Study of frequency and type of adverse analytical findings in the different disciplines of aquatics.

We aimed to analyze the number and distribution of doping control tests in which a banned substance was reported (i.e., adverse analytical finding) in aquatics. The analysis was performed by using the data provided by the WADA Testing Figure Reports from 2015 to 2019. A total of 79,956 doping control tests were analyzed. Sprint swimming, middle-distance swimming and water polo were the disciplines with the highest number of doping control tests. However, there were no differences in the frequency of adverse findings among disciplines (overall, ∼0.56%, from 0.13 in artistic swimming to 0.76% in sprint swimming). Sprinters and long-distance swimmers presented a higher frequency of beta-2-agonists than the remaining aquatic disciplines (p < 0.05). These results indicate that the type of prohibited substances employed is strongly influenced by the intrinsic characteristics of each aquatic discipline.

Frequency and type of adverse analytical findings in athletics: Differences among disciplines.

Athletics is a highly diverse sport that contains a set of disciplines grouped into jumps, throws, races of varying distances, and combined events. From a physiological standpoint, the physical capabilities linked to success are quite different among disciplines, with varying involvements of muscle strength, muscle power, and endurance. Thus, the use of banned substances in athletics might be dictated by physical dimensions of each discipline. Thus, the aim of this investigation was to analyse the number and distribution of adverse analytical findings per drug class in athletic disciplines. The data included in this investigation were gathered from the Anti-Doping Testing Figure Report made available by the World Anti-Doping Agency (from 2016 to 2018). Interestingly, there were no differences in the frequency of adverse findings (overall,~0.95%, range from 0.77 to 1.70%) among disciplines despite long distance runners having the highest number of samples analysed per year (~9812 samples/year). Sprinters and throwers presented abnormally high proportions of adverse analytical findings within the group of anabolic agents (p < 0.01); middle- and long-distance runners presented atypically high proportions of findings related to peptide hormones and growth factors (p < 0.01); racewalkers presented atypically high proportions of banned diuretics and masking agents (p = 0.05). These results suggest that the proportion of athletes that are using banned substances is similar among the different disciplines of athletics. However, there are substantial differences in the class of drugs more commonly used in each discipline. This information can be used to effectively enhance anti-doping testing protocols in athletics.

Outcomes of adverse analytical findings in individual and team sports.

The aim of this investigation was to describe the outcomes of the adverse analytical findings in different Olympic sports. The data included were gathered from the World Anti-Doping Agency Anti-doping Rule Violations Reports (2013-2017). Weightlifting (78.1 ± 9.4%) wrestling (73.2 ± 18.5%) and volleyball (68.3 ± 18.7%) were the sports with the highest proportion of cases that ended in an antidoping sanction. Gymnastics (45.1 ± 10.1%), triathlon (32.6 ± 11.9%) and shooting (29.9 ± 14.1%) were the sports with a higher frequency of cases that were not sanctioned due to medical reasons. Gymnastics (22.4 ± 18.4%), boxing (23.2 ± 16.0%) and taekwondo (17.3.1 ± 16.4%) presented the highest proportion of cases that are still pending resolution. The proportion of cases that ended in no sanction was higher in fencing (26.2 ± 22.7%), skating (23.6 ± 35.1%) and tennis (18.6 ± 26.5%). These results indicate that the sanctions derived from antidoping rule violations were not uniform in all sports disciplines.

Gender Differences in Prevalence and Patterns of Dietary Supplement Use in Elite Athletes.

Purpose: Dietary supplement use by athletes has been the topic of previous research; however, the lack of homogeneity among published studies makes it difficult to analyze the differences, if any, in the patterns of use between male and female athletes. The aim of this study was to determine gender differences in the patterns of dietary supplement use by elite athletes. Methods: A total of 504 elite athletes (329 males and 175 females) participating in individual and team sports completed a validated questionnaire on dietary supplement use during the preceding season. The dietary supplements were categorized according to the latest IOC consensus statement. Results: A higher proportion of male versus female athletes (65.3 versus 56.5%, p < .05) consumed dietary supplements. Both male and female athletes reported a similar mean consumption of dietary supplements (3.2 ± 2.1 versus 3.4 ± 2.3 supplements/season, respectively; p = .45). Protein supplements were the most commonly consumed supplements in male athletes (49.8%) and their prevalence was higher than in female athletes (29.3%, p < .01). In females, multivitamins (39.4%) and branched-chain amino acids (39.4%) were the most commonly consumed supplements and iron supplementation was more prevalent than in males (22.2% versus 10.2%, p = .01). A higher proportion of male athletes relied on themselves to plan dietary supplements use (48.0%), while female appeared to rely more on doctors (34.0%, p < .01). Conclusion: In summary, male athletes had a slightly higher prevalence in the use of supplements than their female counterparts, specifically regarding protein supplements, and were more involved in the self-prescription of supplements.

Sport-Specific Use of Doping Substances: Analysis of World Anti-Doping Agency Doping Control Tests between 2014 and 2017.

Background: In recent years, there has been a solid effort across all sports organizations to reduce the prevalence and incidence of doping in sport. However, the efficacy of current strategies to fight against doping might be improved by using anti-doping polices tailored to the features of doping in each sport. Objectives: The aim of this investigation was to analyze the substances more commonly found in doping control tests in individual and team sports. Material and Methods: The publicly accessible Testing Figures Reports made available by the World Anti-Doping Agency, were analyzed from 2014 to 2017. Results: The most commonly detected groups of banned substances were anabolic agents and stimulants but the distribution of adverse findings per drug class was very different depending on the sports discipline. Weightlifting, athletics, rugby, hockey and volleyball presented abnormally high proportions of anabolic agents (p = 2.8 × 10-11). Cycling, athletics and rugby presented atypically elevated proportions of peptide hormones and growth factors (p = 1.4 × 10-1). Diuretics and masking agents were more commonly found in boxing, wrestling, taekwondo, judo, shooting, and gymnastics than in other sports (p = 4.0 × 10-68). Cycling, rowing, aquatics, tennis, gymnastics and ice hockey presented abnormally high proportions of stimulants (p = 1.8 × 10-5). Conclusions: These results indicate that the groups of banned substances more commonly detected in anti-doping control tests were different depending on the sports discipline. These data suggest the prohibited substances used as doping agents might be substantially different depending on the type of sport and thus, sports-specific anti-doping policies should be implemented to enhance the efficacy of anti-doping testing.

Analysis of doping control test results in individual and team sports from 2003 to 2015.

Background: Determining the prevalence of doping in sport might be useful for anti-doping authorities to gauge the effectiveness of anti-doping policies implemented to prevent positive attitudes toward doping. Using questionnaires and personal interviews, previous investigations have found that the prevalence of doping might be different among different sports disciplines; however, there is no sport-specific information about the proportion of adverse and atypical findings (AAF) in samples used for doping control. The aim of the present investigation was to assess the differences in the frequency of adverse analytical and atypical findings among sports using the data made available by the World Anti-Doping Agency. Methods: The data included in this investigation were gathered from the Testing Figures Reports made available annually from 2003 to 2015 by the World Anti-Doping Agency. These Testing Figures Reports include information about the number of samples analyzed, the number of AAFs reported, and the most commonly found drugs in the urine and blood samples analyzed. A total of 1,347,213 samples were analyzed from the individual sports selected for this investigation, and 698,371 samples were analyzed for disciplines catalogued as team sports. Results: In individual sports, the highest proportions of AAF were 3.3% ± 1.0% in cycling, 3.0% ± 0.6% in weightlifting, and 2.9% ± 0.6% in boxing. In team sports, the highest proportions of AAF were 2.2% ± 0.5% in ice hockey, 2.0% ± 0.5% in rugby, and 2.0% ± 0.5% in basketball. Gymnastics and skating had the lowest proportions at (≤1.0%) for individual sports, and field hockey, volleyball and football had the lowest proportions for team sports (≤1.4%). Conclusion: As suggested by the analysis, the incidence of AAF was not uniform across all sports disciplines, with the different proportions pointing to an uneven use of banned substances depending on the sport. This information might be useful for increasing the strength and efficacy of anti-doping policies in those sports with the highest prevalence in the use of banned substances.

Chronicle of an unintentional MDMA intoxication of a field hockey team to prevent its qualification for the Beijing 2008 Olympics: A case report.

Current doping trends overshadow the traditional interpretation of using prohibited performance-enhancing drugs to improve training and/or sports results. Its definition has evolved due to several recent cases of unconventional manipulation in sports. In this article, we present a case study of an intentional intoxication against the Spanish National Field Hockey team that resulted in its ineligibility for the 2008 Summer Olympics. The events occurred during the pre-qualifying Olympic tournament held in Azerbaijan. The Spanish team won the final match of the tournament against the hosting team and gained qualification for the Olympic Games. One month later, the International Hockey Federation (IHF) reported that two players of the Spanish National Hockey Team had tested positive for MDMA and would subsequently disqualify the Spanish National team from the tournament. The Spanish Hockey Federation then started an appeal process to demonstrate (1) contamination through team's hotel air ventilation and (2) tampering of a urine sample. This process ended with the IHF's final ruling that overturned the sanctions imposed on the Spanish National Team. This manuscript not only outlines a deliberate case to exclude a team from the Olympic Games, but also a federation's difficult efforts to prove an intentional intoxication that resulted in adverse findings.

Prevalence and patterns of dietary supplement use in elite Spanish athletes.

BACKGROUND: Dietary supplementation is a common strategy to achieve a specific health status or performance benefit. Several investigations have focused on the prevalence of dietary supplement use by athletes. However, information on how athletes manage the use and purchase of dietary supplements is scarce. METHODS: Five hundred and twenty-seven high-performance athletes (346 males and 181 females), participating in individual and team sports, completed a validated questionnaire about use and purchase patterns of dietary supplements. The dietary supplements were categorized according to the International Olympic Committee (IOC) consensus. RESULTS: Sixty four percent of the athletes (n = 337) used dietary supplements (median = 3; range 1 to 12). Age, sex, type of sport, level of competition, and professionalism influenced the prevalence of dietary supplement use (all p < 0.05). The most prevalent dietary supplement consumed was proteins (41%; n = 137), followed by amino acids/BCAA-based supplements (37%; n = 124). Additionally, as per group of supplements according to IOC consensus, 18% of the supplements were rated as having a low level of scientific evidence (e.g., glutamine, HMB, L-carnitine, etc). Most athletes (45%, n = 152) purchased dietary supplements in a store and 24% (n = 81) obtained them from a sponsor. Most athletes also (42%, n = 141) reported a self-organization of supplementation and did not consult with any professional. Last, 81% (n = 273) of athletes consuming supplements did not know any platform to check supplement safety/quality. For those who do not use dietary supplements (36% of the total sample, n = 190), most reported that they do not consider supplements necessary (72%, n = 137). CONCLUSION: Dietary supplementation appears to be widely used in sport with a considerable proportion of athletes consuming supplements with low level of scientific evidence. Additionally, athletes seem to rely on inadequate sources of information and may be largely unaware of sources to detect supplement contamination.

Urine Caffeine Concentration in Doping Control Samples from 2004 to 2015.

The ergogenic effect of caffeine is well-established, but the extent of its consumption in sport is unknown at the present. The use of caffeine was considered "prohibited" until 2004, but this stimulant was moved from the List of Prohibited Substances to the Monitoring Program of the World Anti-Doping Agency to control its use by monitoring urinary caffeine concentration after competition. However, there is no updated information about the change in the use of caffeine as the result of its inclusion in the Monitoring Program. The aim of this study was to describe the changes in urine caffeine concentration from 2004 to 2015. A total of 7488 urine samples obtained in official competitions held in Spain and corresponding to athletes competing in Olympic sports (2788 in 2004, 2543 in 2008, and 2157 in 2015) were analyzed for urine caffeine concentration. The percentage of samples with detectable caffeine (i.e., >0.1 µg/mL) increased from ~70.1%, in 2004⁻2008 to 75.7% in 2015. The median urine caffeine concentration in 2015 (0.85 µg/mL) was higher when compared to the median value obtained in 2004 (0.70 µg/mL; p < 0.05) and in 2008 (0.70 µg/mL; p < 0.05). The urine caffeine concentration significantly increased from 2004 to 2015 in aquatics, athletics, boxing, judo, football, weightlifting, and rowing (p < 0.05). However, the sports with the highest urine caffeine concentration in 2015 were cycling, athletics, and rowing. In summary, the concentration of caffeine in the urine samples obtained after competition in Olympic sports in Spain increased from 2004 to 2015, particularly in some disciplines. These data indicate that the use of caffeine has slightly increased since its removal from the list of banned substances, but urine caffeine concentrations suggest that the use of caffeine is moderate in most sport specialties. Athletes of individual sports or athletes of sports with an aerobic-like nature are more prone to using caffeine in competition.

Impact of the UGT2B17 polymorphism on the steroid profile. Results of a crossover clinical trial in athletes submitted to testosterone administration.

This article studies the genetic influence of polymorphism of the UGT2B17 gen on the urinary steroid profile and its implications for the anti-doping field. The study presents the results of a triple-blind randomized placebo-controlled crossover trial with healthy athletes submitted to a single dose of 250 mg of testosterone cypionate. Forty urine samples were collected from each participant. Mass spectrometry-based techniques commonly used in Anti-Doping laboratories, were employed to measure the urinary concentration and the Δδ13C values of a selection of target compounds for testosterone (T) administration together with LH. Twelve volunteers were included in the study; the polymorphism was evenly distributed among them. After T administration, the most meaningful change affected the Testosterone/Epitestosterone ratio (T/E) and the urinary concentration of LH. In relation with T/E, the wild type homozygous (ins/ins) group there was a mean relative increase of 30 (CI 95%: 25.2 to 36.7); in the heterozygous mutant (del/ins) group it was 19.8 (CI 95%:15.9 to 24.7); and in the homozygous mutant (del/del) group it was 19.7 (CI 95% 14.9 to 26.2). In the case of LH, it́s observed how LH values decrease significantly after the administration of Testex homogeneously among the three groups. The main outcome was related to the (del/del) group (homozygous mutant), where due to the depressed basal level of the steroid profile, if the longitudinal steroid profile of the athlete was not available, the analysis by GC/MS would not produce an "atypical" result according to the WADA TD2016EAAS despite the T administration. However, the genotyping of the UGT2B17 polymorphism, the follow up of LH and the use of GC-C-IRMS makes it possible to identify most of these samples as Adverse.

[Validation of a questionnaire to study the prevalence of nutritional supplements used by elite Spanish athletes]. / Validación de una encuesta para determinar la prevalencia en el uso de suplementos en deportistas de élite españoles.

INTRODUCTION: the use of dietary supplements is a widespread strategy performed by high-performance athletes worldwide. However, there is no validated questionnaire to determine the frequency and type of dietary supplements used by elite Spanish athletes. OBJECTIVE: the purpose of this investigation was to test the validity of a questionnaire designed to assess the prevalence in the use of dietary supplements by elite Spanish athletes. MATERIAL AND METHODS: initially, the questionnaire was designed to obtain information about the utilisation of five types of supplements (stimulants, ergogenic aids, supplements for weight control, supplements for improved recovery and medicines). Then, the validity of the questionnaire contents was evaluated by a group of six experts in dietary supplements who ranked the relevance and clarity of each question by using 1-10-point scales. The final version of the questionnaire was test-retested in a group of 39 elite athletes to verify the reproducibility in the answers reported in the questionnaire. RESULTS: after the evaluation of the group of experts, the questionnaire was completed with 81 questions regarding sociodemographic information and data about motives and frequency and conditions of dietary supplements purchase. The test-retest of the questionnaire showed a high reliability in all the answers obtained in the test-retest. CONCLUSION: the questionnaire included in this investigation fulfilled the standards for the obtaining of valid and reproducible data regarding the prevalence in the use of dietary supplements by Spanish athletes.

INTRODUCCIÓN: el uso de suplementos deportivos es una estrategia generalizada entre los deportistas de alto rendimiento. Sin embargo, no existe ningún cuestionario validado en castellano para determinar la prevalencia en el uso de suplementos deportivos en deportistas. OBJETIVO: el objetivo de esta investigación fue validar un cuestionario en castellano para estudiar la prevalencia del uso de suplementos deportivos. MATERIAL Y MÉTODOS: en una primera fase, el cuestionario fue diseñado para recabar información sobre la frecuencia en el uso de cinco categorías de suplementos (estimulantes, potenciadores del rendimiento, suplementos para control de peso, "recuperadores" y medicamentos). Posteriormente, el contenido del cuestionario fue validado por un grupo de seis expertos que valoraron la pertinencia y claridad de cada pregunta del cuestionario en escalas de 1-10 puntos. La versión final del cuestionario fue completada en dos ocasiones separadas por un mes (test-retest) por un grupo de 39 atletas de élite, con el objetivo de verificar la reproducibilidad en las respuestas a este cuestionario. RESULTADOS: la versión final del cuestionario, obtenida tras la validación de contenido, tiene 81 preguntas que recaban información sociodemográficay sobre motivos, frecuencia y condiciones de compra de suplementos deportivos. En el test-retest se comprobó una alta congruencia en todas las preguntas del cuestionario, sin diferencia estadística en ninguna de las respuestas en el test-retest. CONCLUSIÓN: el cuestionario derivado de este estudio cumple con los parámetros de validez y fiabilidad necesarios para la obtención de información vinculada al tipo y frecuencia en el uso de suplementos deportivos.

Thirteen years of the fight against doping in figures.

Every year, the World Anti-Doping Agency (WADA) publishes the main statistics reported by the accredited laboratories, which provide very valuable information for assessing changes in the patterns of doping in sports over time. Using the information provided since 2003 as the basis for the analysis, the evolution of doping/anti-doping figures over the last decade can be examined in reasonable detail, at least in reference to samples analyzed and categories of substances more commonly found in athletes' samples. This brief analysis of the WADA statistical reports leads us to the following outcomes: the increase in anti-doping pressure from 2003 to 2015, as evidenced by increased numbers of samples analyzed and banned substances, has not directly produced a higher frequency of adverse/atypical findings. Although this could be interpreted as steady state in the capacity to detect doping through this whole period, it also resulted in a significant increase in the absolute number of samples catalogued as doping (from 2247 in 2003 to 5912 in 2015). Anabolic agents have been the most common doping substances detected in all statistics reports while the remaining groups of substances are much less frequently found in doping control samples. Given that one might have expected the enhancement of the anti-doping programme led by WADA over this last decade to have increased the percentage of adverse/atypical findings, the fact that it did not might indicate the need to take another step in sampling strategies, such as 'more intelligent testing' based on the differences in the prevalence of doping substances among sports. Copyright © 2017 John Wiley & Sons, Ltd.

Impact of UGT2B17 gene deletion on the steroid profile of an athlete.

The measurement of the testosterone to epitestosterone ratio (T/E ratio) in urine is often used as a marker for testosterone administration in the doping control field. This study examines the frequencies of the different expression forms of the UGT2B17 gene, and assesses their effects on this marker in volunteer subjects. The sample for this descriptive study was composed of male and female athletes aged between 16 and 55 years old who practiced different sports disciplines. All participants underwent a sports-medical physical examination, and subsequently provided 10 urine samples consecutively over a period of 48 h. The dependent variable examined was T/E and the main independent variable was the UGT2B17 gene polymorphism. During 1 year, 1410 urine samples were obtained from 141 athletes. The frequencies of the three genotypes were as follows: wt homozygotes (ins/ins) 48.2% (n = 68), mutant homozygotes (del/del) 12.1% (n = 17), and heterozygotes (ins/del) 39.7% (n = 56). Genotype distributions varied significantly (P < 0.001) according to ethnicity, 80% of Asian subjects being homozygous for the gene deletion (del/del) compared to 6.9% of Caucasian subjects. A multivariate analysis adjusted for genotype, age, sex, and sports discipline revealed that athletes with the del/del polymorphism showed a significantly lower mean T/E than heterozygotes (ins/del). In contrast, homozygous athletes for the gene insertion (ins/ins) showed higher mean T/E ratios than heterozygotes (ins/del). UGT2B17 gene deletion has a strong influence on the T/E ratio in urine, which is the most efficient indicator of testosterone prohormone misuse. Others factors studied seem not to have such an impact. The genotyping of UGT2B17 is an important source of information for understanding steroid profiling in the doping control field; therefore it is suggested that it be included in the Athletes Biological Passport.

Ingestion of a moderately high caffeine dose before exercise increases postexercise energy expenditure.

Caffeine is an ergogenic aid widely used before and during prolonged exercise. Due to its prolonged biological half-life caffeine effects could remain after exercise. We aimed to investigate the metabolic, respiratory, and cardiovascular postexercise responses to preexercise graded caffeine ingestion. Twelve aerobically trained subjects (mean VO2max = 54 ± 7 ml · min⁻¹ · kg⁻¹) cycled for 60-min at 75% VO2max after ingesting placebo (0 mg of caffeine per kg of body weight) or 0.5, 1.5, 3.0 and 4.5 mg · kg⁻¹ on five occasions. During the 3 hr postexercise, heart rate, blood pressure, glucose, lactate, and fatty acids were analyzed. None of these variables were statistically affected by preexercise caffeine ingestion between 0.5 and 4.5 mg · kg⁻¹. However, ingestion of 4.5 mg · kg⁻¹ of caffeine raised postexercise energy expenditure 15% above placebo (233 ± 58 vs. 202 ± 49 kcal/3 hr; p < .05). Ventilation and tidal volume were elevated after the 4.5 mg · kg⁻¹ caffeine dose above placebo (9.2 ± 2.5 L · min⁻¹ and 0.67 ± 0.29 L · breath⁻¹ vs. 7.8 ± 1.5 L · min⁻¹ and 0.56 ± 0.20 L · breath⁻¹, respectively; p < .05). Ventilation correlated with tidal volume (r = .45; p < .05) and energy expenditure (r = .72; p < .05). In summary, preexercise ingestion of ergogenic caffeine doses do not alter postexercise cardiovascular responses. However, ingestion of 4.5 mg · kg⁻¹ of caffeine raises 3-hr postexercise energy expenditure (i.e., 31 kcal) likely through increased energy cost of ventilation.

A caffeinated energy drink improves jump performance in adolescent basketball players.

This study aimed at investigating the effects of a commercially available energy drink on shooting precision, jump performance and endurance capacity in young basketball players. Sixteen young basketball players (first division of a junior national league; 14.9 ± 0.8 years; 73.4 ± 12.4 kg; 182.3 ± 6.5 cm) volunteered to participate in the research. They ingested either (a) an energy drink that contained 3 mg of caffeine per kg of body weight or (b) a placebo energy drink with the same appearance and taste. After 60 min for caffeine absorption, they performed free throw shooting and three-point shooting tests. After that, participants performed a maximal countermovement jump (CMJ), a repeated maximal jumps test for 15 s (RJ-15), and the Yo-Yo intermittent recovery test level 1 (Yo-Yo IR1). Urine samples were obtained before and 30 min after testing. In comparison to the placebo, the ingestion of the caffeinated energy drink did not affect precision during the free throws (Caffeine = 70.7 ± 11.8 % vs placebo = 70.3 ± 11.0 %; P = 0.45), the three-point shooting test (39.9 ± 11.8 vs 38.1 ± 12.8 %; P = 0.33) or the distance covered in the Yo-Yo IR1 (2,000 ± 706 vs 1,925 ± 702 m; P = 0.19). However, the energy drink significantly increased jump height during the CMJ (38.3 ± 4.4 vs 37.5 ± 4.4 cm; P < 0.05) mean jump height during the RJ-15 (30.2 ± 3.6 vs 28.8 ± 3.4 cm; P < 0.05) and the excretion of urinary caffeine (1.2 ± 0.7 vs 0.1 ± 0.1 µg/mL; P < 0.05). The intake of a caffeine-containing energy drink (3 mg/kg body weight) increased jump performance although it did not affect basketball shooting precision.

An automated sample preparation for detection of 72 doping-related substances.

Automation of sample preparation procedures in a doping control laboratory is of great interest due to the large number of samples that have to be analyzed, especially in large events where a high throughput protocol is required to process samples over 24 h. The automation of such protocols requires specific equipment capable of carrying out the diverse mechanical tasks required for accomplishing these analytical methodologies, which include pipetting, shaking, heating, or crimping. An automated sample preparation procedure for the determination of doping-related substances by gas chromatography-mass spectrometry (GC-MS) and gas chromatography-tandem mass spectrometry (GC-MS/MS) analysis, including enzymatic hydrolysis, liquid-phase extraction and derivatization steps, was developed by using an automated liquid handling system. This paper presents a description of the equipment, together with the validation data for 72 doping-related compounds including extraction efficiency, evaluation of carry-over, interferences, and robustness. Validation was approached as a comparison between the results obtained using the manual protocol and the transferred automated one. The described methodology can be applied for sample preparation in routine anti-doping analysis with high sample throughput and suitable performance.

Neuromuscular responses to incremental caffeine doses: performance and side effects.

PURPOSE: The purpose of this study was to determine the oral dose of caffeine needed to increase muscle force and power output during all-out single multijoint movements. METHODS: Thirteen resistance-trained men underwent a battery of muscle strength and power tests in a randomized, double-blind, crossover design, under four different conditions: (a) placebo ingestion (PLAC) or with caffeine ingestion at doses of (b) 3 mg · kg(-1) body weight (CAFF 3mg), (c) 6 mg · kg(-1) (CAFF 6mg), and (d) 9 mg · kg(-1) (CAFF 9mg). The muscle strength and power tests consisted in the measurement of bar displacement velocity and muscle power output during free-weight full-squat (SQ) and bench press (BP) exercises against four incremental loads (25%, 50%, 75%, and 90% one-repetition maximum [1RM]). Cycling peak power output was measured using a 4-s inertial load test. Caffeine side effects were evaluated at the end of each trial and 24 h later. RESULTS: Mean propulsive velocity at light loads (25%-50% 1RM) increased significantly above PLAC for all caffeine doses (5.4%-8.5%, P = 0.039-0.003). At the medium load (75% 1RM), CAFF 3mg did not improve SQ or BP muscle power or BP velocity. CAFF 9mg was needed to enhance BP velocity and SQ power at the heaviest load (90% 1RM) and cycling peak power output (6.8%-11.7%, P = 0.03-0.05). The CAFF 9mg trial drastically increased the frequency of the adverse side effects (15%-62%). CONCLUSIONS: The ergogenic dose of caffeine required to enhance neuromuscular performance during a single all-out contraction depends on the magnitude of load used. A dose of 3 mg · kg(-1) is enough to improve high-velocity muscle actions against low loads, whereas a higher caffeine dose (9 mg · kg(-1)) is necessary against high loads, despite the appearance of adverse side effects.