The supplementation has now also become popular among recreational weight lifters (1,4). When performing short duration high intensity exercise, the majority of energy comes from the adenosine triphosphate (ATP) - phosphocreatine (PCr) system. PCr helps to increase the rate of rephosphorylation of ADP to ATP through the use of the creatine kinase reaction (1,2,3,4,5). As the exercise proceeds and the PCr stores are depleted, the performance levels are reduced as the ATP cannot be restored at the rate it is consumed (1,2,3,4,5). It is important to remember that there is a limited supply of these two substrates, therefore in order for the supplement to have a positive effect, it must increase the total creatine (TCr) and in turn PCr concentration (1,2,3,4). The increase in PCr availability increases fatigue resistance, thus allowing the individual to train at higher volumes (2,3,5,6). Chrusch et al., reported an average of 31% greater training volume for the Cr group (267,914 kg*reps) compared to the placebo group (227,693 kg*reps) (6). This means that participants in the Cr group are able to train at higher work loads for a longer period of time compared to the placebo group for the given training period (6). The authors attributed this increase in training volume to be responsible for the significant increase in 1RM leg press for the …show more content…
They followed a similar creatine supplementation routine of 20g per day for 1 week. As this dosage is similar to previous studies, it neglects the argument that a low dosage may be responsible for negligible improvements seen in the strength performance in the participants. However, this does lead to the question of responders and non responders. Demant & Rhodes (9) reported that 5 out of the 8 participants showed a significant increase in Cr concentrations (19 to 35 mmol/kg dry muscle (dm)), while the other 3 showed minimal increase (8 to 9 mmol/kg dm). Upon further investigation, they found that those who showed significant increase (responders) had an initial Cr concentration of less than 120 mmol/kg dm, and those who did not, had a Cr concentration of greater than 130 mmol/kg dm (9). Similarly, Syrotuik and Bell (12) identified three categories based on the increase in Cr levels; responders (>20 mmol.kg-1 dw increase from preload levels), quasi responders (>10 and <20 mmol.kg-1 dw from preload levels), and non responders (<10 mmol.kg-1 dw from preload levels). The responders had an increase in 1RM for incline leg press scores (+25kg), while the quasi responders and non-responders did not observe a noticeable change in scores (+2.5kg and +2.0 kg respectively) (12). Creatine is mainly present in meats, thus vegetarians would have a lower resting creatine concentration