Creatine

Question 1

Creatine

Answer 1

endogenously synthesised from amino acids (arginine, glycine and methoionine) in liver, pancrease and kidneys
>95% stored in skeletal muscle
~50% obtained from diet

Question 2

Creatine stores

Answer 2

2/3 intramuscular creatine = phosphocreatine (PCr)
1/3 free creatine
total creatine pool (PCr + Cr) = 120mmol/kg dry muscle mass
upper limit = 160 mmol/kg dry muscle mass

vegetarians = lower intramuscular creatine stores (90-110 mmol/kg dm)

Question 3

Creatine turnover

Answer 3

synthesis = excretion
~ 2g/day

Question 4

Creatine synthesis

Answer 4

~2 g/day

1g endogenous
1g exogenous (diet)

Question 5

Creatine exretion

Answer 5

~2 g/day
creatinine (urine)

Question 6

Increasing muscle creatine levels

Answer 6

4 x 5g (20g) creatine for 5 days
= total creatine content increased

Question 7

Effects creatine

Answer 7

increase max work and total work done in 30 sec (isokinetic cycling)
enhance resistance to fatigue
creatine and muscle hypertrophy
increase PCr resynthesis = short-term, high intensity exercise, capacity to perform repeated bouts of high-intensity effort
endurance exercise
brain health - anti-inflammatory and anti-oxidant effects
hypertrophy = creatine + resistance training

Question 8

Creatine metabolism

Answer 8

creatine
phosphocreatine
= creatinine

resynthesize ATP from PCr via enzyme creatine kinase

Question 9

Creatine stores during exercise

Answer 9

PCr levels higher in type II than type I
decrease during max exercise (breakdown sustains high rates ATP production)
depleted in ~10s
80% re-synthesised in ~4mins

Question 10

Supplementation with creatine effects

Answer 10

increase Cr stores 30% = increase PCr resynthesis
increase muscle glycogen
increase growth factor expression
increase protein synthesis
decrease muscle damage
training harder/longer = increase lean mass/strength
drive muscle hypertrophy

Question 11

Creatine sources

Answer 11

diet red meat - beef/pork, fish - tuna, salmon, cod, herring = not enough
creatine monohydrate (CM) white powder 99% absorbed - better uptake mixed with carb containing liquid or food
synthetic (sustainable for vegetarians and vegans)

Question 12

Short high-dose loading protocols

Answer 12

20g/day split in 4 doses for 5 days
0.3g/kg BM split in 3-4 doses for 5 days

Question 13

Long-low dose loading protocol

Answer 13

3-5g/day for 20-30 days

Question 14

Maintenance day

Answer 14

2-5g/day

Question 15

Washout period

Answer 15

4-6 weeks

Question 16

Co-ingestion creatine

Answer 16

ingest with consumption anything that triggers insulin response (carbs) = higher rate absorption and retention

Question 17

Creatine use

Answer 17

single and repeated bouts of high-intensity exercise
high-intensity max efforts <150 sec, largest effect on <30 sec task
power and strength sports (sprints/weightlifting)
team sports
resistance/interval training
endurance
concussion - reduce damage/enhance recovery/improve cog processing
increase body mass

Question 18

Individual variability creatine

Answer 18

individuals high muscle creatine levels = experience low creatine uptake from supplements
low levels = high uptake = greatest potential for increase in response to supplementation

sport performance not determined by PCr availability = creatine no effect

Question 19

Creatine concerns

Answer 19

increase body mass (1-2 kg) - water retention = counteractive for endurance/weight sensitive sports (consider washout period)

myths - no evidence causes kidney damage, muscle cramps, strains, damage/injury or affects fluid balance and heat dissipation

Question 20

Creatine safety issues

Answer 20

no evidence adverse effects with long term use
mild, temporary gut upset - alter with split dose/longer loading protocol/avoid high fibre food with ingestion
contamination - doping risk/use batch-tested supplements