Chapter 6 Lecture Slides

Transcription

1 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 6 Lecture Slides Dietary Protein Protein is one of our most important essential nutrients Structure of body tissues Formation of enzymes May provide energy Implications for sports Protein needs of strength and endurance athletes Implications for health The good proteins in the OmniHeart diet 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.

2 Formation of peptides and protein Is there a difference between animal and plant protein? First, let us consider the two main classes of amino acids Indispensable (essential) amino acids Must be obtained from foods in the diet Dispensable (nonessential) amino acids May be formed in the body

3 Dietary Protein Dietary protein Animal protein Complete protein Contains proper blend of all essential amino acids Contains higher concentration of protein Higher quality protein Plant protein Incomplete protein May be low in one or more essential amino acids Contains lower concentration of protein Essential amino acids Histidine Isoleucine* Leucine* Lysine* Methionine plus cysteine Phenylalanine plus tyrosine Threonine Tryptophan Valine *BCAA Animal and plant protein In natural, unprocessed foods, both animal and plant protein have all 20 amino acids The quality of a protein source is in its ability to provide nitrogen and amino acid requirements for growth, maintenance and repair of tissues Various analytical techniques are used, most focus on the concept of nitrogen balance Protein Digestibility-Corrected Amino Acid Score (PDCAAS) PDCAAS scores range from 1.0 to 0.0 Animal and plant protein Complete proteins Contain adequate amounts of all 9 essential AA Animal foods are complete proteins PDCAAS for egg white is 1.0 PDCAAS for meat is 0.92 Incomplete proteins Limiting AA: A deficiency of one or more essential AA Legumes (methionine) Grains (Lysine) Plant foods are incomplete proteins PDCAAS for legumes is 0.68 PDCAAS for wheat bread is 0.40

4 Animal and plant protein Two ounces of fish 14 grams of protein Two ounces of beans 5 grams of protein Two ounces of cooked macaroni 2 grams of protein Protein complementation Grains and legumes What are some common foods that are good sources of protein? The Food Exchange System High Meat and meat substitutes (legumes) Milk Lower Starch Vegetable Fruit Fat Food Exchange Groups Food Exchange Milk (1 cup) Carbohydrate Fat Protein Calories Skim/very low fat Low fat Whole Meat/substitutes (1 oz) Very lean Lean Medium fat High fat Starch (1 oz; ½ cup) Fruit (1 medium; ½ cup) Vegetable (1/2 cup) Fat (1 teaspoon) Carbohydrate, fat and protein in grams per serving 1 g carbohydrate = 4 Calories; 1 gram fat = 9 Calories; 1 gram protein = 4 Calories

5 Figure 6.4 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 intake

6 Protein RDA Protein AMDR Protein AMDR is 10-35% of daily energy intake Adult Female 132 lbs (60 kg) 2,000 Calorie diet 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 How much of the essential amino acids do I need? RDA have been established for the 9 essential AA

7 What are some dietary guidelines to ensure adequate protein intake? For omnivorous individuals Eat a wide variety of animal and plant foods Select animal foods low in fat Eat animal foods with plant foods 70% from plant foods; 30% from animal foods For vegans Need to ensure consumption of adequate amounts of complementary protein foods Metabolism and Function What happens to protein in the human body? Digestion into specific amino acids Metabolic fate of amino acids Role of the liver Protein synthesis in body cells Protein catabolism Nitrogen: excreted as urea Alpha-ketoacid: Used as energy Converted to carbohydrate or fat

8 Figure 6.5 Formation of carbohydrate and fat from excess protein Glucogenic amino acids Form pyruvate Gluconeogenesis Ketogenic amino acids Form acetyl CoA

9 Formation of carbohydrate and fat from excess protein Glucogenic amino acids 14 glucogenic amino acids Ketogenic amino acids Only leucine and lysine Glucogenic and ketogenic amino acids 5 amino acids can be both glucogenic and ketogenic Isoleucine, phenylalanine Can protein be formed from carbohydrates and fats? Nitrogen from excess amino acids can combine with an alpha-ketoacid to form some non-essential amino acids in the liver. The ketoacids are derived from carbohydrate or fat metabolites or intermediates in the Krebs cycle What are the major functions of protein in human nutrition? Dietary protein serves all three major functions of nutrients Forms the structural basis for the vast majority of body tissues Forms numerous enzymes and hormones to help regulate body metabolism Used as an energy source if needed Importance of carbohydrate for protein-sparing effect

10 Summary of protein functions in the human body Structural Transport Enzyme Hormone and neurotransmitter Immune Acid-base balance Fluid balance Energy Movement Proteins and Endurance Performance Protein Use as Energy Source During rest <5% of total daily expenditure Endurance training may reduce protein oxidation at rest, increasing the amount of energy derived from fat

11 Proteins and Exercise Protein use for energy during exercise Exercise and protein losses Protein metabolism during recovery from exercise Effect of training on protein metabolism Protein needs of athletes Prudent protein recommendations for athletes Are proteins used for energy during exercise? Measures of protein use during exercise Urea concentration Measures of 3-methylhistidine in urine Nitrogen balance Labeled isotopes Protein use during exercise Resistance exercise training Does not appear to increase protein oxidation May provoke muscle tissue catabolism Both catabolism and anabolism may occur during recovery, with anabolism prevailing over time

12 Protein use during exercise Aerobic endurance exercise training Protein use is minimal compared to carbohydrate and fat Dynamic exercise activates BCAA dehydrogenase, an enzyme that oxidizes BCAA Some amino acids are used to promote gluconeogenesis Protein use may increase when body carbohydrates stores decrease Protein use during exercise Aerobic endurance exercise training Exact mechanism not determined, but proposed mechanisms include activation of proteolytic enzymes that degrade myofibrillar protein Six amino acids may be metabolized in the muscle, including the three BCAA Exercise by-products include ammonia, alanine, and glutamine which can transport nitrogen and ketoacids to the liver Glutamine is an important fuel for the immune system Protein use during exercise Leucine and the Glucose-Alanine Cycle Leucine is the major BCAA to be oxidized during exercise The alpha-ketoacid may enter the Krebs cycle The amino group combines with pyruvate to form alanine, which may be transported to the liver to form glucose Estimated glucose generation from alanine is very limited

13 Figure 6.6 Protein use and importance of carbohydrate An important factor affecting the use of protein as an energy source during aerobic endurance exercise is carbohydrate availability Research indicates that elevate endogenous stores of carbohydrate or provision or exogenous carbohydrate during exercise may exert a proteinsparing effect Does exercise increase protein losses in other ways? Urinary losses Proteinuria Greater losses following intense or prolonged exercise Losses are small, about 3 grams per day Sweat losses Losses are minor, about 1 gram of AA/liter of sweat Gastrointestinal losses Minor losses

14 What effect does exercise training have upon protein metabolism? Training induces specific adaptations in body cells depending on the type of training Resistance or strength training Aerobic endurance training In general, exercise training produces a positive protein balance that may contribute to performance enhancement

15 What effect does exercise training have upon protein metabolism? Chronic exercise training appears to decrease protein catabolism during standardized exercise tasks Aerobic endurance training appears to increase the ability of the muscle to use protein as an energy source, if needed. May help preserve glucose for the brain when carbohydrate levels are low Exercise training and protein Training may decrease the formation of ammonia during standardized exercise Ammonia is thought to contribute to fatigue, possibly by impairing muscle cell metabolism Eccentric muscle training may help prevent muscle protein damage and delayed onset of muscle soreness (DOMS) Do individuals in strenuous physical training, including the developing adolescent athletes, need more protein in the diet? Varying viewpoints Need more protein ACSM, ADA, DC Position Statement on Nutrition for the athlete Do not need more protein National Academy of Sciences in DRI report May need less protein Opinion of a protein/exercise scientist

16 Dietary protein needs: Strength-type activities Additional protein is often recommended to help support or promote increases in muscle tissue Photo of body builder Dietary protein needs: Strength-type activities Some exercise scientists recommend an optimal intake of about 1.5 to 1.8 grams/kg body weight The NAS indicates that the RDA is sufficient Michael Rennie suggests training makes athletes more efficient protein users so they may actually need less dietary protein

17 Dietary protein needs: Endurance-type activities 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 Dietary protein needs: Endurance-type activities Some exercise scientists recommend an optimal intake of about 1.1 to 1.4 grams/kg body weight for aerobic endurance athletes, and 1.4 to 1.7 grams/kg body weight for intermittent high-intensity sports The NAS indicates that the RDA is sufficient 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 0.95 to 0.85 g/kg for young athletes About 0.80 g/kg for adult athletes

18 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 One pound of muscle mass Goal: To gain one pound of muscle mass per week in a young teenage athlete (70 kg) whose protein RDA is about 60 g/day 1 pound of muscle = 454 grams Muscle is 22% protein 454 x 0.22 = 100 grams of protein in 1 pound 100 grams/7 days = about 14 grams of protein/day May use 20 grams of protein during exercise Protein needs = 94 grams of protein/day 94 g/70 kg = 1.34 grams of protein/day 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

19 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 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 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

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

21 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 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

22 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 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 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

23 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 High-protein diets and aerobic endurance: Colostrum Preliminary research suggests that colostrum supplementation during training (10-20 grams of colostrum daily for 9-10 weeks) could improve performance in some tasks Cycle time trial after 2-hours of cycling Performance in a 40-kilometer time trial However, the data should be considered preliminary and additional research is recommended Are amino acid, amine, and related nitrogencontaining supplements effective ergogenic aids? Arginine and Citrulline Arginine, Lysine, and Ornithine Tryptophan BCAA Glutamine Aspartates Glycine Glucosamine and Chondroitin Creatine HMB Beta-alanine and Carnosine Tyrosine Inosine

24 Arginine and Citrulline Theory Arginine A precursor for nitric oxide (NO), a vasodilator Theory: Enhanced blood flow and oxygen to muscles Citrulline Metabolism increases blood levels of arginine Main research findings: May improve exercise ability in cardiac patients Research does not support an ergogenic effect with healthy individuals, and arginine may be ergolytic Increased RPE values Decreased time to exhaustion 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 Tryptophan Theory 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

25 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 BCAA supplementation and the Central Fatigue Hypothesis 1. Prolonged aerobic endurance exercise decreases muscle glycogen and increase serum FFA 2. BCAA uptake by exercising muscles is enhanced in prolonged exercise 3. Serum free tryptophan:bcaa ratio (ftrp:bcaa) increases 4. High levels of serum free tryptophan may induce formation of serotonin 5. Elevated brain serotonin may induce fatigue through depressant activity 6. High levels of BCAA compete with free tryptophan for entry into brain cells, thereby decreasing serotonin formation and preventing fatigue 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

26 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. 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 BCAA and the Central Fatigue Hypothesis Main research findings: Physical performance with acute supplementation: Most well-controlled laboratory and field studies have reported no significant effects on exercise performance. Studies usually involved 3 separate treatments: Carbohydrate alone BCAA alone Carbohydrate with BCAA

27 BCAA supplementation Additional research findings: Acute B CAA supplementation does not enhance exercise performance in the heat Results of chronic BCAA supplementation (2 weeks) are equivocal, but generally indicate no ergogenic effect A recent study with leucine (45 g/kg for 6 weeks) found improved endurance in a rowing test 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 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

28 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 Aspartates Theory 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 Glycine Theory 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.

29 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 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 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

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

31 Creatine Supplements: Forms Powder Pills Candy Chews Gels Serum Micronized Runners Advantage TM Male Runners Advantage TM Female Teen Advantage Serum Creatine

32 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 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, Creatine supplementation: Effect on the ATP-PCr energy system An ergogenic effect has been reported for numerous exercise tasks dependent on PCr Maximal force in isometric contraction Strength and endurance in isotonic tests Muscular force and endurance in isokinetic tests Maximal cycle ergometer performance from 6-30 seconds Sprint run, swim, and cycle performance from meters or up to 30 seconds duration These findings may be applicable to sports such as weightlifting, cycle, swim and run sprints, and soccer

33 Creatine Supplementation In general, research findings also indicate that creatine supplementation may enhance performance in very highintensity exercise tasks, such as the 100-meter sprint in track and sprint cycling 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 Creatine supplementation: Effect on the Lactic Acid energy system Fewer studies are available, but research findings suggest an enhancement effect in some events where athletes maximize power output from 30 to 150 seconds Some beneficial effects noted in a 300-meter run No beneficial effects in 100-meter swimming Additional research is merited

34 Creatine supplementation: Effect on the Oxygen energy system There is very little theoretical support Possible adverse effects Weight gain Some theories include: Enhanced performance in events with short sprints Enhanced interval training Creatine Supplementation: Effect on 6-kilometer cross-country run In a well designed Swedish study, 18 habitually active males consumed either a placebo or creatine (20 g/day for 6 days). They ran a 6K terrain run on a forest trail before and after supplementation Major findings: Creatine supplementation significantly Increased body mass 0.9 kg Impaired run performance (pre = 23.36; post = 23.79) Creatine Supplementation: Increase in body water weight

35 Creatine Supplementation Effect On Training For Aerobic Endurance Creatine supplementation has been shown to improve performance in interval run repeats of 300 and 1000 meters. Theoretically, if creatine supplementation could help an athlete train more effectively at shorter distances, conceivably performance in longer distances might eventually be improved. Creatine Supplementation: Effects on Training for Aerobic Endurance Trained competitive rowers undertook standard creatine loading for 5 days with a maintenance dose for 5 weeks, coupled with rowing and resistance training for 6 weeks. Although the training significantly improved body composition, VO 2 max, repeated power interval performance, and 2000-meter rowing times in both groups, creatine provided no additional advantage. 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

36 Creatine supplementation: Other points of consideration Caffeine and creatine Some research suggest caffeine may counteract the effect of creatine in high-power events as the caffeine may prolong muscle relaxation time Formulation Creatine powder has been used in most studies. Serum creatine may not contain significant amounts of creatine 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 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

37 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 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 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

38 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 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 Tyrosine Theory 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

39 Taurine Theory 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 Inosine Theory 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 Dietary Protein: Health Implications Acceptable Macronutrient Distribution Range (AMDR) 10-35% of daily energy intake for adults 10-30% of daily energy intake for older children 5-20% of daily energy intake for younger children

40 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 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 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 The OmniHeart diet plan focuses on good proteins, such as from plants and very lean meat, fish and poultry Soy protein in natural, whole foods may have beneficial health effects

41 Soy protein Cardiovascular disease and cancer Soy products include tofu, tempeh, soy nuts, soy milk and others; Soy products meeting recommendations may carry a health claim Soy protein and intact phytochemicals (isoflavones; omega- 3 fatty acids) may elicit a favorable serum lipid profile; however, the effect is small compared to other strategies Isoflavones may function as phytoestrogens and block effects of natural estrogen, possibly preventing breast cancer before menopause Some scientists think excess isoflavones may function as estrogens and promote cancer after menopause 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 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

42 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 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

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