Sports Exam 2

Protein

• made up of chains of amino acids that are called peptides

• It can provide energy – 4 kcal/g; but this process is VERY inefficient

Contractile proteins

actin and myosin in human skeletal muscle (movement)

Structrual proteins

collagen, keratin (bones, cartilage, tendons, skin, hair)

Defense proteins

antibodies (immunity)

Enzymes and hormones

absolutely critical for digestion, metabolism, and bodily function

Transport proteins

hemoglobin is critical for the transport of oxygen to muscles

Essential amino acids

• Must be consumed in the diet

• There are 9 essential amino acids

Non-essential amino acids

• Can be synthesized in the body

• There are 11 essential amino acids

Conditionally essential amino acids

• Nonessential amino acids that become essential because the body cannot produce

• Two examples – tyrosine, glycine

BCAAs and Exercise

• make up 40 – 50% of essential amino acids that build muscle

• Leucine in particular plays a critical role in maximizing anabolic muscle building

• inhibit muscle protein breakdown during exercise

• can be used by muscles for energy during exercise – importance for weight lifting and ultraendurance races

Pros - animal protein

1. Complete proteins – contain all essential amino acids and often rich in BCAA

2. Nutrient-dense and rich in iron, B12

3. Exellent digestibility (90 – 99%) + high bioavailability of amino acids (appearance in blood and tissue)

cons - animal protein

1. Environmental and ethical impact

2. Higher in saturated fat and cholesterol

pros - plant protein

1. Better cardiometabolic health – higher fiber, antioxidants, vitamins and minerals

2. Environmental sustainability + Ethics

cons - plant protein

1. Incomplete proteins – missing essential AAs

2. Lower bioavailability

3. Increased risk for iron and B12 deficiency

Exercise ↑↑↑ protein requirements in athletes due to:

Increased demand for protein to facilitate muscle repair, remodeling, and synthesis

Exercise & Protein Requirements

• Increased protein oxidation (use of protein for fuel e.g. ultraendurance)

• Increased enzyme and protein production (aerobic metabolism)

• Increased protein for immune support

Muscle protein turnover

continuous process of muscle protein synthesis (MPS) and muscle protein breakdown (MPB)

• Consumption of dietary protein increases the concentration of amino acids in the blood which are transported into the muscle and increase muscle protein synthesis

• Prolonged fasting states ↑ muscle protein breakdown

Muscle net protein balance (NPB)

MPS – MPB

Muscle proteins is a collective term referring to

Myofibrillar protein, Sarcoplasmic protein, Mitochondrial protein

Myofibrillar protein

makes up 60% of total

Sarcoplasmic protein

makes up 30% of total

Mitochondrial protein

makes up 10% of total

true or false - Both resistance and endurance exercise increases muscle protein

turnover but they may differ in terms of which proteins are impacted

True

true or false - Direct measurement of muscle protein synthesis is the most accurate way via biopsy

true

Effects of Resistance Exercise on MPS

• Resistance exercise is anabolic

• Acute resistance exercise causes a positive net muscle protein balance

• Postexercise feeding is critical for supporting and augmenting positive net protein balance

Chronic resistance training leads to

• Myofibrillar protein accretion

• Increase in muscle fiber size

• Increased lean body mass

Effects of Endurance Exercise on MPS

• Also increases muscle protein synthesis but the response is smaller in both amplitude and duration compared with resistance exercise

• High-intensity aerobic exercise elicits greater and longer lasting increases in muscle protein synthesis

Remodeling of muscle proteins during recovery from aerobic exercise for

• Replacing damaged proteins

• Synthesizing mitochondrial-related proteins and enzymes

• Result : increased oxidative capacity in muscle

Recommended Dietary Allowance (RDA) for protein in normal healthy adults is

0.8 g/kg/day

_____g of high-quality protein leads to maximal stimulation of muscle protein synthesis (muscle building) after resistance exercise

20-30

20-30g : This dosage of protein every _____ hours leads to greater muscle protein synthesis over time, which may lead to greater muscle building

3 or 4

Anabolic Window and Best Time to Eat

Eating protein within 1 hour of resistance training does not enhance MPS versus

eating the same overall amount of protein spread out throughout the day

Unbalanced Distribution of Protein Intake

• Western diets are typically characterized by an unbalanced distribution of protein during the day

• Poor intake in the morning

• High intake at night

• These feeding patterns may preclude the ability to support maximal rates of muscle protein synthesis over a 24-hour period

Isolated soy and animal-based proteins such as beef, egg, and dairy

have higher essential amino acid compositions than plant-based proteins such as rice and legumes

Digestion rate is fastest in

whey and soy proteins

Digestion rate is slowest in

casein

Leucine Trigger Hypothesis

A certain leucine threshold must be reached within the blood or muscle intracellular pool in order to maximally activate muscle protein synthesis

• 2 – 3 grams of leucine per meal is optimal (I have read 2.5 g is minimum)

• Most high-quality proteins that contain 20 – 30 g of protein contain enough leucine

Protein quality is determined by either

• Protein digestibility-corrected amino acid score (PDCAAS)

• Digestible indispensable amino acid score (DIAAS)

Soy and Vegetable Proteins

• still a quality protein

• Less anabolic and has less leucine versus whey

• does yield beneficial increases in lean mass and has positive overall effect on muscle protein synthesis

• Quinoa is an interesting plant-protein  high leucine content

Endurance Training Athletes

1.2 ‒ 1.4 g/kg/day

Resistance Training Athletes

1.6 ‒ 1.8 g/kg/day

Updated recommendations for 90kg athlete

• 0.4 g/kg/meal : 36g of protein with each meal; 36g X 4 = 144g protein

• 0.55 g/kg/meal : 50 of protein with each meal; 50g x 4 = 200g protein

The most abundant carbohydrate (CHO) is

glucose

glucose

• is the preferred energy source for the brain and CNS

• It is also CRITICAL for high-intensity exercise performance

CHO are classified as

• Simple CHO – monosaccharides and disaccharides

• Oligosaccharides

• Complex Carbohydrates – polysaccharides

Plants store glucose in the form of

starch

Amylopectin

• Branched chains of polysaccharides found in starch – easy to digest

• 60% of starch is amylopectin

Amylose

• Straight chains of polysaccharides found in starch – harder to digest

• 40% of starch is amylose

Glycogen

• Main storage form of glucose in the human body

• Long branched chains of glucose

• Stored in the liver and muscle

liver glycogen

controls blood glucose levels

muscle glycogen

energy for muscles to move

carb AMDR

45 – 65 % of total caloric intake (general population)

Body sources of carbohydrate

1. Muscle glycogen 300 – 400 g CHO (1,200 – 1,600 kcal)

2. Liver glycogen 75 – 100 g CHO (300 – 400 kcal)

3. Blood glucose 5 g (20 kcal)

Muscle glycogen provides

• 50% of energy for moderate-intensity exercise (65% VO2max)

• >70% of energy for high-intensity exercise (85% VO2max)

true or false - It is impossible to meet ATP requirements for high-intensity, high-power output exercise when you have exhausted glycogen

true

Strategies to Increase CHO Availability

1. Consuming CHO in the hours or days before exercise

2. Ingesting CHO during exercise

3. Consuming CHO after exercise

Daily carbohydrate intake should be individualized based on the athlete’s

body weight (accounts for muscle mass) and training loads

Glycemic index (GI)

ranks CHO foods according to blood glucose response

High GI

glucose, white bread, potatoes

Mod GI

soft drinks, oats, bananas

Low GI

fructose, milk, beans, pasta, apples

Glycemic load

GI X CHO content of food

Before exercise

Low GI foods to promote sustained CHO availability

During or after exercise

Mod- to High GI foods to promote CHO oxidation during exercise and replenish glycogen

Fast-digesting starches (High GI)

• Vitargo (fractionated barley amylopectin)

• 35 g CHO per scoop mix with water

• Marketed as fastest carb from mouth to muscle

• Several scientific studies to back up these claims by reputable research labs

• Greatest efficacy during and after exercise

Slow-digesting starches (Low GI)

• UCAN (modified corn starch)

• 29 g CHO per scoop mix with water

• Easy to digest

• Less of a glucose and insulin spike and greater fat oxidation during exercise

• But no studies showing improved performance

• Greatest efficacy pre-exercise

Carbohydrate loading

can increase muscle glycogen stores from normal resting values of 130 mmol/kg to 220 mmol/kg and improve performance in endurance events lasting longer than 90 minutes

Classic regimen of CHO loading:

• 3-day depletion phase of hard training and low-carbohydrate intake

• Followed by 3-day loading phase of tapered training and high CHO intake

New Carbohydrate Loading Guidelines

• Rest for 36 – 48 hours

• Consume 10 – 12 g/kg/day during this time

Consuming CHO-rich foods and fluids in the 4 hours prior to exercise:

1. Restores liver glycogen, particularly after overnight fast

2. Increases muscle glycogen stores

3. Prevents hunger

4. Provides glucose for the central nervous system

Pre-exercise meal should contain

1 – 4 g CHO per kg and should be consumed 1 – 4 hours before exercise

General Guidelines for the Pre-Exercise Meal

• To avoid potential GI distress reduce the CHO and energy content of the meal the closer you get to exercise

• Avoid foods high in fat, protein, and fiber to reduce risk of GI issues

• Liquid meals : ideal for close to race, athletes with anxiety/nerves

Potential mechanisms for improved performance include

1. ↓ muscle glycogen utilization

2. ↑ muscle glycogen resynthesis during the rest or low-intensity periods

3. ↑ blood glucose

Post-Exercise CHO Intake to Optimize Recovery

• Restoration of muscle and liver glycogen is critical for recovery and subsequent performance

• Effective refueling strategies after strenuous exercise promotes optimal glycogen resynthesis

CHO Intake After Glycogen-Depleting Exercise

• When exercise sessions are < 8 hours apart, start consuming CHO immediately after exercise to maximize glycogen resynthesis

• 1 – 1.2 g CHO/kg per hour for the first 4 hours after exercise

• Eating small amounts of CHO every 15 – 30 min for first 4 hours after exercise may enhance glycogen resynthesis

• Medium and high-GI foods may help to maximize glycogen resynthesis particularly if time to recover is limited

When CHO intake is < 1 g/kg/h during recovery, 25 g of protein =

greater glycogen storage

However, when CHO is adequate (> 1. 2 g/kg/h), protein has

no effect on glycogen storage

Saturated fats

solid at room temperature, there are no double bonds (“saturated with hydrogens”)

Monounsaturated fats

liquid at room temperature, there is 1 double bond – e. g. Oleic acid.

Polyunsaturated fats

liquid at room temperature, there is ≥ 2 double blonds – e. g. omega 3 fatty acids

Trans fats

commonly found in processed and fried foods, associated with negative health outcomes

Incorporating Fats Into the Diet

• Adding olive oil to salads, vegetables and cooking (low to medium temps)

• Add nuts and seeds as snacks or topping for salads

• Eat fish 2 days per week (oily fish 1 x)

• Avocadoes and nut butters

Prior to exercise or during carbohydrate loading

Chronic fat restriction is not advised as it limits overall energy intake and increases the risk of fat-soluble vitamin and essential fatty acid deficiencies, which can impair performance

Influence of Exercise Intensity on Lipid Metabolism

↑↑↑ fat oxidation and use of fat as primary fuel during low to moderate intensity exercise

↓↓↓ fat oxidation and use of fat as primary fuel during high intensity exercise

Influence of Exercise Duration on Lipid Metabolism

↑↑↑ fat oxidation and use of fat as primary fuel with LONGER duration

Impact of Exercise Training on Fat Oxidation

• Elite athletes have multiple adaptations that improve their ability to use fat for energy during exercise including:

↑ storage of intramuscular triglyceride (IMTG)

↑ delivery and uptake of free fatty acids into the muscle

↑ mitochondrial volume and enzyme capacity – improved ability to burn fat for energy during exercise

Why do Athletes Want to Lose Weight?

1. Weight Classes : Wrestling, MMA, Boxing

2. ↑ Power to Weight Ratio : Cycling, Rowing

3. Aesthetic purpose : gymnastics, diving, figure skating

4. NIL & Advertising Money

5. Pressure from societal standards of what is acceptable body type

Factors Influencing the Ability to Achieve Optimal Body Composition in Athletes

genetics, energy intake, energy expenditure

Actual weight loss or weight gain is almost always ____ than predicted weight loss or weight gain

less

Inducing a caloric excess or deficit ___ cause weight gain or weight loss

does

Heterogeneity of response (between individual variation) is huge due to

genetics

Set-Point Theory

biological set point for body weight much like the set points for other physiological variables

high risk periods for weight gain

• Off-season

• Injuries

Dietary Patterns Specific to Athletes

• Reliant on dining halls, restaurants and fast food

• Limited time and cooking skills

• High-calorie, energy-dense foods are often a reward for a victory

• Sports bars, gels, drinks are designed to fuel performance during and following training but they are not suitable in other instances

Traditional Dietary Approach to Weight Loss

• Low-fat diets to reduce overall energy intake

• Avoids jeopardizing carbohydrate, protein, and micronutrient intake

• Encourage intake of nutrient-dense, high-fiber carbohydrates

• ↑ low-fat dairy and overall calcium intake

Two approaches for energy restriction

• ↓ total energy intake by 500 kcal per day

• ↓ total energy intake by 10% initially and progress towards 20%

Exercise Prescription for Weight and Fat Loss

• When feasible (particularly in offseason) additional exercise can be added to maximize the caloric deficit and futher weight loss

• Both moderate-intensity and high-intensity exercise are effective for assisting weight and fat loss

• However, high-intensity interval exercise may be more effective for fat loss and it’s more fun and time efficient

Both HIIT and MICT (Regular Exercise) ____ fat

decrease

Potential Mechanisms for HIIT Superiority

• Greater energy expenditure in less time (time efficiency)

• Greater excess post-exercise oxygen consumption (EPOC)

• Greater ↑↑↑ in fat oxidation enzymes

• Greater satiety

How Much HIIT Should Athletes Do?

• 30 – 40 min on 3 days per week

• Frequency is dependant on athlete’s availability and time of season