PROTEIN: PUNY TO POWERFUL

Lona Sandon, M.Ed., R.D., L.D.Assistant Professor

R IH2N – C – C = O I I H OH

OBJECTIVES

Discuss the importance of proteins in the diet Discuss the main functions of proteins in the body Discuss how much protein should be consumed and

the various factors that can affect the protein needs of athletes

Discuss protein supplementation and its place in sport nutrition

Explain the importance of protein intake for the athlete involved in daily training

Discuss the type, quantity, and timing of protein consumption before, during, & after exercise.

IMPORTANCE OF PROTEIN

2nd only to water as an ingredient for tissues & structures

Needed for muscle maintenance Constant turnover – breakdown & rebuild Can be metabolized for energy Must be replaced daily Critical for enzymes & body functions Inadequate protein can hinder sports

performance

TYPES OF PROTEIN FOR ATHLETES

COMPOSITION QUALITY Complete

contain all essential AA Animal products & soy

Incomplete May contain all essential AA

but in inadequate amounts Mainly plant sources

Complementary PRO 2 or more incomplete PROs

to make a complete PRO

High Typically animal proteins Contain all essential AA Enough AA for synthesis

of non-essential AA Good digestibility (95%)

Low Plant sources Limiting amino acids

Ex. Grains & low lysine Limited digestibility (85%)

HIGH-QUALITY PROTEIN

A complete protein

Contains extra amino acids for protein synthesis

Good digestibility

Usually from animal-derived foods & soy

LOW-QUALITY PROTEIN

An incomplete protein

One or more limiting amino acids

Usually from plant-derived foods

COMPLEMENTARY PROTEIN COMBINATIONS

Ex: Whole grain breads, cereals, rice, pastas

Ex: Kidney, black, or pinto beans, lentils, split peas

Ex: peanuts, almonds, walnuts, flaxseeds, sunflower seeds

NITROGEN BALANCE

Used as indicator of adequacy of total calorie & protein intake

When calorie intake is low, protein is broken down resulting in negative N2 balance

Negative N2 balance can result in poor athletic performance, muscle loss

N2 balance = (Nitrogen in) – (Nitrogen out)

NORMAL PROTEIN TURNOVER

Muscle ProteinSynthesis Breakdown

De novo formation Oxidation

Muscle free amino acid

pool

Blood amino acidsBody

proteinDietaryprotein

Adapted from: Gibala & Hawarth, 2006

PROTEIN TURNOVER

Endurance/aerobic exercise seems to have little impact on PRO synthesis or breakdown

Resistance exercise stimulates PRO synthesis (muscle anabolism) while also increasing breakdown (muscle catabolism) Being in a fed state increases synthesis during

exercise recovery, promoting muscle growth 6-10 g essential AA acids stimulate anabolism

post training

HOW MUCH PROTEIN IS NEEDED?

AMDR = 10-35% of daily caloriesAdapted from: Fink, Burgoon, Mikesky, 2006

FACTORS INFLUENCING PROTEIN NEEDS

Total energy intake If adequate kcal, calculate PRO needs in middle of range Adequate calories allow for maximum use of PRO

Desire to lose or gain weight Calculate PRO needs at high end of range for both weight

loss or gain Higher level needed for muscle recovery & maintain

positive N2 balance

Carbohydrate availability If CHO intake low, calculate PRO at higher end of range

FACTORS INFLUENCING PROTEIN NEEDS

Exercise intensity and duration High levels require higher PRO needs 2-6% energy may come from PRO

breakdown during endurance training

Training status/fitness level Higher levels for less fit athletes Training adaption occurs after ~2 weeks, then

become more efficient using PRO, requiring less

FACTORS INFLUENCING PROTEIN NEEDS

Dietary protein quality Vegetarians have higher PRO needs,

calculate at higher end of range

Age Youth athletes need higher end of range Masters athletes may need higher levels

PROBLEMS OF TOO MUCH PROTEIN

Used for energy or converted to fat Increases fluid needs & risk of

dehydration High PRO sometimes means high fat &

cholesterol intake Displaces other healthful foods; missing

essential vitamins/minerals Fat weight gain not muscle

PROTEIN SUPPLEMENTS?

Ask the following questions: What is the quantity of protein or amino acids in the product?

Is the supplement necessary? Evaluate usual intake first.

What is the cost? Will it enhance performance? Does the supplement have any harmful effects?

WHEN ARE PRO SUPP. NEEDED?

Very high calorie & PRO needs due to training

During traveling or when food availability it limited

Vegan athletes Kcal restricting

athletes Female athletes more

likely to eat low PRO

RISKS OF PRO SUPPLEMENTS

Allergic reactions to added ingredients

Contaminated with banned substances

Nutrient-nutrient interactions

Lost money

PRO & DAILY TRAINING

Aim to maximize muscle PRO synthesis Repair microtrauma of muscles caused

by training If inadequate, rely on body sources

leading to protein losses Decreased performance Increases risk of illness

Sports anemia Low hemoglobin

PRE-TRAINING PROTEIN

Recent research suggests PRO prior to exercise may: Provide energy for muscle cells Decrease catabolism of muscle tissue Increase muscle protein synthesis

Decreases gastric emptying Leading to longer satiety Gradual release of nutrients into blood stream Prevent hunger during training/competition Consume 1-3 hours prior to training

May increase perceived exertion

4-24 HOURS PRIOR TO TRAINING

Consider time before training

Choose lean proteins 3-6 ounces of meat or

equivalent complementary non-meat PRO sources

8-12 fl oz of dairy 1 oz nuts, seeds

CHOs, not proteins, should predominate

Familiar foods

1 -4 HOURS BEFORE TRAINING

Focus on CHO Small amounts of

PRO may be tolerated

2–4 oz lean meat 8 fl oz milk, yogurt

Lean protein sources preferable

PROTEIN DURING TRAINING/COMPETITION?

PRO can serve as an energy source

Too slow for intense activity Must go through liver before

getting to muscle except BCAAs

Benefit of consumption questionable

Hydration beverages (Accelerade) with PRO does not appear to improve performance/endurance

AA taste bad in sports drinks

PROTEIN DURING TRAINING/COMPETITION?

Research supporting BCAAs

Ingestion may prevent central nervous system fatigue due to low blood levels

Research results inconsistent

Limited effect on performance

PROTEIN AFTER TRAINING

Critical for recovery Increased rate of PRO synthesis

Availability of food effects synthesis rate Positive PRO balance dependent on:

AA composition AA blood concentration Timing of feeding

PROTEIN AFTER TRAINING

Type: Influences

hyperaminoacidemia

Complete PROs Casein Whey Soy

Foods containing essential AAs

Whole food sources recommended

PROTEIN AFTER TRAINING

Better absorption when consumed with CHOIncreased circulating

insulin promotes protein synthesis

Improved recovery & muscle repair

Best if consumed within 60 min to 3 hours of exercise

PROTEIN AFTER TRAINING

HOW MUCH? EXAMPLES

6 grams essential AAs PRO synthesis

General recommendations

6-20 g PRO post exercise

Consume within 3 hours or less of exercise for maximum effect of muscle building hormones

Chocolate milk Yogurt & nuts Meat sandwich on whole

wheat

CHOCOLATE MILK FOR RECOVERY

Provides PRO & CHO in amounts shown to promote muscle synthesis & glycogen repletion

Provides essential AA & BCAA important for muscle anabolism

Provides Na+ & K+ lost in sweat Promotes greater fluid replacement &

retention compared to sports drinks Contains many other essential

vitamins/minerals

SUMMARY

PRO is a key nutrient for muscle mass Complete, high quality & complementary PRO can

provide essential AAs for athletes Athletes should achieve a positive N2 balance for

muscle building & repair Athletes have higher PRO needs than non-athletes

1.4-2 strength, 1.2-2 endurance, 1.2-1.6 team sports PRO needs depend on: weight, training status,

calorie & CHO intake, weight gain/loss, quality & type

PRO before & after exercise can benefit athletes

REFERENCES

Fink HH, Burgoon LA, Mikesky AE, eds. Practical Applications in Sports Nutrition. Sudbury, MA: Jones and Bartlett; 2012

Gibala MJ. Howarth KR. Protein and exercise. In: Dunford M, ed. Sports Nutrition: A Practice Manual for Professionals, 4th ed. American Dietetic Association; 2006.

Roy BD. Milk: the new sports drink? A review. J Int Soc Sports Nutr. 2008;5:15.