The effects of creatine dietary supplementation on anterior compartment pressure in the lower leg during rest and following exercise

Dietary supplements and team-sport performance

A well designed diet is the foundation upon which optimal training and performance can be developed. However, as long as competitive sports have existed, athletes have attempted to improve their performance by ingesting a variety of substances. This practice has given rise to a multi-billion-dollar industry that aggressively markets its products as performance enhancing, often without objective, scientific evidence to support such claims. While a number of excellent reviews have evaluated the performance-enhancing effects of most dietary supplements, less attention has been paid to the performance-enhancing claims of dietary supplements in the context of team-sport performance. Dietary supplements that enhance some types of athletic performance may not necessarily enhance team-sport performance (and vice versa). Thus, the first aim of this review is to critically evaluate the ergogenic value of the most common dietary supplements used by team-sport athletes. The term dietary supplements will be used in this review and is defined as any product taken by the mouth, in addition to common foods, that has been proposed to have a performance-enhancing effect; this review will only discuss substances that are not currently banned by the World Anti-Doping Agency. Evidence is emerging to support the performance-enhancing claims of some, but not all, dietary supplements that have been proposed to improve team-sport-related performance. For example, there is good evidence that caffeine can improve single-sprint performance, while caffeine, creatine and sodium bicarbonate ingestion have all been demonstrated to improve multiple-sprint performance. The evidence is not so strong for the performance-enhancing benefits of β-alanine or colostrum. Current evidence does not support the ingestion of ribose, branched-chain amino acids or β-hydroxy-β-methylbutyrate, especially in well trained athletes. More research on the performance-enhancing effects of the dietary supplements highlighted in this review needs to be conducted using team-sport athletes and using team-sport-relevant testing (e.g. single- and multiple-sprint performance). It should also be considered that there is no guarantee that dietary supplements that improve isolated performance (i.e. single-sprint or jump performance) will remain effective in the context of a team-sport match. Thus, more research is also required to investigate the effects of dietary supplements on simulated or actual team-sport performance. A second aim of this review was to investigate any health issues associated with the ingestion of the more commonly promoted dietary supplements. While most of the supplements described in the review appear safe when using the recommended dose, the effects of higher doses (as often taken by athletes) on indices of health remain unknown, and further research is warranted. Finally, anecdotal reports suggest that team-sport athletes often ingest more than one dietary supplement and very little is known about the potential adverse effects of ingesting multiple supplements. Supplements that have been demonstrated to be safe and efficacious when ingested on their own may have adverse effects when combined with other supplements. More research is required to investigate the effects of ingesting multiple supplements (both on performance and health).

Dietary supplements for football

Physical training and competition in football markedly increase the need for macro- and micronutrient intake. This requirement can generally be met by dietary management without the need for dietary supplements. In fact, the efficacy of most supplements available on the market is unproven. In addition, players must be cautious of inadequate product labelling and supplement impurities that may cause a positive drug test. Nonetheless, a number of dietary supplements may beneficially affect football performance. A high endurance capacity is a prerequisite for optimal match performance, particularly if extra time is played. In this context, the potential of low-dose caffeine ingestion (2 - 5 mg . kg body mass(-1)) to enhance endurance performance is well established. However, in the case of football, care must be taken not to overdose because visual information processing might be impaired. Scoring and preventing goals as a rule requires production of high power output. Dietary creatine supplementation (loading dose: 15 - 20 g . day(-1), 4 - 5 days; maintenance dose: 2 - 5 g g . day(-1)) has been found to increase muscle power output, especially during intermittent sprint exercises. Furthermore, creatine intake can augment muscle adaptations to resistance training. Team success and performance also depend on player availability, and thus injury prevention and health maintenance. Glucosamine or chondroitin may be useful in the treatment of joint pain and osteoarthritis, but there is no evidence to support the view that the administration of these supplements will be preventative. Ephedra-containing weight-loss cocktails should certainly be avoided due to reported adverse health effects and positive doping outcomes. Finally, the efficacy of antioxidant or vitamin C intake in excess of the normal recommended dietary dose is equivocal. Responses to dietary supplements can vary substantially between individuals, and therefore the ingestion of any supplement must be assessed in training before being used in competition. It is recommended that dietary supplements are only used based on the advice of a qualified sports nutrition professional.

Medication and supplement use by athletes

Athletes are affected in various ways by medications and supplements. Physicians caring for athletes need to be aware of medicines that athletes are taking and how they may interact with performance, exercise, environment, and other medicines. Athletes may attempt to gain a performance advantage with the use of a variety of dietary supplements and performance enhancers. Physicians must be knowledgeable of these so that athletes are properly educated about potential benefits and risks and physical effects. This article first reviews common medicines that athletes use and their potential efficacy and interactions with exercise and environment, then reviews dietary supplements and the data on their efficacy for performance enhancement. Finally, current and future doping issues are discussed.

Effects of creatine supplementation on cerebral white matter in competitive sportsmen

OBJECTIVES

To determine the neurobiochemical sequelae of oral creatine monohydrate supplementation in active athletes.

DESIGN/PARTICIPANTS

Eighteen sportsmen underwent single-voxel proton magnetic resonance spectroscopy of the deep frontal cerebral white matter before and after 5 days of oral ingestion: 12 of 18 swallowed 4 x 5 g creatine monohydrate per day, and the remaining swallowed a placebo.

MAIN OUTCOME MEASUREMENTS

Creatine, choline, and N-acetyl spectral resonances were evaluated at both long (135 ms) and short (20 ms) echo times.

RESULTS

A mixed-design factorial ANOVA demonstrated no interaction over time in any of the measures (P at least 0.081).

CONCLUSIONS

The results suggest that, for the given dosage regimen, ingested creatine augmentation does not alter the magnetic resonance visible creatine pool in the deep frontal cerebral white matter of young active sportsmen.

Risk assessment of the potential side effects of long–term creatine supplementation in team sport athletes

BACKGROUND

Use of creatine has become widespread among sportsmen and women, although there are no conclusive evidences concerning possible health risks of long-term creatine supplementation.

THE AIM OF THE STUDY

To investigate long-term effects of creatine monohydrate supplementation on clinical parameters related to health.

METHODS

Eighteen professional basketball players of the first Spanish Basketball League participated in the present longitudinal study. The subjects were ingesting 5 g creatine monohydrate daily during three competition seasons. Blood was collected in the morning after an overnight fast, five times during each of the three official competition seasons of the first National Basketball League (September 1999-June 2000, September 2000-June 2001 and September 2001-June 2002) and the European League. Standard clinical examination was performed for 16 blood chemistries.

RESULTS

The plasma concentrations of all clinical parameters did not alter significantly during the analyzed time frames of creatine supplementation. All of these parameters were, with the exception of creatinine and creatine kinase, within their respective clinical ranges at all time points.

CONCLUSION

Our data shows that low-dose supplementation with creatine monohydrate did not produce laboratory abnormalities for the majority of the parameters tested.

Drug Use in Sports: A Veritable Arena for Pharmacists

OBJECTIVE

To describe opportunities and obligations for pharmacists regarding doping control in sports, and to present information and resources on drugs and dietary supplements that are popular among athletes for performance enhancement.

DATA SOURCES

Sports medicine journals and articles in English obtained from Medline (1966 through June 2003) using the search terms doping in sports, drugs in sports, dietary supplements, sports, amphetamine, stimulants, ephedrine, ephedra, caffeine, anabolic steroids, human growth hormone, erythropoietin, darbepoetin, androstenedione, dehydroepiandrosterone, and creatine. Information was also obtained from sports-governing agencies, such as the National Collegiate Athletic Association and the International Olympic Committee.

STUDY SELECTION

Studies and reports that were credible and scientifically sound that evaluated the ergogenic effects of drugs and dietary supplements.

DATA EXTRACTION

By the author.

DATA SYNTHESIS

Pharmacists can participate in doping control programs in a number of ways. Pharmacists also have an obligation when counseling, advising, and treating athletes to help them avoid banned substances. Athletes use a host of drugs for their performance-enhancing effects, many of which are banned by major sports-governing bodies. Myriad dietary supplements are marketed to athletes, claiming to have ergogenic effects. Some of these popular supplements have proven performance-enhancing effects, while others do not. Adverse effects of these drugs and dietary supplements are discussed.

CONCLUSION

A variety of drugs and dietary supplements have proven performance-enhancing effects in athletes. However, many of these substances have adverse effects and are banned by various sports-governing organizations. Pharmacists can play a key role in participating in doping control programs, and can prevent athletes from inadvertently consuming a banned substance.

Popular sports supplements and ergogenic aids

This article reviews the evidence-based ergogenic potential and adverse effects of 14 of the most common products in use by recreational and elite athletes today. Both legal and prohibited products are discussed. This is an aggressively marketed and controversial area of sports medicine worldwide. It is therefore prudent for the clinician to be well versed in the more popular supplements and drugs reputed to be ergogenic in order to distinguish fact from fiction.Antioxidants, proteins and amino acids are essential components of diet, but additional oral supplementation does not increase endurance or strength. Caffeine is ergogenic in certain aerobic activities. Creatine is ergogenic in repetitive anaerobic cycling sprints but not running or swimming. Ephedrine and pseudoephedrine may be ergogenic but have detrimental cardiovascular effects. Erythropoietin is ergogenic but increases the risk of thromboembolic events. beta-Hydroxy-beta-methylbutyrate has ergogenic potential in untrained individuals, but studies are needed on trained individuals. Human growth hormone and insulin growth factor-I decrease body fat and may increase lean muscle mass when given subcutaneously. Pyruvate is not ergogenic. The androgenic precursors androstenedione and dehydroepiandrosterone have not been shown to increase any parameters of strength and have potentially significant adverse effects. Anabolic steroids increase protein synthesis and muscle mass but with many adverse effects, some irreversible. Supplement claims on labels of product content and efficacy can be inaccurate and misleading.

Magnesium-creatine supplementation effects on body water

This study evaluated magnesium-creatine (MgCre) supplementation on body water and quadriceps torque. Maltodextran (Placebo), Mg oxide plus Cre (MgO-Cre), and Mg-creatine chelate (MgC-Cre) at 800 mg Mg and 5 g Cre per day were used for 2 weeks in 35 subjects in a random assignment, blinded study. Pre-post measures were completed with bioimpedance to determine total body water (TBW), extracellular water (ECF), and intracellular water (ICF), and an isokinetic device at 180 degrees per second for knee extension peak torque (T), total work (W), and power (PWR). Body weights increased for both treatment groups, MgO-Cre Delta 0.75 kg (P <.05) and MgC-Cre Delta 0.4 kg (P =.07). Significant pre-post differences (P <.05) were noted only for MgC-Cre in ICW (26.29 v 28.01 L) and ECW (15.75 v 14.88 L). MgC-Cre had significant peak T (Nm) increase (124.5 v135.8, P <.05), while MgO-Cre (116.4 v 124.9, P =.06) and placebo (119.8 v 123.7, P =.343) did not. Both treatment groups had increased PWR (P <.05). MgC-Cre affects cellular fluid compartments. The peak torque changes were significant only in the MgC-Cre group, which had increases in ICW that may infer more muscular creatine due to its osmotic effect, and with increased cellular hydration, perhaps increased protein synthesis.

Oral creatine supplementation and skeletal muscle metabolism in physical exercise

Creatine is the object of growing interest in the scientific literature. This is because of the widespread use of creatine by athletes, on the one hand, and to some promising results regarding its therapeutic potential in neuromuscular disease on the other. In fact, since the late 1900s, many studies have examined the effects of creatine supplementation on exercise performance. This article reviews the literature on creatine supplementation as an ergogenic aid, including some basic aspects relating to its metabolism, pharmacokinetics and side effects. The use of creatine supplements to increase muscle creatine content above approximately 20 mmol/kg dry muscle mass leads to improvements in high-intensity, intermittent high-intensity and even endurance exercise (mainly in nonweightbearing endurance activities). An effective supplementation scheme is a dosage of 20 g/day for 4-6 days, and 5 g/day thereafter. Based on recent pharmacokinetic data, new regimens of creatine supplementation could be used. Although there are opinion statements suggesting that creatine supplementation may be implicated in carcinogenesis, data to prove this effect are lacking, and indeed, several studies showing anticarcinogenic effects of creatine and its analogues have been published. There is a shortage of scientific evidence concerning the adverse effects following creatine supplementation in healthy individuals even with long-term dosage. Therefore, creatine may be considered as a widespread, effective and safe ergogenic aid.