Why is protein a dietary necessity for physical activity?
- Major component of all cells (collagen, elastin, etc)
- Contractile proteins in skeletal muscle (actin, myosin, troponin)
- Enzymes: facilitate biochemical reactions (synthetic, metabolic, regulatory)
- Transport molecules from one place to another (hemoglobin, myoglobin, albumin)
- Hormones: messenger proteins (insulin)
Why is too much dietary protein a health concern?
Major end product of protein metabolism is urea
- ammonia from oxidative deamination reactions must be removed from the body
- urea cycle converts ammonia to urea
- occurs in liver, but urea is transported to kidneys for exrection
- too much protein can overload the kidneys
What are the dietary protein requirements for specific physical activity levels?
What are methods of assessment that can be used to ascertain protein status?
- *Anthropometric Assessment:**
- Body composition estimations
- Mid-arm muscle circumference/area
- *Laboratory Assessment:**
- Serum Albumin
- other serum proteins (transferrin, pre-albumin, retinol-binding protein)
- Urinary creatine excretion
- total lymphocyte count
What serum markers can be used to assess protein status?
Albumin: Maintains serum osmolality and transports small molecules
Transferrin: Transport protein for iron
Transthyretin/Pre-Albumin: binds to retinol binding protein and thyroxine
What amino acids, peptides, and metabolites are most useful for muscle protein balance and performance?
- *- Branched chain amino acids/metabolites:**
- Leucine appears to be specific effector of protein synthesis
- beta-Hyroxy-beta-Methylbutyrate (HMB)
- alpha-KetoisoCaproic acid (KIC)
- Beta-alanine
- Creatine
Why is leucine important for muscle development and performance?
- It’s a potent, independent stimulator of muscle protein synthesis
- Adding leucine to an EAA supplement during steady state exercise elicits a greater muscle synthesis than EAA alone (not the sam result from resistance exercise)
Why is beta-Hyroxy-beta-Methylbutyrate (HMB) important for muscle development and performance?
HMB may be a signal to activate protein synthesis or inhibit protein degredation
Purported benefits of HMP:
- decreased muscle breakdown during exercise/muscle wasting and disease
- decreased muscle damage from strenuous exercise
Why is beta-Alanine/Carnosine important for muscle development and performance?
Carnosine has very high lvels in skeletal muscle
- protects against free radicals and lipid peroxidation
- has membrane-protecting activity and proton buffering capacity
What are the “essential” amino acids?
Histidine
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Threonine
Tryptophan
Valine
What are the “Conditionally Essential” amino acids?
Cysteine
Glycine
Taurine
Proline
Tyrosine
Arginine
Glutamine
Selenocystenine
How is creatine synthesized?
Requires 3 Amino Acids:
Met (as S-adenosyl Met) + Gly + Arg
Methylation rxn from guanidinoacetate to craetine represents major use of SAM in the body
quantitatively major pathway in AA metabolism
What is creatine’s role in energy metabolism?
Phosphorylated creatine allows for the Phosphagen energy system to produce ATP
Quantity depends on muscle mass
Maintenance of creatine pool requries continuous synthesis
Synthesis prepresents metabolic burden, particularly on AA metabolism
What is Creatine Kinase and what is it used as an index for?
Creatine kinase reversibly catalyzes transfer of phosphate between ATP and creatine phosphate
Index of:
Myocardial Infarction
Muscle Damage
Musclular Dystrophy
Severe Exertion
What is considered a safe and effective dose of creatine for muscle performance?
3 g of creatine monohydrate per day
- loading phase not necessary
- Should be given in a 28 day cycle (28 on/28 off) as it takes > 28 days to go back to pre-supplement levels
What are some pros and cons of creatine supplements?
Pros:
- creatine supplements may enhance explosive strength or performance for short-term bouts of high intensity activities
Cons:
- does not improve endurance performance
- not everyone who takes it sees improvments (responders vs non-reponders)
- has been shown to increase anterior compartment pressure of lower leg muscles
Define Health/Fitness
- Non-specific outcome
Overall health/wellness, quality of life
- Targets limited parameters
Cardiovascular endurance, muscular strength adn endurance, flexibility
- non-periodized
Relatively consisten pattern of intensity, duration, and frequency
- emotionally balanced
life stress coping, self-esteem, positive outlook
Define Human Performance
- Well-defined outcome
ability to perform specific task(s) under specific conditions
- targets full spectrum parameters
Cardiovascular endurace, muscular strength and endurance, power, speed, agility, flexibility
- Periodized
cycles training objectives by manipulating intensity, duration, and/or frequency
- Mission Mindset
arousal regulation, pain tolerance, harness high-stakes stress, self-preservation/mission completion balance
What is the standard metabolic equivalent?
MET:
- index of energy expenditure
- one MET = energy expended sitting quietly at rest
- physical activity intensity is often expressed in MET units
What are components of physical fitness?
Cardiorespiratory Fitness
- Cardiac Output
Muscular strength and endurance
- Body composition
- Flexibility
Neuromotor (functional) fitness
What is cardiorespiratory fitness?
The ability of circulatory and respiratory systems to supply fuel during sustained physical activity and to eliminate metabolic by-products after supplying fuel
- frequently measured by VO2 max
What is cardiac output?
Amount of blood ejected from heart each minute:
Stroke Volume x Heart Rate
Primary determinant = heart rate
What is muscluar strength?
ability of muscle to exert force
- strength is health-related fitness component that is assessed by the maximal amount of resistance or force sustained in single effort
What is muscular endurance?
relates amount of external force a muscle can exert over an extended period of time
