1. Creatine Supplementation

2. What is Creatine? Naturally occurring constituent found in food Also synthesized in the kidneys, liver, and pancreas from amino acids arginine, glycine, and methionine.

3. Where is Creatine Found? Creatine is a naturally occurring amino acid found in the body (primarily muscle tissue) The daily requirement of creatine is about 2-3 grams/day About half of the daily needs are obtained from the diet (primarily meat and fish) The remaining daily need for creatine is synthesized from the amino acids glycine, arginine, and methionine primarily in the liver

5. Creatine Stores Normal creatine content in muscle tissue is 120-140 mmol/kg dm (60% as PCr, 40% as Cr) Dietary availability of creatine may result in higher or lower stores Creatine supplementation can increase creatine stores to as much as 160 mmol/kg dm

6. Forms of Creatine Supplements Creatine Monohydrate – Most Common Creatine Phosphate Creatine Citrate Creatine blended w/CHO, Proteins, AA, Caffeine –Powders –Tablets –Gel –Liquid

7. Supplement Strategies Load 20 g/day (4 equal doses 5g) - 5-7 days –Increase TCr stores approx. 20% (Grande) Maintain 3-5 g/day (0.03 g/kg) Others recommend 2-3g/day over longer load period (1mo.)- just as effective

8. Factors Affecting Cr Loading Success Cr w/ CHO (glucose) = Insulin Effect –Studies shown 60% greater increase in TCr stores over Cr only Ingestion following exercise is best Greatest increase occur in those with lowest initial levels There are responders and non-responders (20- 30%) Best response is in Type II muscle. No differences between genders

9. Documented Side Effects Potential side effects are minor Gastrointestinal (GI) distress No renal or liver dysfunction No cramping in controlled studies Increased Body Mass (water retention in muscle cell due to osmotic changes) Urinary Volume decrease during loading

10. Creatine Enhancing Performance

11. Function of Creatine The body only has limited stores of ATP & ADP When a Cr supplement is ingested, & enters the intestines, a majority of Cr is absorbed into the bloodstream. Cr from bloodstream is taken up by skeletal and cardiac muscle through insulin-mediated active transport

12. Function of Creatine (cont.) After absorption, a portion of Cr combines with phosphate to form PCr This storage of Cr and PCr allows rapid resynthesis of ATP to meet energy demands via the creatine kinase (CK) reaction Theoretically, Cr supplementation will increase Cr and PCr stores, providing more PCr to be utilized in CK reactions

13. History of Cr Supplementation Soviets and Eastern block countries began using Cr as potential performance (1960’s & 70’s) First real studies of Cr supplementation for performance enhancement began in 1990’s in US and GB GB Olympic Champions Linford Christie (100m) and Sally Gunnell (400 hurdles) - 1992 Barcelona games

14. Mechanisms of Performance Enhancement Increased PCr concentrations in muscle should aid in rapid resynthesis of ATP via the Cr kinase reaction Increases PCr diffusion between mitochondria and myosin heads. Reduce muscle acidity by consuming H+ in process of ADP-ATP –Muscle can accumulate more lactic acid before reaching limiting muscle pH = Increase duration of high intensity exercise

15. Mechanisms of Performance Enhancement Causes osmotic changes in muscle cell which increases water content of cell –Stimulus for protein synthesis –Decreases rate of protein degradation Facilitates calcium uptake by the sarcoplasmic reticulum which shortens relaxation time.

16. Does IT Work? High intensity, short duration activities lasting < 2 min especially repeated with short rest periods Sprints, jumps, weight lifting, sprinting, etc.

17. Does It Work? (cont.) No effect in continuous aerobic activities Effective in both genders Effective in young and old. Effectiveness is greatest in novice athletes.