A Critical Review of Contemporary and Popular Reports Within the ‘Lay’ Literature on the Use of Nutritional Supplements for Performance Benefits.

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A critical review of contemporary and popular reports within the ‘lay’ literature on the use of nutritional supplements for performance benefits.

There is an endless list of ergogenic aids that claim to enhance sports performance that are religiously supplemented by amateur and professional athletes. Almost half of the general population have reported taking at least one form of dietary supplement, and the vast majority, if not all professional athletes use legal supplements, with a certain few resulting to using illegal methods to improve their performance (Ahrendt, 2001). Currently, the Australian Institute of Sport (AIS) provides a program list of supplements classified into four groups according to their effectiveness, safety and legal status as reviewed in scientific studies. (AIS, 2011). The supplements in; Group A are supported for use in specific situations in sport; Group B are considered for provision to AIS athletes only under a research protocol; Group C show little proof of beneficial effects and the supplements in Group D should not be used by AIS athletes. Creatine has been reported as the top-selling nutritional supplement in the world, mainly due to it being, affordable, relatively free from side-effects and because it works. Creatine is made up of three amino acids; glycine, arginine, and methionine. The liver naturally produces about 1 gram (g) of creatine per day; the rest is mainly found in foods such as meat and fish. An average diet will also ingest about 1g of creatine per day. Creatine as a supplement can be taken in the form of a tablet or as a powder to be mixed with water. It is generally claimed (Smith, 2011) that supplementing creatine has several benefits for hard training athletes as when creatine is taken, it bonds with phosphate molecules to form creatine phosphate (CP). The phosphate molecules in creatine phosphate are then able bond with adenosine diphosphate (ADP) to form adenosine tri-phosphate (ATP), the energy currency of the cell, used in all cellular functions and muscular contraction. Therefore, it is believed that supplementing creatine will cause an increase in the body's ATP production leading to performance improvements and decreased fatigue in intense, short duration exercise such as weightlifting and sprinting (McArdle et al, 2007). Additionally creatine is thought to benefit athletes as it improves hydration of muscle cells. (Mens Health, 2011). Creatine draws fluid from outside the muscle cell into the cell membrane. Due to the increase in water retention of the muscle cell, other ions such as nitrogen are drawn into the muscle cell leading to an increase in muscle protein synthesis allowing athletes to recover from exercise faster and increase muscle growth (Mens Health, 2011). Creatine supplementation is recommended to be specifically beneficial to athletes participating in high intensity exercise that require short, sharp bursts of energy. (McArdle et al, 2007). There is a considerable body of research studies that supports the efficacy of creatine in increasing body mass and performance in high intensity, short duration exercise. A study by Kraemer et al (1997) was undertaken to investigate the effect of creatine supplementation on muscular performance during high-intensity resistance exercise. The researchers compared the effect of 25g/day creatine supplementation for a week against that of a placebo on 10 repetition maximum bench press and squat in 14 active men. They found that there was no improvement in the placebo group, but those men supplementing creatine had significant improvements in both their maximum bench press and squat. Additionally, the participants who were supplementing creatine showed a body mass increase of upto 3kg. A similar study by Tarnopolshy and MacLennon (2000) also found that active men and women who supplemented creatine also showed an improvement in an anaerobic cycle test, 1RM leg extension and grip strength. The participants...
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