Why supplement with creatine?

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Why supplement with creatine?

• The energy that fuels most metabolic functions
  comes from the splitting of high-energy phosphate
  compounds.
• ATP is the major source of fuel for metabolism.
  ATP is constantly resynthesized so that there is
  a continual source of ATP for biologic work.
• The major energy sources for ATP resynthesis are
  fats and carbohydrates. However, phosphocreatine
  (PCr) is another high-energy phosphate that can
  be hydrolyzed to provide the energy to form ATP
  from ADPP (it is often called an energy
  reservoir).

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• Creatine is found in meat, poultry, and fish.
  Until recently, scientists believed that
  vegetarians had normal levels of muscle creatine
  because the body synthesizes creatine from amino
  acids in the diet.
• However, a study
• published in 2003
• offers the first
• evidence that
• vegetarians
• have lower muscle
• creatine.

Tarnopolsky et al MSSE 2003
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amino acid
excreted in the urine
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• About 95 of the bodys total creatine is
  contained in skeletal muscle as one of two forms.
• PCr (60) and free creatine (40).
• CK stimulated to hydrolyze PCr to Cr by buildup
  of ADP. This makes sense since a large amount of
  ADP is indicative of low energy in the cell and
  PCr is used to create more ATP.
• PCr is referred to as buffering the ATP levels
  in the cell - meaning the presence of PCr keeps
  ATP levels from falling.

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Creatine Metabolism
ATP
ADP
H
Creatine Kinase (CK)
Creatine
Phosphocreatine
Pi
H2O
H2O
Creatinine
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• PCr is used as an energy source for quick,
  intense bouts of work.
• H PCr ADP ? ATP Cr
• enzyme is creatine kinase (CK)
• The idea behind creatine supplementation is that
  increasing the bodys stores of PCr will provide
  an advantage for high power, short-duration work.
  
• The key was thought to be an increase in PCr.

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• As the data below show, PCr is the predominant
  energy source for ATP synthesis for very short
  duration, high intensity muscle contraction.
• Rate of ATP production (mmol/sec/kg) during
  maximal contraction in human muscle
• Duration
• PCr glycolysis
• 0-1.3 sec 9.0 2.0
• 1.4-2.5 sec 7.5 4.3
• 2.6-5 sec 5.3 4.4
• 5-10 sec 4.2 4.5
• 10-20 sec 2.2 4.5
• 20-30 sec 0.2 2.1 Greenhaff, Int.
  J. Sport Nutr. 1995

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• PCr may also shuttle intramuscular phosphate
  between the mitochondria and muscle filament
  cross-bridge sites (the actual sites of muscle
  contraction).
• Theoretically, high levels of PCr should also
  lessen the reliance on anaerobic glycolysis.
  Remember that H ions are produced during
  glycolysis which are buffered by pyruvate which
  reduces to lactate.
• The rate controlling step of glycolysis is
  catalyzed by an enzyme called phosphofructose
  kinase (PFK). PCr levels exert some control over
  the activity of this enzyme. As PCr levels
  decrease the activity of PFK goes up, increasing
  the rate of glycolysis.

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Potential mechanism
ATP ? ADP
mitochondria
? ? ATP ? ADP Cr ? CrP
? ? ? ? Cr
? CrP ATP ? ADP
Actin and myosin
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Summary Role of PCr in Muscle

• 1. Fast production of ATP (maximal work?)
• 2. Buffers change in ATP/ADP (maintain high rate
  of work?)
• 3. Faster high energy phosphate diffusion (faster
  recovery?)
• 4. Buffers intracellular hydrogen ions (less
  fatigue?)
• 5. Reduced PCr, increased Pi may activate
  glycolysis (less reliance on glycolysis less
  glycogen use?

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Cr Supplementation Era

• 1993 - 2000 ??? human studies
• Major focus
• Exercise performance
• Body composition
• Optimizing uptake
• Recent Studies
• Clinical - elderly, muscle disease, CHF, COPD,
  Arthritis, Gyrate Atrophy other diseases

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Cr Supp Performance

• Exercise performance involving short periods of
  extremely powerful activity can be enhanced,
  especially during repeated bouts.
• .enhanced accrual of strength in
  strength-training programs.

Terjung et al. ACSM Creatine Roundtable. MSSE,
2000
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Creatine and Performance

• N 8 fit men/group
• Randomized, double-blind
• 30 g Cr/d for 6 d
• 4 familiarization trials
• 10 x 6s maximal cycling
• 30s rest intervals
• Target rpm 140/min
• Balsom et al., Scand. J. Med. Sci.
• Sports 3143-149, 1993

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Kreider et al (1998) Effects of creatine
supplementation on body composition, strength,
and sprint performance.

• Creatine (16 g/d) 11 football players
• Placebo 14 (matched on
  body weight)
• Resistance training 4 d/wk monitored
• Sprint/agility training 3 d/wk Diets
  monitored

Addition of creatine to the glucose/taurine/electr
olyte supplement promoted greater gains in
fat/bone- free mass, isotonic lifting volume,
and sprint performance during intense
resistance/agility training.
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• Becque et al.  Effects of oral creatine
  supplementation on muscular
• strength and body composition. MSSE, 2000
• Biceps training for 6 weeks with either Cr
  (20g/d for 5 days and then 2g/d) or placebo.
• After 6 weeks increase of 2.0 kg in Cr group
  (0.4 with placebo) with FFM increasing 1.6 kg.
  Upper arm area incr. 8 cm3 with Cr and 2.5 cm3
  with placebo.
• 1 RM incr. 2x more with Cr than with training
  alone.
• Authors conclude creatine supplementation
  during arm flexor strength training lead to
  greater increases in arm flexor muscular
  strength, upper arm muscle area, and fat-free
  mass than strength training alone

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Cr Supp Body Mass

• Consistent ? in body mass (1 - 3 kg)
• Acute - Most likely water retention
• ? urine vol. during Cr supp (Hultman et al. 1996)
• Water retention 1st?
• Protein synthesis 2nd?
• Both together?

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Cr Protein Synthesis

• ? synthesis of myosin, actin, CK in vitro in
  vivo (Ingwall et al. 1972 -1976)
• Rat Studies
• ? protein content (Flisinska - Bojanowska 1996)
• Ø in CK or myosin (Brannon et al. 1997)
• ? satellite cell activity (Dangott et al. 2000)

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How to use creatine effectively...

• Remember, the benefits of creatine are related to
  an athletes ability to train harder.
• This means that creatine alone (without training)
  likely wont increase strength.
• Most common creatine supplementation regime
• LOADING PHASE 5-10 days (20-25g/day)
• MAINTENANCE PHASE (2-5g/day)
• Goal of maintenance phase is maintain muscle
  saturation.
• Creatine absorption appears to be enhanced when
  the supplement is taken with a high CHO drink
  (ex juice)
• - Tarnopolsky et al., 2001

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Cr uptake and Glucose ingestion
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Creatine and Body Mass Conclusions

• Body mass does tend to increase with creatine
  supplementation.
• 2. The increase is almost exclusively fat free
  mass
• 3. Although there may be some retention water in
  the short-term, there is some evidence that
  longer-term use (gt6-8 weeks) may increase
  myofibrillar protein?
• 4. Do size and strength gains result because
  creatine allows faster recovery between bouts so
  that people can train at a higher
  intensity/longer duration?

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Creatine and Caffeine

• Vandenberghe et al. (1996) looked at whether
  combining Cr and caffeine would increase Cr
  uptake by muscle.
• 0.5g/kg BW of Cr
• 0.5mg/kg BW of caffiene (equivalent to about 3
  cups of coffee for 70kg male)
• Expected additive effect but Cr in muscle was
  same with or w/o caffeine.
• Unexpectedly, addition of caffeine eliminated
  ergogenic effects of creatine on knee extensor
  force.

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This recent work suggests that caffeine
ingestion disrupts the mechanism through which
creatine ingestion increases muscle creatine
levels.May be due to muscle contraction
relaxation time being prolonged (Hepsel et al
2002) thereby interrupting recovery of
PCr?Based on these and other studies, athletes
who use creatine are often told to abstain from
caffeine during the loading phase of creatine
supplementation when loading the muscleCaffiene
known to enhance prolonged bouts of exercise, not
necessarily high intensity exercise
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Side Effects

• Anecdotally reported
• Gastrointestinal distress
• Nausea
• Dehydration
• Muscle cramping
• Long term effects of creatine supplementation
  have not been documented in healthy individuals
  but no adverse events have been linked to
  creatine use gt 5yrs.
• Individuals with pre-existing kidney or liver
  dynsfunction often not recommended to ingestion
  Cr supplementation

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• Conclusions from a host of different studies
• Creatine supplementation increases total Cr, but
  not necessarily CR-P in skeletal muscle
• 2. Size of the increase is related to initial
  Cr levels (start low bigger response) and
  individual responses vary a lot
• 3. In many people, Cr supplementation enhances
  performance of repeated, high-intensity exercise
• 4. Caffeine use (and probably hard training)
  probably reduce the size of the creatine effect

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• Conclusions from a host of different studies
• 5. Supplementation results in an initial
  increase in body mass (likely due to water
  retention)
• May have an age related effect. Older
  individuals may show greater improvement
  compared to younger individuals. Not clearly
  shown.
• Seems that there is no clear effect of training
  status or gender on performance outcomes after
  creatine supplementation. (Due to large variance
  among individuals taking creatine)