Protein and Sports

Dietary Protein

• Complex chemical structure containing carbon, hydrogen, oxygen, and nitrogen

• Made up of a combination of 20 different amino acids

– 9 essential a.a. (can’t be made by body)

– 11 non-essential a.a.

• Proteins are made when 2 or more a.a. are held together by peptide bond

– 2 a.a. denote a dipeptide

– More than 2 a.a. denote a polypeptide

Is there a difference between animal and plant protein?

• Animal protein is regarded to be of higher quality than protein found in plants

– This is because animal protein contains each essential a.a. in proper proportion to human needs, whereas plants usually don’t

• Foods containing all essential a.a. are known as complete protein foods (usually in animal protein)

• Foods lacking one or more essential a.a. are known as incomplete protein foods (usually in plant protein)

• Foods having essential a.a but in smaller amounts are known as limited protein foods (usually in plant protein)

Common Foods of Good Protein Sources

• Milk and meat groups

• Legumes (classified within milk & meat group)

– Examples: dry beans (garbanzo, kidney, lima, lentils, peas, etc.)

How much dietary protein is needed for average individual?

• 12-15% of daily caloric intake

• Grams of protein needed per kilogram of body weight vary during lifespan

Dietary Guidelines for Adequate Protein Intake

• Eat a wide variety of animal and plant foods

• If eating primarily plant sources, then will most likely need more to satisfy protein needs (i.e. instead of 56 g of protein from animal sources, will likely need 65 g of protein from plant sources)

– A 30% animal protein source + 70% protein source = 100% animal protein source

Protein Metabolism

• Digestion of protein takes several hours

– However, once a.a. enter bloodstream, they are taken up in 5-10 min

• Most important metabolic fate is formation of proteins necessary for structure

• Excess a.a. will be processed in liver to become sources of CHO and fat

Can protein be formed from CHO and Fats?

• Yes, but with some limitations

– If nitrogen is present, by-products of CHO breakdown (pyruvic acid) and Fat breakdown (acetoacetic acid) can form non-essential a.a.

Major Functions of Protein

• Formation of tissue structure, e.g. contractile muscle protein

• Transport of substances in the blood, e.g. lipoproteins

• Formation of enzymes

• Formation of hormones

• Formation of immune components, e.g. antibodies

Major Functions of Protein

• Buffering of acids and bases in blood to maintain optimal pH

• Exert osmotic pressure to maintain appropriate fluid balance in body tissues, particularly the blood

• Provide a source of energy

• Provide movement of muscle fibers during contraction

How much protein is used for energy during sport activity?

• Less than 5% of the total energy cost

• In latter stages of a prolonged exercise, it could contribute up to 15% of total energy cost; mimicking a state of starvation

What happens to muscle protein during exercise?

• The rate of protein synthesis slows down and the rate of protein breakdown speeds up

– It appears that exercise activates certain proteolytic enzymes that degrade muscle fiber structure

• This occurrence appears to be related to fatigue

– It appears that 6 different a.a. are broken down in the muscle and form ammonia, glutamine, and alanine

Outcomes of muscle protein breakdown

• Ammonia may contribute to fatigue

– Impairs oxidative processes which decrease energy production in the muscle

– When it gets into the blood, it will go to liver for processing and also will go to brain

• It may impair brain function resulting in “central” fatigue

• Glutamine

– Important fuel source for immune function

Outcomes of muscle protein breakdown

• Leucine (a branched-chain a.a. – BCAA)

– Can be converted to pyruvate and then oxidized for energy in muscle

• Note: BCAA’s (leucine, isoleucine, valine – constitute a significant amount of muscle tissue) can also be made in liver and supplied to muscle for energy during endurance activity

– Can be converted to Alanine

• Can be converted to glucose in liver and used as energy by central nervous system or muscles

Outcomes of muscle protein breakdown

• Magnitude of muscle protein breakdown during exercise will be dependent upon:

– Intensity and duration of exercise

– Availability of other fuels (i.e. glycogen) in the muscle

Does exercise increase protein losses in other ways

• It causes elevated level of protein in the urine (proteinuria)

– A greater amount occurs from a higher intensity of exercise; also a very prolonged endurance activity

• Appears to be due to a decreased reabsorption by the kidneys during exercise

• Protein is lost in the sweat

– The greater the intensity, the greater the loss

What happens to protein metabolism during recovery?

• Protein breakdown is reduced

• Protein synthesis is either increased or unchanged; particularly in the exercised muscle groups

– Leucine balance has been shown to return to normal in 24 hours

– With weight training exercise, protein anabolism is generally high 24-48 hours post-lifting; may be slight protein breakdown immediately after exercise

– Eccentric exercise tends to cause more protein breakdown; hence a longer protein balance recovery

How does exercise training affect protein metabolism?

• Trained individuals, at rest, tend to spare more protein as fat is more readily used as an energy source

• Aerobic exercise training tends to increase the formation of more mitochondria and oxidative enzymes; this increases potential for muscle to use BCAA’s for energy

• Resistance training promotes more synthesis of contractile proteins

How does exercise training affect protein metabolism?

• Decreases production and accumulation of ammonia

– Appears to be incorporated into other a.a.’s

– May help reduce potential fatigue

• Reduces potential muscle damage which might normally occur with eccentric exercise

– However, overtraining seems to be associated with decreased glutamine

Do weight training athletes need more protein in the diet?

• Varying opinions exist

– National Research Council suggests that no increment is needed provided enough Calories are ingested in diet

– Many investigators believe that a range of 1.1-1.8 grams/kg of body weight is appropriate, depending upon the type of sport activity

Specific sport needs of protein

• Strength-type activities

– Optimal intake recommendations range from 1.5 to 1.8 g/kg body wt per day

• Some research suggest higher intakes

• 0.8 g/kg/day may actually limit growth in strength-training individuals

– An additional 200 Calories per day are also recommended; intake should include CHO also

Specific sport needs of protein

• Endurance-type activities

– Optimal intake recommendations range from 1.1 to 1.4 g/kg body wt per day

– Intensive endurance athletes should consider 1.8 to 2.0 g/kg body wt per day

– Female athletes may need more dietary protein than “recommendations” since energy intakes are usually lower than males

– Athletes attempting to lose wt for competition will likely need a greater protein intake

Specific sport needs of protein

• Intermittent high intensity-type activities

– Optimal intake recommendations range from 1.4 to 1.7 g/kg body wt per day

– Much more research needs to be done in this area

Specific sport needs of protein

• Sports Anemia

– A lack of hemoglobin; reduced O₂-carrying capacity

– Believed to occur in early stages of endurance training due to increase in protein synthesis for myoglobin, mitochondria, and other muscle proteins (at the expense of taking the protein from hemoglobin)

– Cause could also be due to expansion of water volume in the blood

– 1.25 to 2.0 g/kg body wt is suggested within 1^st month of training to prevent anemia

Protein Need Based Upon Weight Gain Goal

• Based upon a 70 kg individual who lifts weights

– Background

• 1 pound of muscle = 454 grams

• 70% of muscle is water

• 7% of muscle is lipid (fat)

• 22% of muscle is protein

– Gaining 1 pound of muscle/week (since 454 x .22 = 100; then 100 ÷ 7 days = ~14 grams per day)

• 14 grams of additional protein/day

• Double this amount to gain 2 lbs/week

Are there certain sports that may need extra protein in diets?

• Wrestlers and Gymnasts may need extra protein due to low Calorie intakes

• Young athletes may need extra protein due to growth and development

• Ultra endurance athletes may require more protein due to greater potential muscle damage

Is Timing of Protein Intake Important for Athletes?

• Protein intake within 1-3 hours following exercise may stimulate protein synthesis

• Small, multiple meals throughout day, with adequate protein, may stimulate protein synthesis

• Other considerations in meals

– Adequate CHO helps spare protein

– Adding protein to CHO supplement during recovery increases glycogen resynthesis

• Protein/CHO supplements shown to elicit hormone responses favorable to muscle growth

Protein: Ergogenic Effects

• Are high protein diets or supplements really necessary?

– Athletes involved in strenuous, resistance exercise generally require more protein than the suggested RDA for the average individual

– Protein supplements of natural sources don’t offer any more benefits than those from food sources

• May attain protein requirements from high-protein foods such as powdered milk, skim milk, eggs, and chicken

Protein: Ergogenic Effects

• Are high protein diets or supplements really necessary?

– For athletes “on the go” commercial supplements may be important to get necessary protein

• Examples

– Nutrament, Nitrofuel, GatorPro (supplement to balanced diets)

– Spirulina (algae), brewer’s yeast (protein with vitamins and minerals; not ergogenic)

– Enzymes and DNA (degraded in digestive tract)

Protein: Ergogenic Effects for Strength-Type Activities?

• Earlier, less controlled studies suggested body weight gains from extra protein

• Recent, well-designed studies do not show any additional gain in muscle mass or strength when comparing 2.6 g/kg to 1.35 g/kg of protein intake

• Recommendation: Do not take in more than 2 g/kg since there is no additional benefit to body composition or performance

Protein: Ergogenic Effects for Endurance -Type Activities?

• No studies have shown that endurance athletes can gain any benefit from additional protein intake above the RDA of 0.8 grams/kg of body wt.; however, it does appear to be safe to consume 1.1 to 1.4 grams/kg of protein, just in case

• More studies are necessary

Protein: Ergogenic Effects

• What about a.a. supplements?

– Arginine, lysine, & ornithine

• Arginine, lysine, & ornithine can stimulate release of human growth hormone (HGH) and insulin; 2 anabolic hormones

• Arginine can cause dilation of blood vessels and stimulate epinephrine release

– No sound evidence to suggest that supplementation with arginine, lysine, or ornithine enhance muscle development or increase endurance

Protein: Ergogenic Effects

• What about a.a. supplements?

– Tryptophan

• Tryptophan may stimulate release of HGH but also may form 2 neurotransmitters in brain (serotonin & 5-hydroxytrptamine) that may decrease perception of pain; suggest greater pain tolerance and resistance to fatigue

– Tryptophan does not appear to be effective in enhancing performance for either short- or long-term exercise tasks

Protein: Ergogenic Effects

• What about a.a. supplements?

– Branched-Chain Amino Acids (BCAA)

• Thought to enhance performance by:

– Fuel for exercise to prevent adverse changes in neuromuscular function

– Spare use of muscle glycogen

– Prevent or decrease rate of protein degradation

• Potential effectiveness resides with Central Fatigue Hypothesis

– High levels of serum free-tryptophan in conjunction with low BCAA may result in significant serotonin production; serotonin depresses brain function

Protein: Ergogenic Effects

• BCAA supplementation

– If BCAA’s decrease with prolonged exercise, then this might be a good reason to take supplements

• Muscle can use BCAA’s for energy

– BCAA supplementation and mental performance

• Some studies have shown more alertness in games or lessened perception of fatigue in moderate to intense endurance events

• Overall, no significant benefits proven

Protein: Ergogenic Effects

– BCAA supplementation and physical performance

• Taking dosages ranging from 5-20 grams/day on an acute or chronic basis (several weeks)

– No significant benefit to trained endurance athletes

– May be effective with less trained individuals in endurance events

– Overall, BCAA supplementation has not been proven to be effective in improving performance of endurance athletes

Protein: Ergogenic Effects

• BCAA supplementation and body composition

– May slow muscle protein breakdown during exercise while body breaks down fat as an energy source

• This could result in maintenance of muscle and loss of body fat

• More studies need to be done in this area

Protein: Ergogenic Effects

• What about a.a. supplements?

– Glutamine

• Made in muscle

• Functions

– Removal of excess amino groups from the muscle

– Stimulate protein synthesis through increasing HGH levels

– Helps rebuild glucose and glycogen

• Important for rebuilding CHO in recovery from exercise

– Fuel for lymphocytes and macrophages (immune cells)

• May help in preventing “overtraining”

• May help in treatment of burn patients

Protein: Ergogenic Effects

• Glutamine supplementation

– Not been proven to lessen overtraining symptoms

– Not conclusive in reducing incidence of infection

Protein: Ergogenic Effects

• What about a.a. supplements?

– Aspartates (non-essential)

• May enhance fat metabolism and spare glycogen

• May reduce accumulation of ammonia in muscle

• May improve psychological motivation

– Aspartate supplements (10 grams doses)

• No significant benefits to anaerobic performance

• May have beneficial effect on endurance performance; more studies necessary

Protein: Ergogenic Effects

• What about a.a. supplements?

– Glycine (non-essential)

• Involved in formation of creatine, hence PCr

• Gelatin contains ~ 25% glycine

– Glycine supplementation

• Not been shown to be any benefit to performance

Protein: Ergogenic Effects

• What about other protein supplements?

– Chondroitin and Glucosamine

• Protein derived from connective tissue for use in promoting healthy joints

• Both may be synthesized from a.a. and are found in human cartilage

– Chondroitin gives cartilage its resiliency

– Glucosamine helps for cartilage structure

• These supplements have been shown to prevent osteoarthritis from getting worse, particularly in older athletes

• No data yet to suggest that it prevents development of joint pain in young, healthy athletes

• Reasonable intake: 1,200 mg chondroitin and 1,500 mg glucosamine for 2-4 months; check for pain symptoms

– Safety issues

• May cause bloating or diarrhea

• May cause insulin resistance in diabetics

Protein: Ergogenic Effects

• What about other protein supplements?

– Creatine

• Found primarily in meat products, but can be made in kidney and liver from certain a.a.’s and delivered to muscle

• Theory is that extra creatine would bolster PCr, so that a drop in power output during high intensity effort would not occur.

• Supplementation has shown increase in muscle content

Protein: Ergogenic Effects

• What about other protein supplements?

– Creatine Supplementation protocol

– Average individual needs to replace ~ 2 grams of creatine per day; 1 gram of which can be obtained from red meat

– One supplementation strategy

• Total of 20-30 grams of creatine (pure creatine monohydrate)

• Taken in 4 equal doses (5-7 grams per dose) over the course of day

• Combining creatine with simple CHO will help in transport into muscle; e.g. 5 grams of creatine with 90 grams CHO (per dose)

Protein: Ergogenic Effects

• Creatine Supplementation Effects on Performance

– Improvement in total and max force in repetitive isometric muscle contractions

– Improvement in muscle strength and endurance in isotonic strength test, e.g. 1 RM

– Improvement in muscle force/torque and endurance in isokinetic strength tests

– Improvement in cycle ergometer performance in max efforts of 6 to 30 seconds

Protein: Ergogenic Effects

• Other creatine supplementation benefits

– Some evidence suggests a benefit to high intensity efforts of 30-150 seconds (400-800 meter track events); more research needed

– Not likely to improve VO₂ max or exercise events of long duration

– Increase in body mass likely to occur in 1^st week of supplementation; primarily due to water retention; may make it difficult to lose wt for competition since creatine tends to stay in muscle for several weeks before disappearing

– Creatine improves ability to do repeated contractions during training

Protein: Ergogenic Effects

• Creatine supplementation + caffeine

– Caffeine may negate benefit of creatine since it could block PC resynthesis during recovery from exercise

Protein: Ergogenic Effects

• Safety of Creatine supplementation

– No apparent significant adverse effects with 12 weeks of use in healthy individuals

– Individuals with kidney problems should avoid creatine supplementation; extra load on kidney metabolism

– May cause some gastrointestinal problems particularly if taken immediately prior to event

– Suggested to result in muscle cramps due to dilution of electrolytes

Protein: Ergogenic Effects

• Summary of Creatine Supplementation

– ACSM Statement

• Apparent absence of health risks does not mean that creatine is safe

– Creatine appears to enhance performance in events where the amount of PCr may be a limiting factor

• i.e. If PCr levels in muscle are increased with creatine supplementation, then performance may be enhanced

• Benefit does not appear to be due to greater PCr resynthesis during exercise recovery

Protein: Ergogenic Effects

• HMB (Beta-Hydroxy-Beta-Methylbutyrate) Supplementation

– A by-product of leucine metabolism (made by body)

– Theory is that it inhibits breakdown of muscle tissue during strenuous exercise

• Also, theorized to ↑ lean muscle mass, ↓ body fat, and ↑ muscle strength and power

– Supplementation results (1-3 grams/day)

• May slow rate of muscle breakdown in untrained resistance-training individuals (initial 3 weeks)

• Does not benefit resistance-trained individuals; no additional benefit if combined with creatine or CHO/protein supplement

• 8 weeks of HMB supplementation had no adverse effects on health

Protein: Ergogenic Effects

• Choline Supplementation

– An amine found in lecithin (found in egg yolks liver, nuts, wheat germ, cauliflower, soybeans)

– Helps in formation of acetylcholine, a neurotransmitter in CNS

– Theory

• Since plasma choline levels are reduced with long duration, exhaustive exercise, this may lead to fatigue

• Choline supplementation may lessen chance of fatigue

– Supplementation results

• Shown to ↓ run time and improve mood in some studies but no change in others; results are equivocal

Protein: Ergogenic Effects

• Inosine Supplementation

– Not an a.a. but is a nucleoside that helps form purines (nonprotein nitrogen compounds); i.e. associated with ATP

– Theory

• Improves ATP production in muscle so may benefit strength-type athletes and aerobic athletes

– Supplementation results (1-10 g/day doses)

• Not shown to enhance performance, and likely to hamper performance (lessened effort on supramaximal cycling test)

• Should not be taken by individuals predisposed to gout due to potential for uric acid formation

Protein Supplementation: Ergogenic or Health Effects

• At present time, there is inadequate scientific data to support ergogenic or health benefits to individual amino acid supplementation in healthy individuals