Risk or benefit? Side effects of caffeine supplementation in sport: a systematic review.

PURPOSE: The aim of this study was to systematically review evidence on the prevalence and magnitude of side effects associated with caffeine supplementation in athletes. METHODS: Systematic searches through the PubMed, VHL, Scopus, and Web of Science databases were conducted according to the PRISMA guidelines. Peer-reviewed articles written in English that reported the prevalence/percentage or magnitude/effect size of side effects after caffeine supplementation in athletes in a sports context were included. Studies were grouped by the dose of caffeine administered as follows: low = ≤ 3.0 mg/kg; moderate = from 3.1 to 6.0 mg/kg; high = ≥ 6.1 mg/kg. The magnitude of the side effects was calculated with effect sizes. RESULTS: The search retrieved 25 studies that met the inclusion/exclusion criteria with a pooled sample of 421 participants. The supplementation with caffeine produced a higher prevalence or magnitude of all side effects under investigation when compared to placebo/control situations. The prevalence (magnitude) was between 6 and 34% (ES between 0.13 and 1.11) for low doses of caffeine, between 0 and 34% (ES between -0.13 and 1.20) for moderate doses of caffeine, and between 8 and 83% (ES between 0.04 and 1.52) with high doses of caffeine. The presence of tachycardia/heart palpitations and the negative effects on sleep onset had the highest prevalence and magnitude, in athletes using supplementation with caffeine. CONCLUSION: In summary, caffeine supplementation in the doses habitually used to enhance physical performance produces several side effects, both after exercise and at least 24 h after the ingestion. However, the prevalence and magnitude of side effects with high doses of caffeine were habitually higher than with low doses of caffeine. From a practical perspective, using ~3.0 mg/kg of caffeine may be the dose of choice to obtain the ergogenic benefits of caffeine with the lowest prevalence and magnitude of side effects.

Manejo anestésico en usuarios de esteroides anabólicos androgénicos: scooping review / Anesthetic management in anabolic androgenic steroid users: scooping review

OBJECTIVE: Update the perioperative confrontation of Anabolic Androgenic Steroids users. MATERIALS AND METHODS: Scooping review. Two clinical cases related to anesthetic management in anabolic androgenic steroid users, published between 2000 and 2020, were included, and two narrative reviews on the subject were analyzed. The databases were used: Pubmed, Proquest, Web of Science and Science Direct. RESULTS: The clinical cases show the complications and the management due to the use of anabolic androgenic steroids and the narrative reviews the pre-anesthetic, intraoperative and postoperative considerations based on the pathophysiology and pharmacology. CONCLUSION: There is a lack of data on the anesthetic implications of anabolic steroid abuse, but understanding the physiological implications may help guide the treatment of these patients.

OBJETIVO: Actualizar el enfrentamiento perioperatorio de usuarios de Esteroides Anabólicos Androgénicos. MATERIALES Y MÉTODOS: Scooping review. Se incluyeron 2 casos clínicos relacionados con manejo anestésico en usuarios de esteroides anabólicos androgénicos, publicados entre 2000 y 2020, y se analizaron dos revisiones narrativas sobre el tema. Se emplearon las bases de datos: Pubmed, Proquest, Web of Science y Science Direct. RESULTADOS: Los casos clínicos muestran las complicaciones y el manejo debido al uso de esteroides anabólicos androgénicos y las revisiones narrativas las consideraciones preanestésicas, intraoperatorias y postoperatorias a partir de la fisiopatología y la farmacología. CONCLUSIÓN: Existe escasez de datos sobre las implicaciones anestésicas del abuso de esteroides anabólicos, pero la comprensión de las implicaciones fisiológicas puede ayudar a guiar el tratamiento de estos pacientes.

Timing of Creatine Supplementation around Exercise: A Real Concern?

Creatine has been considered an effective ergogenic aid for several decades; it can help athletes engaged in a variety of sports and obtain performance gains. Creatine supplementation increases muscle creatine stores; several factors have been identified that may modify the intramuscular increase and subsequent performance benefits, including baseline muscle Cr content, type II muscle fibre content and size, habitual dietary intake of Cr, aging, and exercise. Timing of creatine supplementation in relation to exercise has recently been proposed as an important consideration to optimise muscle loading and performance gains, although current consensus is lacking regarding the ideal ingestion time. Research has shifted towards comparing creatine supplementation strategies pre-, during-, or post-exercise. Emerging evidence suggests greater benefits when creatine is consumed after exercise compared to pre-exercise, although methodological limitations currently preclude solid conclusions. Furthermore, physiological and mechanistic data are lacking, in regard to claims that the timing of creatine supplementation around exercise moderates gains in muscle creatine and exercise performance. This review discusses novel scientific evidence on the timing of creatine intake, the possible mechanisms that may be involved, and whether the timing of creatine supplementation around exercise is truly a real concern.

Effects of Caffeine Supplementation on Physical Performance of Soccer Players: Systematic Review and Meta-Analysis.

CONTEXT: Caffeine is 1 of the most popular supplements consumed by athletes, and the evidence for improving soccer performance remains limited. OBJECTIVE: To investigate and update the effects (benefits and harms) of caffeine to improve performance on soccer players. DATA SOURCES: Electronic search in Medline (via PubMed), CENTRAL, Embase, SPORTDiscus, and LILACS, from inception to March 28, 2020. STUDY SELECTION: Randomized clinical trials (RCTs) assessing the effects of caffeine on the performance of soccer players. STUDY DESIGN: Systematic review with meta-analysis. LEVEL OF EVIDENCE: Level 1. DATA EXTRACTION: Data extraction was conducted independently by 2 authors using a piloted form. We assessed methodological quality (Cochrane risk-of-bias [RoB] table) and the certainty of the evidence (GRADE [Grading of Recommendations Assessment, Development and Evaluation] approach). RESULTS: Sixteen RCTs were included. Overall methodological quality was classified as unclear to low risk of bias. When assessing aerobic endurance, meta-analyses did not demonstrate the differences between caffeine and placebo (mean difference [MD], 44.9 m; 95% confidence interval [CI], -77.7 to 167.6). Similarly, no difference was observed during time to fatigue test (MD, 169.8 seconds; 95% CI, -71.8 to 411.6). Considering anaerobic power, meta-analyses also did not find differences for vertical jump (MD, 1.01 cm; 95% CI, -0.68 to 2.69) and repeated sprint tests (MD, -0.02 seconds; 95% CI, -0.09 to 0.04), as well as reaction time agility test (MD, 0.02 seconds; 95% CI, -0.01 to 0.04) and rating of perceived exertion (MD, 0.16 points; 95% CI, -0.55 to 0.87). Regarding safety, a few minor adverse events were reported. Based on the GRADE approach, the certainty of this evidence was classified as very low to low. CONCLUSION: We found no significant improvement in soccer-related performance with caffeine compared with placebo or no intervention. However, caffeine appears to be safe.

Potential risk for developing severe COVID-19 disease among anabolic steroid users.

A severe case of COVID-19 was observed in an otherwise healthy 28-year-old man who had taken oxandrolone 40 mg/day as an anabolic steroid. The patient had been taking oxandrolone for enhanced bodybuilding 30 days prior to presenting to an outpatient clinic with COVID-19 symptoms. The patient reported that his symptoms have rapidly worsened over the course of 4 days prior to presenting at the clinic. As part of an experimental antiandrogen treatment for hyperandrogenic men suffering from COVID-19, he was administered a single 600 mg dose of the novel antiandrogen proxalutamide. Twenty-four hours after administration of this dose, marked improvement of symptoms and markers of disease severity were observed. To our knowledge, this is the first case that potentially links anabolic steroid use to COVID-19 disease severity.

Creatine supplementation improves performance, but is it safe? Double-blind placebo-controlled study.

BACKGROUND: Creatine represents a natural supplement and ergogenic aid for sport performance, but there are several concerns regarding its safety for health. The present double-blind placebo-controlled study evaluated the effect of creatine monohydrate supplementation on a panel of blood and urine health indicators in resistance training practitioners. METHODS: Eighteen males performing resistance training three times per week were supplemented with 0.3 g/kg per day creatine monohydrate for 7 days and compared with matched controls supplemented with dextrosol. Blood and urine samples were collected pre- and 30 days post-supplementation to evaluate 41 biochemical parameters and renal function. RESULTS: Creatine monohydrate supplementation did not cause adverse events and, as expected, promoted an increase of the performance and body weight. No modification of red blood cells parameters, white blood cells profile, blood lipid profile, metabolic and urine markers, hepatic and renal function were observed in the supplemented group. CONCLUSIONS: Despite the expected weight increase, the creatine monohydrate supplementation is safe for health and no detrimental effects on different organs and physiological systems were observed in our cohort of volunteers.

Effect of caffeine supplementation on exercise performance, power, markers of muscle damage, and perceived exertion in trained CrossFit men: a randomized, double-blind, placebo-controlled crossover trial.

BACKGROUND: Caffeine is a popular nutritional supplement among athletes. It is frequently used as an ergogenic aid to improve physical performance, delay fatigue, and increase muscle power. However, these effects have not been tested in CrossFit athletes. The aim of this study was to evaluate the effects of acute caffeine supplementation on workout performance, power, markers of muscle damage, and soreness in trained CrossFit men. METHODS: Nine men (28±2 years) with experience in CrossFit (2±0.3 years) were investigated in a randomized, double-blind, placebo-controlled crossover trial, with a 7-day washout between treatment periods. The athletes received anhydrous caffeine (CAF: 6 mg/kg body mass) or placebo (PLA) 60 minutes before a CrossFit workout with tasks that involved muscle strength, power, gymnastic movements, and metabolic conditioning. Blood samples were collected for creatine kinase (CK), C-reactive protein, and glucose determination. Workout performance, rating of perceived exertion (RPE), delayed-onset muscle soreness (DOMS), muscle strength (handgrip strength) and power (bench throw, jump squat and countermovement jump) were also evaluated. RESULTS: CAF resulted in higher glucose concentration after workout compared to PLA (+3.2 mmol/L, 95% CI: 2.1 to 4.3 vs. +1.5, 95% CI: -0.1 to 3.0 mmol/L, P=0.01). No differences were found between treatments in workout performance, CK, DOMS, RPE, muscle power and strength. CONCLUSIONS: Acute CAF supplementation did not alter performance, markers of muscle damage, power, and RPE in trained CrossFit men.

Caffeine Increased Muscle Endurance Performance Despite Reduced Cortical Activation and Unchanged Neuromuscular Efficiency and Corticomuscular Coherence.

The central and peripheral effects of caffeine remain debatable. We verified whether increases in endurance performance after caffeine ingestion occurred together with changes in primary motor cortex (MC) and prefrontal cortex (PFC) activation, neuromuscular efficiency (NME), and electroencephalography-electromyography coherence (EEG-EMG coherence). Twelve participants performed a time-to-task failure isometric contraction at 70% of the maximal voluntary contraction after ingesting 5 mg/kg of caffeine (CAF) or placebo (PLA), in a crossover and counterbalanced design. MC (Cz) and PFC (Fp1) EEG alpha wave and vastus lateralis (VL) muscle EMG were recorded throughout the exercise. EEG-EMG coherence was calculated through the magnitude squared coherence analysis in MC EEG gamma-wave (CI > 0.0058). Moreover, NME was obtained as the force-VL EMG ratio. When compared to PLA, CAF improved the time to task failure (p = 0.003, d = 0.75), but reduced activation in MC and PFC throughout the exercise (p = 0.027, d = 1.01 and p = 0.045, d = 0.95, respectively). Neither NME (p = 0.802, d = 0.34) nor EEG-EMG coherence (p = 0.628, d = 0.21) was different between CAF and PLA. The results suggest that CAF improved muscular performance through a modified central nervous system (CNS) response rather than through alterations in peripheral muscle or central-peripheral coupling.

Influência do enxágue oral com carboidrato na glicemia em equinos / Influence of carbohydrate mouth rinse on blood glucose in horses / Influencia del enjuague oral con carbohidratos en la glucemia en los equinos

Mecanismos ainda não plenamente esclarecidos levam a melhora no desempenho atlético de indivíduos submetidos à enxágue oral com carboidratos, dentre eles a maltodextrina. Estudos recentes em humanos sugerem que a presença de possíveis receptores para carboidratos na orofaringe sejam os responsáveis por melhorar o desempenho,porém por meio de mecanismo ainda não decifrados. O objetivo do presente estudo foi verificar se o procedimento de enxágue oral em equinos permite a ingestão e absorção da solução, levando a uma alteração na curva glicêmica. Analisamos oito animais que foram submetidos a um enxágue oral com uma solução contendo maltodextrina. Foram realizadas dez coletas de sangue para avaliação da curva glicêmica de cada animal, sendo a primeira coleta realizada antes do enxágue oral para definir valores basais de glicose plasmática, e as nove demais coletas foram realizadas após o enxágue oral em até 3 horas, a fim de obter informações suficientes para determinação da curva glicêmica em equinos. Não houveram alterações significativas nos valores de glicose plasmática, sugerindo que não houve ingestão e absorção do carboidrato durante o processo de enxágue oral.(AU)

The mechanism related to the practice of oral carbohydrate supplementation prior exercise for athletic horses remains unclear. Recent studies in humans suggest that the presence of possible receptors for carbohydrates in the oropharynx are responsible for improving performance, but with mechanisms not yet deciphered. The aim of the present study was to verify if the carbohydrates mouth rinse procedure in horses allows the ingestion and absorption of the solution, leading to changes in the glycemic curve. We used eight animals that underwent mouth rinse with a solution containing maltodextrin. Ten blood samples were taken to evaluate the glycemic curve of each animal. The first sample was performed prior to mouth rinse to determine baseline plasma glucose levels, and the remaining nine samples were taken after mouth rinse in up to 3 hours. There were no significant changes in plasma glucose values, suggesting that there was no carbohydrate ingestion and absorption during the mouth rinse process.(AU)

Mecanismos aún no plenamente aclarados conduce a la mejora en el desempeño atlético de individuos sometidos al enjuague oral con carbohidratos, entre ellos la maltodextrina. Estudios recientes en humanos sugieren que la presencia de posibles receptores para carbohidratos en la orofaringe sean los responsables de mejorar el desempeño, pero através de un mecanismo aún no descifrado. El objetivo del presente estudio fue verificar si el procedimiento de enjuague oral en equinos permite la ingestión y absorción de la solución, llevando a una alteración en la curva glucémica. Se analizaron ocho animales que se sometieron a un enjuague bucal con una solución que contenía maltodextrina. Se realizaron diez colectas de sangre para evaluar la curva glucémica de cada animal, siendo la primera colecta realizada antes del enjuague oral para definir valores basales de glucosa plasmática, y las nueve otras colectas se realizaron después del enjuague oral en hasta 3 horas, de obtener información suficiente para determinar la curva glucémica en equinos. No hubo cambios significativos en los valores de glucosa plasmática, sugiriendo que no hubo ingestión y absorción del carbohidrato durante el proceso de enjuague oral.(AU)

Influência do enxágue oral com carboidrato na glicemia em equinos / Influence of carbohydrate mouth rinse on blood glucose in horses / Influencia del enjuague oral con carbohidratos en la glucemia en los equinos

Mecanismos ainda não plenamente esclarecidos levam a melhora no desempenho atlético de indivíduos submetidos à enxágue oral com carboidratos, dentre eles a maltodextrina. Estudos recentes em humanos sugerem que a presença de possíveis receptores para carboidratos na orofaringe sejam os responsáveis por melhorar o desempenho,porém por meio de mecanismo ainda não decifrados. O objetivo do presente estudo foi verificar se o procedimento de enxágue oral em equinos permite a ingestão e absorção da solução, levando a uma alteração na curva glicêmica. Analisamos oito animais que foram submetidos a um enxágue oral com uma solução contendo maltodextrina. Foram realizadas dez coletas de sangue para avaliação da curva glicêmica de cada animal, sendo a primeira coleta realizada antes do enxágue oral para definir valores basais de glicose plasmática, e as nove demais coletas foram realizadas após o enxágue oral em até 3 horas, a fim de obter informações suficientes para determinação da curva glicêmica em equinos. Não houveram alterações significativas nos valores de glicose plasmática, sugerindo que não houve ingestão e absorção do carboidrato durante o processo de enxágue oral.

The mechanism related to the practice of oral carbohydrate supplementation prior exercise for athletic horses remains unclear. Recent studies in humans suggest that the presence of possible receptors for carbohydrates in the oropharynx are responsible for improving performance, but with mechanisms not yet deciphered. The aim of the present study was to verify if the carbohydrates mouth rinse procedure in horses allows the ingestion and absorption of the solution, leading to changes in the glycemic curve. We used eight animals that underwent mouth rinse with a solution containing maltodextrin. Ten blood samples were taken to evaluate the glycemic curve of each animal. The first sample was performed prior to mouth rinse to determine baseline plasma glucose levels, and the remaining nine samples were taken after mouth rinse in up to 3 hours. There were no significant changes in plasma glucose values, suggesting that there was no carbohydrate ingestion and absorption during the mouth rinse process.

Mecanismos aún no plenamente aclarados conduce a la mejora en el desempeño atlético de individuos sometidos al enjuague oral con carbohidratos, entre ellos la maltodextrina. Estudios recientes en humanos sugieren que la presencia de posibles receptores para carbohidratos en la orofaringe sean los responsables de mejorar el desempeño, pero através de un mecanismo aún no descifrado. El objetivo del presente estudio fue verificar si el procedimiento de enjuague oral en equinos permite la ingestión y absorción de la solución, llevando a una alteración en la curva glucémica. Se analizaron ocho animales que se sometieron a un enjuague bucal con una solución que contenía maltodextrina. Se realizaron diez colectas de sangre para evaluar la curva glucémica de cada animal, siendo la primera colecta realizada antes del enjuague oral para definir valores basales de glucosa plasmática, y las nueve otras colectas se realizaron después del enjuague oral en hasta 3 horas, de obtener información suficiente para determinar la curva glucémica en equinos. No hubo cambios significativos en los valores de glucosa plasmática, sugiriendo que no hubo ingestión y absorción del carbohidrato durante el proceso de enjuague oral.

Heteropterys tomentosa A. Juss: Toxicological and adaptogenic effects in experimental models.

BACKGROUND: The constant pursuit of improved athletic performance characterizes high-performance sport and the use of medicinal plants as dietary supplements is becoming widespread among athletes to enhance long-term endurance performance. AIM: The present study evaluated the toxicity of Heteropterys tomentosa (HEHt) and its acute adaptogenic effects. METHODS: The in vitro safety profile was evaluated on CHO-k1 cells using the alamar Blue assay, at concentrations ranging from 3.125 to 200 µg/mL. In vivo acute oral toxicity was conducted in male and female mice with oral administration of graded doses of HEHt from 400 to 2000 mg/kg. A subchronic oral toxicity study was completed by oral administration of HEHt (50, 200 or 1000 mg/kg) and vehicle for 30 days in male Wistar rats. Clinical observations and toxicological related parameters were determined. Blood was collected for biochemical and hematological analyses, while histological examinations were performed on selected organs. Thereafter, an adaptogenic test consisting of progressive loads until exhaustion was conducted in rats ( n = 5/group) orally pre-treated with the vehicle and HEHt (25, 100 or 400 mg/kg). RESULTS: HEHt exhibited no cytotoxic effects on the CHO-k1 cells and, apparently, no acute toxicity in mice and no subchronic toxicity in rats. An ergogenic effect was observed only at the dose of 25 mg/kg compared with the vehicle in relation to time to exhaustion and exercise load ( p = .011 and .019, respectively). HEHt is safe at up to 400 mg/kg, contains astilbin and taxifolin as the major phytochemical compounds, and exhibited a potential adaptogenic effect. CONCLUSIONS: These results justify its anecdotal usage as a tonic, show that the hydroethanolic maceration of the root does not cause toxicity, and provide scientific evidence of its potential as a source of new adaptogenic substance(s).

Caffeine effects on VO2max test outcomes investigated by a placebo perceived-as-caffeine design.

BACKGROUND: Ergogenic effects of caffeine (CAF) ingestion have been observed in different cycling exercise modes, and have been associated with alterations in ratings of perceived exertion (RPE). However, there has been little investigation of maximal oxygen uptake (VO2MAX) test outcomes. AIM: This study aimed to verify whether CAF may reduce RPE, thereby improving maximal incremental test (MIT) outcomes such as VO2MAX, time to exhaustion and peak power output (WPEAK). METHODS: Nine healthy individuals performed three MITs (25 W/min until exhaustion) in a random, counterbalanced fashion after ingestion of CAF, placebo perceived as caffeine (PLA), and no supplementation (baseline control). VO2 was measured throughout the test, while RPE was rated according to overall and leg effort sensations. The power output corresponding to submaximal (RPE = 14 according to the 6-20 Borg scale) and maximal RPE was recorded for both overall (O-RPE14 and O-RPEMAX) and leg RPE (L-RPE14 and L-RPEMAX). RESULTS: VO2MAX did not change significantly between MITs; however, CAF and PLA increased time to exhaustion (↑ ∼18.7% and ∼17.1%, respectively; p < .05) and WPEAK (↑ ∼13.0% and ∼11.8%, respectively; p < .05) when compared with control. When compared with control, CAF ingestion reduced submaximal and maximal overall and leg RPEs, the effect being greater in maximal (likely beneficial in O-RPEMAX and L-RPEMAX) than submaximal RPE (possibly beneficial in O-RPE14 and L-RPE14). Similar results were found when participants ingested PLA. CONCLUSIONS: Compared with control, CAF and PLA improved MIT performance outcomes such as time to exhaustion and WPEAK, without altering VO2MAX values. CAF effects were attributed to placebo.

Creatine supplementation elicits greater muscle hypertrophy in upper than lower limbs and trunk in resistance-trained men.

BACKGROUND: Creatine (Cr) supplementation associated with resistance training produces greater muscular strength improvements in the upper compared with the lower body; however, no study has investigated if such region-specific results are seen with gains in muscle mass. AIM: We aimed to evaluate the effect of Cr supplementation in combination with resistance training on lean soft tissue changes in the upper and lower limbs and trunk in resistance-trained young adult men. METHODS: In a randomized, double-blind and placebo-controlled design, 43 resistance-trained men (22.7 ± 3.0 years, 72.9 ± 8.7 kg, 177.9 ± 5.7 cm, 23.0 ± 2.5 kg/m2) received either creatine (Cr, n = 22) or placebo (PLA, n = 21) over an 8-week study period. The supplementation protocol included a loading phase (7 days, four doses of 0.3 g/kg per day) and a maintenance phase (7 weeks, single dose of 0.03 g/kg per day). During the same period, subjects performed resistance training four times per week using the following two-way split routine: Monday and Thursday = pectoral, shoulders, triceps, and abdomen, Tuesday and Friday = back, biceps, thighs, and calves. Lean soft tissue of the upper limbs (ULLST), lower limbs (LLLST), and trunk (TLST) was assessed by dual-energy X-ray absorptiometry before and after the intervention. RESULTS: Both groups showed significant ( p < 0.001) improvements in ULLST, LLLST, TLST, and the Cr group achieved greater ( p < 0.001) increases in these outcomes compared with PLA. For the Cr group, improvements in ULLST (7.1 ± 2.9%) were higher than those observed in LLLST (3.2 ± 2.1%) and TLST (2.1 ± 2.2%). Otherwise, for PLA group there was no significant difference in the magnitude of segmental muscle hypertrophy (ULLST = 1.6 ± 3.0%; LLLST = 0.7 ± 2.8%; TLST = 0.7 ± 2.8%). CONCLUSION: Our results suggest that Cr supplementation can positively augment muscle hypertrophy in resistance-trained young adult men, particularly in the upper limbs.

Probiotic supplementation in sports and physical exercise: Does it present any ergogenic effect?

BACKGROUND: Probiotics are live microorganisms that promote health benefits to the host. Evidence indicates that some probiotic strains play an immunomodulatory role and reduce the incidence of respiratory and gastrointestinal infections in athletes and in physical activity practitioners. For this reason, probiotic supplementation could indirectly improve exercise performance. However, recent studies have observed direct ergogenic effects of probiotics, but the mechanisms of action are poorly elucidated. OBJECTIVE: In this study, we aim to synthesize available knowledge on the effect of probiotics on physical exercise, identify the mechanisms of action by which probiotics could improve performance directly and indirectly, and verify whether probiotics have any ergogenic effect. METHODS: The study was performed in the PubMed database in February 2017, without limitation as to the publication period. The keyword combinations used were: 'Probiotics' and 'Sports' ( n = 17 articles), 'Probiotics' and 'Exercise' ( n = 26 articles) and 'Probiotics' and 'Athletes' ( n = 11 articles). RESULTS: Of the 16 studies evaluated, only six applied performance tests, of which only two demonstrated that probiotic supplementation increases performance, but one of them was performed with mice. CONCLUSIONS: According to the studies evaluated, probiotic supplementation does not present ergogenic effect, however, considering the small number of studies, this subject should be better investigated.

[Protein supplement consumption and its possible association with kidney damage in Mexican elite athletes]. / Consumo de suplemento proteico y su posible asociación con daño renal en atletas mexicanos de alto rendimiento.

BACKGROUND: Protein supplements are one of the most used ergogenic supplements by elite athletes. Nonetheless, it has been postulated that the use of these type of supplements may cause chronic renal failure. The objective of this study is to analyze the effects of the consumption of protein supplements in the renal function of elite athletes of the Mexican Olympic Training Center. METHODS: 74 athletes provided urine samples in order to quantify urinary proteins. Some of them were excluded since they had conditions that could cause proteinuria or alter the quality of the samples. Those that were not excluded were divided into two groups: the experimental group, which included those individuals that had the antecedent of consuming protein supplements, and the control group, that encompassed those individuals that did not had the antecedent of consuming protein supplements. RESULTS: Of the 74 analyzed athletes, 44 were excluded, 11 individuals were included in the experimental group, and 19 in the control group. Microproteinuria was encountered in only one urine sample (control group), and it was determined that there was no significant differences between both groups. CONCLUSION: From the gathered results it can be concluded that protein supplements do not affect renal function. Nonetheless, in the future protein supplements should be evaluated in groups with pathologies or conditions that may compromise renal function.

Introducción: los suplementos proteicos son unos de los suplementos ergogénicos más utilizados por los atletas de alto rendimiento. Sin embargo, se ha postulado que el consumo de estos pudiese ser causa de insuficiencia renal crónica. El objetivo fue analizar los efectos del consumo de suplementos proteínicos en la función renal de los atletas de alto rendimiento del Centro Deportivo Olímpico Mexicano. Métodos: se evaluaron 74 atletas, en cuya muestra de orina se cuantificaron las proteínas. Se excluyeron los atletas con antecedentes o condiciones que pudiesen causar proteinuria o que pudieran alterar la calidad de la muestra. Los elegidos se dividieron en dos grupos con base en el antecedente de consumo de suplemento proteico: el grupo experimental lo conformaron los consumidores y el control los no consumidores. Resultados: de 74 atletas analizados, 44 fueron excluidos, 11 se incluyeron al grupo experimental y 19 al grupo control. Se obtuvo un resultado positivo para microproteinuria en este último grupo. Se determinó estadísticamente que ambos grupos eran similares y se estableció, en relación con el resultado positivo de microproteinura, que no existe una diferencia significativa entre ambos grupos. Conclusión: el consumo de suplemento proteico no ha afectado la función renal de los atletas analizados. Pese a esto, consideramos que la seguridad del suplemento proteico debe ser evaluada en un futuro en ciertos grupos con patologías o antecedentes que pudieran comprometer la función renal.

Increased atherothrombotic markers and endothelial dysfunction in steroid users.

BACKGROUND: The use of androgenic anabolic steroids (AAS) may be associated with changes in atherothrombotic markers and endothelial function. The purpose of this study was to compare atherothrombotic markers and endothelial function of AAS users and non-users. DESIGN: Cross-sectional study. METHODS: Ten athletes who were users of AAS (confirmed by urine analysis) and 12 non-user athletes were evaluated. Body weight, blood pressure, exercise load (hours/week), complete blood count (CBC), platelets, fibrinogen, lipids, high-sensitivity C-reactive protein (hs-CRP), follicle-stimulating hormone, testosterone and estradiol were measured. Endothelium-dependent and independent functions were assessed by brachial artery ultrasound. RESULTS: AAS users had higher body mass and blood pressure (p < 0.05). Platelet count was higher whereas HDL-cholesterol was lower in AAS users compared with non-users (p < 0.05). Levels of hs-CRP were higher in AAS users (p < 0.001). Follicle-stimulating hormone was suppressed in all users and not suppressed in non-users (p < 0.001). Compared with non-users, flow-mediated dilation was significantly reduced in AAS users (p = 0.03), whereas endothelium-independent function was similar in both groups. Additionally, flow-mediated dilation was positively associated with levels of HDL- cholesterol (r = 0.49, p = 0.03). CONCLUSIONS: AAS users present important changes in blood lipids as well as in inflammatory markers, which are compatible with increased cardiovascular risk. Furthermore, this profile is accompanied by a reduction in the endothelial function.

Inhibitory effects of modafinil on emotional memory in mice.

Modafinil (MOD), a psychostimulant used to treat narcolepsy, excessive daytime sleepiness, and sleepiness due to obstructive sleep apnea, appears to promote a possible facilitatory effect on cognitive function. In the present study, we investigated the effects of the acute administration of MOD on the different steps of emotional memory formation and usage (acquisition, consolidation and retrieval) as well as the possible participation of the state-dependency phenomenon on the cognitive effects of this compound. Mice were acutely treated with 32, 64 or 128 mg/kg MOD before training or testing or immediately after training and were subjected to the plus-maze discriminative avoidance task. The results showed that although pre-training MOD administration did not exert any effects on learning, the doses of 32 or 64 mg/kg induced emotional memory deficits during testing. Still, the post-training acute administration of the higher doses of MOD (64 and 128 mg/kg) impaired associative memory consolidation. When the drug was administered pre-test, only the 32 mg/kg dose impaired the task retrieval. Importantly, the cognitive impairing effects induced by 32 mg/kg MOD were not related to the phenomenon of state-dependency. In all, our findings provide pre-clinical evidence of potential emotional memory amnesia induced by MOD. This article is part of a Special Issue entitled 'Cognitive Enhancers'.