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Orchard J. W., P. A. Fricker, S. L. White, L. M. Burke, and D. J. Healey. The use and misuse of performance-enhancing substances in sport. Medical Journal of Australia 184: 132-136, 2006.

Cox G. R., B. Desbrow, P. G. Montgomery, M. E. Anderson, C. R. Bruce, T. A. Macrides, D. T. Martin, A. Moquin, A. Roberts, J. A. Hawley and L. M. Burke. Effect of different protocols of caffeine intake on metabolism and endurance performance. Journal of Applied Physiology 93: 990-999, 2002.

Cox G. R., I. Mujika, D. Tumilty, and L. M. Burke. Acute creatine supplementation and performance during a field test simulating match play in elite female soccer players.  International Journal Sport Nutrition Exercise Metabolism 12: 33-46, 2002.

Baylis A, D. Cameron-Smith and L. Burke. Inadvertent doping through supplement use by athletes: assessment and management of the risk in Australia.  International Journal Sport Nutrition and Exercise Metabolism 11: 365-83, 2001.

Burke, L. M. Positive drug tests from supplements. Sportscience 4, 2000.
http://www.sportsci.org/jour/0003/lmb.html

Burke, L., B. Desbrow, and M. Minehan. Dietary supplements and nutritional ergogenic aids. In: Clinical Sports Nutrition (2nd ed.), edited by L. Burke and V. Deakin. Sydney: McGraw-Hill, 2000, p. 455-528.

Hitchins, S., D. T. Martin, L. Burke, K. Yates, K. Fallon, A. Hahn, and G.P. Dobson. Glycerol hyperhydration improves cycle time trial performance in hot humid conditions. European Journal of Applied Physiology 80: 494-501, 1999.

Burke, L. M., D. B. Pyne, and R. D. Telford. Effect of oral creatine supplementation on single-effort sprint performance in elite swimmers. International Journal of Sport Nutrition 6: 222-223, 1996.

Burke, L. M., and R. S. Read. Dietary supplements in sport. Sports Medicine 15: 43-65, 1993.


Orchard J. W., P. A. Fricker, S. L. White, L. M. Burke, and D. J. Healey. The use and misuse of performance-enhancing substances in sport. Medical Journal of Australia 184: 132-136, 2006.

Doctors need to know if a patient is an athlete subject to drug testing, and to be aware of the legal situation surrounding drugs they prescribe such patients. Antidoping laws generally exist in order to provide a safe and fair environment for participation in sport. These laws should prevent and protect athletes from subjecting themselves to health risks through the use of unsafe, but performance-enhancing drugs. Because of difficulties in proving intent to cheat, the World Anti-Doping Agency enforces a principle of strict liability for positive test results for banned substances. An area of major controversy with respect to liability is the "sports supplement" industry, which is poorly regulated when compared with prescription drugs yet is a potential source of doping violations. Medical practitioners can be found guilty of anti-doping violations if they traffic banned drugs, prescribe these to athletes or otherwise assist athletes in taking banned substances. Medical practitioners are also now required to complete paperwork (therapeutic use exemption forms) to enable athletes to take banned substances which are required on medical grounds for specific illnesses.

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Cox G. R., B. Desbrow, P.G. Montgomery, M.E. Anderson, C.R. Bruce, T. A. Macrides, D. T. Martin, A. Moquin, A. Roberts, J.A. Hawley, and L. M. Burke.  Effect of different protocols of caffeine intake on metabolism and endurance performance.  Journal of Applied Physiology 93: 990-999, 2002.

Competitive athletes completed two studies of 2-h steady-state (SS) cycling at 70% peak O 2 uptake followed by 7kJ/kg time trial (TT) with carbohydrate (CHO) intake before (2g/kg) and during (6% CHO drink) exercise.  In Study A, 12 subjects received either 6mg/kg caffeine 1 h preexercsie (Precaf), 6 x 1 mg/kg caffeine every 20 min throughout SS (Durcaf), 2 x 5 ml/kg Coca-Cola between 100 and 120 min SS and during TT (Coke), or placebo.  Improvements in TT were as follows: Precaf, 3.4% (0.2-6.5%, 95% confidence interval): Durcaf, 3.1% (-0.1-6.5%): and Coke, 3.1% (-0.2-6.2%).  In Study B, eight subjects received 3 x 5 ml/kg of different cola drinks during the last 40 min of SS and TT: decaffeinated, 6% CHO (control); caffeinated, 6% CHO; decaffeinated, 11% CHO; and caffeinated, 11% CHO (Coke).  Coke enhanced TT by 3.3 % (0.8-5.9%), with all trials showing 2.2% TT enhancement (0.5-3.8%; P<0.05) due to caffeine.  Overall, 1) 6mg/kg caffeine enhanced TT performance independent of timing of intake and 2) replacing sports drink with Coca-Cola during the latter stages of exercise was equally effective in enhancing endurance performance, primarily due to low intake of caffeine (~1.5 mg/kg).

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Cox G. R., I. Mujika, D. Tumilty, and L. M. Burke.  Acute creatine supplementation and performance during a field test simulating match play in elite female soccer players.  International Journal Sport Nutrition Exercise Metabolism 12: 33-46, 2002.

This study investigated the effects of acute creatine (Cr) supplementation on the performance of elite female soccer players undertaking an exercise protocol simulating match play.  On two occasions, 7 days apart, 12 players performed 5 x 11-min exercise testing blocks interspersed with 1 min of rest.  Each block consisted of 11 all-out 20-m running sprints, 2 agility runs, and 1 precision ball-kicking drill, separated by recovery 20-m walks, jogs, and runs.  After the initial testing session, subjects were assigned to either a CREATINE (5 g of Cr, 4 times per day for 6 days) or a PLACEBO group (same dosage of a glucose polymer) using a double-blind research design.  Body mass (BM) increased (61.7± 8.9 to 62.5 ± 8.9 kg, p <0.01) in the CREATINE group; however, no change was observed in the PLACEBO group (63.4 ± 2.9 kg to 63.7 ± 2.5 kg).  No overall change in 20-m sprint times and agility run times were observed, although the CREATINE group achieved faster post-supplementation times in sprints 11, 13, 14, 16, 21, 23, 25, 32, and 39 ( p <0.05), and agility runs 3, 5, and 8 ( p <0.05).  The accuracy of shooting was unaffected in both groups.  In conclusion, acute Cr supplementation improved performance of some repeated sprint and agility tasks simulating soccer match play, despite an increase in BM.

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Baylis A, D. Cameron-Smith, and L. Burke. Inadvertent doping through supplement use by athletes: assessment and management of the risk in Australia.  International Journal Sport Nutrition and Exercise Metabolism 11: 365-83, 2001.

Many athletes report using a wide range of special sports foods and supplements. In the present study of 77 elite Australian swimmers, 99% of those surveyed reported the use of these special preparations, with 94% of swimmers reporting the use of non-food supplements. The most popular dietary supplements were vitamin or mineral supplements (used by 94% of the group), herbal preparations (61%), and creatine (31%). Eighty-seven percent of swimmers reported using a sports drink or other energy-providing sports food. In total, 207 different products were reported in this survey. Sports supplements, particularly supplements presented as pills or other non-food form, are poorly regulated in most countries, with little assurance of quality control. The risk of an inadvertent "positive doping test" through the use of sports supplements or sports foods is a small but real problem facing athletes who compete in events governed by anti-doping rules. The elite swimmers in this survey reported that information about the "doping safety" of supplements was important and should be funded by supplement manufacturers. Although it is challenging to provide such information, we suggest a model to provide an accredited testing program suitable for the Australian situation, with targeted athlete education about the "sports safety" of sports supplements and foods.

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Burke, L. M. Positive drug tests from supplements. Sportscience 4, 2000.

http://www.sportsci.org/jour/0003/lmb.html

There is a small but real risk that athletes will test positive to a banned substance as a result of ingesting supplements and sports foods. Lack of regulation of quality control and labeling of products in the supplement industry makes it impossible to identify supplements and sports foods that are risk free. Incentives or punishments for the supplement industry to improve manufacturing processes are therefore needed. Meanwhile sports authorities place the responsibility for a positive test with the athlete, necessitating better education of athletes, coaches and support staff.

Link to full article.


Burke, L., B. Desbrow, and M. Minehan. Dietary supplements and nutritional ergogenic aids. In: Clinical Sports Nutrition (2nd ed.), edited by L. Burke and V. Deakin. Sydney: McGraw-Hill, 2000, p. 455-528.

The sports world is filled with special foods, potions, pills and powders that promise to provide the athlete with a performance edge. Advertisements and testimonials for these products claim prolonged endurance, faster recovery, increases in muscle mass and strength, losses of body fat, and resistance to fatigue, illness or infection. Such promises are attractive to athletes and coaches, especially in elite competition where very small differences separate the fame and fortune of winning from the anonymity of the rest of the field. Yet external rewards provide only part of the drive to find a ‘magic bullet’, because even non-elite and recreational athletes show considerable interest in using sports supplements.

Further details on Clinical Sports Nutrition can be found in the Publications section of our site.


Hitchins, S., D. T. Martin, L. Burke, K. Yates, K. Fallon, A Hahn, and G. P. Dobson. Glycerol hyperhydration improves cycle time trial performance in hot humid conditions. European Journal of Appied Physiology 80: 494-501, 1999.

Eight competitive cyclists [mean peak oxygen consumption, (VO2(peak)) = 65 ml x min(-1) x kg(-1)] undertook two 60-min cycle ergometer time trials at 32 degrees C and 60% relative humidity. The time trials were split into two 30-min phases: a fixed-workload phase and a variable-workload phase. Each trial was preceded by ingestion of either a glycerol solution [1 g x kg(-1) body mass (BM) in a diluted carbohydrate (CHO)-electrolyte drink] or a placebo of equal volume (the diluted CHO-electrolyte drink). The total fluid intake in each trial was 22 ml x kg(-1) BM. A repeated-measures, double blind, cross over design with respect to glycerol was employed. Glycerol ingestion expanded body water by approximately 600 ml over the placebo treatment. Glycerol treatment significantly increased performance by 5% compared with the placebo group, as assessed by total work in the variable-workload phase (P < 0.04). There were no significant differences in rectal temperature, sweat rate or cardiac frequency between trials. Data indicate that the glycerol-induced performance increase did not result from plasma volume expansion and subsequently lower core temperature or lower cardiac frequencies at a given power output as previously proposed. However, during the glycerol trial, subjects maintained a higher power output without increased perception of effort or thermal strain.

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Burke, L. M., D. B. Pyne, and R. D. Telford. Effect of oral creatine supplementation on single-effort sprint performance in elite swimmers. International Journal of Sport Nutrition 6: 222-223, 1996.

Oral supplementation with creatine monohydrate (Cr.H2O) has been reported to increase muscle creatine phosphate levels. The aim of the present study was to determine the effect of such supplementation on performance of a single-effort sprint by elite swimmers. Thirty-two elite swimmers (M = 18, F = 14; age = 17-25 years) from the Australian Institute of Sport were tested on two occasions, 1 week apart. Tests performed were 25-m, 50-m, and 100-m maximal effort sprints (electronically timed with dive start, swimmers performing their best stroke), each with approximately 10 min active recovery. A 10-s maximal leg ergometry test was also undertaken. Swimmers were divided into two groups matched for sex, stroke/event, and sprint time over 50 m, and groups were randomly assigned to 5 days of Cr.H2O supplementation (4 . day-1 x 5 g Cr.H2O + 2 g sucrose, n = 16) or placebo (4 . day-1 x 5 g Polycose + 2 g sucrose, n = 16) prior to the second trial. Results revealed no significant differences between the group means for sprint times or between 10-s maximal leg ergometry power and work. This study does not support the hypothesis that creatine supplementation enhances single-effort sprint ability of elite swimmers.

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Burke, L. M., and R. S. Read. Dietary supplements in sport. Sports Medicine 15: 43-65, 1993.

Studies of the dietary practices of athletes report that nutritional supplements are commonly used. Supplementation practices vary between sports and individual athletes; however, there is evidence that at least some athletes use a large number of supplements concurrently, often in doses that are very high in comparison with normal dietary intakes. In exploring supplementation practices we propose a classification system separating the supplements into dietary supplements and nutritional erogogenic aids. The dietary supplement is characterised as a product which can be used to address physiological or nutritional issues arising in sport. It may provide a convenient or practical means of consuming special nutrient requirements for exercise, or it may be used to prevent/reverse nutritional deficiencies that commonly occur among athletes. The basis of the dietary supplement is an understanding of nutritional requirements and physiological effects of exercise. When the supplement is used to successfully meet a physiological/nutritional goal arising in sport it may be demonstrated to improve sports performance. While there is some interest in refining the composition or formulation of some dietary supplements, the real interest belongs to the use or application of the supplement; i.e. educating athletes to understand and achieve their nutritional needs in a specific sports situation.

The sports drink (carbohydrate-electrolyte replacement drink) is a well known example of a dietary supplement. Scientific attitudes towards the sports drink have changed over the past 20 years. Initial caution that carbohydrate-electrolyte fluids compromise gastric emptying during exercise has now been shown to be unjustified. Numerous studies have shown that 5 to 10% solutions of glucose, glucose polymers (maltodextrins) and other simple sugars all have suitable gastric emptying characteristics for the delivery of fluid and moderate amounts of carbohydrate substrate. The optimal concentration of electrolytes, particularly sodium, remains unknown. Most currently available sports drinks provide a low level of sodium (10 to 25 mmol/L) in recognition that sodium intake may promote intestinal absorption of fluid as well as assist in rehydration. The sodium level of commercial oral rehydration fluids (used in the clinical treatment of diarrhoea and dehydration) is higher than that of the present range of sports drinks. However, even if research indicates that intestinal glucose transport is optimally stimulated at higher sodium concentrations, concern for the palatability of sports drinks may impose a lower ceiling for sodium levels. Commercial viability of a sports drink requires that it provide a refreshing and palatable fluid replacement across a wide variety of sports and exercise situations.

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