Creatine Supplementation in Athletes

editor — Tue, 18 Nov 2008 15:25:11 +0000

Over the years, numerous nutritional supplements have been purported to affect physiological responses to exercise, enhance training adaptations, and/or improve exercise performance. Although research has generally indicated that many of these nutrients do not affect performance, creatine has consistently proven to be one of the most effective nutritional supplements available to athletes. To date, over 200 research studies have evaluated the safety and effectiveness of short- and/or long-term creatine supplementation in various untrained, trained, and diseased populations. The majority of these studies indicate that short-term creatine supplementation (0.3 g/kg/day for 5 to 7 days) increases muscle creatine and phosphocreatine content by 10-30%, has the ability to improve the ability to maintain high-intensity single effort and/or repetitive sprint performance, and may improve work output during repeated sets of muscle contractions. There is also evidence that creatine supplementation may affect exercise bouts involving anaerobic glycolysis (30 to 150 sec) and high-intensity endurance exercise (150 to 600 see). The improved exercise capacity has been attributed to a creatinestimulated enhancement of the phosphagen energy system, the buffering of acidity, and the shuttling of mitochondrial ATP by phosphocreatine into the cytoplasm. Additionally, longterm creatine supplementation during training (e.g., 0.3 g/kg/ day for 5-7 days followed by 0.03 to 0.3 g/kg/day) has been reported to increase strength, sprint performance, and training volume, and promote greater gains in fat-free mass and muscle fiber diameter. These findings suggest that creatine supplementation may improve the quality of training, leading to greater training adaptations. Although not all studies report ergogenic benefit, it is my view that, with the exception of carbohydrate, creatine is the most effective nutritional supplement for athletes involved in high-intensity exercise bouts that rely on anaerobic energy systems.

Although creatine has been reported to be an effective ergogenic aid, there have been some concerns regarding the medical safety of creatine supplementation. Some reports, primarily in the popular media, suggest that creatine supplementation may adversely affect renal and liver function, cause long-term suppression of creatine synthesis, alter fluid and electrolyte status-promoting dehydration and muscle cramping, and/or increase the incidence of musculoskeletal injury in athletes. Additionally, some have expressed concern regarding possible side effects of long-term creatine use. Note that there is no evidence from well-controlled shortand/or long-term clinical studies (up to 5 yrs) to support any of these concerns. Furthermore, a number of recent studies that have attempted to evaluate the validity of these concerns have found no adverse effects of short- or long-term creatine supplementation on markers of clinical status.

This said, the question still remains as to whether athletes should take creatine to enhance performance. Adolescent athletes involved in serious training should consider creatine supplementation only with the approval and supervision of parents, trainers, coaches, and qualified health professionals. If the athlete plans to take creatine, quality supplements should be purchased from reputable vendors. Athletic administrators in organized sports who want to establish policies on creatine supplementation for teams should base such policies on the scientific literature. Any formal administration policy should be supervised by a qualified health professional. Although more research is needed, available studies indicate that creatine supplementation does not appear to pose a health risk when taken at recommended doses and may provide therapeutic benefits for various medical populations.

Creatine Monohydrate » anaerobic glycolysis

Creatine Supplementation in Athletes