Performance and Drugs: Creatine/Caffeine

Normal creatine levels

• 120 mmol/kgDW

What percent of creatine is stored as phosphocreatine in muscle?

• 2/3

How much creatine does the body need to replenish and maintain normal storage?

• 1-3g creatine/day

Where is creatine produced?

• kidneys and liver from arginine and glycine

1lb of uncooked beeg/salmon contains____g of creatine

• 1-2g

Supplementation of creatine monohydrate can increase muscle creatine store by ___

• 20-40%

what is the typical loading dose of creatine?

• 5g(o.3g/kg) for 5-7days

How long till creatine levels go back to normal?

• 4-6 weeks

What population responds best to creatine use?

• elderly

• vegetarians

True/False: Creatine can help with early dementia

• true

What enzyme converts creatine to PCr?

• creatine kinase

ATP is high at rest so creatine kinase drives reaction towards___

• PCr formation (creatine to PCr)

During exercise ATP is low and ADP rises, creatine kinase drives the reaction towards___

• ATP regeneration

What is PCr responsible for?

• regenerate ATP

• converts ADP to ATP

What are the ergogenic benefits of creatine supplementation?

• single and repetitive sprint performance

• work performed during sets of maximal effort muscle contraction

• muscle mass and strength adaptations during training

• anaerobic threshold

• work capacity

• enhanced glycogen synthesis

• enhanced recovery

• greater training tolerance

What are the adverse effects of creatine supplementation?

• weight gain

What is the primary fuel for high intensity, short duration exercise?

• ATP-PCr

PCr is depleted in ____ seconds during high intensity exercise

• 10-15 seconds

PCr can be completely recovered in ___ seconds after intermittent exercise

• 60-120 seconds

Caffeine

Is caffeine prohibited?

• no

• only monitored

What are the ways to consume caffeine?

• gums

• drink

• capsule

Which method of administration works fastest?

• gums increase speed of absorption

What is the typical half-life of caffeine?

4-6 hours

Peak caffeine concentration occurs ___ minutes after oral ingestion

• 30-120 minutes

Is caffeine effected by 1st pass metabolism?

• no

• bioavailability near 100%

Where caffeine absorbed?

• GI tract

Caffeine is chemically classified as _____

• methylxanthine

Where is caffeine metabolized?

• liver (>95%)

What are the primary metabolites of caffeine?

• paraxanthine

• theobromine

• theophylline

The primary metabolites are further broken down into ____. Where is caffeine excreted?

• urates

• excreted in urine

What enzyme is responsible for 95% of caffeine metabolism?

• CYP1A2 enzyme

Slow metabolizers have a ___ number of CYP1A2 enzymes

• low

What risk are slow metabolizers susceptible to when they consume caffeine?

• myocardial infarction

• hypertension

• elevated blood pressure

• pre-diabetes

Caffeine acts via _____

• adenosine receptor antagonism

What are the effects of adenosine receptor antagonism?

• increased neurotransmitter release

• increased motor firing rates

• pain suppression

• alters catecholamine release

Caffeine has high affinity to the ____ adenosine receptors

• A1 and A2 adenosine receptors

Performance effects of caffeine

• increased time to exhaustion

• increase alertness

• improved reaction time

• improved glycogen resynthesis in recovery (with carbs)

what is a lethal dose?

• Absolute dose of 10g. Relative dose of 140 mg/kg

What dose of caffeine is most beneficial?

• 0.1-0.2 g

• 1.5-3.0 mg/kg

What are the side effects of caffeine?

• tachycardia, arrythmia, tremor

• increased BP

• sleep disturbances

• headache, nervousness

What dose of caffeine seems to be most effective without symptoms?

• 3-6 mg/kg body weight

Who tends to benefit most from using caffeine during anaerobic exercise?

• trained individuals

Who will respond more to 200 mg caffeine, slow or fast metabolizer?

• slow metabolizer