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La guia CONSORT (CONsolidated Standards Of Reporting Trials)de 2010 (http://www.consort-statement.org/consort-2010) fuedesarrollada para mejorar el informe de ensayos clinicoscontrolados aleatorios de grupos paralelos, por lo que elcumplimiento de los estandares establecidos se puede demostrarmediante la cumplimentacion de la lista de chequeo CONSORT20101. Las principales revistas medicas han respaldado estainiciativa, que sin duda ha mejorado la realizacion y el informe deresultados de la investigacion clinica y sanitaria. La investigacionen el campo de la nutricion deportiva y el metabolismo delejercicio se beneficiara de estandares similares, pero comunmenteutiliza disenos de investigacion diferentes a los ensayos clinicos degrupos paralelos, como los experimentos cruzados.Se ha publicado recientemente una ampliacion de CONSORT queaborda ensayos cruzados aleatorios2, con una lista de verificacionrevisada que se centra en cuestiones de primera relevancia paraensayos clinicos que abordan tratamientos medicos o deasistencia medica. Sin embargo, estas cuestiones especificas de losensayos clinicos, pueden tener una relevancia diferente, cuando seconsideran en relacion con los experimentos mecanicistas,estrictamente controlados, realizados en laboratorio, que sonhabituales en la ciencia del ejercicio. Por ejemplo, los disenoscruzados pueden implicar efectos de orden entre evaluaciones; enlos ensayos clinicos, esto suele ocurrir con mayor frecuenciadebido al tratamiento o la intervencion en si, lo que requiere unintervalo de lavado suficiente, antes de repetir las evaluaciones.Por el contrario, la tendencia en la investigacion sobre nutriciondeportiva, se relaciona comunmente con la evaluacion en simisma, que a menudo, tiende a ser mas invasiva o exigente para elparticipante, que una instantanea sobre su estado de salud. Dehecho, las pruebas fisicas de rendimiento humano sonparticularmente propensas a efectos de aprendizaje o fatiga eincluso algunas adaptaciones fisicas pueden persistir durantesemanas o meses despues del primer test. Por ejemplo, eldenominado “efecto de intentos repetidos”, que describe como unasola exposicion a un ejercicio fisico desacostumbrado que producedano muscular puede inducir una profunda y duradera proteccionante ejercicios similares en el futuro3,4. Los participantes enensayos de ejercicio tambien pueden ser atletas de elite, cuyosniveles habituales de actividad fisica (y dieta) pueden mostrarvariaciones profundas a lo largo del tiempo (es decir,periodizacion), lo que complica aun mas la interpretacion deestudios longitudinales.La lista de chequeo PRESENT (Proper Reporting of Evidence inSport & Exercise Nutrition Trials) 2020 (Ver Anexo), por tanto, seha adaptado de la guia CONSORT para abordar especificamente lacombinacion unica de desafios y oportunidades que enfrentan losinvestigadores dentro de los amplios campos de la nutriciondeportiva y el metabolismo del ejercicio. El presente documentocomplementa y desarrolla la lista de verificacion CONSORT alponer enfasis y proveer ejemplos comunes o de mayor relevanciapara la investigacion en esta area tematica. La lista decomprobacion PRESENT 2020 se diseno teniendo en cuenta lanecesidad de minimizar a los autores la sobrecarga que suponeasegurarse de que el informe de sus resultados cumpla con losrequisitos de calidad; deberia permitir a los investigadoresdeterminar rapidamente si toda la informacion relevante estaincluida en su manuscrito. Por supuesto, es posible cumplir contodos los factores en la lista de verificacion a pesar de haberrealizado un mal estudio y/o haber informado mal de un buenestudio, mientras que algunos elementos de la lista de chequeopueden no ser aplicables incluso para investigacionesrigurosamente realizadas. No obstante, la consideracion ydiscusion de los factores identificados en la lista de chequeodeberia mejorar la comunicacion de los resultados de lainvestigacion relacionada con el ejercicio y la nutricion, en elfuturo inmediato, y tiene el potencial de mejorar el diseno y larealizacion de ensayos a largo plazo.

Accumulating evidence suggests that most elite cyclists have lower bone mineral density (BMD) values when compared with their nonelite counterparts (1) or sedentary young males (2, 3). This raises the question whether these ostensibly healthy athletes have a higher acute bone fracture risk and a higher risk of osteoporosis and associated comorbidities later in life. Although treatment of low BMD seems warranted in elite cyclists, the benefits of treatment for health and performance in this population remain to be established. In this viewpoint, we describe the etiology and consequences of impaired bone health in elite cyclists and discuss the need for interventions to optimize bone health in this unique population.

Large interindividual variation exists in maximal fat oxidation (MFO) rates and the exercise intensity at which it occurs (FATMAX). However, there are no data describing the shape of the fat oxidation curve or if individual differences exist when tested on separate occasions. Furthermore, there are limited data on fat metabolism in professional team sport athletes. Therefore, the aim of this study was to test-retest the concavity (shape) and intercept (height) of fat oxidation curves within a group of professional soccer players.On two occasions, 16 professional male soccer players completed a graded exercise test in a fasted state (≥5 h). Rates of fat oxidation were determined using indirect calorimetry. Maximal oxygen uptake (V˙O2max) was measured to calculate FATMAX (%V˙O2max). The shape of the fat oxidation curves were modeled on an individual basis using third-degree polynomial. Test-by-test differences, in the shape and vertical shift of the fat oxidation curves, were established to assess within-individual variability.Average absolute MFO was 0.69 ± 0.15 g·min (range, 0.45-0.99 g·min). On a group level, no significant differences were found in MFO between the two tests. No differences were found (P0.05) in the shape of the fat oxidation curves in 13 of 16 players (test 1 vs test 2). There were also no differences (P0.05) in the vertical shift of the fat oxidation curves in 10 players.In general, the shape of the fat oxidation curve does not change within an individual; however, the vertical shift is more susceptible to change, which may be due to training status and body composition. Understanding a player's metabolism may be of value to practitioners working within sport, with regard to personalizing nutrition strategies.

Distance events in Athletics include cross country, 10,000-m track race, half-marathon and marathon road races, and 20- and 50-km race walking events over different terrain and environmental conditions. Race times for elite performers span ∼26 min to >4 hr, with key factors for success being a high aerobic power, the ability to exercise at a large fraction of this power, and high running/walking economy. Nutrition-related contributors include body mass and anthropometry, capacity to use fuels, particularly carbohydrate (CHO) to produce adenosine triphosphate economically over the duration of the event, and maintenance of reasonable hydration status in the face of sweat losses induced by exercise intensity and the environment. Race nutrition strategies include CHO-rich eating in the hours per days prior to the event to store glycogen in amounts sufficient for event fuel needs, and in some cases, in-race consumption of CHO and fluid to offset event losses. Beneficial CHO intakes range from small amounts, including mouth rinsing, in the case of shorter events to high rates of intake (75–90 g/hr) in the longest races. A personalized and practiced race nutrition plan should balance the benefits of fluid and CHO consumed within practical opportunities, against the time, cost, and risk of gut discomfort. In hot environments, prerace hyperhydration or cooling strategies may provide a small but useful offset to the accrued thermal challenge and fluid deficit. Sports foods (drinks, gels, etc.) may assist in meeting training/race nutrition plans, with caffeine, and, perhaps nitrate being used as evidence-based performance supplements.

Hypohydration increases physiological strain and reduces physical and technical soccer performance, but there are limited data on how fluid balance responses change between different types of sessions in professional players. This study investigated sweat and fluid/carbohydrate intake responses in elite male professional soccer players training at low and high intensities in cool and hot environments. Fluid/sodium (Na+) losses and ad-libitum carbohydrate/fluid intake of fourteen elite male soccer players were measured on four occasions: cool (wet bulb globe temperature (WBGT): 15 &plusmn, 7 &deg, C, 66 &plusmn, 6% relative humidity (RH)) low intensity (rating of perceived exertion (RPE) 2&ndash, 4, m&middot, min&minus, 1 40&ndash, 46) (CL), cool high intensity (RPE 6&ndash, 8, m&middot, 1 82&ndash, 86) (CH), hot (29 &plusmn, 1 &deg, C, 52 &plusmn, 7% RH) low intensity (HL), hot high intensity (HH). Exercise involved 65 &plusmn, 5 min of soccer-specific training. Before and after exercise, players were weighed in minimal clothing. During training, players had ad libitum access to carbohydrate beverages and water. Sweat [Na+] (mmol&middot, L&minus, 1), which was measured by absorbent patches positioned on the thigh, was no different between conditions, CL: 35 &plusmn, 9, CH: 38 &plusmn, 8, HL: 34 &plusmn, 70.17, HH: 38 &plusmn, 8 (p = 0.475). Exercise intensity and environmental condition significantly influenced sweat rates (L&middot, h&minus, 1), CL: 0.55 &plusmn, 0.20, CH: 0.98 &plusmn, 0.21, HL: 0.81 &plusmn, 0.17, HH: 1.43 &plusmn, 0.23 (p =0.001), and percentage dehydration (p &lt, 0.001). Fluid intake was significantly associated with sweat rate (p = 0.019), with no players experiencing hypohydration &gt, 2% of pre-exercise body mass. Carbohydrate intake varied between players (range 0&ndash, 38 g&middot, 1), with no difference between conditions. These descriptive data gathered on elite professional players highlight the variation in the hydration status, sweat rate, sweat Na+ losses, and carbohydrate intake in response to training in cool and hot environments and at low and high exercise intensities.

Infographic 1: UEFA 2020 expert group statement in elite football: Training day. Infographic 2: UEFA 2020 expert group statement in elite football: match-day. Infographic 3: UEFA 2020 expert group statement in elite football: Best of the rest—8 other key take-home messages. UEFA commissioned an expert group statement on nutrition in elite football.1 Gathering 32 global experts in football and nutrition research …

It is becoming increasingly clear that adaptations, initiated by exercise, can be amplified or reduced by nutrition. Various methods have been discussed to optimize training adaptations and some of these methods have been subject to extensive study. To date, most methods have focused on skeletal muscle, but it is important to note that training effects also include adaptations in other tissues (e.g., brain, vasculature), improvements in the absorptive capacity of the intestine, increases in tolerance to dehydration, and other effects that have received less attention in the literature. The purpose of this review is to define the concept of periodized nutrition (also referred to as nutritional training) and summarize the wide variety of methods available to athletes. The reader is referred to several other recent review articles that have discussed aspects of periodized nutrition in much more detail with primarily a focus on adaptations in the muscle. The purpose of this review is not to discuss the literature in great detail but to clearly define the concept and to give a complete overview of the methods available, with an emphasis on adaptations that are not in the muscle. Whilst there is good evidence for some methods, other proposed methods are mere theories that remain to be tested. ‘Periodized nutrition’ refers to the strategic combined use of exercise training and nutrition, or nutrition only, with the overall aim to obtain adaptations that support exercise performance. The term nutritional training is sometimes used to describe the same methods and these terms can be used interchangeably. In this review, an overview is given of some of the most common methods of periodized nutrition including ‘training low’ and ‘training high’, and training with low- and high-carbohydrate availability, respectively. ‘Training low’ in particular has received considerable attention and several variations of ‘train low’ have been proposed. ‘Training-low’ studies have generally shown beneficial effects in terms of signaling and transcription, but to date, few studies have been able to show any effects on performance. In addition to ‘train low’ and ‘train high’, methods have been developed to ‘train the gut’, train hypohydrated (to reduce the negative effects of dehydration), and train with various supplements that may increase the training adaptations longer term. Which of these methods should be used depends on the specific goals of the individual and there is no method (or diet) that will address all needs of an individual in all situations. Therefore, appropriate practical application lies in the optimal combination of different nutritional training methods. Some of these methods have already found their way into training practices of athletes, even though evidence for their efficacy is sometimes scarce at best. Many pragmatic questions remain unanswered and another goal of this review is to identify some of the remaining questions that may have great practical relevance and should be the focus of future research.

Football is a global game which is constantly evolving, showing substantial increases in physical and technical demands. Nutrition plays a valuable integrated role in optimising performance of elite players during training and match-play, and maintaining their overall health throughout the season. An evidence-based approach to nutrition emphasising, a ‘food first’ philosophy (ie, food over supplements), is fundamental to ensure effective player support. This requires relevant scientific evidence to be applied according to the constraints of what is practical and feasible in the football setting. The science underpinning sports nutrition is evolving fast, and practitioners must be alert to new developments. In response to these developments, the Union of European Football Associations (UEFA) has gathered experts in applied sports nutrition research as well as practitioners working with elite football clubs and national associations/federations to issue an expert statement on a range of topics relevant to elite football nutrition: (1) match day nutrition, (2) training day nutrition, (3) body composition, (4) stressful environments and travel, (5) cultural diversity and dietary considerations, (6) dietary supplements, (7) rehabilitation, (8) referees and (9) junior high-level players. The expert group provide a narrative synthesis of the scientific background relating to these topics based on their knowledge and experience of the scientific research literature, as well as practical experience of applying knowledge within an elite sports setting. Our intention is to provide readers with content to help drive their own practical recommendations. In addition, to provide guidance to applied researchers where to focus future efforts.

From the breakthrough studies of dietary carbohydrate and exercise capacity in the 1960s through to the more recent studies of cellular signaling and the adaptive response to exercise in muscle, it has become apparent that manipulations of dietary fat and carbohydrate within training phases, or in the immediate preparation for competition, can profoundly alter the availability and utilization of these major fuels and, subsequently, the performance of endurance sport (events >30 min up to ∼24 hr). A variety of terms have emerged to describe new or nuanced versions of such exercise–diet strategies (e.g., train low, train high, low-carbohydrate high-fat diet, periodized carbohydrate diet). However, the nonuniform meanings of these terms have caused confusion and miscommunication, both in the popular press and among the scientific community. Sports scientists will continue to hold different views on optimal protocols of fuel support for training and competition in different endurance events. However, to promote collaboration and shared discussions, a commonly accepted and consistent terminology will help to strengthen hypotheses and experimental/experiential data around various strategies. We propose a series of definitions and explanations as a starting point for a more unified dialogue around acute and chronic manipulations of fat and carbohydrate in the athlete’s diet, noting philosophies of approaches rather than a single/definitive macronutrient prescription. We also summarize some of the key questions that need to be tackled to help produce greater insight into this exciting area of sports nutrition research and practice.

L’apport en glucides (ou CHO) au cours de l’exercice est un facteur important de la performance dans les epreuves olympiques d’endurance d’une duree superieure a 30 minutes. Bien que cette constatation puisse s’appliquer a de nombreuses activites sportives, ce tour d’horizon de la litterature existante s’interessera particulierement aux activites d’endurance et, dans une moindre mesure, aux activites intermittentes. Afin de repondre aux besoins en CHO des muscles actifs, il est possible de mettre en place une strategie nutritionnelle individualisee en fonction de la duree et de l’intensite de l’exercice. Alors que les bienfaits des CHO sur la performance en endurance sont reconnus depuis les annees 1980, leurs modalites d’ingestion (type et quantite optimale) n’ont ete etudiees qu’au cours des dix dernieres annees. Les recherches realisees entre 1980 et 1990 montrent que les CHO ingeres pendant l’exercice sont oxydes a un taux de 60 g.h-1. Ces CHO pourraient etre divises en deux categories : ceux oxydes lentement, tels le fructose, le galactose et l’amidon insoluble ; ceux oxydes rapidement, tels le glucose, le sucrose, le maltose, les maltodextrines. Cependant, meme avec des apports tres importants en CHO, l’oxydation des CHO exogenes ne va pas au-dela de 250 Cal.h-1, alors que la depense energetique, dans de nombreuses activites, peut facilement depasser 1 000 Cal.h-1. Il s’est alors avere evident que l’absorption intestinale constituait le principal facteur limitant la fourniture des muscles actifs en CHO exogenes. Cette limitation peut etre en partie surmontee par le recours a differents types de CHO transportables dont l’ingestion accelere l’absorption par l’intestin et l’oxydation (jusqu’a 105 g.h-1), ce qui permet d’ameliorer la performance en endurance. Tout recemment, des etudes ont tente de demontrer une relation de dose-reponse entre le taux d’oxydation des CHO exogenes et la performance ; elles ont suggere que celle-ci pouvait etre amelioree par une augmentation des apports. Selon ces etudes, une ingestion de 90 g.h-1 de CHO au cours d’efforts de plus de 2 h 30 permettrait d’obtenir le meilleur compromis entre praticite et effet ergogene. Il semble egalement possible d’accroitre la capacite d’absorption de l’intestin en adoptant une ration riche en CHO. Certes, de nombreuses questions restent sans reponses, mais il est possible de developper plusieurs strategies afin d’ameliorer la fourniture en CHO et, par la meme, la performance en endurance. Ces strategies doivent aussi viser a maintenir un statut hydrique optimal (eviter une perte superieure a 2 % de masse corporelle) afin de prevenir l’apparition de la fatigue.

Purpose To determine effects of intensified training (IT) and carbohydrate supplementation on overreaching and immunity. Methods In a randomized, double-blind, crossover design, 13 male cyclists (age 25 ± 6 years, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}O_{2\hbox{max} }$$\end{document}V˙O2max 72 ± 5 ml/kg/min) completed two 8-day periods of IT. On one occasion, participants ingested 2 % carbohydrate (L-CHO) beverages before, during and after training sessions. On the second occasion, 6 % carbohydrate (H-CHO) solutions were ingested before, during and after training, with the addition of 20 g of protein in the post-exercise beverage. Blood samples were collected before and immediately after incremental exercise to fatigue on days 1 and 9. Results In both trials, IT resulted in decreased peak power (375 ± 37 vs. 391 ± 37 W, P

Few studies have investigated the effects of exercise training on sleep physiology in well-trained athletes. We investigated changes in sleep markers, mood state and exercise performance in well-trained cyclists undergoing short-term intensified training and carbohydrate nutritional intervention. Thirteen highly-trained male cyclists (age: 25 ± 6y, O2max: 72 ± 5 ml/kg/min) participated in two 9-day periods of intensified training while undergoing a high (HCHO) or moderate (CON) carbohydrate nutritional intervention before, during and after training sessions. Sleep was measured each night via wristwatch actigraphy. Mood state questionnaires were completed daily. Performance was assessed with maximal oxygen uptake (. Percentage sleep time fell during intensified training (87.9 ± 1.5 to 82.5 ± 2.3%; p

Intermittent sports (e.g., team sports) are diverse in their rules and regulations but similar in the pattern of play; that is, intermittent high-intensity movements and the execution of sport-specific skills over a prolonged period of time (~1–2 h). Performance during intermittent sports is dependent upon a combination of anaerobic and aerobic energy systems, both of which rely on muscle glycogen and/or blood glucose as an important substrate for energy production. The aims of this paper are to review: (1) potential biological mechanisms by which carbohydrate may impact intermittent sport performance; (2) the acute effects of carbohydrate ingestion on intermittent sport performance, including intermittent high-intensity exercise capacity, sprinting, jumping, skill, change of direction speed, and cognition; and (3) what recommendations can be derived for carbohydrate intake before/during exercise in intermittent sports based on the available evidence. The most researched intermittent sport is soccer but some sport-specific studies have also been conducted in other sports (e.g., rugby, field hockey, basketball, American football, and racquet sports). Carbohydrate ingestion before/during exercise has been shown in most studies to enhance intermittent high-intensity exercise capacity. However, studies have shown mixed results with regards to the acute effects of carbohydrate intake on sprinting, jumping, skill, change of direction speed, and cognition. In most of these studies the amount of carbohydrate consumed was ~30–60 g/h in the form of a 6%–7% carbohydrate solution comprised of sucrose, glucose, and/or maltodextrin. The magnitude of the impact that carbohydrate ingestion has on intermittent sport performance is likely dependent on the carbohydrate status of the individual; that is, carbohydrate ingestion has the greatest impact on performance under circumstances eliciting fatigue and/or hypoglycemia. Accordingly, carbohydrate ingestion before and during a game seems to have the greatest impact on intermittent sports performance towards the end of the game.

We previously reported that a 7 day ingestion of caffeinated green tea extract (cGTE) induced marked metabolic differences during rest and exercise. Here, we report the metabolic effects of 1, 7, and 28 day ingestions of decaffeinated GTE (dGTE). In this crossover placebo-controlled study, 19 healthy males ingested dGTE or placebo (PLA) for 28 days, separated by a 28 day wash-out period. On days 1, 7, and 28, participants completed a 30 min cycling exercise 2 h after the ingestion of dGTE or PLA. Blood samples were collected at rest (t = 0 and 120 min) and during exercise (t = 150 min). Plasma was analyzed using untargeted four-phase metabolite profiling and targeted profiling of catecholamines and catechins. dGTE abolished several metabolic effects when compared to our previous study with cGTE. However, following 7 and 28 day dGTE ingestions, increases in 3-hydroxybutyrate, a metabolic marker of fat oxidation, were observed at t = 0 min. dGTE ingestion did not induce significant acute or acute-on-chronic effects on endogenous metabolites just prior to and during exercise.

The present study examined whether a high protein diet prevents the impaired leukocyte redistribution in response to acute exercise caused by a large volume of high-intensity exercise training. Eight cyclists (VO2max: 64.2 ± 6.5 mL kg−1 min−1) undertook two separate weeks of high-intensity training while consuming either a high protein diet (3 g kg−1 protein BM−1 day−1) or an energy and carbohydrate-matched control diet (1.5 g kg−1 protein BM−1 day−1). High-intensity training weeks were preceded by a week of normal-intensity training under the control diet. Leukocyte and lymphocyte sub-population responses to acute exercise were determined at the end of each training week. Self-reported symptoms of upper-respiratory tract infections (URTI) were monitored daily by questionnaire. Undertaking high-intensity training with a high protein diet restored leukocyte kinetics to similar levels observed during normal-intensity training: CD8+ TL mobilization (normal-intensity: 29,319 ± 13,130 cells/μL × ∼165 min vs. high-intensity with protein: 26,031 ± 17,474 cells/μL × ∼165 min, P > 0.05), CD8+ TL egress (normal-intensity: 624 ± 264 cells/μL vs. high-intensity with protein: 597 ± 478 cells/μL, P > 0.05). This pattern was driven by effector-memory populations mobilizing (normal-intensity: 6,145 ± 6,227 cells/μL × ∼165 min vs. high-intensity with protein: 6,783 ± 8,203 cells/μL × ∼165 min, P > 0.05) and extravastating from blood (normal-intensity: 147 ± 129 cells/μL vs. high-intensity with protein: 165 ± 192 cells/μL, P > 0.05). High-intensity training while consuming a high protein diet was associated with fewer symptoms of URTI compared to performing high-intensity training with a normal diet (P < 0.05). To conclude, a high protein diet might reduce the incidence of URTI in athletes potentially mediated by preventing training-induced impairments in immune-surveillance.

Durante los últimos años se han producido cambios significativos en la comprensión del papel que juegan los carbohidratos durante el ejercicio, y esto permite realizar un asesoramiento más específico y más individualizado en cuanto a la ingestión de carbohidratos durante el ejercicio. Las nuevas directrices propuestas tienen en cuenta la duración (y la intensidad) del ejercicio y el asesoramiento no se limita a la cantidad de carbohidratos, sino que también propone el tipo de estos. La ingesta recomendada de carbohidratos se puede lograr consumiendo bebidas, geles con pocas grasas o alimentos sólidos bajos en proteínas y en fibra (barritas) y la elección debe basarse en las preferencias personales. Debe tenerse en cuenta que la mayoría de estudios se basan en descubrimientos realizados con corredores y ciclistas, por lo que es necesario investigar más para establecer los efectos y los mecanismos subyacentes de la ingestión de carbohidratos en los componentes de habilidad de deportes intermitentes de equipo.

Dietary supplementation with beetroot juice (BR), containing approximately 5–8 mmol inorganic nitrate (NO3−), increases plasma nitrite concentration ([NO2−]), reduces blood pressure, and may positively influence the physiological responses to exercise. However, the dose-response relationship between the volume of BR ingested and the physiological effects invoked has not been investigated. In a balanced crossover design, 10 healthy men ingested 70, 140, or 280 ml concentrated BR (containing 4.2, 8.4, and 16.8 mmol NO3−, respectively) or no supplement to establish the effects of BR on resting plasma [NO3−] and [NO2−] over 24 h. Subsequently, on six separate occasions, 10 subjects completed moderate-intensity and severe-intensity cycle exercise tests, 2.5 h postingestion of 70, 140, and 280 ml BR or NO3−-depleted BR as placebo (PL). Following acute BR ingestion, plasma [NO2−] increased in a dose-dependent manner, with the peak changes occurring at approximately 2–3 h. Compared with PL, 70 ml BR did not alter the physiological responses to exercise. However, 140 and 280 ml BR reduced the steady-state oxygen (O2) uptake during moderate-intensity exercise by 1.7% ( P = 0.06) and 3.0% ( P < 0.05), whereas time-to-task failure was extended by 14% and 12% (both P < 0.05), respectively, compared with PL. The results indicate that whereas plasma [NO2−] and the O2 cost of moderate-intensity exercise are altered dose dependently with NO3−-rich BR, there is no additional improvement in exercise tolerance after ingesting BR containing 16.8 compared with 8.4 mmol NO3−. These findings have important implications for the use of BR to enhance cardiovascular health and exercise performance in young adults.

At rest, administration of the short-chain fatty acid acetate suppresses fat oxidation without affecting carbohydrate utilization. The combined effect of increased acetate availability and exercise on substrate utilization is, however, unclear. With local ethics approval, we studied the effect of ingesting either sodium acetate (NaAc) or sodium bicarbonate (NaHCO3) at a dose of 4 mmol·kg-1 body mass 90 min before completing 120 min of exercise at 50% VO2peak. Six healthy young men completed the trials after an overnight fast and ingested the sodium salts in randomized order. As expected NaAc ingestion decreased resting fat oxidation (mean ± SD; 0.09 ± 0.02 vs. 0.07 ± 0.02 g·min-1 pre- and post-ingestion respectively, p < .05) with no effect upon carbohydrate utilization. In contrast, NaHCO3 ingestion had no effect on substrate utilization at rest. In response to exercise, fat and CHO oxidation increased in both trials, but fat oxidation was lower (0.16 ± 0.10 vs. 0.29 ± 0.11 g·min-1, p < .05) and carbohydrate oxidation higher (1.67 ± 0.35 vs. 1.44 ± 0.22 g·min-1, p < .05) in the NaAc trial compared with the NaHCO3 trial during the first 15 min of exercise. Over the final 75 min of exercise an increase in fat oxidation and decrease in carbohydrate oxidation was observed only in the NaAc trial. These results demonstrate that increasing plasma acetate concentration suppresses fat oxidation both at rest and at the onset of moderate-intensity exercise.

Peak exogenous carbohydrate oxidation rates typically reach 1 g center dot min(-1) during exercise when ample glucose or glucose polymers are ingested. Fructose co-ingestion has been shown to further increase exogenous carbohydrate oxidation rates. The purpose of this study was to assess the impact of fructose co-ingestion provided either as a monosaccharide or as part of the disaccharide sucrose on exogenous carbohydrate oxidation rates during prolonged exercise in trained cyclists. Ten trained male cyclists (VO(2)peak: 65 +/- 2 mL center dot kg(-1)center dot min(-1)) cycled on four different occasions for 180 min at 50% W-max during which they consumed a carbohydrate solution providing 1.8 g center dot min(-1) of glucose (GLU), 1.2 g center dot min(-1) glucose + 0.6 g center dot min(-1) fructose (GLU + FRU), 0.6 g center dot min(-1) glucose + 1.2 g center dot min(-1) sucrose (GLU + SUC), or water (WAT). Peak exogenous carbohydrate oxidation rates did not differ between GLU + FRU and GLU + SUC (1.40 +/- 0.06 vs. 1.29 +/- 0.07 g center dot min(-1), respectively, p = 0.999), but were 46% +/- 8% higher when compared to GLU (0.96 +/- 0.06 g center dot min(-1): p

Carbohydrates during exercise can improve exercise performance even when the exercise intensity is high (>75% V˙O2max) and the duration relatively short (approximately 1 h), but the underlying mechanisms for the ergogenic effects are different from those during more prolonged exercise. Studies have even shown effects of oral carbohydrate mouth rinses compared to placebo with improvements typically between 2% and 3% during exercise lasting approximately 1 h. The effects appear more profound after an overnight fast, but effects are still present even after ingestion of a meal. Brain imaging studies have identified brain areas involved, and it is likely that the oral carbohydrate mouth rinse results in afferent signals capable of modifying motor output. These effects appear to be specific to carbohydrate and are independent of taste. Further research is warranted to fully understand the separate taste transduction pathways for various carbohydrates as well as the practical implications.

Background Green tea catechins have been hypothesized to increase energy expenditure and fat oxidation by inhibiting catechol- O -methyltransferase (COMT) and thus promoting more sustained adrenergic stimulation. Metabolomics may help to clarify the mechanisms underlying their putative physiological effects. Objective The study investigated the effects of 7-day ingestion of green tea extract (GTE) on the plasma metabolite profile at rest and during exercise. Methods In a placebo-controlled, double-blind, randomized, parallel study, 27 healthy physically active males consumed either GTE ( n =13, 1200 mg catechins, 240 mg caffeine/day) or placebo ( n =14, PLA) drinks for 7 days. After consuming a final drink (day 8), they rested for 2 h and then completed 60 min of moderate-intensity cycling exercise (56%±4% VO 2 max). Blood samples were collected before and during exercise. Plasma was analyzed using untargeted four-phase metabolite profiling and targeted profiling of catecholamines. Results Using the metabolomic approach, we observed that GTE did not enhance adrenergic stimulation (adrenaline and noradrenaline) during rest or exercise. At rest, GTE led to changes in metabolite concentrations related to fat metabolism (3-β-hydroxybutyrate), lipolysis (glycerol) and tricarboxylic acid cycle (TCA) cycle intermediates (citrate) when compared to PLA. GTE during exercise caused reductions in 3-β-hydroxybutyrate concentrations as well as increases in pyruvate, lactate and alanine concentrations when compared to PLA. Conclusions GTE supplementation resulted in marked metabolic differences during rest and exercise. Yet these metabolic differences were not related to the adrenergic system, which questions the in vivo relevance of the COMT inhibition mechanism of action for GTE.

The aim of this study was to describe maximal fat oxidation (MFO) rates in an athletic population.In total, 1121 athletes (933 males and 188 females), from a variety of sports and competitive level, undertook a graded exercise test on a treadmill in a fasted state (≥5 h fasted). Rates of fat oxidation were determined using indirect calorimetry.The average MFO was 0.59 ± 0.18 g·min, ranging from 0.17 to 1.27 g·min. Maximal rates occurred at an average exercise intensity of 49.3% ± 14.8% V˙O2max, ranging from 22.6% to 88.8% V˙O2max. In absolute terms, male athletes had significantly higher MFO compared with females (0.61 and 0.50 g·min, respectively, P0.001). Expressed relative to fat-free mass (FFM), MFO were higher in the females compared with males (MFO/FFM: 11.0 and 10.0 mg·kg·FFM·min, respectively, P0.001). Soccer players had the highest MFO/FFM (10.8 mg·kg·FFM·min), ranging from 4.1 to 20.5 mg·kg·FFM·min, whereas American Football players displayed the lowest rates of MFO/FFM (9.2 mg·kg·FFM·min). In all athletes, and when separated by sport, large individual variations in MFO rates were observed. Significant positive correlations were found between MFO (g·min) and the following variables: FFM, V˙O2max, FATMAX (the exercise intensity at which the MFO was observed), percent body fat, and duration of fasting. When taken together these variables account for 47% of the variation in MFO.MFO and FATMAX vary significantly between athletes participating in different sports but also in the same sport. Although variance in MFO can be explained to some extent by body composition and fitness status, more than 50% of the variance is not explained by these variables and remains unaccounted for.

Purpose: We examined whether exercise-induced lymphocytosis and lymphocytopenia are impaired with high-intensity training.Methods: Eight trained cyclists (V·O2max = 64.2 ± 6.5 mL·kg-1·min-1) undertook 1 wk of normal-intensity training and a second week of high-intensity training. On day 7 of each week, participants performed a cycling task, consisting of 120 min of submaximal exercise followed by a 45-min time trial. Blood was collected before, during, and after exercise. CD8+ T lymphocytes (CD8+TLs) were identified, as well as CD8+TL subpopulations on the basis of CD45RA and CD27 expression.Results: High-intensity training (18,577 ± 10,984 cells per microliter × ~165 min) was associated with a smaller exercise-induced mobilization of CD8+TLs compared with normal-intensity training (28,473 ± 16,163 cells per microliter × ~165 min, P = 0.09). The response of highly cytotoxic CD8+TLs (CD45RA+CD27-) to exercise was smaller after 1 wk of high-intensity training (3144 ± 924 cells per microliter × ~165 min) compared with normal-intensity training (6417 ± 2143 cells per microliter × ~165 min, P < 0.05). High-intensity training reduced postexercise CD8+TL lymphocytopenia (-436 ± 234 cells per microliter) compared with normal-intensity training (-630 ± 320 cells per microliter, P < 0.05). This was driven by a reduced egress of naive CD8+TLs (CD27+CD45RA+). High-intensity training was associated with reduced plasma epinephrine (-37%) and cortisol (-15%) responses (P < 0.05).Conclusions: High-intensity training impaired CD8+TL mobilization and egress in response to exercise. Highly cytotoxic CD8+TLs were primarily responsible for the reduced mobilization of CD8+TLs, which occurred in parallel with smaller neuroendocrine responses. The reduced capacity for CD8+TLs to leave blood after exercise with high-intensity training was accounted for primarily by naive, and also, highly cytotoxic CD8+TLs. This impaired CD8+TL redistribution in athletes undertaking intensified training may imply reduced immune surveillance.

The term 'fat burner' is used to describe nutrition supplements that are claimed to acutely increase fat metabolism or energy expenditure, impair fat absorption, increase weight loss, increase fat oxidation during exercise, or somehow cause long-term adaptations that promote fat metabolism. Often, these supplements contain a number of ingredients, each with its own proposed mechanism of action and it is often claimed that the combination of these substances will have additive effects. The list of supplements that are claimed to increase or improve fat metabolism is long; the most popular supplements include caffeine, carnitine, green tea, conjugated linoleic acid, forskolin, chromium, kelp and fucoxanthin. In this review the evidence for some of these supplements is briefly summarized. Based on the available literature, caffeine and green tea have data to back up its fat metabolism-enhancing properties. For many other supplements, although some show some promise, evidence is lacking. The list of supplements is industry-driven and is likely to grow at a rate that is not matched by a similar increase in scientific underpinning.

The way in which metabolic fuels are utilized can alter the expression of behaviour in the interests of regulating energy balance and fuel availability. This is consistent with the notion that the regulation of appetite is a psychobiological process, in which physiological mediators act as drivers of behaviour. The glycogenostatic theory suggests that glycogen availability is central in eliciting negative feedback signals to restore energy homeostasis. Due to its limited storage capacity, carbohydrate availability is tightly regulated and its restoration is a high metabolic priority following depletion. It has been proposed that such depletion may act as a biological cue to stimulate compensatory energy intake in an effort to restore availability. Due to the increased energy demand, aerobic exercise may act as a biological cue to trigger compensatory eating as a result of perturbations to muscle and liver glycogen stores. However, studies manipulating glycogen availability over short-term periods (1-3 days) using exercise, diet or both have often produced equivocal findings. There is limited but growing evidence to suggest that carbohydrate balance is involved in the short-term regulation of food intake, with a negative carbohydrate balance having been shown to predict greater ad libitum feeding. Furthermore, a negative carbohydrate balance has been shown to be predictive of weight gain. However, further research is needed to support these findings as the current research in this area is limited. In addition, the specific neural or hormonal signal through which carbohydrate availability could regulate energy intake is at present unknown. Identification of this signal or pathway is imperative if a casual relationship is to be established. Without this, the possibility remains that the associations found between carbohydrate balance and food intake are incidental.

Current recommendations for CHO intake in the field for all modes of endurance exercise are largely on the basis of laboratory studies that measured oxidation of ingested CHO. However, the majority of these laboratory studies used cycling as the mode of exercise, and it is not known whether these results can be extrapolated to running. Purpose: The purpose of this study was to investigate exogenous CHO oxidation from a CHO drink during moderate-intensity running (RUN) compared with cycling (CYCLE). Methods: Eight athletes with comparable CYCLE and RUN training backgrounds (mean ± SD: age = 37 ± 7 yr, weight = 75 ± 7 kg, height = 1.77 ± 0.05 m; V?O2max CYCLE = 63 ± 3 mL·kg-1·min-1, V?O2max RUN = 65 ± 4 mL·kg-1·min-1) performed four exercise trials in random order. The trials consisted of either running or cycling at approximately 60% of the exercise specific V?O2max for 120 min while receiving either a CHO drink (2:1 glucose-fructose blend; 1.5 g·min-1) or a similar volume of plain water (WAT; 675 mL·h-1). Results: The set workload elicited similar relative exercise intensities of 59.7% ± 2.0% and 59.2% ± 1.9% V?O2max for RUN and CYCLE, respectively. Peak and average exogenous CHO oxidation rates were not significantly different between RUN and CYCLE trials and showed a similar time course (peak at 120 min = 1.25 ± 0.10 vs 1.19 ± 0.08 g·min-1, respectively, P = 0.13; average over final hour = 1.14 ± 0.10 and 1.11 ± 0.11 g·min-1, respectively, P = 0.94). Furthermore, total fat oxidation rates were higher during RUN compared with CYCLE. The difference was significant with ingestion of WAT (P = 0.02) and failed to reach statistical significance with CHO (P = 0.09). Conclusions: This study demonstrates that exogenous CHO oxidation rates are similar between prolonged running and cycling at a similar relative moderate intensity. These data suggest that previous exogenous CHO oxidation results from cycling studies can be extrapolated to running.

DON'T FORGET THE GUT—IT IS AN IMPORTANT ATHLETIC ORGAN! {#article-title-2} to the editor: It was with great interest that we read the Journal of Applied Physiology Viewpoint on the 2-h marathon barrier ([3][1]). We would argue that, alongside having a superlative Vo2max, lactate threshold

An athlete’s carbohydrate intake can be judged by whether total daily intake and the timing of consumption in relation to exercise maintain adequate carbohydrate substrate for the muscle and central nervous system (‘‘high carbohydrate availability’’) or whether carbohydrate fuel sources are limiting for the daily exercise programme (‘‘low carbohydrate availability’’). Carbohydrate availability is increased by consuming carbohydrate in the hours or days prior to the session, intake during exercise, and refuelling during recovery between sessions. This is important for the competition setting or for high-intensity training where optimal performance is desired. Carbohydrate intake during exercise should be scaled according to the characteristics of the event. During sustained high-intensity sports lasting *1 h, small amounts of carbohydrate, including even mouth-rinsing, enhance performance via central nervous system effects. While 30–60 g h 71 is an appropriate target for sports of longer duration, events42.5 h may benefit from higher intakes of up to 90 g h 71 . Products containing special blends of different carbohydrates may maximize absorption of carbohydrate at such high rates. In real life, athletes undertake training sessions with varying carbohydrate availability. Whether implementing additional ‘‘train-low’’ strategies to increase the training adaptation leads to enhanced performance in well-trained individuals is unclear.

PURPOSE Both liver and muscle glycogen stores play a fundamental role in exercise and fatigue but the effect of different CHO sources on liver glycogen synthesis in humans is unclear. The aim was to compare the effect of maltodextrin (MD) drinks containing galactose fructose or glucose on postexercise liver glycogen synthesis. METHODS In this double blind triple crossover randomized clinical trial 10 well trained male cyclists performed three experimental exercise sessions separated by at least 1 wk. After performing a standard exercise protocol to exhaustion subjects ingested one of three 15 CHO solutions namely FRU (MD + fructose 2:1) GAL (MD + galactose 2:1) or GLU (MD + glucose 2:1) each providing 69 g CHO·h( 1) during 6.5 h of recovery. Liver glycogen changes were followed using (13)C magnetic resonance spectroscopy. RESULTS Liver glycogen concentration increased at faster rates with FRU (24 ± 2 mmol·L( 1)·h( 1) P < 0.001) and with GAL (28 ± 3 mmol·L( 1)·h( 1) P < 0.001) than with GLU (13 ± 2 mmol·L( 1)·h( 1)). Liver volumes increased (P < 0.001) with FRU (9 ± 2) and with GAL (10 ± 2) but not with GLU (2 ± 1 NS). Net glycogen synthesis appeared linear and was faster with FRU (8.1 ± 0.6 g·h( 1) P < 0.001) and with GAL (8.6 ± 0.9 g·h( 1) P < 0.001) than with GLU (3.7 ± 0.5 g·h( 1)). CONCLUSIONS When ingested at a rate designed to saturate intestinal CHO transport systems MD drinks with added fructose or galactose were twice as effective as MD + glucose in restoring liver glycogen during short term postexercise recovery.

Carbohydrate feeding has been shown to be ergogenic, but recently substantial advances have been made in optimizing the guidelines for carbohydrate intake during prolonged exercise.It was found that limitations to carbohydrate oxidation were in the absorptive process most likely because of a saturation of carbohydrate transporters. By using a combination of carbohydrates that use different intestinal transporters for absorption it was shown that carbohydrate delivery and oxidation could be increased. Studies demonstrated increases in exogenous carbohydrate oxidation rates of up to 65% of glucose: fructose compared with glucose only. Exogenous carbohydrate oxidation rates reach values of 1.75 g/min whereas previously it was thought that 1 g/min was the absolute maximum. The increased carbohydrate oxidation with multiple transportable carbohydrates was accompanied by increased fluid delivery and improved oxidation efficiency, and thus the likelihood of gastrointestinal distress may be diminished. Studies also demonstrated reduced fatigue and improved exercise performance with multiple transportable carbohydrates compared with a single carbohydrate.Multiple transportable carbohydrates, ingested at high rates, can be beneficial during endurance sports in which the duration of exercise is 3 h or more.

Purpose: The aim of this study was to determine whether adding protein to a CHO beverage would improve late-exercise cycle time-trial performance over CHO alone. Furthermore, we examined the effects of coingesting protein with CHO during exercise on postexercise markers of sarcolemmal disruption and the recovery of muscle function. Methods: In a double-blind, crossover design, 12 trained male cyclists performed 120 min of steady-state (SS) cycling at approximately 55% V[spacing dot above]O2max followed by a time trial lasting approximately 1 h. At 15-min intervals during SS exercise, participants consumed either a CHO or a CHO + protein (CHO + Pro) beverage (providing 65 g[middle dot]h-1 CHO or 65 g[middle dot]h-1 CHO plus 19 g[middle dot]h-1 protein). Twenty-four hours after the onset of the SS cycle, participants completed a maximum isometric strength test. At rest and 24 h postexercise, a visual analog scale was used to determine lower-limb muscle soreness, and blood samples were obtained for plasma creatine kinase concentration. Dietary control was implemented 24 h before and during the time course of each trial. Results: Average power output sustained during time trial was similar for CHO and CHO + Pro, with no effect of treatment on the time to complete the time trial (60:13 +/- 1:33 and 60:51 +/- 2:40 (min:s) for CHO and CHO + Pro, respectively). Postexercise isometric strength significantly declined for CHO (15% +/- 3%) and CHO + Pro (11% +/- 3%) compared with baseline (486 +/- 28 N). Plasma creatine kinase concentrations, and visual analog scale soreness significantly increased at 24 h postexercise, with no difference between treatments. Conclusions: The present findings suggest that CHO + Pro coingestion during exercise does not improve late-exercise time-trial performance, ameliorate markers of sarcolemmal disruption, or enhance the recovery of muscle function at 24 h postexercise over CHO alone.

Purpose: The purpose of this study was to examine the role of branched-chain amino acid (BCAA) supplementation during recovery from intense eccentric exercise. Methods: Twenty-four non-weight-trained males were assigned to one of two groups: one group (supplementary, SUP) ingested BCAA beverages (n = 12); the second group (placebo, PLA) ingested artificially flavored water (n = 12). Diet was controlled throughout the testing period to match habitual intake. The eccentric exercise protocol consisted of 12 x 10 repetitions of unilateral eccentric knee extension exercise at 120% concentric one repetition maximum. On the day of the exercise, supplements were consumed 30 min before exercise, 1.5 h after exercise, between lunch and dinner, and before bed. On the following 2 d, four supplements were consumed between meals. Muscle soreness, muscle function, and putative blood markers of muscle damage were assessed before and after (1, 8, 24, 48, and 72 h) exercise. Results: Muscle function decreased after the eccentric exercise (P < 0.0001), but the degree of force loss was unaffected by BCAA ingestion (51% +/- 3% with SUP vs -48% +/- 7% with PLA). A decrease in flexed muscle soreness was observed in SUP compared with PLA at 48 h (21 +/- 3 mm vs 32 +/- 3 mm, P = 0.02) and 72 h (17 +/- 3 mm vs 27 +/- 4 mm, P = 0.038). Flexed muscle soreness, expressed as area under the curve, was lower in SUP than in PLA (P = 0.024). Conclusions: BCAA supplementation may attenuate muscle soreness, but it does not ameliorate eccentric exercise-induced decrements in muscle function or increases in reputed blood markers of muscle damage, when consumed before exercise and for 3 d after an eccentric exercise bout.

Fatmax and lactate increase above baseline (LIAB) were measured in 11 adolescent girls and 8 adolescent boys during incremental cycling. Fatmax was the exercise intensity at the point of maximal fat oxidation rate (MFO). The LIAB was the exercise intensity coincident with a sustained increase in blood (lactate) above an initial baseline. We defined the minimum important difference (MID) between the exercise intensity at Fatmax and LIAB as ±8% of both peak $$ {\dot{V}}{\text{O}}_{2} $$ and peak heart rate (HR). Systematic bias was examined via the mean difference between parameters and its uncertainty, with inference based on the disposition of the confidence interval to the MID. Individual-level agreement was the proportion of differences between Fatmax and LIAB falling within the MID. MFO was at 35 (6)% peak $$ {\dot{V}}{\text{O}}_{2} $$ with LIAB at 39 (7)% peak $$ {\dot{V}}{\text{O}}_{2}. $$ Systematic bias was −3.8% of peak $$ {\dot{V}}{\text{O}}_{2} $$ and −4.4% of peak HR. The estimated population proportion with between-variable agreement within ±8% was 0.76 for both % peak $$ {\dot{V}}{\text{O}}_{2} $$ and % peak HR. Within the tolerance limits of the MID, the mean bias is ‘almost certainly not’ important; similarly, there is good agreement between the two parameters at the individual level. We conclude that Fatmax and lactate increase above baseline coincide in adolescents.

Background/Aims: Carbohydrate ingested 30–60 min before exercise may result in hypoglycaemia during exercise, a phenomenon often called rebound or reactive hypoglycaemia. There is considerable confusion regarding pre-exercise carbohydrate feeding with advice that ranges from ‘consume carbohydrate in the hour before exercise’ to ‘avoid carbohydrate in the 60 min prior to exercise’. Methods: We analysed the studies available in the literature to draw conclusions about the use of carbohydrate in the pre-exercise period. Results: Without performing a meta-analysis, it is clear that the risk of reduced performance is minimal as almost all studies point towards unaltered or even improved performance. This is despite the rather large metabolic changes that occur in response to pre-exercise carbohydrate feeding. Conclusion: It can be concluded that advice to avoid carbohydrate feeding in the hour before exercise is unfounded. Nevertheless athletes may develop symptoms similar to those of hypoglycaemia, even though they are rarely linked to actual low glucose concentrations. An individual approach may therefore be necessary to minimize these symptoms even though they do not appear to be related to exercise performance.

Data from the health survey for England 2006, showed that the prevalence of type 2 diabetes mellitus (T2DM) has more than doubled in men and women since 1991. In the USA certain States have a prevalence of T2DM of greater than 10%. Globally it has been reported that this increase is by no means slowing down and that the number of individuals with the disease is expected to rise from 171 million cases reported in 2000 to 366 million by the year 2030. Physical inactivity and obesity are two major risk factors for the development of T2DM. In this review we will discuss evidence of an association between physical inactivity, obesity and T2DM from prospective cohort studies and clinical trials. We will also discuss some of the potential mechanisms that are thought to link obesity and physical inactivity with the major pathophysiological precursor of T2DM, insulin resistance.

Several nutritional strategies have been used in cycling to improve performance. Carbohydrate feeding during exercise has been shown to be effective, but recent studies have suggested that recommendations may have to be adjusted to take into account recent findings. Protein co-ingested with carbohydrate during exercise has received a lot of recent interest, but the evidence is equivocal, at best. Thus, in the absence of a plausible mechanism, it is difficult to see how protein would increase endurance performance. There also has been a lot of interest in training with low glycogen to maximize training adaptations, but the longer-term effects upon performance are still unclear. Various supplements have been suggested to improve endurance performance, but most of these nutrition supplements lack the scientific support that would warrant the recommendation.

It has been reported previously that mouth rinsing with a carbohydrate-containing solution can improve cycling performance. The purpose of the current study was to investigate the impact of such a carbohydrate mouth rinse on exercise performance during a simulated time trial in a more practical, postprandial setting. Fourteen male endurance-trained athletes were selected to perform 2 exercise tests in the morning after consuming a standardized breakfast. They performed an ~1-hr time trial on a cycle ergometer while rinsing their mouths with either a 6.4% maltodextrin solution (CHO) or water (PLA) after every 12.5% of the set amount of work. Borg’s rating of perceived exertion (RPE) was assessed after every 25% of the set amount of work, and power output and heart rate were recorded continuously throughout the test. Performance time did not differ between treatments and averaged 68.14 ± 1.14 and 67.52 ± 1.00 min in CHO and PLA, respectively (p = .57). In accordance, average power output (265 ± 5 vs. 266 ± 5 W, p = .58), heart rate (169 ± 2 vs. 168 ± 2 beats/min, p = .43), and RPE (16.4 ± 0.3 vs. 16.7 ± 0.3 W, p = .26) did not differ between treatments. Furthermore, after dividing the trial into 8s, no differences in power output, heart rate, or perceived exertion were observed over time between treatments. Carbohydrate mouth rinsing does not improve time-trial performance when exercise is performed in a practical, postprandial setting.

The aim of this study is to investigate the effects of CHO ingestion during high intensity exercise performance lasting approximately 25 min. Twelve endurance trained male cyclists (age 19–41 years; body mass 73.2 ± 4.2 kg; VO2max 66.4 ± 6.2 ml kg-1 min-1) completed a simulated 16 km time trial (457 ± 37 kJ) time trial in the lab on three occasions. Once they received a 6% carbohydrate electrolyte solution (CHO) and twice they received the same electrolyte containing placebo drink (PLA). Carbohydrate or placebo drinks were ingested 5 min before the start (4 ml kg-1) and at 25, 50, and 75% of completion of the time trial (1.4 ml kg-1). The CHO drink was a 6% sucrose–glucose–electrolyte solution. No differences were observed in the time to complete the time trials with either treatment. Time in min:s were 25:30 ± 1:34 and 25:27 ± 1:46 for the two placebo trials and 25:38 ± 1:59 in the CHO trial. Power output during the time trials was also remarkably similar: 300 ± 37 W, 301 ± 39 W and 299 ± 40 W, respectively. Pacing strategies and heart rate were identical in all three trials. From the two placebo trials, a coefficient of variation for this performance task was calculated to be 1.1%. Data from this study provides evidence that carbohydrate ingestion during short high intensity exercise (*30 min, 85–90% VO2max) does not improve performance. Furthermore, this study found a very low coefficient of variation (1.1%) for a simulated 16 km time trial. Gatorade Sport Science Institute/[]/GSSI/Estados Unidos UCR::Vicerrectoría de Docencia::Ciencias Sociales::Facultad de Educación::Escuela de Educación Física

Carbohydrate ingestion can improve endurance capacity and performance. Since the 1980s, research has focused on optimizing the delivery strategies of these carbohydrates. The optimal dose of carbohydrate is still subject to debate, but recent evidence suggests that there may be a dose–response effect as long as the carbohydrate ingested is also oxidized and does not result in gastrointestinal distress. Oxidation rates of a single type of carbohydrate do not exceed 60 g·h−1. However, when multiple transportable carbohydrates are ingested (i.e. glucose and fructose), these oxidation rates can be increased significantly (up to 105 g·h−1). To achieve these high oxidation rates, carbohydrate needs to be ingested at high rates and this has often been associated with poor fluid delivery as well as gastrointestinal distress. However, it has been suggested that using multiple transportable carbohydrates may enhance fluid delivery compared with a single carbohydrate and may cause relatively little gastroin...

Green tea consumption is reportedly associated with various health-promoting properties. For example, it has been shown to promote fat oxidation in humans at rest and to prevent obesity and improve insulin sensitivity in mice.We investigated the effects of acute ingestion of green tea extract (GTE) on glucose tolerance and fat oxidation during moderate-intensity exercise in humans.Two studies were performed, both with a counter-balanced crossover design. In study A, 12 healthy men performed a 30-min cycling exercise at 60% of maximal oxygen consumption (VO2max) before and after supplementation. In study B, 11 healthy men took an oral-glucose-tolerance test before and after supplementation. In the 24-h period before the experimental trials, participants ingested 3 capsules containing either GTE (total: 890 +/- 13 mg polyphenols and 366 +/- 5 mg EGCG) or a corn-flour placebo (total: 1729 +/- 22 mg).Average fat oxidation rates were 17% higher after ingestion of GTE than after ingestion of placebo (0.41 +/- 0.03 and 0.35 +/- 0.03 g/min, respectively; P0.05). Moreover, the contribution of fat oxidation to total energy expenditure was also significantly higher, by a similar percentage, after GTE supplementation. The insulin area under the curve decreased in both the GTE and placebo trials (3612 +/- 301 and 4280 +/- 309 microIU/dL . 120 min, respectively; P0.01), and there was a concomitant increase of 13% in insulin sensitivity.Acute GTE ingestion can increase fat oxidation during moderate-intensity exercise and can improve insulin sensitivity and glucose tolerance in healthy young men.

Performance testing is one of the most common and important measures used in sports science and physiology. Performance tests allow for a controlled simulation of sports and exercise performance for research or applied science purposes. There are three factors that contribute to a good performance test: (i) validity; (ii) reliability; and (iii) sensitivity. A valid protocol is one that resembles the performance that is being simulated as closely as possible. When investigating race-type events, the two most common protocols are time to exhaustion and time trials. Time trials have greater validity than time to exhaustion because they provide a good physiological simulation of actual performance and correlate with actual performance. Sports such as soccer are more difficult to simulate. While shuttle-running protocols such as the Loughborough Intermittent Shuttle Test may simulate physiology of soccer using time to exhaustion or distance covered, it is not a valid measure of soccer performance. There is a need to include measures of skill in such protocols. Reliability is the variation of a protocol. Research has shown that time-to-exhaustion protocols have a coefficient of variation (CV) of >10%, whereas time trials are more reliable as they have been shown to have a CV of

We investigated the effects of modifying a normal dietary fatty-acid composition and the ingestion of high-fat exercise supplements on gastrointestinal distress, substrate oxidation, and endurance cycling performance. Five female cyclists completed a randomized triple-crossover comprising a 2-week diet high in octanoate-rich esterified oil (MCFA), or twice, long-chain fatty acids (LCFA). Following the diets, the participants performed 3 h of cycling at 50% peak power followed by ten maximal sprints while ingesting: a carbohydrate (CHO)+MCFA-rich oil emulsion after (a) the 2-week MCFA-rich dietary condition (MC-MC, Intervention), and (b) after one LCFA-rich dietary condition (LC-MC, Placebo), or (c) CHO only following a second LCFA-rich diet (LC-CHO, Control). Ingestion of the CHO+MCFA-rich oil emulsion during 3-h steady-state exercise substantially reduced endogenous-fat oxidation by 88% (90% confidence interval: 59 to 117%) and 74% (40 to 108%) in the MC-MC and LC-MC conditions, respectively, re...

Purpose: The effect of different quantities of carbohydrate (CHO) intake on CHO metabolism during prolonged exercise was examined in endurance-trained females. Method: On four occasions, eight females performed 2 h of cycling at approximately 60% V?O2max with ingestion of beverages containing low (LOW, 0.5 g·min-1), moderate (MOD, 1.0 g·min-1), or high (HIGH, 1.5 g·min-1) amounts of CHO, or water only (WAT). Test solutions contained trace amounts of [U-13C] glucose. Indirect calorimetry combined with measurement of expired 13CO2 and plasma 13C enrichment enabled calculation of exogenous CHO, liver-derived glucose, and muscle glycogen oxidation during the last 30 min of exercise. Results: The highest rates of exogenous CHO oxidation were observed in MOD, with no further increases in HIGH (peak rates of 0.33 ± 0.02, 0.50 ± 0.03, and 0.48 ± 0.05 g·min-1 for LOW, MOD, and HIGH, respectively; P < 0.05 for LOW vs MOD and HIGH). Endogenous CHO oxidation was lowest in MOD (0.99 ± 0.06, 0.82 ± 0.08, 0.70 ± 0.07, and 0.89 ± 0.09 g·min-1; P < 0.05 for MOD vs all other trials). Compared with WAT, CHO ingestion reduced liver glucose oxidation during exercise by approximately 30% (P < 0.05 for WAT vs all CHO). Differential rates of muscle glycogen oxidation were observed with different CHO doses (0.57 ± 0.07, 0.53 ± 0.08, 0.41 ± 0.07, and 0.60 ± 0.09 g·min-1 for WAT, LOW, MOD, and HIGH respectively; P < 0.05 for MOD vs HIGH). Conclusion: In endurance-trained women, the highest rates of exogenous CHO oxidation and greatest endogenous CHO sparing was observed when CHO was ingested at moderate rates (1.0 g·min-1, 60 g·h-1) during exercise.

Context:Monitoring mood state is a useful tool for avoiding nonfunctional overreaching. Brain-derived neurotrophic factor (BDNF) is implicated in stress-related mood disorders.Purpose:To investigate the impact of intensified training-induced mood disturbance on plasma BDNF concentrations at rest and in response to exercise.Methods: Eight cyclists performed 1 wk of normal (NT), 1 wk of intensified (INT), and 1 wk of recovery (REC) training. Fasted blood samples were collected before and after exercise on day 7 of each training week and analyzed for plasma BDNF and cortisol concentrations. A 24-item Profile of Mood State questionnaire was administered on day 7 of each training week, and global mood score (GMS) was calculated.Results:Time-trial performance was impaired during INT (P = .01) and REC (P = .02) compared with NT. Basal plasma cortisol (NT = 153 ± 16 ng/mL, INT = 130 ± 11 ng/mL, REC = 150 ± 14 ng/ml) and BDNF (NT = 484 ± 122 pg/mL, INT = 488 ± 122 pg/mL, REC = 383 ± 56 pg/mL) concentrations were similar between training conditions. Likewise, similar exercise-induced increases in cortisol and BDNF concentrations were observed between training conditions. GMS was 32% greater during INT vs NT (P < .001).Conclusions: Consistent with a state of functional overreaching (FOR), impairments in performance and mood state with INT were restored after 1 wk of REC. These results support evidence for mood changes before plasma BDNF concentrations as a biochemical marker of FOR and that cortisol is not a useful marker for predicting FOR.

We investigated the effects of modifying a normal dietary fatty acid composition and ingestion of high-fat exercise supplements on gastrointestinal distress, substrate oxidation, and endurance cycling performance. Nine well-trained male cyclists completed a randomized triple-crossover comprising a 2-wk diet high in octanoate-rich esterified oil (MCFA) or twice long-chain fatty acids (LCFA). Following the diets, participants performed 3-h of cycling at 50% of peak power followed by 10 maximal sprints while ingesting either 1) a carbohydrate (CHO)+MCFA-rich oil emulsion after the 2-wk MCFA-rich dietary condition (MC-MC, Intervention) and 2) after one of the LCFA-rich dietary conditions (LC-MC, Placebo) or 3) CHO only following a LCFA-rich diet (LC-CHO, Control). During the 3-h ride MCFA-adaptation decreased octanoic-acid oxidation by 24% (90% confidence interval: 14-34%). The CHO+MCFA-rich oil emulsion reduced endogenous fat oxidation by 61% (33-89%) and 110% (89-131%) in the MC-MC and LC-MC conditions, respectively, and MCFA-adaptation reduced endogenous-carbohydrate oxidation by 10% (-3-23%). MCFA-adaptation attenuated gastrointestinal distress and nausea during the sprints, but the effect of the oil emulsion was to lower sprint power by 10.9% (7.7-14.1%) in the LC-MC condition and by 7.1% (5.7-8.5%) in the MC-MC condition, relative to the LC-CHO control; every one unit increase in nausea decreased mean power by 6.0 W (3.2-8.8 W). We conclude that despite some attenuation of endogenous-carbohydrate oxidation and gastric distress following adaptation to a MCFA-rich diet, repeat sprint performance was substantially impaired in response to the ingestion of a CHO+MCFA-rich oil emulsion.