c) special nutrition needs due to an athlete's health problems or stage in the life cycle. The problems should be ranked in order of importance and discussed with the athlete. Since poor nutrition will adversely affect physical performance, a counselor should first address problems associated with normal nutrition.

In ranking the nutritional requirements associated with training and competition, typically fluids, electrolytes, carbohydrates, and calories are the most critical nutritional needs. The age of the athlete, type of sport, level of training, and special health concerns could shift the relative importance of the needs, and this will require professional judgment. For example, in working with adolescent or pregnant athletes, addressing the nutrient needs associated with growth and development is more important than focusing on competitive goals.

Involving athletes in the development of their nutrition plans will help them understand their special needs and instill a sense of ownership in the process of change. Together, an athlete and a sport nutrition counselor can identify steps that will solve each nutrition problem and develop a timeline for follow-up and reevaluation. The nutrition counseling process should embrace the psychological well-being of the athlete and result in nutritious eating habits that are suited to an active lifestyle. A follow-up system for monitoring goal achievement and key variables, such as weight and body composition, will provide the opportunity to reinforce changes and adjust the nutrition plan as needed.

References 1. American College of Sports Medicine. Position stand on weight loss in wrestlers.

Med. Sci. Sports Erer. 8(2):xi-xiii, 1976.

2. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Dis- orders (3rd ed. rev.). Washington, DC: Author, 1986.

3. Berning, J. Swimmers' nutrition knowledge and practice. Sports Nutr. News 4(6): 1- 4, 1986.

4. Brouns, F.J.P.H., W .H.M. Saris, and F.T. Hoor. Dietary problems in the case of strenuous exertion. J. Sports Med. 26:306, 1986.

5. Dwyer, J.T. Assessment of dietary intake. In Modem Nutrition in Health and Disease (7th ed.), M.E. Shils and V.R. Young (Eds.), Philadelphia: Lea & Febiger, 1988, pp. 887-905.

6. Foster, C., N.N. Thompson, J. Dean, and D.T. Kirkendall. Carbohydrate supplementation and performance in soccer players. Med. Sci. Sports Exer. 18:S12, 1986.

7. Grandjean, A.C. The vegetarian athlete. Phys. Sportsmed. 15(6): 191-194, 1987. 8. Green, D.R., C. Gibbons, M. O'Toole, and W.B.O. Hiller. An evaluation of dietary

intakes of triathletes: Are RDAs being met? J. Amer. Diet. Assoc. 89(11): 1653-1654, 1989.

9. Huber, S. Starving for competition. Sports Nutr. News 2(3): 1-4, 1983. 10. Kleiner, S.M., T.L. Bazzarre, and M.D. Litchford. Metabolic profiles, diet, and

health practices of championship male and female bodybuilders. J. Amer. Diet. Assoc. 90(7):962-967, 1990.

11. Long, P. J., and B. Shannon. Nutrition: An Inquiry Into the Issues. Englewood Cliffs, NJ: Prentice Hall, 1983.

12. Loosli, A.R., J. Benson, D.M. Gillien, and K. Bourdet. Nutrition habits and knowledge in competitive adolescent female gymnasts. Phys. Sportsmed. 14(8): 1 18-130, 1986.

13. Marcus, J.B. (Ed.) Sports Nutrition: A Guide for the ProfessioM Working With Active People. Chicago: Sports and Cardiovascular Nutrition Practice Group, the American Dietetic Association, 1986.

14. McArdle, W.D., F.I. Katch, and V.L. Katch. Exercise Physiology: Energy, Nutri- tion, and Human Pelformance (2nd ed.). Philadelphia: Lea & Febiger, 1986.

15. O'Neil, F.T., M.T. Hynak-Hankinson, and J. Gorman. Research and application of current topics in sports nutrition. J. Arner. Diet. Assoc. 86(8): 1007-1012, 1986.

16. Position of the American Dietetic Association: Nutrition for physical fitness and athletic performance for adults: Technical support paper. J. Amer. Diet. Assoc. 87(7):933-938, 1987.

17. Rosen, L.W., D.B. McKeag, D.O. Hough, and V. Curley. Pathogenic weight- control behavior in female athletes. Phys. Sportsmed. 14(1):79-86, 1986.

18. Slavin, J. Protein and amino acid needs of athletes. Nutr. Overview, 3(2): 1-5, 1988. 19. Storlie, J., and M. Mullen. Unpublished observations from work with the Chicago

White Sox. 20. Tilgner, S.A., and M.R. Schiller. Dietary intakes of female college athletes: The

need for nutrition education. J. Amer. Diet. Assoc. 89(7):967-969, 1989. 21. Tipton, C.M. Making and maintaining weight for interscholastic wrestling. Sports

Sci. Exch. 2(22), 1990. 22. Welch, P.K., K.A. Zager, J. Endres, and S. Won Poon. Nutrition education, body

composition, and dietary intake of female college athletes. Phys. Sportsmed. 15(10): 63-74, 1987.

23. Williams, M.H. Nutrition for Fitness and Sport. Dubuque, IA: Brown, 1988.

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Physical Performance Rndicators and A ModeB for lntegrati ... · PDF fileof studies that have assessed the protein requirements of athletes ... Certainly athletes can benefit from