05 Creatine - Lecture notes 5 PDF

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Optimal strategies, dose, and performance impact of the supplement....

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04/03/19

05 Creatine Learning Outcomes - Describe the effects of creatine Supplementation on performance in different exercise and sports settings (Certain setting where creatine can be useful for performance and training adaptations) - Describe creatine metabolism and considerations for creatine supplementation (Do we need to co ingest for best responses??) - Explain the mechanisms for improved performance following creatine supplementation - Make recommendations for best practice with creatine supplementation

Background Info - Non-essential amino acid compound (a-methylguanidinoacetic acid) - An average 70kg adult has a total body creatine pool of ~120g - Most of the creatine pool is stored in skeletal muscle (95%) (65% as PCr- Used to resynthesise ATP during periods of high ATP turnover) - Creatine stored more in fast twitch fibres (Type II) than slow twitch fibres (Type I) (Role in more forceful contractions) - Creatine is spontaneously and continuously degraded to creatinine at a rate of ~2g per day (~1.6%), its not fixed at 120g all the time, have to think about the supply demand - Continued creatine synthesis required to maintain muscle creatine pool

- Can we get creatine through the diet?? - Creatine- Nitrogenous compound- Meat is the largest natural source of creatine (Beef- ~4.5g/ kg) (Pork ~5g/kg) - Fish- Salmon (4.5g/kg), cod (3g/kg), tuna (4g/kg) - Milk (~0.1g creatine/kg)

- Balanced diet- People get around 1g/day - If your eating more meat and or kcals are higher, you will be getting more creatine through the diet

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Considerations for Food Preparation - Cooking time will lower the creatine content of the meat - Boiling for 20min lowers creatine content by 10% (Cooking a broth) - Boiling for 60min lowers creatine content by 30% (Slow cooker) - What do you do with the water? The creatine leaks into the water

Background Information (Synthesis of creatine)

Arginine Glycine AGAT   Ornithine Guanidinoacetate GAMT   Creatine - Creatine can be endogenously synthesised in the kidney, liver and pancreas (But not skeletal muscle) from three amino acids: - L-Arginine (Semi-Essential) - Glycine (Semi-Essential) - Methionine (Essential)

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- Creatine not formed in the skeletal muscle (Inter organ process) - Naturally synthesise 1-2g/day

- Arginine and Glycine combine in the kidney - Which forms GAA + L-ornithine (Enzyme- AGAT) - This then moves into the blood stream - Methionine then added in the liver, to make creatine Typically- This process synthesises 1-2g/d

Depending on the diet (Intestine)- We can then add an additional 1-2g/day to the system and maintain what the body uses naturally - So the net balance, close to 0

- AGAT- Arginine Glycine AmidinoTransferase - GAA- Guanidoacetic Acid - GAMT- Guanidinoacetate methyltransferase - AdoHcy- S-adenosyl-L-homocysteine - AdoMet- S-adenosyl-L-methionine

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History of Creatine Use by Athletes - Performance- Popularity of creatine as an ergogenic aid arose following reports that British sprinter used this to win gold medals at the Barcelona Olympics - Been around for quite some time - Creatine supplementation is a very popular supplement -US alone- $400m spent per year on creatine! - Its use is more prevalent in males

How does Creatine Supplementation Work??

     ATP  Cr PCr  ADP  H    CreatineKinase - Creatine produced in combination with kidney and liver - Main storage form of creatine in the body- Phosphocreatine (PCr) - PCr- Important for high intensity, short duration tasks - Bigger PCr store- Larger store to complete the high intensity bout of muscular work, providing the fuel for CK equilibrium reaction, to then restore ATP for muscular work - We break down the creatine- By liberating PCr, then donating the phosphate to ADP to reform ATP

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Think about muscle metabolism in different ways - Have lots of fat- But cannot use it at a such intensity (Very slow ATP turnover rate that would not be sufficient for high intensity exercise) - Very low capacity for PCr, but the turnover rate is very fast - Short term training does NOT improve muscle creatine and PCr storage - Creatine and PCr content of type II (Fast-twitch) muscle is greater than type I (Slow twitch muscle) - Sprinters- Higher muscle creatine and PCr content than endurance athletes (Faster ATP turnover rate for longer)

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Creatine Supplementation Strategies

- Plasma creatine increases dose dependently - 20g in one go- You will pee it all out (Can only transport a certain amount of creatine in one go)

- A single creatine dose not sufficient to optimise muscle creatine stores - Maximal transporting capacity of creatine- At around 400umol/L (Which is around 5g) (No point taking any more, protein transporters saturated, and you will pee it out) - Creatine HAS to be taken in smaller doses – As the transporter is working at a maximal rate and cannot take any more into the muscle (No point just taking it into the blood, need it in the key organ of interest) - Best approach- Repeated doses- 4-6 x 5g doses daily with ~4hrs between each dose

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Harris et al. 1992 Clin Sci - First to shown increased Total Creatine and PCr in human skeletal muscle after 4-7 days supplementation with 5g consumed 4-6 times per day

- Long periods- 4-7 days- Found an increase in total muscle creatine from 126.8mmol/kg to 148.6mmol/kg- More ability to produce high sustainable muscular contractions - Can then generate more ATP through the PCr/ATP pathway - Of the increase- 20-40% was PCr (~8mmol/kg dm) - Beef contains 4.5g/kg of beef- Need to eat 6kg of beef to get that 5g (Need to supplement! Have to supplement!)

04/03/19 - Creatine retention- Measurement of urinary creatinine (Excreting out the creatine- starting to saturate the muscle) - Over 7 days- Body starts removing more creatine, muscles are saturated - 3 day supplementation period (6 x 5g/day)- 40% of creatine returned in urine on day 1, 61% on day 2 and 68% on day 3 - As you extend the days of supplementation, the amount of ingested creatine excreted in urine increases

- Not everyone responds to it- 2 participants were non-responders (Harris et al. 1992), these participants already had high total muscle creatine (>145mmol/kg dm) - If you are close to the threshold at the start of supplementation, you are going to excrete a lot fo the urine out

- Ability to increase total creatine and PCr, linked to pre-supplementation levels of muscle total creatine and PCr

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Creatine & CHO

- Do you need to co-ingest? CHO linked with creatine supplementation - Muscle creatine uptake is insulin dependent (Same as AA- Amino Acids) - Good creatine uptake particularly with simple sugars - Grey circles- The greater the insulin infusion rate, the amount of PCr in the muscle increases linearly - Take creatine on board with some simple sugars!

- Further evidence of better creatine infusion when creatine ingested with CHO - Issue- First studies- Each 5g creatine dose was accompanied with 93g of CHO - 93g of simple sugars 4x per day- Not great with overall health - More recent studies- Ingesting 1g CHO/kg bm 2x daily can increase muscle creatine stores - If you don’t want to load it up with CHO, you may just have to creatine load for a longer period

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Creatine around Exercise - Theory- Exercise will aid blood flow and that might aid the depositing of creatine within the muscle

- Lower bars- Better (Less urinary output) - Results again support the intake of creatine with CHO - Taking creatine around exercise- Kind of debunked (Just as effective as taking creatine with some simple sugars) - Effect of insulin more important than muscle blood flow for increasing muscle creatine stores

Creatine Supplementation Ceiling - There’s a ceiling for muscle creatine stores (150-165mmol/kg)- Usually achieved after 3-7days of supplementation with 20g/day in 5g servings

- Maintenance doses- 2g maintenance dose of creatine maintains muscle creatine stores - Taking the creatine- Loading phase- 20g per day for 4-7 days, then have a maintenance phase of 2g for 1 month, then have a week off! - Need to cycle creatine- If you keep taking it at 20g/day- Body will ultimately lower the amount of creatine in your skeletal muscle for you

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- Loading phase- It Is necessary to load to reach the maximal muscle creatine

Creatine Supplementation and Exercise Performance - Endurance performance (90s)- Very little evidence to suggest- Only potential in the end sprint - Creatine more likely to be negative than positive (Side effect- Weight gain will compromise power to weight ratio and running economy- DO NOT recommend to endurance exercise) - Creatine supplementation can improve performance in short duration, maximal intensity events (...