1. Chapter 6
Protein
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2. What is protein?
Protein is a complex structure containing carbon, hydrogen, oxygen, and nitrogen, and in some cases sulfur. These elements combine to form amino acids.

3. Formation of peptides and protein

4. Amino Acids Two types: 1) Essential (9) 2) Nonessential (11)
Must be obtained from foods in the diet
2) Nonessential (11)
May be formed in the body

6. Animal vs. Plant Protein
Complete proteins
Contain adequate amounts of all 9 essential AA
Are found in animal foods
Contains a higher concentration of protein
Incomplete proteins
Limiting AA: A deficiency of one or more essential AA
Legumes (methionine) Grains (Lysine)
Plant foods are incomplete proteins
Contains a smaller concentration of protein

7. What are some common foods that are good sources of protein?
The Food Groups
High
Meat and meat substitutes (legumes)
Milk
Lower
Starch
Vegetable
Fruit
Fat

8. Figure 6.4

10. How much protein do I need?
Humans need enough protein to provide adequate amounts of nitrogen and essential amino acids
Recommended Dietary Allowance (RDA)
Based on age and body weight
Acceptable Macronutrient Distribution Range (AMDR)
Based on percentage of daily energy/calorie intake

11. Protein RDA

12. Protein RDA and AMDR Adult RDA is 0.8 g pro/kg body Wt
Protein AMDR is 10-35% of daily energy intake
Example - Female, 135 lbs (60 kg), eating 2,000 cal/d
RDA is 48 grams of protein (60 x 0.8)
AMDR of 10% provides 50 grams of protein
2,000 x 0.10 = 200 protein Calories
200/4 Calories per gram of protein = 50 grams of protein
AMDR of 35% provides 175 grams of protein

13. Summary of protein functions in the human body
Structural
Transport
Enzyme
Hormone and neurotransmitter
Immune
Acid-base balance
Fluid balance
Energy
Movement

16. Dietary protein needs: Strength-Type Athletes
Additional protein is often recommended to help support or promote increases in muscle tissue

17. Dietary protein needs: Endurance-Type Athletes
Need to recognize that carbohydrate is the main fuel for endurance-type athletes
More dietary protein is recommended to
Restore protein used for energy
Promote synthesis of oxidative enzymes and mitochondria
Help prevent sports anemia

18. 1. Obtain the RDA for protein
What are some general recommendations relative to protein intake for athletes?
1. Obtain the RDA for protein
All athletes should obtain at least their RDA for protein
About to 0.85 g/kg for young athletes
About 0.80 g/kg for adult athletes

19. Recommendations for protein intake in athletes
2. Increase the protein RDA by 50 to 100 %
Will increase an adult’s protein intake to 1.2 to 1.6 grams/kg body weight, and a young athlete to about 1.7 to 1.9 grams/kg body weight
These values are within the AMDR of 10-35% of daily energy intake

20. Recommendations for protein intake in athletes
3. Obtain about 15 percent or more of daily energy intake from protein
Some athletes may need more protein than others
Athletes in weight-control sports
Female endurance athletes with low energy intake
Protein intake is within the AMDR

21. Protein intake in a wrestler
College wrestler of 132 pounds (60 kg)
RDA is 48 grams of protein/day
Diet of 1,600 Calories to maintain body weight
A diet with 12% protein will provide the RDA
0.12 x 1,600 = 192 Calories; 192/4 = 48 g of protein
A diet with 20% protein will provide about 1.7 grams of protein/kg body weight, which is near the recommendation for strength athletes
0.20 x 1,600 = 320 Calories; 320/4 = 80 g of protein
80/48 = 1.66 grams of protein/kg

22. Recommendations for protein intake in athletes
4. Consume protein, preferably with carbohydrate, before and after workouts: The concept of Nutrient Timing.
There appears to be little difference in anabolic responses if protein is consumed either before or after exercise
The protein source should contain all essential amino acids
About 0.1 gram per kg body weight is recommended
7 grams for a 70-kg individual

23. Recommendations for protein intake in athletes
Consuming carbohydrate with the protein may also enhance the anabolic effects after exercise, possibly attributed to increase insulin secretion
Whole foods, such as a turkey breast sandwich, appear to be as effective as amino acid solutions
The carbohydrate: protein ratio should be about 3:1 or 4:1
Commercial products such as Endurox
Chocolate milk

24. Recommendations for protein intake in athletes
5. Be prudent regarding protein intake.
There is insufficient evidence that increased protein intake will enhance exercise performance
Experts contend that given sufficient energy intake, lean muscle mass may be maintained within a wide range of protein intakes
There is a metabolic rationale for increasing protein intake if muscle hypertrophy is the goal, but the intake need not be excessive and may be within the AMDR of 10-35% of daily energy intake

26. Protein: Ergogenic Aspects
Three of the top 5 most popular sport supplements
Protein
Amino acids
Creatine

27. What types of protein supplements are marketed to physically active individuals?
Variety of products, but the protein source is usually natural protein from milk, eggs, or soy
Special high protein foods or diets
Commercial liquid meals such as Nutrament
Sports drinks and shakes; sports bars
Whey and colostrum
Whey protein isolates from cheese-making process
Colostrum is first milk form cows (Theory: IGF-1)
Other protein sources
Protein/carbohydrate solutions

29. Do high-protein diets or protein supplements increase muscle mass and strength in resistance-trained individuals?
High-protein diets
Research data are equivocal, but suggest additional protein may increase lean body mass but has no effect on measures of strength
Consuming protein after strenuous resistance exercise may enhance muscle repair

30. Do high-protein diets or protein supplements increase muscle mass and strength in resistance-trained individuals?
Whey
Research findings are mixed, but in general show positive effects of whey protein supplementation, about grams per kg body weight daily, on lean body mass and muscular strength. In one study, soy protein was also effective.
Colostrum
Several studies suggest colostrum supplementation may increase lean body mass, but effects on strength are mixed
Additional research is recommended to evaluate the ergogenic potential of whey and colostrum

31. Do high-protein diets or protein supplements improve aerobic endurance performance in endurance-trained individuals?
High-protein diets or meals
The Zone Diet (40:30:30), a high-protein diet, has been advocated for endurance athletes
Studies do not support an ergogenic effect of high-protein diets on aerobic endurance
Several studies suggest that a Zone Diet eating plan over the course of a week may actually impair aerobic endurance performance, particularly if protein replaces carbohydrate in the diet

32. High-protein diets and aerobic endurance: Protein/Carbohydrate Preparations
Effects on aerobic endurance performance
Early studies have shown increased endurance with protein/carbohydrate versus carbohydrate alone; however, the protein/carbohydrate solutions contained more energy
More recent studies balanced the energy content of both solutions and report no difference between the two

33. High-protein diets and aerobic endurance: Protein/Carbohydrate Preparations
Effects on recovery from exercise
Recent studies find that when energy content is balanced, protein/carbohydrate solutions provide no advantage over carbohydrate alone on subsequent exercise performance
Some data suggest protein/carbohydrate solutions may prevent muscle soreness, while other research does not

34. Arginine, Lysine, and Ornithine
Theory
Infusion of these amino acids may increase human growth hormone (HGH); may increase IGF-1
Main research findings:
Arginine may decrease HGH response to exercise
Early, poorly controlled research found ergogenic effects
More recent well controlled studies report
No significant increases in HGH
No favorable changes in body composition
No increases in strength

35. Tryptophan Theory Main research findings:
Needed to form serotonin, a neurotransmitter in the brain, which has been theorized to decrease pain perception and delay fatigue during exercise
Main research findings:
Findings from studies are somewhat equivocal, but in general suggest that tryptophan supplementation is not an effective ergogenic aid for either strength or aerobic endurance exercise

36. Branched Chain Amino Acids (BCAA)
Leucine, isoleucine, and valine are three major amino acids in muscle tissue
Theoretical ergogenic mechanisms:
Use as a fuel during exercise and spare muscle glycogen
Decrease the rate of muscle tissue degradation
Prevent adverse changes in brain neurotransmitter function

37. BCAA and the Central Fatigue Hypothesis
Main research findings:
Some human research suggests increases in serotonin may be associated with fatigue, but other neurotransmitters, like dopamine, are also involved
BCAA supplementation may be used for energy and may help maintain serum BCAA levels

38. BCAA and the Central Fatigue Hypothesis
Main research findings:
Mental performance: Results of field studies are equivocal, but several have found enhanced mental alertness in prolonged sport events, such as tennis and soccer
Perceived exertion: Results of laboratory studies involving intense endurance exercise are equivocal.

39. BCAA and the Central Fatigue Hypothesis
Main research findings:
Physical performance with acute supplementation
Study with 193 marathon runners suggested improved performance in slower runners (3:05-3:30) but not faster runners (<3:05) when consuming 7-12 grams during running
Suggested slower runners may have depleted muscle glycogen earlier and thus benefited more from supplementation
Criticism of the study
Unorthodox statistical procedure

40. BCAA supplementation Additional research findings:
BCAA supplementation not necessary if carbohydrate is available
Carbohydrate is the best fuel for endurance athletes
Carbohydrate helps attenuate decreases in fTRP:BCAA
BCAA supplementation may be an effective protocol for athletes in weight-control sports who are on a diet
Research is needed to help clarify the role of BCAA supplements, or protein in general, on muscle tissue recovery following strenuous exercise

41. Glutamine Supplementation and Endurance Performance
Theory
May promote muscle growth
Stimulate HGH
Increase cell volume
May stimulate glycogen synthesis
Glutamine is gluconeogenic
Major fuel for key cells in the immune system
Prevent infections associated with overtraining

42. Glutamine Supplementation and Endurance Performance
Main research findings
Recent studies and reviews indicate that glutamine supplementation will increase plasma glutamine levels but will not
Increase muscle mass or strength
Provide any advantage over adequate carbohydrate on muscle glycogen levels
Prevent the effects of overtraining
Decrease the frequency of respiratory infections

43. Aspartates Theory Main research findings
Potassium and magnesium aspartates hypothesized to
Spare muscle glycogen
Reduce accumulation of ammonia
Improve psychological motivation
Main research findings
Studies are equivocal, finding
Either increased or decreased ammonia levels
Laboratory cycling tests to exhaustion
Additional research recommended: Dosage may be a factor

44. Glycine Theory Main research findings
Glycine is used in the formation of creatine
Main research findings
Contemporary research reveals no ergogenic effect of glycine supplementation
Glycine is part of a multicomponent supplement containing arginine and alpha-ketoisocaproic acid that has been found to enhance sprint power in one study. Additional research is needed for confirmation.

45. Glucosamine and Chondroitin
Dietary supplements
Glucosamine derived from shellfish; chondroitin from cattle cartilage
Theory
Glucosamine helps form the structural basis of cartilage (proteoglycans), and chondroitin helps provide resiliency
May help prevent joint pain associated with exercise training

46. Glucosamine and Chondroitin
Research findings
Limited research with highly trained individuals; most are with older, arthritic individuals
A substantial number of studies and reviews indicate supplementation reduced joint pain and improved mobility
Large NIH study (GAIT) found no overall reduction in knee pain in osteoarthritic individuals, but the supplement did provide relief to a subset of individuals with moderate to severe knee pain

47. Glucosamine and Chondroitin
Research findings
Beneficial effects were minimal in two studies with younger, physically active males
Glucosamine sulfate appears to be the most effective form; chondroitin is not effective

48. Glucosamine and Chondroitin
Precautions and recommendations for use
Considered safe, but may cause bloating and diarrhea
Consult with your physician as there may be complications, such as with blood glucose control in diabetics
Reasonable dose would be 1,500 mg of glucosamine and 1,200 mg of chondroitin for 2-4 months. If pain symptoms have not improved, they probably are not going to.

49. Creatine Creatine is found naturally in animal foods, especially meat
Creatine may also be synthesized by the liver and kidney
Food g/Kg
Milk 0.1
Tuna 4.0
Salmon 4.5
Beef 4.5
Pork 5.0

50. Creatine Discovered 1927 Synthesized in 1990s as a dietary supplement
Research as an ergogenic aid progressed rapidly

51. Creatine Supplementation
Theory
May increase muscle levels of PCr
May increase performance in very high intensity exercise
May enhance performance in prolonged endurance events which incorporate short sprints
May enhance interval training

52. Recommended Protocol Loading phase
Fast protocol: grams/day for 5-7 days
Slow protocol: 3 grams/day for 30 days
Maintenance phase
2-5 grams/day
Creatine Supplementation (20g/day for 5 days) with and without Carbohydrate (360g)
Adapted from Green, A., et al. ACTA Physiol Scand, 1996.

53. Creatine Supplementation
In general, research findings also indicate that creatine supplementation may enhance performance in very high-intensity exercise tasks, such as the 100-meter sprint in track and sprint cycling

54. Creatine Supplementation
Of seven recent well-controlled studies using a standard creatine-loading protocol and evaluating the effect on single or repetitive sprint-run or sprint-cycle performance ranging from 5 to 100 meters, creatine supplementation improved performance in five of the trials, but had no effect in the other two.
For example, one study reported significant improvements in male sprinters in 100-meter sprint velocity and time to complete six intermittent 60-meter sprints.
A meta-analysis of 57 studies revealed an effect size of 0.24 favoring creatine over the placebo treatment

55. Creatine Supplementation: Effect on body mass
In general, research indicates increases in body mass, mainly as muscle tissue, in both males and females, including both trained and untrained
Studies report increases in myosin and myonuclei concentration

56. Creatine supplementation: Safety
Kidney and liver function
Consuming recommended dose does not appear to increase health risks
Those with liver or kidney disease may be at risk
Gastrointestinal distress
Large doses may cause nausea, vomiting and diarrhea
Dehydration, muscle cramps and tears
Appears to cause few problems with exercise in the heat
Possibility of anterior compartment syndrome
Overdoses and contaminants
Creatine appears to be safe at 5 grams per day
Some products may contain contaminants, like ephedrine

57. Creatine supplementation: Medical applications
Increased strength in some conditions
Muscular dystrophy
Patients with heart disease
Injury to the spinal cord
Facilitate rehabilitation from musculoskeletal injury
Reduce the loss of muscle mass (sarcopenia) with aging

58. Beta-Hydroxy-Beta-Methylbutyrate (HMB)
Theory
Beta-hydroxy-beta-methylbutyrate (HMB), a by-product of leucine metabolism, is theorized to inhibit the breakdown of muscle tissue during strenuous exercise

59. Beta-Hydroxy-Beta-Methylbutyrate (HMB)
Main research findings with strength-trained athletes
Overall, research findings are equivocal regarding the ergogenic effect of HMB supplementation on muscle mass and strength in untrained individual
The available data indicate that HMB supplementation does not appear to affect muscle strength, body composition, or anaerobic exercise performance in resistance-trained individuals
Research does not support any protective effects against muscle tissue damage during resistance training

60. Beta-Hydroxy-Beta-Methylbutyrate (HMB)
Main research findings with endurance athletes
One study with distance runners reported HMB supplementation (3 g/day for 6 months) decreased markers of muscle damage following a 20K run
One recent study found HMB could increase VO2max during 5 weeks of interval training in active college students
No studies have shown improvement in endurance exercise performance following HMB supplementation

61. Beta-alanine and Carnosine
Theory
Beta-alanine may increase intramuscular stores of carnosine, which can serve as an antioxidant or as a buffer of hydrogen ions, reducing acidity, and increasing the lactate threshold
Beta-alanine may also form another peptide, anserine, which may function as an antioxidant in muscles

62. Beta-alanine and Carnosine
Main research findings
Anserine supplementation increases muscle carnosine
Research findings are equivocal relative to ergogenic effects on anaerobic-type exercise performance
Improved performance 110% VO2max
No effect on 400-meter run time
No ergogenic effect on aerobic-endurance
No effect on maximal aerobic power

63. Tyrosine Theory Main research findings
Tyrosine is a precursor for the catecholamine hormones and neurotransmitters epinephrine, norepinephrine, and dopamine; augmentation may have an ergogenic effect
Main research findings
Research is very limited
No effect on aerobic endurance, anaerobic power, or muscular strength

64. Taurine Theory Main research findings
Taurine is synthesized from amino acids, but is not classified as an amino acid
Theorized to help prevent muscle tissue damage during exercise; may function as an antioxidant
Main research findings
One study has shown ↑ stroke volume during exercise
One study reported ↑ VO2max and exercise time to exhaustion associated with antioxidant effects
These preliminary findings need further research

65. Inosine Theory Main research findings
Inosine is a nucleoside, not an amino acid
Theorized to improve ATP production and also to improve oxygen delivery to muscles during exercise
Main research findings
Well-controlled studies indicate inosine supplementation
Does not increase VO2max or related physiological variables
Does not improve 3-mile treadmill run time
Has no effect on cycling tests of the three energy systems
May impair anaerobic energy production

66. Does a deficiency of dietary protein pose any health risks?
Protein-Calorie malnutrition is a worldwide problem
Political and economic problems
Impaired immune functions
The elderly may be prone to protein undernutrition
May impair immune functions; increase infections
May hamper optimal bone development
Young athletes in weight-control sports
Loss of muscle mass and hemoglobin

67. Does excessive protein intake pose any health risks?
Excess amounts of specific proteins may cause allergic reactions in some individuals
AMDR range is 10-35% of energy intake
No UL has been established for protein intake
High protein intake poses no health risks to most persons
NAS indicates the source of protein may be related to various health risks

68. Excessive protein intake and health risks
Cardiovascular disease and cancer
Dietary protein itself does not appear to cause CHD or cancer
High meat diets may be rich in saturated fats
AICR indicates there is convincing evidence that red and processed meats contribute to colorectal cancer
High protein diets may actually help promote weight loss, a preventive measure against CHD
Soy protein in natural, whole foods may have beneficial health effects

69. Excessive protein and health risks
Liver and kidney function
The liver processes ammonia and the kidneys excrete urea and ketones, which are formed on high protein diets
In general, high-protein diets do not have adverse effects on individuals with normal liver and kidney functions
Individuals prone to liver or kidney disease should use caution with protein intake
Chronic kidney or liver disease
Diabetics
Individuals prone to kidney stones

70. Excessive protein and health risks
Bone and joint health
Excessive protein intake may increase urine acidity, which may increase calcium excretion
Calcium loss is predicted to be 1 mg of calcium for an average increase of 1 gram of dietary protein
A diet low in calcium and high in protein may promote bone loss
The key is to obtain adequate calcium and protein because both are needed in adequate amounts for bone formation

71. Excessive protein and health risks
Heat illnesses
The excretion of urea and ketone bodies in urine could lead to excessive fluid losses and dehydration
A high-protein diet could increase resting energy expenditure
Both of these effects could compromise temperature regulation during exercise in the heat, which will be discussed in chapter 9

72. Does the consumption of individual amino acids pose any health risks?
No UL has been established for specific AA, but the NAS notes caution is warranted in using any single AA in amounts greater than normally found in food
Free AA are manufactured to serve as drugs or dietary supplements
Excessive amounts may cause health problems
Interfere with absorption of other AA
Cause gastrointestinal distress
Sound advice is to obtain your AA through foods