Creatine Supplementation

13 proposed mechanisms of action it has been

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Unformatted text preview: to 1 minute). 1.3 Proposed Mechanisms of Action It has been suggested that Cr supplementation can act through a number of distinct mechanisms. First, if PCr concentrations are increased in skeletal muscle, PCr can then aid in the rapid rephosphorylation of adenosine diphosphate (ADP) back to adenosine triphosphate (ATP) by the Cr kinase reaction Sports Med 2005; 35 (2) The Effects of Creatine in Sport and Exercise during high-intensity, very short duration activities, especially if the bouts of intense activity are repeated with short rest periods between them.[7,8,14,15] Examples of this type of activity include sprints, jumping events and weight lifting. Secondly, it can enhance the capacity for high-energy phosphate diffusion between the mitochondria and myosin heads, thus, better enabling the heads to engage in crossbridge cycling and tension maintenance.[7,9,16] Thirdly, Cr can act to buffer pH changes brought about by an increasing acidosis by utilising the hydrogen ions during the Cr kinase reaction and the rephosphorylation of ADP to ATP and improve cellular homeostasis.[7,9] Fourthly, declining levels of PCr in the cell due to the increased need to rephosphorylate ADP can stimulate phosphfructokinase, the rate-limiting enzyme for glycolysis, thus increasing the rate of glycolysis in order to increase the rapid production of ATP.[7,9] Once again, activities lasting between 10 seconds and 2 minutes would benefit from this mechanism, i.e. 200m, 400m and 800m sprints. It has also been suggested that increased concentrations of PCr can be associated with muscle hypertrophy and increased protein synthesis. Cr may cause an osmotic loading effect resulting in the movement of extracellular water into the muscle cell, which is a stimulus for protein synthesis or by decreasing the rate of protein degradation.[17] Changes in body mass following Cr ingestion is somewhat controversial but often it is reported that significant increases occur.[18] Lastly, Cr has been suggested to shorten relaxation time during intermittent maximal isometric contraction by facilitating calcium uptake by the sarcoplasmic...
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This note was uploaded on 01/28/2014 for the course BI 231 taught by Professor Richardmay during the Fall '13 term at Southern Oregon.

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