Creatine and nitrate Flashcards
(42 cards)
What is creatine?
Endogenously synthesised from AA (arginine, glycine and methionine) in the liver, pancreas and kidneys.
> 95% is stored in the skeletal muscle
Approx. 50% obtained from the diet
How is creatine stored in the body?
2/3 stored as PCr in intramuscular and the rest being free creatine
Total creatine pool (PCr and Cr) averages at 120 mmol/kg dry muscle mass
Upper limit seems to be ~ 160 mmol/kg dry muscle mass
What are the reported storage capacity for vegetarians?
Intramuscular creatine stores are seen to be 90 - 110 mmol/kg dm
What are the creatine turn over rates?
Synthesis = 2 g/day (1g endogenous + 1g exogenous)
Excretion = 2 g/day as creatinine in the urine
Increasing muscle creatine levels; Loading phase?
6 days of 20g per day (4 dosage split into 5g)
What is the effect of creatine?
Increases in maximal work
Increase in total work done in 30 seconds (isokinetic cycling)
Greater upper body hypertrophy
Greater lower body hypertrophy
What is the mechanism for why creatine supplementation increases hypertrophy?
Increase PCr resynthesis = short-term, high-intensity exercise capacity to perform repeated bouts of high intensity effort
What is creatines effect on brain health?
Evidence to suggest it helps cognitive function, recovery from traumatic head injuries and the cognitive decline in elderly.
PCr stores are greater in what type of muscle fibre?
Greater in type II compared to type I
Why are PCr stores decreased during maximal exercise?
Breakdown of PCr is rapid and therefore can sustain the high rates of ATP production that are required.
How quickly can PCr stores be depleted?
Approximately 10 seconds
What percentage of PCr stores can be re-synthesised in 4 mins?
80% but to achieve 100% it takes much longer
Mechanisms of action with creatine supplementation
Increase Cr stores 30% = increase in PCr resynthesis
Increase muscle glycogen synthesis
Increase growth factor expression (may be reason for increased muscle mass)
Increase protein synthesis (not much evidence)
Decrease muscle damage
Which allows training to be harder, longer = increased lean muscle mass/strength
Creatine sources
Diet (red meat, some fish [salmon, tuna, cod])
Creatine monohydrate (CM)
- White powder (99% absorbed)
- Significant evidence
- Better uptake mixed with CHO
- Synthetic (therefore suitable for vegetarians)
Is there an acute effect to consuming creatine monohydrate?
NO
Describe the short, high dose protocol?
20 g/day (split dosage 4) for 5 days
0.3 g/kg BM (split in 3-4 doses for 5 days)
Describe the long, low dose protocol?
3-5 g/day for 20-30 days
What is the recommended maintenance dose?
2-5 g/day
How long is the washout period of creatine?
4-6 weeks
Benefits of creatine are significantly increased when consumed with CHO?
Yes - much better loading effect and the dosage would need to be significant e.g. 90 g of CHO
When is its use considered?
For single and repeated bouts of high intensity exercise
High intensity max effort < 150 sec, largest effects on <30 seconds task.
What are other applications of creatine? Endurance?
Recent evidence shows combination of creatine and CHO loading can increase power output during repeated sprint efforts during the late stages of prolonged simulated TT cycling
Other applications of creatine? Concussion?
Improvements in cognitive processing in the brain and potentially reduced damage and enhance recovery from mild traumatic brain injury/concussion
Individual variability?
Individuals that have high muscle creatine levels will experience low creatine uptake from supplementation.
Very sport dependant
