K1N334 F1NAL Flashcards
What are the 5 levels of body composition?
Level 1: Atomic (H2, Carbon, O2)
Level 2: Molecular (Protein, Lipid, Water)
Level 3: Cellular (Extracellular solids, fluid, cells)
Level 4: Tissue-Organ (Visceral Organs, Bone, Adipose Tissue, Skeletal muscle)
Level 5: Whole Body (Head, trunk, appendages)
What is the Obesity Paradox?
- Individuals with obesity → survival advantage when only BMI is taken into account
- <10% used a direct measure of body composition
- When muscle mass is taken into account
→ a high BMI has no protective effect in the presence of low muscle mass
When should BMI not be used??
Should not be used for making clinically important decisions at the individual patient level
What are 4 techniques to measure body composition?
Bioelectrical Impedance Analysis
Dual-Energy X-Ray Absorptiometry
Ultrasonography
Computed Tomography
For body composition changes, what are examples of Physiological Factors and Non-Physiological Factors (1 each)
Physiological Factors:
eg, Aging
Non-Physiological Factors:
eg, Illness, Injury
What are 7 types of body composition changes?
Malnutrition
Acute Illness
Injury
Hospitalization
Inflammation
Sedentary Lifestyle
Chronic Diseases
What age do body composition abnormalities typically happen at?
Can happen at any age!
What are 4 body composition abnormalities that negatively impact health?
Osteopenia / Osteoporosis
Obesity
Sarcopenia
Sarcopenic Obesity
What 7 things happen if someone has low muscle mass?
Physical Impairment/ Disability
Greater Length of Hospital Stay
Need for Rehabilitation
Post-Operative
Complications Toxicity
Shorter Time to Tumor Progression
Poorer QoL
How is malnutrition diagnosed?
Having 2 or more of:
Insufficient EI
Weight Loss
Loss of Muscle Mass
Loss of Subcutaneous Fat
Fluid Accumulation
↓ Functional Status
What does low msucle mass and malnutrition result in?
↑ Morbidity
↑ Mortality
↓ QoL
↓ Functionality
↑ Health Care Costs
↑ Rehospitalization Rates
What is the Acute effect of endurance exercise?
- High intensity exercise (~75% VO2max; 1 hr) depletes liver glycogen 50%.
- Supramax, repetitive work also depletes
- Time to exhaustion directly related to resting glycogen stores
What is the Effect of endurance-training?
- glycogen-sparing
- improved mitochondrial metabolism enhances lipid oxidation
- larger glycogen stores in skeletal muscle
What should the Macronutrient intake (CHO) be?
About 12-16 g of CHO per kg of muscle
How much can liver glycogen be depleted after an overnight fast?
Higher concentration than muscle but lower total amount (~100g) can be depleted to below 20g after an overnight fast
What is important to remember about glucose?
Glucose is not just for muscle contractions, it’s critical for brain function
What is the Glycemic index?
Pure glucose is the standard reference (100)
What can influence the GI of a food?
- the biochemical structure of the carbohydrate
- the absorption process,
- the size of the food particle,
- the co-ingestion of fat, fiber, or protein
What is GI affected by?
GI affected by biochemical structure of CHO, absorption, co-ingestion of fat/protein/fiber
Glycemic load (GL) =
GI × g CHO/ 100
What foods have a Low GI <55
Most fruit and vegetables (except potatoes), whole grains, basmati rice, pasta
What foods have Medium GI 56 - 70
Sucrose, croissant, some brown rices
What foods have High GI >70
Corn flakes, baked potato, some white rices (e.g. jasmine), white bread
What are the General CHO intake guidelines – ACSM
Daily intake 6-10 g/kg of body weight
* Daily (mod duration, low intensity): 5-7 g/kg
* Daily (mod to heavy endurance): 7-12 g/kg
* Daily (extreme, 4-6 hrs): 10-12g+/kg
What is the goal of CHO days before competition?
To replenish/maximize muscle glycogen
SUPERCOMPENSATION (CHO loading)
– ↑ time to fatigue by 20%
– ↓ time to complete task 2-3%
– Mostly for activities > 60-90 minutes
Any potential issues with classical supercompensation?
- -hypoglycemia when CHO is low
- -may not be not practical (meal prep)
- -GI problems
- -Mood
- -Tenseness without training
Why might glycogen stores be different?
- Women tend to have a greater reliance on fat oxidation.
- Carb loading may increase weight – issues?
- If carb loading is not increasing muscle glycogen, where does it go?
Carbohydrate loading – Muscle vs. liver glycogen?
Muscle glycogen is often super-compensated before full recovery of liver glycogen (muscle takes precedence)
Carbohydrate loading - Fructose (fruits/honey) vs. glucose (pasta)?
Fructose can lead to slower muscle glycogen but similar liver glycogen replenishment.
How does it work to take CHO hours before competition?
– Goal: to replenish/maximize liver glycogen and increase glucose delivery to muscle
– 0-4 hrs before exercise:
– Meal 3-4 hour before exercise can increase muscle glycogen.
– 1 hour before liver glycogen can be increased (but likely not muscle)
– 1.0-1.2 g/kg snack 30-60 min before exercise (more controversial but recently accepted)
* Concerns over “reactive hypoglycemia” (which may be less common if consumed closer to exercise (e.g. 15 min) or if warm up is included.
* Consequence of excessive insulin released which continues past eating.
* ~200-300g 3-4h before exercise
* Fructose (slower absorption – requires conversion in liver) may not be as effective
What is important while CHO loading before competition?
- Needs to be tailored to the needs of the athlete and competition.
- Always test out in advance of the competition
What is the goal for CHO during competition?
- ~ 30-60 g/hr (liquid or solid) benefits high intensity, long duration work (extends time to exhaustion)
– 0.7g/kg/hr - training state does not improve ability to utilize oral CHO
- Better to provide every 15-20 min than after 2h
- Not high fructose (slower to absorb, more GI symptoms)
- Controversy for events lasting <1hr
- Adding some fructose can help
- Exercise induced elevation in epinephrine depresses the release of insulin!
What is the goal of CHO intake after exercise?
To replenish muscle and liver glycogen
* Create positive glycogen repletion environment (increase insulin, increase tissue sensitivity to insulin, reduce catecholamines, increase glycogen synthase)
Why carbohydrate load after competition?
- Replenish depleted liver and muscle glycogen stores.
- Glycogen stores is directly related to performance!
What affects rate of glycogen synthesis?
- Availability of glucose.
- Insulin.
- Prior exercise – increases insulin sensitivity
What should the timing be of CHO intake after exercise?
- Rapid phase of glycogen synthesis (1-2 hours) – glycogen synthase (exercise upregulates this rate-limiting enzyme) and glucose availability
- Slow phase of glycogen synthesis – insulin availability
- Eat immediately after you get the greatest rate of glycogen synthesis.
- Wait 2h – much slower
What is the optimal rate of ingestion of CHO intake after exercise?
Optimal rate is ~1.2g/min
How does the Type of CHO influence ingestion?
Muscle glycogen synthesis may be up to 50% slower with fructose or low GI meals (initial fructose may be preferentially store in liver as glycogen or is converted to glucose)
Why might adding protein help if CHO intake is lower?
AA’s can increase Insulin release!
– BUT CHO is the limiting factor
What is important for CHO recovery?
- Total energy intake must match expenditure or glycogen stores deplete
- Time to replenish glycogen stores varies (2-6 days)
- Some studies have been able to show good
supercompensation (attain supranormal muscle glycogen values) following a very short bout of very intense exercise (<24 hours)
How does fat metabolism change with training?
- improved ability to oxidize FFA
– ↑ FFA faster
– enhanced capillarization (# and density –
access fats) - FFA transport through plasma membrane and mitochondria
- Increased number of oxidative enzyme
- mitochondrial adaptations (↑density + size)
When can a high fat diet be beneficial?
Eat high fat diet then CHO.
* Same glycogen stores as high CHO but increased fat metabolism!
How does the high fat diet work to help athletes?
- Injecting intralipid into blood to raise FA.
- Spares glycogen reserves.
For endurance athlete’s, is it better to have a high fat or high CHO diet?
High CHO!
What is the theory behind a high fat diet?
High fat diets could increase ability to oxidize fat and spare muscle glycogen (particularly if muscle glycogen is replenished before exercise)
Why are proteins important?
– Structural and regulatory functions.
– Fuel source.
– Can be converted to glucose (gluconeogenesis)
What % of muscle protein is BCAA? What does this mean?
20% for muscle synthesis
What 3 essential acids are BCAA?
Isoleucine
Leucine
Valine
What are the limiting amino acids for the following protein sources?
Wheat
Rice
Legumes
Maize
Egg, chicken
Lysine
Lysine
Tryptophan or methionine (or cysteine)
Lysine and tryptophan
None
Why do we do Protein breakdown?
– To replace damaged proteins
– Synthesize neurotransmitters (serotonin) or hormones (adrenaline)
– To provide energy (converted to glucose, ketones or fatty acids)
What are the two ways to remove the amino group?
– Transamination or deamination
(ammonia (NH3) converted to urea)
What’s the difference between protein intake and protein turnover?
Protein turnover is several times greater than protein intake.
Protein intake accounts for what % of the AA that enter the AA pool every day
25%
Where does the remaining protein come from?
Comes from protein in the gut, kidney, liver which synthesize and resynthesize
Muscle is MUCH slower
How can you estimate protein metabolism?
Eat specific foods (known nitrogen content) and measure nitrogen excretion.
During exercise, nitrogen excretion is substantial and must be included in the measurements.
What is the Nitrogen Balance Method?
– ~16% of protein is nitrogen
– Nitrogen Intake – Nitrogen loss
* Loss: fecal, urine, sweat, ~breath(ammonia)
– Overall underestimates nitrogen excretion
(therefore overestimates retention).
– When eating high protein diet, can result in
overestimate
Those who believe that protein requirements are greater for athletes often state?
- AAs may be oxidized during exercise.
- Increased protein synthesis is necessary to repair damage and training adaptations.
What should protein intake usually be for the general population?
– 0.8 g/kg of body weight per day
– 10-35% of TDEI
What should protein intake usually be for endurance athletes?
– 1.2–1.4 g/kg of body weight per day
– Perhaps more for ultra-endurance athletes
– Usually not a problem because caloric intake is up
What should protein intake usually be for strength training athletes?
– 1.2–1.7 g/kg of body weight per day
– Especially early phases of training
What are some Strategies to favor protein synthesis?
– Co-ingestion with CHO (due to insulin response)
– Amount of protein (20-25 g?)
– Timing of protein (peri-exercise)
– Type of protein (whey vs casein vs soy)
– Ergogenic Amino acids
Protein supplementation is less effective in which populations?
Older populations
Above what amount of protein do we see no further gains in FFM?
1.6g/kg/day