Week 9 - Creatine

Question 1

Where is creatine synthesized?

Answer 1

endogenously synthesised from AA (arginine, glycine and methionine) in the liver, pancreas, and kidneys

Question 2

Where is creatine stored?

Answer 2

> 95% stores in skeletal muscle

Question 3

What % of creatine is obtained from diet?

Answer 3

50% - meat and fish

Question 4

In what form is creatine stored in the muscle?

Answer 4

2/3 Phosphocreatine (PCr)
1/3 Free creatine

Question 5

What is the average total creatine pool in muscles?
What about the upper limit of creatine storage?

Answer 5

120 mmol/kg dry muscle mass
160mmol/kg dry muscle mass

Question 6

What is the average IM creatine stored in vegetarians?

Answer 6

90-110mmol/kg dry muscle

Question 7

In terms of creatine turnover, how much is synthesized and how much is excreted?

Answer 7

Synthesis - 2g/day –> 1g endogenous + 1g exogenous (diet)

Excretion - 2g/day –> creatinine (urine)

Question 8

During a 30sec cycling exercise bout, what are the benefits of increased creatine?

Answer 8

Maximal work and total work increases.

Question 9

What does creatine enhance?

Answer 9

resistance to fatigue

Question 10

What are the benefits of combining creatine supplementation and resistance training?

Answer 10

Hypertrophy - small increase of skeletal muscle hypertrophy in both the upper and lower body.

Question 11

What is the main effect of creatine supplementation?

Answer 11

Increases PCr resynthesis
- This increases short-term, high-intensity exercise capacity to perform repeated bouts of high-intensity effort.

Question 12

Describe the mechanism of action of creatine supplementation.

Answer 12

Its important in Phosphocreatine resynthesis. It increases levels of creatine in the muscle which means we can take a phosphate from ATP to add to creatine making phosphocreatine (via creatine kinase).

Question 13

PCr levels are higher in which type of fiber?

Answer 13

type II fibers

Question 14

When are PCR levels decreased? How long does it take for PCr to be depleted?

Answer 14

During maximal exercise (because its breakdown sustains high rates of ATP production) + 10seconds

Question 15

How long does it take for 80% re-synthesis of PCr?

Answer 15

4 minutes

Question 16

What are the benefits of creatine supplementation?

Answer 16

• Increased Cr stores 30% = Increased PCr resynthesis
• Increased muscle glycogen
• Increase growth factor expression
• Decreased muscle damage
• Training harder and longer = increase lean mass/strength

Question 17

What are the best creatine sources?

Answer 17

• Diet - red meat (beef/pork) and fish (tuna, salmon, cod, herring)
• Creatine monohydrate (CM): white powder, 99% absorbed, better uptake mixed with a carb containing liquid or food, synthetic (suitable for vegetarians and vegans)

Question 18

Describe a short, high-dose creatine loading protocol.

Answer 18

• 20g/day (split into 4 doses) for 5 days
• 0.3 g/kg BM (split into3-4 doses) for 5 days

Question 19

Describe a long, low-dose creatine loading protocol.

Answer 19

3-5g/day for 20-30 days

Question 20

How much would be a maintenance dose of creatine?

Answer 20

2-5g/day

Question 21

Does creatine have an acute effect?

Answer 21

No - we need loading protocols

Question 22

When is creatine supplementation most effective? Explain why.

Answer 22

When its co-ingested with carbohydrates or carbs + protein.

When you combine creatine supplementation with carbs, carbohydrates produce an insulin response which means creatine uptake into the muscle is more effective leading to greater phosphocreatine and creatine.

Question 23

What is an issue with co-ingestion of creatine with carbs?

Answer 23

Massive amounts of carbs are required to maximize muscle creatine content.

Insulin response becomes hampered as time goes on so its more of a one off type protocol.

Question 24

Using examples, when should we consider the use of creatine supplementation?

Answer 24

 Single (+1-5%) and repeated bouts (+5-15%) of high-intensity exercise.
 High-intensity max efforts <150 sec, largest effects on
<30 sec tasks.

Examples include;
- Power and strength sports: 100m, weightlifting
- Intermittent sports: hockey, football
- Resistance training aimed to incr. lean mass and muscular strength.

Question 25

What has recent evidence shown on the effect of the combination of creatine and CHO loading during prolonged TT cycling?

Answer 25

it may increased power output during repeated high-intensity sprint efforts during the late stages of prolonged TT cycling

Question 26

How can creatine supplementation reduce concussions?

Answer 26

Improvements in cognitive processing in the brain and potentially reduced damage and enhance recovery from mild traumatic brain injury/concussion.

Question 27

What are individual variability considerations in creatine supplementation?

Answer 27

Baseline levels of muscle creatine
- Individuals with high muscle creatine levels will experience low creatine uptake from supplements.
- Individuals with low muscle creatine levels have the greatest potential for increases in response to supplementation.

Sport type
- In sports where performance isn’t determined by PCr availability (or fast ATP resynthesis) creatine supplementation will likely not have any effects (e.g. ultra-endurance or exclusively skill-based).

Question 28

Why may there be an increase in body mass (1-2kg) when taking creatine?

Answer 28

likely as a result of water retention

Question 29

How long would a washout period after using creatine be?

Answer 29

4-6 weeks

Question 30

Are there any safety concerns with taking creatine? How can this be attenuated?

Answer 30

Mild, temporary gut upset can occur but can be attenuated with split dose, longer loading protocol and avoidance of high fibre foods with ingestion.