Creatine W9 X (Not on 2nd Exam) Flashcards
How much creatine is stored in skeletal muscle?
> 95%
How much creatine is obtained from diet?
50%
What amino acids is creatine endogenously synthesised from?
Arginine
Glycine
Methionine
Where in the body is creatine endogenously synthesised from?
Liver
Pancreas
Kidneys
How is creatine stored within the body?
2/3 as phosphocreatine
1/3 free creatine
What is the total creatine pool within the muscle? (PCr + Cr) mmol/kg
120mmol/kg dry muscle mass
What is the upper limit of creatine storage?
160mmol/kg dry muscle mass
What is the reported stores for creatine in vegetarians?
90-110mmol/kg dm
What happens when creatine supplementation is combined with resistance training?
There is a small increase in the direct measures of skeletal muscle hypertrophy in both the upper and lower body
What are the effects of increased creatine?
Increased PCr resynthesis
Increased brain health (anti-inflammatory and anti-oxidant effects)
Increased short-term, high-intensity exercise capacity to perform repeated bouts of high-intensity effort
How much PCr is resynthesized in 4 seconds?
80%
Why does maximal exercise cause a reduction in creatine levels?
Because its breakdowns sustains high rates of ATP production
What muscle fibre type has higher PCr levels?
Type II fibres
What exercise causes PCr levels to decrease?
Maximal exercise
How quick can PCr be depleted?
10 seconds
What are the “mechanisms of action” when undertaking creatine supplementation?
Increases Creatine stores 30%= Increases PCr resynthesis
Increases growth factor expression
Increases muscle glycogen
Training harder, longer= increases lean mass/strength
*Decreases muscle damage and increases protein synthesis
What are the 2 main sources of creatine?
Diet
Creatine Monohydrate
What foods contains creatine?
Red Meat (beef, pork)
Fish (Tuna, salmon, cod, herring)
What is creatine monohydrate?
White powder, 99% absorbed
Better uptake mixed with a carbohydrate containing liquid or food
Synthetic (suitable for vegetarians and vegans)
How long should a washout period of creatine?
4-6weeks
What is the maintenance dose of creatine?
2-5g/day
What does a long, low dose of ingestion of creatine look like?
3-5g/day for 20-30 days
What does a short, high dose of ingestion of creatine look like?
20g/day (split in 4 doses) for 5 days
0.3g/kg BM (split in 3-4 doses) for 5 days
When should you use creatine?
Single and repeated bouts of high-intensity exercise
High-intensity max efforts >150secs, largest effects on <30sec tasks
What is the individual variability of creatine? (Baselines levels of muscle creatine)
Individuals have high muscle creatine levels will experience low creatine uptake from supplements, and vice-versa
Therefor individuals with low muscle creatine levels have the greatest potential for increases in response to supplementation
What are the safety issues of creatine use?
No evidence of adverse effects with long term (4years) creatine supplementation at appropriate dosages in healthy individuals
Mild, Temporary gut upset can occur but can be attenuated with split doses
Contamination
What is the individual variability of creatine? (Sport Type)
Sports where performance is not determined by PCr availability creatine supplementation will likely not have any effects
What is the major concern of creatine?
Increase in body mass (1-2kg)
How much creatine do we turnover a day?
2g/day
Synthesis- 1g/day endogenously and exogenously
How do we excrete creatine?
Creatinine (in the urine)
What is creatinine?
Irreversible product converted from creatine which is then excreted via urine
What are the 3 key mechanism of actions of creatine?
Increased Cr stores 30%= Increased PCr synthesis
Increased growth factor expression
Training harder, longer= increase in lean mass/strength
What is creatines transport and storage linked too?
Insulin availability
Is co-ingestion of creatine effective and why?
Yes
Leads to better retention of free creatine and phosphocreatine= greater total creatine
Increased muscle uptake
Is co-ingestion sustainable?
No, its an aggressive approach and insulin effect gets dampened
What may concurrent co-ingestion with a mixed protein/CHO source (50g protein+CHO) lead to?
Enhanced muscle creatine uptake due to increased insulin stimulation
What does creatine enhance?
Resistance to fatigue
