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Contemporary Nutrition Strategies to Optimize Performance in Distance Runners and Race Walkers
Abstract
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.
... Burke y colaboradores realizaron un estudio en el que se incluía un protocolo de entrenamiento de 2 semanas con mayor ingesta de carbohidratos para una supercompensación de glucógeno e ingesta de carbohidratos durante la actividad de aproximadamente 2 horas, donde se concluyó que a pesar de ser bien tolerada la estrategia para aumentar la disponibilidad de carbohidratos, no se tradujo en una mejora en el rendimiento de la carrera que la observada en el grupo control. (8) Así mismo, en el presente estudio, no hubo diferencias estadísticamente significativas entre el esfuerzo percibido durante los entrenamientos con y sin protocolo de ingesta de carbohidratos; esto pudo ser debido al tamaño de la muestra, siendo poco representativo para generar respuestas con el protocolo establecido. Sin embargo, estudios han demostrado que un adecuado consumo de carbohidratos antes y durante una actividad tiene un papel clave en el rendimiento físico de los atletas debido a que las estrategias que mantienen una alta disponibilidad de carbohidratos permiten equilibrar las reservas de glucógeno y de glucosa sanguínea (9) con las demandas de combustible propias del entrenamiento mientras que la disminución y agotamiento de las mismas, se relaciona con la presencia de fatiga, deterioro del rendimiento y aumento de la percepción del esfuerzo(10,11). ...
... Además se ha demostrado que la prescripción dietética y la disponibilidad de carbohidratos endógenos y exógenos, antes y durante el ejercicio puede influir en las respuestas agudas al ejercicio de resistencia y así generar mejoras en la potencia y la velocidad del ciclismo (13,14). Los alimentos inadecuados o en grandes cantidades pueden deteriorar el rendimiento deportivo o alimentos insuficientes pueden generar una pronta disminución de la energía y esto, tener consecuencias en la percepción del esfuerzo (8). Se han realizado otras estrategias respecto al consumo de carbohidratos, por ejemplo, manipular la disponibilidad de carbohidratos antes y durante las sesiones de entrenamiento promueve mejoras significativas en la economía del ciclismo y el tiempo de carrera de 10 kilómetros en atletas de resistencia entrenados. ...
... Es bien sabido que los carbohidratos son el macronutriente más importante en deportes de resistencia debido a que el cuerpo depende en su mayoría de estos como fuente de energía durante los entrenamientos de larga duración (16). Las pautas actuales de nutrición deportiva sugieren un consumo de 1 a 4 gramos de carbohidratos por kilogramo de masa corporal de 1 a 4 horas previas al ejercicio (8). Sin embargo, también se ha evidenciado que, 15 minutos antes de la ejecución de una actividad deportiva de resistencia, el consumo de un gel energético deportivo con un aporte de 25 g de carbohidratos de múltiples transportadores (glucosa:fructosa) puede mejorar la resistencia y rendimiento en ejercicios prolongados (9,17). ...
Introducción: Una ingesta óptima de carbohidratos permite un buen desempeño y recuperación en deportes de resistencia como en el ciclismo de ruta. Objetivo: Evaluar la percepción del esfuerzo según los criterios de “la escala de Borg” bajo la implementación de acompañamiento nutricional que controla de manera individual la ingesta de carbohidratos en los momentos del antes y el durante un entrenamiento de resistencia de 4 horas de duración, en ciclistas aficionados. Materiales y métodos: Se realizó una investigación evaluativa, con dos momentos de medición transversal; uno sin acompañamiento nutricional y un segundo momento, con prescripción alimentaria para el antes y durante un entrenamiento. Para ello, se seleccionaron por conveniencia 8 ciclistas recreativos de la ciudad de Medellín. Resultados: No se mostraron diferencias estadísticamente significativas en la percepción del esfuerzo tras la prescripción de carbohidratos para el antes y durante, respecto a la percepción del esfuerzo obtenida previa a dicha prescripción. Conclusión: Como principal hallazgo se identificaron variables metabólicas y de composición que pueden ser tenidas en cuenta en futuras intervenciones para establecer correlaciones fisiológicas y de alimentación en deportes de resistencia.
... The use of SSs is widespread among both recreational and elite athletes, with the primary goal of enhancing athletic performance [6,7,[14][15][16][17][18][19]. The type of physical activity, level of competition, and sex are factors that influence the consumption of these supplements. ...
... Evidence shows an increase in SS consumption among elite competitive athletes compared to those at lower levels in the same sport [18,19]. Although there are a wide range of SSs available, a high percentage of supplements are particularly popular, such as carbohydrate drinks, protein bars, sports gels, caffeine, whey protein, creatine, and branched-chain amino acids (BCAAs) [6,7,[15][16][17][18][19] One aspect that appears to influence the consumption of sports supplements (SSs) is sex [12,17]. It seems that SS consumption is higher in men than in women of the same category, level, and sport [12,17,18]. ...
... Nutrients 2024,16, 2563 ...
Although the extensive use of sports supplements (SSs) is prevalent among cyclists, this area has been poorly explored; in fact, no studies have been conducted on this topic regarding women cyclists to date. This descriptive, cross-sectional study, which included 316 federated female road cyclists, aimed to analyze SS consumption patterns in relation to scientific evidence and various categories. SSs were categorized according to the groups and subgroups established by the Australian Sport Institute (AIS, 2023) based on the level of evidence supporting their use. The analysis found that 85.1% of the female road cyclists surveyed used SSs, with an average consumption of 7 ± 6 supplements per individual. Pharmacies (60.8%), dietitian-nutritionists (58.9%), and health status (60.1%) were the primary purchase location, source of information, and reason for use, respectively. The most frequently consumed supplements were sports bars (77.5%), sports gels (61.4%), and caffeine (49.1%). Significantly, 80% of the ten most commonly used supplements were from the group with the highest evidence level, as classified by the AIS, with an average intake of 5 ± 3 supplements per cyclist. In summary, the use of SSs is prevalent among female road cyclists, with reliable sources for both purchasing and obtaining advice on supplements.
... Such rates of energy demand rely more on carbohydrate (CHO) oxidation (4) derived from endogenous stores (hepatic and skeletal muscle glycogen). However, longer duration endurance events (e.g., >60 min) may require additional CHO supplementation at higher intensities to help maintain such reliance on CHO as endogenous stores become depleted (5)(6)(7)(8)(9). Sufficient exogenous CHO intake throughout the entirety of a marathon is necessary to prevent performance loss (5,6) attendant to muscle glycogen depletion (10,11) and diminished rates of ATP synthesis achievable with fat versus CHO oxidation (12). ...
... Contemporary consensus for exogenous CHO intake to support marathon performance is 30-90 g·h À1 , dependent upon the CHO mixture and gastrointestinal (GI) tolerability (9). When consuming >60 g·h À1 of exogenous CHO, a mixture of glucose and fructose increases exogenous CHO oxidation by increasing intestinal absorption capabilities, enhancing bioavailability (5,6). ...
... Intestinal absorption improves above $60 g·h À1 by co-ingesting monosaccharide sources that utilize separate intestinal transporters for absorption, such as fructose (14). Previous work established an approximate tolerable upper limit of exogenous CHO being $90 g·h À1 to facilitate optimal monosaccharide absorption via SGLT1 and glucose transporter 5 (GLUT5), respectively (5,6,9). However, recent research reports higher exogenous CHO oxidation rates (1.51 ± 0.22 g·min À1 ) when male cyclists consumed 120 g·h À1 at a ratio of 1:0.8 glucose to fructose compared with 90 g·h À1 with a 2:1 ratio (1.29 ± 0.16 g·min À1 ) (15). ...
Introduction: Carbohydrate (CHO) availability sustains high metabolic demands during prolonged exercise. The adequacy of current CHO intake recommendations, 30-90 g•hr ⁻¹ dependent on CHO mixture and tolerability, to support elite marathon performance is unclear. Purpose: We sought to scrutinize the current upper limit recommendation for exogenous CHO intake to support modeled sub-2-hour marathon (S2M) attempts across elite male and female runners. Methods: Male and female runners (n = 120 each) were modeled from published literature with reference characteristics necessary to complete a S2M (e.g., body mass and running economy). Completion of a S2M was considered across a range of respiratory exchange rates, with maximal starting skeletal muscle and liver glycogen content predicted for elite male and female runners. Results: Modeled exogenous CHO bioavailability needed for male and female runners were 93 ± 26 and 108 ± 22 g•h ⁻¹ , respectively (p < 0.0001, d = 0.61). Without exogenous CHO, males were modeled to deplete glycogen in 84 ± 7 minutes, females in 71 ± 5 minutes (p < 0.0001, d = 2.21) despite higher estimated CHO oxidation rates in males (5.1 ± 0.5 g•h ⁻¹ ) than females (4.4 ± 0.5 g•h ⁻¹ ; p < 0.0001, d = 1.47). Conclusion: Exogenous CHO intakes < 90 g•h ⁻¹ are insufficient for 65% of modeled runners attempting a S2M. Current recommendations to support marathon performance appear inadequate for elite marathon runners but may be more suitable for male runners in pursuit of a S2M (56 of 120) than female runners (28 of 120).
... In general, mountain runners are aware of the importance of carbohydrate and liquid consumption during this type of event. Specifically, the three most used SS were supplements, which are usually used in this type of competition due to their ease of transport and tolerance, as well as their provision of carbohydrates [37][38][39][40]. In general, these results coincide with those reported in other studies, in which the most consumed SS were sports bars, isotonic or sports drinks, and multivitamins, with no statistically significant differences between sexes [15][16][17][18][19][20]22]. ...
... There are many factors that can influence the success or failure of mountain runners [6][7][8][10][11][12]. The physiological characteristics of the MR explain the choice of the most consumed SS, i.e., the use of energy substrates by the body during these tests, which the athletes will have to provide exogenously in order to obtain the desired performance to carry out the competition [1,[37][38][39][40]. The bars and gels provide large amounts of carbohydrates in a small amount of product, which in addition to producing less gastrointestinal discomfort, allows the athletes to optimize the space they have in their means of food transport (backpacks, belts, pockets.) ...
... The bars and gels provide large amounts of carbohydrates in a small amount of product, which in addition to producing less gastrointestinal discomfort, allows the athletes to optimize the space they have in their means of food transport (backpacks, belts, pockets.) [1,4,24,36,38]. Another important reason that can explain the consumption of sports drinks is thermoregulation [43][44][45][46]. Especially when the race takes place in hot environmental conditions, there is an increase in the production of internal body heat that must be controlled through different strategies (acclimatization, hydration . . . ) to maintain body homeostasis, which will allow the athlete to have greater success [43][44][45][46][47]. ...
Background:
The use of sports supplements (SS) to improve sports performance is widespread in all types of athletes, however, the specific characteristics of mountain races may require the use of certain SS. Despite being a sport where the consumption of SS seems widespread, few studies have been conducted in this regard. The objective of this study is to analyze the pattern of SS consumption of mountain runners in relation to the degree of scientific evidence, sex, and level of competition.
Methods:
Descriptive and cross-sectional study on the consumption and habitual use of SS of 357 federated mountain runners in Spain. Data were collected through a validated questionnaire.
Results:
From the total sample, 93.84% of the athletes stated that they consumed SS, with no differences observed based on the competitive level or in terms of sex; however, there were significant differences according to the competitive level in terms of the number of SS consumed, with consumption being greater at a higher competitive level (p = 0.009). The most consumed SS were sports bars (66.1%), sports drinks (60.5%), sports gels (52.9%), and caffeine (46.2%).
Conclusions:
The consumption of SS in mountain races is high, and the number of SS consumed is higher as the competition level increases. The four SS most consumed by the participants in this study were all included in category A in the classification of the Australian Institute of Sport (AIS), this category is the one with the greatest scientific evidence.
... Every cell requires protein factually, Proteins are found throughout the entire body with muscle tissue being the major location. Athletes consume dietary protein to repair and rebuild DOI: 10.31080/ASMS.2024. 08.1967 Citation: Naseer Ud Din Waza and Nishan Singh Deol. ...
... with non-sports persons, this discrepancy may reflect the demands of protein metabolism in endurance athletes who commonly adopt a high-carbohydrate focus to support their energy requirements (and inadvertently restrict intake for muscle maintenance and repair) instead prioritizing carbohydrate consumption over that from other macronutrients like proteins [10]. Research suggests that runners need sufficient amounts of protein for recovery however, carbohydrate-centric dietary choices leave them underconsuming [11,12]. ...
Background: Protein plays an essential role in muscle tissue’s repair, maintenance, and growth. Athletes, especially those involved in long-distance running, experience increased protein turnover because of the physical strain on their muscles, which requires a higher protein intake for effective recovery and adaptation. On the other hand, non-athletes have lower protein requirements due to their lesser physical activity and muscle demands. Analyzing the protein content between these two groups illustrates how physical activity affects protein metabolism, muscle health, and overall nutritional needs, providing valuable insights for customized dietary recommendations that can benefit both athletes and non-athletes.
Objective: To investigate the protein content among university-level long-distance runners and non-sports persons.
Study Design: This study utilized a cross-sectional design.
Material and Methods: Sixty (60) university-level students with long-distance runners (n = 30) and non-sports persons (n = 30) from Punjabi University Patiala were selected using a random sampling technique. To achieve the purpose of the study, the Body composition analyzer GS6.5B Body Building Weight Test System (Version 1.0) was used to measure the protein content of the subjects.
Results: The study found a significant difference in variable protein content between long-distance runners and non-sports persons. The t-value regarding protein content was 3.40 and the p-value was 0.001 and was found to be statistically significant at 0.05 level of significance p<0.05.
Conclusion: This study compared the protein content between university-level long-distance runners and non-sports persons. The protein content of long-distance runners was lower than that of non-sports persons
... This might be explained by the particular demands of endurance training and competition as well as the prolonged duration of the activity. When engaging in cardiovascular exercise, it is generally recommended that individuals consume 30-60 grams of carbohydrate per hour of training up to 2.5 hours, and 90-120 grams per hour for training lasting longer than 2.5 hours (Burke et al., 2019). Hydration recommendations aim to maintain a net fluid deficit of less than two to three percent of body mass (Burke et al., 2019). ...
... When engaging in cardiovascular exercise, it is generally recommended that individuals consume 30-60 grams of carbohydrate per hour of training up to 2.5 hours, and 90-120 grams per hour for training lasting longer than 2.5 hours (Burke et al., 2019). Hydration recommendations aim to maintain a net fluid deficit of less than two to three percent of body mass (Burke et al., 2019). Therefore, unlike many shorter duration sports, nutrition is crucial in distance running. ...
... Given the current popularity and ever-growing interest of marathoners across the population, research is warranted to better understand individual characteristics and lifestyle factors that contribute to marathon runner performance to direct training guidelines and recommendations. Previous research has implicated individual characteristics, such as age and sex, as well as lifestyle factors, such as caffeine consumption and overall diet, on endurance runner performance [3][4][5]. However, despite the well-established relationship between sleep health and athletic performance [6], the influence of sleep health on endurance runner performance is understudied, with the majority of the existing literature performed in ultramarathoners (50 km to 160 km races) [7][8][9]. ...
... Assess the influence of lifestyle factors, including sleep tracker, electronic device, alcohol, and caffeine use, on sleep health outcomes. 4. ...
Despite sleep health being critically important for athlete performance and well-being, sleep health in marathoners is understudied. This foundational study explored relations between sleep health, individual characteristics, lifestyle factors, and marathon completion time. Data were obtained from the 2016 London Marathon participants. Participants completed the Athlete Sleep Screening Questionnaire (ASSQ) along with a brief survey capturing individual characteristics and lifestyle factors. Sleep health focused on the ASSQ sleep difficulty score (SDS) and its components. Linear regression computed relations among sleep, individual, lifestyle, and marathon variables. The analytic sample (N = 943) was mostly male (64.5%) and young adults (66.5%). A total of 23.5% of the sample reported sleep difficulties (SDS ≥ 8) at a severity warranting follow-up with a trained sleep provider. Middle-aged adults generally reported significantly worse sleep health characteristics, relative to young adults, except young adults reported significantly longer sleep onset latency (SOL). Sleep tracker users reported worse sleep satisfaction. Pre-bedtime electronic device use was associated with longer SOL and longer marathon completion time, while increasing SOL was also associated with longer marathon completion. Our results suggest a deleterious influence of pre-bedtime electronic device use and sleep tracker use on sleep health in marathoners. Orthosomnia may be a relevant factor in the relationship between sleep tracking and sleep health for marathoners.
... Nutritional planning is highly relevant in most competitions, especially in endurance sports such as cycling [6,14,39]. A wide range of ergogenic aids with a variety of flavours, shapes, and textures are currently available [40]. ...
... Finally, although energy bars can help during sporting events by slowing down the feeling of fatigue and improving performance [14,16], the organoleptic sensations they can provoke may allow the food to be accepted or rejected [18,56,57]. Indeed, the sensations generated by the texture and organoleptic characteristics of foods can vary a large amount from one person to another [58]. ...
In cycling, a wide range of ergogenic foods with a variety of flavours, shapes, and textures are available. The timing of their consumption and their correct oral processing can influence the performance of athletes. Furthermore, the differences in the texture of energy bars could result in differences in the chewing required. Nonetheless, research in this area is still scarce. The aim of this study was to analyse how the consumption of two energy bars with different textures (viscous versus hard) influenced the variables of oral processing, pedalling intensity, and the perception of satisfaction among cyclists. Ten cyclists performed two 15 min sections on a cycle ergometer at a moderate intensity (120–130 W) and consumed one of the two energy bars at random in each of the sections. The results showed that a shorter chewing duration and a fewer number of chews were required to consume the softer bar (p < 0.05, ES > 0.7). However, no differences among the cyclists were observed in the intensity of pedalling or perception of satisfaction. Nevertheless, participants were able to distinguish between the two different textures while pedalling. In conclusion, the texture of energy bars altered the oral processing of cyclists but did not affect pedalling intensity or perception of satisfaction.
... However, the increased effort in sustained training program and decreased recovery period trigger fatigue and limit performances. The new determinant of sports performance relied mostly on dietary supplements or energetic drink from plant extract to enhance exercise capacity and improve performance [4,5]. Interestingly, sports performers are orientated toward plant extracts, fatty and high carbohydrate diets as source of energy supply in replacement of identified substances that trigger excess release of catecholamine [6,7]. ...
... A recent study has shown an upsurge in the use of natural products in African countries to ameliorate sport performance and improve on the threshold of fatigue [5]. Fatigue is the complexity to commence and maintain a voluntary effort, characterise by the sensation of physical or mental tiredness and impotence, occurring after a prolong period of stress, sustained physical and mental activities [8,9]. ...
Ethnopharmacological relevance: Traditionally, Mimosa pudica Linn. (Fabaceae) is used for its anti-inflammatory, sedative, anxiolytic, antioxidant and antifatigue properties. Aim: To determine the antifatigue effects of Mimosa pudica aqueous extracts in experimental model of weight loaded force swimming test. Materials and methods: Mice were divided into seven groups and treated for 28 consecutive days as follows: groups one and two received orally distilled water (10 mL/kg) and served as normal group and negative control group, respectively. Groups three to six, (test groups) received orally graded doses of Mimosa pudica (20, 40, 80 and 160 mg/kg) and group seven (positive control) received vitamin C (50 mg/kg), respectively. One hour after the treatment, mice were subjected to the weight loaded force swimming test with tail load, except for the normal group; and the swimming duration, body weight, food and water intake were measured. Twenty-four hours after the last treatment the serum level of noradrenaline, dopamine and serotonin, and the relative organs weight were measured. Results: Mimosa pudica aqueous extracts significantly and dose-dependently increased the swimming duration and the weight of heart and lungs. The extracts did not induce a significant variation in the level of food and water intake, body weight, and serum of noradrenaline, dopamine and serotonin. Conclusion: Pretreatment of mice with Mimosa pudica aqueous extracts was observed to have better antifatigue properties mediated via amelioration of swimming capacity and physical aptitude in the weight loaded force swimming model.
... Nutritional strategies and dietary patterns may predict the nutrient requirements of athletes and play significant roles in the adaptations and performance of endurance runners [5,6]. While the consumption of high-carbohydrate meals has been recommended to endurance runners on pre-event days and hours within carbohydrate loading strategies as part tapering strategies, they are advised to avoid high-fat, high-protein, and high-fiber ...
... Nevertheless, while FFQs have been found to be a simple, fast, and low-cost assessment tool with a low burden on participants [46], reports indicate that the FFQ is the most proper survey method to assess the dietary intake of athletes [46,47]. Compared to sedentary people, athletes are shown to be at a higher risk of low energy supply, and this risk increases for athletes with unbalanced or inappropriately planned diets [5,48]. Given the importance of diet and nutritional supply in health and performance, dietary assessment is the first and most crucial step in any sports nutrition practice and is necessary for personalized nutritional strategies [45]. ...
While the popularity of distance running is growing worldwide, endurance runners’ dietary challenges associated with their prolonged training and racing activities have not yet been fully understood. The present investigation was conducted with the aim of examining the association between race distance and dietary intake of distance runners. A total of 317 runners initially participated, and after data clearance, 211 endurance runners (57% females) were finally considered the study sample. Runners were assigned to three race distance groups: 10-km (n = 74), half-marathon (n = 83), and marathon/ultra-marathon (n = 54). An online survey was used to collect data; dietary intake was monitored using a comprehensive food frequency questionnaire, including 53 food groups categorized in 14 basic and three umbrella clusters. There was no significant difference (p > 0.05) between race distance groups in consumption of most food clusters except for “fruits and vegetables” and “total of protein”, with a predominance of 10-km runners compared to half-marathoners and (ultra-)marathoners (p ≤ 0.05). Age was a significant predictor for the consumption of only five (out of 17) food clusters (p ≤ 0.05), including “fruit and vegetables”, “unprocessed meat”, “processed meat”, “eggs”, and “plant protein”. Future investigations with a larger sample size and more differentiated (sub)groups may help provide comparable data to develop a better understanding of the dietary behaviors among shorter versus longer distance runners.
... Besides traditional physiological parameters, external factors have also been recognized as relevant to marathon performance. These external factors include course profile, environmental conditions, pacing strategy, drafting, nutrition, and footwear 4,7,8 . In particular, footwear has become a field of increased attention in research due to its potential to influence running mechanics and energy expenditure. ...
... It is obviously important to establish a personalized fluid replenishment plan to avoid the risk of developing hyponatremia. Furthermore, dehydration can increase the risk of gastrointestinal discomfort [6] and other health and performance risks including acute kidney injury (AKI) [7,8], hyponatremia (EAH), and muscle cramps (EAMC) [9]. ...
This case report examines the correlation between hydration, weight variation, and perceived effort in a 43-year-old amateur athlete during a self-supported 81.5 km crossing of Death Valley, completed over 3 days with significant elevation changes. Studies have shown that a body mass loss greater than 2-3% can lead to an increased perception of effort and a decline in performance. Specifically, during passive and active heat exposures, the average body mass loss was found to be 1.4 ± 0.3% and 4.1 ± 0.7%, respectively. Salivary osmolarity has demonstrated a sensitivity of 86% and specificity of 91% in diagnosing dehydration of ≥ 2%, suggesting its potential as a non-invasive indicator of hydration status. The subject monitored their own body weight, hydration (via salivary osmolarity), and perceived effort using a rate of perceived exertion (RPE) scale. Nutritional intake included isocaloric meals and nutritional bars, and hydration was managed using water and a hydroelectrolytic solution. Key bioimpedance parameters were measured to assess body composition and hydration status. A progressive decrease in body weight correlated with an increase in perceived effort (RPE score) and salivary osmolarity. Resistance (Rx) remained stable, while reactance (Xc) showed a biphasic trend and was inversely correlated with the sodium/potassium ratio (NAK). There were significant linear correlations between perceived effort and both weight loss and salivary osmolarity, indicating that salivary osmolarity is a potential early predictor of these changes. The findings highlight a linear correlation between weight loss, perceived effort, and salivary osmolarity, suggesting that monitoring salivary osmolarity would be useful for the field assessment of hydration and exertion. Further research with larger populations is necessary to validate these observations.
... age and sex; Besson et al., 2022;Cook et al., 2023;Nikolaidis et al., 2019), lifestyle (e.g. diet and sleep; Burke et al., 2019;Costa et al., 2019;Furber et al., 2021;Lopes et al., 2023) and training characteristics (Carrasco-Poyatos et al., 2022;Haugen et al., 2022;Prieto-González & Sedlacek, 2022). However, this area of research is still relatively understudied, limiting the progression of efficacious, individualizable training strategies and protocols. ...
Burgeoning interest in marathons necessitates an understanding of performance determinants. Research has highlighted the importance of diet, training and sleep, yet relations of circadian preference and sleep inertia with marathon performance remain largely unexplored. Because marathons generally start early‐to‐mid morning, these characteristics may have relevant impact. This study investigates relationships of circadian preference, sleep inertia and their interaction with marathon completion time. Consenting participants in a 2016 large mass‐participation city marathon completed self‐report questionnaires capturing circadian preference and sleep inertia, along with demographics and other characteristics. Circadian preference and sleep inertia were described across subgroups. Analyses examined the associations and interactions of circadian preference and sleep inertia with marathon completion times, with adjusted analyses accounting for age, sex and sleep health. Participants were marathon finishers ( n = 936; 64.5% male; 66.3% young‐adults), with a majority reporting morningness tendencies (60.8%). Results supported a linear association between increasing eveningness preference with slower marathon times ( p = 0.003; p adjusted = 0.002), while some support was provided for a linear relationship between greater sleep inertia and slower marathon times ( p = 0.04; p adjusted = 0.07). A significant interaction was observed ( p = 0.02; p adjusted = 0.01), with the directionality suggesting that the circadian preference relationship weakened when sleep inertia severity increased, and vice‐versa. Our results suggest deleterious associations of increasing eveningness preference and greater sleep inertia with marathon completion time. These features may aid identifying marathoners who could be at a disadvantage, while also serving as modifiable targets for personalized training regimens preceding competition.
... Sporcuların yoğun fizyolojik talepleri vardır ve bu taleplerine en uygun hale getirilmiş beslenmeye ihtiyaç duyarlar (Burke, Jeukendrup, Jones, & Mooses, 2019). Uyku yoksunluğu, karbonhidrat metabolizmasını, iştahı, enerji alımını ve protein sentezini etkileyebilen glikoz metabolizmasını ve nöroendokrin (sinir hücrelerinden ve endokrin hücrelerinden (hormon üreten hücreler) oluşan sistem) fonksiyonunu olumsuz etkiler. ...
... Elite athletes dedicate their lives to attaining peak physical performance across diverse disciplines, each with unique physiological demands and training regimens. 1 The rigorous training requires substantial energy intake to maintain optimal physiological function and meet high energy demands. 2 Energy availability (EA) is crucial, representing the energy available for physiological functions after accounting for energy expended in physical activity. 3 Low energy availability (LEA) occurs when insufficient energy to support all physiological functions threatens overall health. ...
Background
Low energy availability (LEA) occurs when athletes’ energy intake fails to match the energy expended during exercise, resulting in insufficient energy to support essential functions for optimal health, a condition known as relative energy deficiency in sports (REDs).
Objective
This study aims to explore the prevalence of LEA among Malaysian national athletes and its associations with health-related outcomes.
Methods
A total of 43 athletes (51.2% males, aged 18–40) identified previously as having moderate or high risk of REDs through a questionnaire underwent comprehensive clinical assessments. Resting metabolic rate (RMR) was measured using indirect calorimetry, with an RMR ratio of <0.90 indicating LEA. Weight and height were measured, and fasting blood samples were analysed for ferritin, free triiodothyronine (fT3), follicle-stimulating hormone (FSH), luteinising hormone (LH), estradiol (female athletes) and testosterone (male athletes). Bone mineral density (BMD) of the lumbar spine and total left hip, as well as body composition, were measured using dual-energy X-ray absorptiometry (DXA).
Results
Out of the 43 athletes, 12 showed evidence of LEA, exhibiting at least one of the following characteristics: low estradiol levels (87.5%), low testosterone (75.0%), low fT3 (66.7%), low LH (58.3%), low FSH (58.3%), low ferritin (25.0%) and low BMD (8.3%). Notably, fT3, estradiol and testosterone were significant predictors for LEA.
Conclusions
A low but noteworthy incidence of LEA among Malaysian national athletes was associated with hormone imbalances. Awareness about LEA among athletes and sports personnel is essential for early detection and appropriate intervention.
... Regarding to uids intake, athletes consumed 7.2 ± 4.1 ml/kg of water in the previous hour before the race. Since pre-race uids intake may in uence the hydration status during the event, athletes should start the activity euhydrated and consider speci c race conditions (34). It is recommended to carefully monitor hydration status before the race and to individualise uid intake according to personal and environment characteristics. ...
Background
Endurance athletes’ competitions have increased over the decades and marathon races are becoming increasingly popular. Proper nutrition is critical for optimal performance and long-term health in marathon athletes. This study aimed to investigate runners’ nutritional intake, especially fluids, food, and supplements, competing in the Seville Marathon. A descriptive and cross-sectional study was carried out to obtain information on the consumption of liquids, food, and supplements. A total of 160 runners who were primarily men (87.5%) aged 42.2 ± 7.3 years who participated in the 2022 Seville marathon took part in the study.
Results
There was no significant difference (p > 0.050) between marathon finish time or sports experience and fluid, CHO, sodium, and caffeine intake pre- and post-competition, except for athletes who met CHO intake recommendations during the competition that were more likely to finish the marathon in less than 180 minutes.
Conclusions
The intake of CHO, sodium and caffeine was low compared to the current recommendations. The intake of fluids was at the lower limit of recommendations. Most athletes did not receive nutritional counselling by a D-N, which may explain why athletes failed to meet specific nutrient recommendations. Future investigations with a larger sample size are warranted to assess the relationship between dietary intake and finish time.
... Um dos principais mitos que diz respeito a baixa ingestão de carboidratos, voltada para perda de gordura corporal, pois ele é o principal macronutriente para o desempenho funcional. Logo, à medida que a demanda de energia aumenta, a ingestão de carboidratos aumentara também (BURKE, 2021;BURKE et al., 2019;JEUKENDRUP, 2013;JEUKENDRUP, 2017a;MCKAY;PEELING et al., 2022). Como atualmente a sociedade moderna sofre grande influência da mídia e da industrialização, mudando o seu padrão de vida e os hábitos alimentares, observa-se significativo aumento da densidade energética, aumento no consumo de carnes, leite e derivados ricos em gorduras e redução do consumo de frutas, cereais, verduras e legumes. ...
presente trabalho é uma revisão sistemática de literatura, e as informações necessárias
foram coletadas por meio das bases de dados do Pubmed, Scielo e Google
Acadêmico. O objetivo desta revisão foi reunir técnicas fotográficas e montar um
guia fotográfico para procedimentos de Harmonização Orofacial, usando câmera de smartphone.
A fotografia tem se tornado uma ferramenta de grande importância para profissionais
da área da odontologia estética e geral, pois os registros auxiliam no planejamento,
na análise e no acompanhamento de procedimentos estéticos faciais como na Harmonização
Orofacial. A fotografia com smartphone além de ser um equipamento que grande
maioria possui, pode fornecer – de forma nítida, prática e eficaz – imagens padronizadas
para montar um plano de tratamento único para cada paciente. Nesta revisão de literatura,
pode ser observada que diversos autores estabelecem técnicas fotográficas semelhantes,
transformando as fotos em guias e protocolando para profissionais que pretendem capturar
imagens de qualidade de seus casos odontológicos.
Palavras-chave: fotografia, harmonização orofacial, odontologia, smartphone.
Abstract
The present work is a systematic literature review, and the necessary information was
collected through the Pubmed, Scielo and Google Scholar databases. The objective
of this review was to bring together photographic techniques and put together a
photographic guide for Orofacial Harmonization procedures, using a smartphone camera.
Photography has become a tool of great importance for professionals in the field of aesthetic
and general dentistry, as records help in planning, analyzing and monitoring facial
aesthetic procedures such as Orofacial Harmonization. Smartphone photography, in addition
to being equipment that the vast majority have, can provide – in a clear, practical and
effective way – standardized images to create a unique treatment plan for each patient. In
this literature review, it can be observed that several authors establish similar photographic
techniques, transforming photos into guides and protocols for professionals who intend to
capture quality images of their dental cases.
Keywords: photography, orofacial harmonization, dentistry, smartphone
... Irrigation strategies should be tailored to the individual needs of the runner, taking into account weather conditions and effort intensity. Monitoring of electrolytes, especially sodium, is important in preventing electrolyte disturbances such as hyponatraemia [31,32]. ...
Introduction and Purpose: Long-distance running, especially marathons, tests human endurance and physical limits. While the benefits of marathon running are well-documented, the associated health risks often go unnoticed. This review aims to synthesize current knowledge on the health risks and complications faced by marathon runners, providing crucial insights for both amateur and professional athletes.State of Knowledge: Marathon running imposes significant stress on the cardiovascular system, musculoskeletal structure, and metabolic processes. Issues such as acute myocardial injury, overhydration leading to hyponatremia, and musculoskeletal injuries are prevalent. The review also examines less common but severe risks like rhabdomyolysis and marathon-related cardiac arrests. Despite the robust fitness levels of runners, these health risks remain a serious concern, necessitating preventive strategies and proper health monitoring.Summary: Marathon runners must be aware of the potential health risks associated with prolonged endurance activities. Precautionary measures, including tailored training programs, dietary adjustments, and regular medical check-ups, are essential to mitigate these risks. Additionally, further research is required to develop more effective interventions and guidelines that can safeguard the health of marathon participants. This review underscores the need for a balanced approach that respects the physiological demands of marathon running while ensuring the health and safety of the runners.
... For the marathon, nutrition, with carbohydrate (CHO) loading and hydration strategies, has been improved in the 2000th. The nutrition strategies include CHO-loading prior to the race and in-race intake of 30-60 g CHO per hour from drinks or gels (Burke et al., 2019). Also road running has been more attractive since the 1990th with increased prize money, and many major cities starting to have their own marathon in the 1980th. ...
Running world records (WRs) contain information about physiological characteristics that determine running performance. The progression of WRs over time encode the evolution of these characteristics. Here we demonstrate that a previously established model for running performance describes WRs since 1918 for men and since 1984 for women with high accuracy. The physiological parameters extracted from WR for each year are interpreted in terms of historical changes in training approaches and corresponding physiological adaptions, technological progress, social effects, and also the use of performance enhancing drugs. While the last two decades had witnessed stagnation of WRs, recent improvements in endurance have enable new WRs, presumably aided by recent technological advancements.
... By analyzing anaerobic outcomes from an experimental design with CRE and CAF in isolated and in combination, sports nutritionists could determine whether both supplements are necessary to improve anaerobic performance. In fact, potential interactions between concurrently used supplements are of high priority for scientific-based prescription (Burke et al., 2019). Further, as anaerobic performance can be reliably measured using the Wingate test, assessing the effect of combining CAF and CRE on peak (PP) and mean power (MP) during the Wingate test can provide important information in relation to the effects of CAF and CRE on anaerobic performance. ...
There is a lack of evidence on the additional benefits of combining caffeine (CAF) and creatine (CRE) supplementation on anaerobic power and capacity. Thus, the aim of the present study was to test the effects of combined and isolated supplementation of CAF and CRE on anaerobic power and capacity. Twenty-four healthy men performed a baseline Wingate anaerobic test and were then allocated into a CRE ( n = 12) or placebo (PLA; n = 12) group. The CRE group ingested 20 g/day of CRE for 8 days, while the PLA group ingested 20 g/day of maltodextrin for the same period. On the sixth and eighth days of the loading period, both groups performed a Wingate anaerobic test 1 hr after either CAF (5 mg/kg of body mass; CRE + CAF and PLA + CAF conditions) or PLA (5 mg/kg of body mass of cellulose; CRE + PLA and PLA + PLA conditions) ingestion. After the loading period, changes in body mass were greater ( p < .05) in the CRE (+0.87 ± 0.23 kg) than in the PLA group (+0.13 ± 0.27 kg). In both groups, peak power was higher ( p = .01) in the CAF (1,033.4 ± 209.3 W) than in the PLA trial (1,003.3 ± 204.4 W), but mean power was not different between PLA and CAF trials ( p > .05). In conclusion, CAF, but not CRE ingestion, increases anaerobic power. Conversely, neither CRE nor CAF has an effect on anaerobic capacity.
... It can be said that sporting activities are enhanced by well-chosen nutrition strategies (3). In other words, the nutritional strategies will support the training and the competition goals (4). The nutritional requirements of tactical athletes to support optimal health and performance (5). ...
... It can be said that sporting activities are enhanced by well-chosen nutrition strategies (3). In other words, the nutritional strategies will support the training and the competition goals (4). The nutritional requirements of tactical athletes to support optimal health and performance (5). ...
Background. Athletes' poor understanding of sports nutrition could place their health in danger, degrade their performance, and have an impact on their lean body mass and energy levels. Objective. The research study aims to study the perception of Thai national youth athletes regarding nutrition understanding and the relation between endurance, power, and mixed sports and believing in the food selection before, during, and after the competition. Methods. The quantitative research was used with 216 respondents divided into three categories (Endurance Sport, Power Sport, and Mix Sport) which consisted of the Thai national youth athletes for each category in Thailand, and analyzed by the descriptive statistics, and the chi-square test by using SPSS. Results. The result of the chi-square test between the athlete samples of endurance, power, and the mixed sport and believing in the food selection before the competition found that by having the correlation efficiency (Chi-Square: 2) = 1241.381, DF=32, and the p-value were 0.01. During the competition found that the food selection was related to the sports categories by having the correlation efficiency (Chi-Square: 2) = 485.438, DF=26, and the p-value was 0.01, and after the competition found that the food selection was related to the sports categories by having the correlation efficiency (Chi-Square: 2) = 718.997, DF=30, and the p-value were 0.01. Conclusion. The result of this research may be applied as important information for developing an effective guideline for Thai national youth athletes in the future.
... It can be said that sporting activities are enhanced by well-chosen nutrition strategies (3). In other words, the nutritional strategies will support the training and the competition goals (4). The nutritional requirements of tactical athletes to support optimal health and performance (5). ...
... During intense and prolonged exercise, such as a marathon race at elite level, the glycogen content of active muscle cells can be substantially reduced but does not fall further than approximately 10% of initial values (25). The calculated carbohydrate utilization during the WRM possibly exceeds the glycogen stores in a 54kg female athlete and therefore carbohydrate supplementation at a rate of at least 90 gr·h −1 is recommended to maintain exercise intensity (13,26). ...
Marathon | World record | Metabolic profile | VLamax | Substrate utilization | Mathematical modelling Headline Scientific research on marathon performance has focused on aerobic metabolism. However, anaerobic metabolism cannot be neglected as for a givenV O2max, the lower the glycolytic power (VLamax) the higher the metabolic steady-state performance (1-4) and the lower the carbohydrate combustion rate at a given speed (5). In contrast, elite marathon runners use sudden pace changes as a tactical weapon (6). Obviously, such efforts require additional anaerobic energy. Therefore, an optimal range for VLamax in marathon running is expected. Aim The importance of the aerobic metabolism to cover the energy requirements in marathon running is extensively documented in the scientific literature. Not surprisingly, elite marathon runners have high aerobic power (V O2max), the ability to use a high fraction ofV O2max at metabolic steady-state and excellent running economy (7-9). Elite marathon runners use sudden pace changes as a tactical weapon (6). Such efforts are likely above physiological steady state and require additional anaerobic energy. To the best of our knowledge, no scientific information on glycolytic (∼anaerobic) power (VLamax) has been published in elite marathon runners. Running a marathon at world record pace carbohydrate utilization might be the main energy source, however no RER data have been published to validate this statement (10). Carbohydrate availability from endogenous sources is clearly a limiting factor to sustain the required running speed given the clear improvement in endurance performance upon carbohydrate ingestion (11,12). This includes for instance a study showing that carbohydrate provision at a rate of 60 gr·h −1 increased the running speed during a marathon (13). The aims of current case study are to estimate both the maximal glycolytic power (VLamax) and the substrate utilization during a world record marathon (WRM) in an elite female marathon runner. This information can be used by coaches and athletes to understand the physiological requirements and optimize training and nutrition strategies for such an event. Abbreviations BLC Blood lactate concentration CHO Carbohydrate CRS Critical running speed FFA Free fatty acids GE Gross efficiency LT1 First lactate threshold LT2 Second lactate threshold MLSS Maximal lactate steady state RER Respiratory exchange ratiȯ V O2max Maximal oxygen consumption VLamax Maximal glycolytic rate W Watt WRM World record marathon Methods The data for this study is retrieved from the paper of Jones (2006) (9) (table 1) and is used to feed a mathematical model of muscle metabolism (INSCYD GmbH, version 2.0, Salenstein, Switzerland). Individual data used to run these calculations were: sex, height, body mass, percentage body fat, V O2max, gross efficiency (GE) and MLSS. As the power at MLSS is a function of the maximal oxygen uptake (V O2max) and the maximal glycolytic rate (VLamax) (1-4), and using LT2 as an approximation for the MLSS, VLamax could be calculated from the available data. Based on the measured and calculated metrics, carbohydrate combustion rate during the WRM (2h 15m 25s) was estimated. Table 1. Anthropometric and physiological data of an elite female marathon runner retrieved from Jones (2006). Height (cm) Weight (kg) Body fat (%)V O2max (ml·kg −1 ·min −1) LT1 (km·h −1) LT2 (km·h −1)V O2 at 16 km·h −1 (ml·kg −1 ·min −1) WRM (km·h −1) 173 54 10 70 18.5 20 46,67 18.7 sportperfsci.com 1 SPSR-2023 | October | 209 | v1
... In this study, we investigated the presence of risk factors for the development of eating disorders within the sporting context [32][33][34]. This need arises from the fact that the expansion of such disorders raises an alarming and prevalent issue among different levels of the community, particularly among athletes [12,35,36]. From the analysis of the results, there is no signifi cant difference between genders in the scores obtained on the EAT-26 test, this highlights how, although women are most affected by eating disorders, cases in males are increasing at a constant rate [37]. ...
Eating Disorders represent one of the fastest-growing mental health problems in the world. While a diagnosis of an eating disorder can only be made after careful psychiatric evaluation, the detection of “at-risk” individuals can be conducted through screening programs that use tools such as the Eating Attitude Test (EAT-26), a test used to measure the symptoms and concerns characteristic of eating disorders. This observational study was designed to evaluate the presence of at-risk individuals, using the EAT-26, among young athletes in “lean sports”, young athletes in non-”lean sports”, young non-athlete sportspeople, and young people who did not practice any sports. In addition, the presence of a correlation between the risk of developing eating disorders, gender, and age was also investigated. The results identified a prevalence of risk of 13% among study participants. None of the subjects who did not engage in any physical activity obtained a test score that could be considered at risk. Furthermore, no correlation was found between gender and the scores obtained. These results should be taken into consideration to emphasize the importance of nutritional intervention by expert and qualified personnel within various sports societies, in order to prevent the development of these pathologies and at the same time increase and improve performance.
... General dietary guidelines for athletes describe the importance of include high-carbohydrate doses during exercise to optimize physical performance (Burke et al. 2019a). Has been reported how an appropriate nutrition during exercise promotes physiological and performanceenhancing benefits under acute conditions, mainly due to the rapid contribution for provide energy while maintaining expected metabolic homeostasis (Aoi et al. 2006;Corbo et al. 2014;Burke et al. 2019b;Costa et al. 2019;Urdampilleta et al. 2020). In this regard, most of the energy sources consumed during exercise are sport functional foods, which are considered as artificial ultra-processed foods (Aoi et al. 2006;Corbo et al. 2014). ...
To improve performance and recovery faster, athletes are advised to eat more often than usual and consume higher doses of simple carbohydrates, during and after exercise. Sports energetic supplements contain food additives, such as artificial sweeteners, emulsifiers, acidity regulators, preservatives, and salts, which could be harmful to the gut microbiota and impair the intestinal barrier function. The intestinal barrier plays a critical function in bidirectionally regulation of the selective transfer of nutrients, water, and electrolytes, while preventing at the same time, the entrance of harmful substances (selective permeability). The gut microbiota helps to the host to regulate intestinal homeostasis through metabolic, protective, and immune functions. Globally, the gut health is essential to maintain systemic homeostasis in athletes, and to ensure proper digestion, metabolization, and substrate absorption. Gastrointestinal complaints are an important cause of underperformance and dropout during endurance events. These complications are directly related to the loss of gut equilibrium, mainly linked to microbiota dysbiosis and leaky gut. In summary, athletes must be cautious with the elevated intake of ultra-processed foods and specifically those contained on sports nutrition supplements. This review points out the specific nutritional interventions that should be implemented and/or discontinued depending on individual gut functionality.
... 2,43 Nutritional strategies that increase muscle and liver glycogen storage and improve hydration status, two potentially limiting factors to endurance performance (increased sweat rates and glycogen use, when competing in hot weather conditions), may also be used as part of an athlete's individual pre-event nutritional plan and may be combined with other supplementation practices. 19,50,51 Consideration of pacing strategies is also warranted, given the requirement to modify pacing tactics in hot conditions. [52][53][54] Further investigation of how such strategies are used by elite athletes and how such strategies may be combined with longer-term approaches to heat and altitude training is warranted. ...
Purpose
To document a world-class race walking athlete's preparation for the 2019 International Association of Athletics Federations (IAAF) World Championships (Doha, Qatar), including periodized training, physiological data, cooling strategies and nutritional practices.
Methods
Physiological data (VO 2max , mL·kg ⁻¹ ·min ⁻¹ ; submaximal economy, mL·kg ⁻¹ ·min ⁻¹ ; and %VO 2max ), training volume (km) and intensity (min·km ⁻¹ ) were recorded (January–May 2019). Additional training strategies and interventions (altitude training, heat acclimation/acclimatization, cooling methods and pre- and during-race nutrition) were described (February–October 2019). Performances in IAAF-sanctioned 20 km races were also reported.
Results
The athlete's highest VO 2max result was 74.6 mL·kg ⁻¹ ·min ⁻¹ , and his highest 4 mmol·L ⁻¹ walking speed was 15.7 km·h ⁻¹ . The best submaximal economy measures (the lowest proportional oxygen use at 13 km·h ⁻¹ ) were 48.4 mL·kg ⁻¹ ·min ⁻¹ (65.2% VO 2max ). The best performance outcome was a bronze medal-winning performance at the 2019 IAAF World Championships (32°C; 77% RH). Six blocks of altitude training were performed (119 days). Five blocks of heat acclimatization training (127 days), one block of heat acclimation training (8 days) and two blocks of post-training passive heat sessions (16 days) were completed. Internal and external cooling strategies were used, and the athlete's nutritional intake focused on carbohydrate and fluid intake prior to and during races, pre-race supplementation with sodium bicarbonate using chronic and acute protocols, caffeine supplementation during races and pre-race hyperhydration.
Conclusion
The strategies used by this elite athlete included repeated heat acclimation, heat acclimatization, passive heat exposure, hypoxic training and heat mitigation strategies. Similar strategies may provide benefit to elite athletes preparing for major international competitions in hot conditions.
... The provision of supplements also needs to be controlled by professionals because it is often found that athletes consume supplements that are not supposed to, have a bad content and come from the 'black market' which will affect the athlete's health [32]. Foods that help the athlete's sports or physical performance in the form of food, snacks or drinks can meet the nutritional plan for training or competition athletes also with caffeine or nitrates used as supplements for athletes [33]. Even daily energy, carbohydrates, proteins, and fat intake are not significantly correlated with BMI for age, however it is significantly related to the percentage of body fat then an increase in consumption of healthy food according to the diet still needs to be done to avoid nutritional problems in athletes [34]. ...
... The importance of adequate CHO availability during endurance exercise to the maintenance of CP, and therefore performance, is likely linked to differences in the O 2 cost of ATP production for CHO compared to fat (Krogh & Lindhard, 1920). Theoretically, provided there is sufficient glycogen availability, maintaining a higher RER and therefore a higher rate of CHO oxidation will require a lowerV O 2 for a given power output and would be expected to enhance performance (Burke et al., 2019). This is illustrated by the work of Passfield & Doust (2000) who showed that the reduction in the total work that could be done during a 5-min maximal exercise bout following Figure 3. Effects of exercise duration and carbohydrate ingestion on critical power A, time course for the reduction in estimated critical power (CP) during 2 h of heavy intensity exercise. ...
Endurance exercise performance is known to be closely associated with the three physiological pillars of maximal O2 uptake (V̇O2max), economy or efficiency during submaximal exercise, and the fractional utilisation of V̇O2max (linked to metabolic/lactate threshold phenomena). However, while ‘start line’ values of these variables are collectively useful in predicting performance in endurance events such as the marathon, it is not widely appreciated that these variables are not static but are prone to significant deterioration as fatiguing endurance exercise proceeds. For example, the ‘critical power’ (CP), which is a composite of the highest achievable steady‐state oxidative metabolic rate and efficiency (O2 cost per watt), may fall by an average of 10% following 2 h of heavy intensity cycle exercise. Even more striking is that the extent of this deterioration displays appreciable inter‐individual variability, with changes in CP ranging from <1% to ∼32%. The mechanistic basis for such differences in fatigue resistance or ‘physiological resilience’ are not resolved. However, resilience may be important in explaining superlative endurance performance and it has implications for the physiological evaluation of athletes and the design of interventions to enhance performance. This article presents new information concerning the dynamic plasticity of the three ‘traditional’ physiological variables and argues that physiological resilience should be considered as an additional component, or fourth dimension, in models of endurance exercise performance. image
... To win a race, athletes are trained to preserve their muscle glycogen as much as possible until the end of the race so that they can make a last spurt. For these endurance athletes, especially 50-km racewalkers, unique nutritional strategies such as carbohydrate loading have been proposed to prepare them for races 5 . The general recommended amount of carbohydrate for the preparation over 90 min of the race is 10-12 g·kg -1 ·day -1 for 36-48 h 5, 6 . ...
Purpose:
Muscle glycogen storage before a race is necessary for endurance athletes to achieve the best performance. Generally, the recommended carbohydrate intake for preparation over 90 min of the race is 10-12 g·kg--1·day--1. However, it remains unclear whether an elite athlete with an already high-carbohydrate diet can further increase muscle glycogen through a very-high-carbohydrate intake. Therefore, we compared the effects of three types of glycogen loading in a 28-year-old male athlete who belongs to the top 50 racewalkers in the world, consuming a daily energy intake of 4507 kcal and a carbohydrate intake of 12.7 g·kg--1·day--1.
Methods:
The racewalker consumed very-high-carbohydrate diets three times for 2 days each, 13.7 g·kg--1·day--1 for trial 1, 13.9 g·kg--1·day--1 for trial 2, and 15.9 g·kg--1·day-1 for trial 3. Muscle glycogen concentrations in the anterior (vastus lateralis and vastus intermedius) and posterior thighs (semimembranosus, semitendinosus, and biceps femoris) were measured using carbon-13 magnetic resonance spectroscopy.
Results:
Muscle glycogen concentrations in both the anterior and posterior thighs increased in all trials, particularly in trial 3. Body mass also increased by 1.5 kg in trials 1 and 2 and by 1.8 kg in trial 3 before and after the trials. The participant felt satiated throughout the day and experienced stomach discomfort during trial 3.
Conclusion:
We found that a 2-day very-high-carbohydrate diet and tapering of training could further increase the muscle glycogen concentration in athletes. However, we speculated that 15.9 g·kg--1·day--1 carbohy.
... This might explain the divergence of opinions found in our study. For example, distance runners, who are highly advised to include strategies to store muscle glycogen prior to the race [28], considered the stage of competition more important than throwers, who do not depend considerably on these nutritional strategies. Our data revealed that middle-distance runners considered protein to be a more important macronutrient compared with sprinters. ...
In competitive events, athletes’ performances can be affected by their food choices. In addition, nutrition labels are essential to sustain informed decisions and to allow athletes to comply with their dietary planning. Knowing what influences athletes’ food choices will help to improve the food provision in future championships. Therefore, we aimed to study the factors influencing athletes’ choices, their knowledge on nutrition labels, and their opinion on the food service at two European Athletics Championships. Questionnaires were completed by 339 athletes (57% males, 19.6 ± 1.3 years) competing at the 2019 European Athletics Under 20 and Under 23 Championships. Factors that may impact performance (time of the day and nutrient composition) were rated as important and very important by a higher percentage of athletes (78% and 74%, respectively) compared to the presence of teammates (32%) and the coach (23%). Among the athletes who knew what nutrition labels are (49%), 72% would like to have additional nutritional information in future championships. Furthermore, our study revealed that for most athletes (72%), food temperature is important or very important for food choices. Overall, food provision had positive results, but further research is needed to help organizers better tailor food provision to athletes’ needs.
... The results obtained showed a greater use of SS on competition days as compared to the rest of the options (81.9 %), regardless of gender or level of competition. This may be due to the importance of the availability/use of energy substrates and hydration during competition in this type of competitions, as well as the possibility and variety of existing SS for it, since its alternated consumption is very useful for complying with the carbohydrate, sodium and fluid intake recommendations during competition (7,19,28). Proof of this is observed when verifying that sport bars (81.9 %) and sport drinks (75.0 %) were the two most commonly consumed SS by the study sample. Both supplements are important for hydration and nutrient replenishment during competitions, for providing energy and nutrients or seeking to counteract the high sweating rates generated by climatic conditions in this type of event (29). ...
Introduction:
sports supplements (SS) are widely used by all types of athletes to improve their performance. These SS are classified according to the ABCD system of the Australian Institute of Sports (AIS) from higher to lower scientific evidence. In mountain runners, their use could be necessary due to the physiological demands required by this sport. However, the literature on the use of SS by mountain runners is scarce.
Objective:
to analyze the pattern of SS consumption in mountain runners by studying differences according to sex and competitive level (regional vs national).
Methodology:
this was a descriptive and cross-sectional study on the consumption and use of SS by mountain runners participating in the Alcoy Solidarity Trail. Data were collected through a validated questionnaire based on content, applicability, structure, and presentation. This questionnaire was completed online by the athletes, who could fill it out voluntarily and at their convenience, as well as anonymously.
Results:
the results showed that 87.5 % of participants reported consuming SS, with no significant differences observed with respect to competitive level, although differences were found with respect to sex (92.7 % in men vs 70.6 % in women; p = 0.029), with a higher consumption found in men compared to women. The most consumed SS were sports bars (81.9 %), sports drinks (75.0 %), caffeine (48.6 %), magnesium (38.9 %), and electrolytes (27.8 %).
Conclusions:
among mountain runners consumption of SS is high, and 4 of the 5 most habitually consumed SS belong in the category of greater scientific evidence.
... A low dietary fiber diet (<10 g/d) can reduce fecal matter and gastrointestinal secretions and thereby extend gastrointestinal tract transit time (40). However, due to variable gastrointestinal tract transit times, a low-fiber diet may require implementation 1-3 days before exercise (41), which may not be practical habitually. Furthermore, adult women and men are recommended to consume 25-30 g/d of dietary fiber to ensure proper gastrointestinal tract function and reduce the risk of several chronic diseases, including diabetes, heart disease, and certain cancers (42). ...
This exploratory study investigated endurance athletes self-reported exercise-associated gastrointestinal symptoms (Ex-GIS) and associated strategies to manage symptomology. Adult endurance athletes with a history of Ex-GIS (n = 137) participating in events ≥ 60 min completed an online validated questionnaire. Respondents included runners (55%, n = 75), triathletes (22%, n = 30), and non-running sports (23%, n = 32), participating at a recreationally competitive (37%, n = 51), recreationally non-competitive (32%, n = 44), and competitive regional/national/international (31%, n = 42) levels. Athletes identified when Ex-GIS developed most frequently either around training (AT), around competitions (AC), or equally around both training (ET) and competitions (EC). Athletes reported the severity of each symptom before, during, and after exercise. Athletes predominantly categorized Ex-GIS severity as mild (< 5/10) on a 0 (no symptoms) to 10 (extremely severe symptoms) visual analog symptomology scale. The Friedman test and post hoc analysis with Wilcoxon signed rank test was conducted with a Bonferroni correction applied to determine differences between repeated measures. The only severe symptom of significance was the urge to defecate during training in the ET group (Z = –0.536, p = 0.01). Ex-GIS incidence was significantly higher during training and competitions in all categories. A content review of self-reported strategies (n = 277) to reduce Ex-GIS indicated popular dietary strategies were dietary fiber reduction (15.2%, n = 42), dairy avoidance (5.8%, n = 16), and a low fermentable oligosaccharides, monosaccharides, and polyols (FODMAP) diet (5.4%, n = 15). In contrast, non-dietary strategies included the use of medications (4.7%, n = 13) and relaxation/meditation (4.0%, n = 11). On a Likert scale of 1–5, the most successful dietary strategies implemented were dietary fiber reduction (median = 4, IQR = 4, 5), low FODMAP diets (median = 4, IQR = 4, 5), dairy-free diets (median = 4, IQR = 4, 5), and increasing carbohydrates (median = 4, IQR = 3, 4). Accredited practicing dietitians were rated as the most important sources of information for Ex-GIS management (n = 29). Endurance athletes use a variety of strategies to manage their Ex-GIS, with dietary manipulation being the most common.
Background: Previous research has individually investigated how different types of training affect the physical, physiological, and training characteristics of distance runners. However, there is a lack of studies that collectively examine the effects of interval and power training programs on these factors in trained distance runners. Objectives: This study aims to provide a more comprehensive and up-to-date understanding of how combined training approaches may impact the physical, physiological, and training characteristics of competitive distance runners. Methods: A census sampling approach was used, with all 108 athletes (100%) participating in the study. Participants were divided into three parallel training groups: The interval training group (ITG), the power training group (PTG), and the control training group (CTG). Each group contained 36 participants, and a randomized block design was implemented within each group, with 12 athletes in each block. The intervention lasted for 32 weeks, with three training sessions per week, on non-consecutive days, lasting 45 - 60 minutes per session. The intensity of the training sessions was maintained between 50 - 70% of the participants' exercise capacity. The measured physical characteristics included demographic and anthropometric variables such as age, sex, height, weight, Body Mass Index (BMI), fat and fat-free mass, and various circumferences. The physiological characteristics assessed included resting heart rate, exercise heart rate, maximum oxygen consumption, measures of leg strength (LS) and power, endurance performance metrics such as time trials (TTs), and aerobic thresholds. The training characteristics assessed included living and training altitude, training habits, training experience, training volume, training sessions, recovery practices, and nutritional intake. Statistical significance was determined with a P-value of < 0.05, and effect size was calculated (η² > 0.14). Results: Interval and power training led to improvements in several physical characteristics, including chronological age (P = 0.02), Body Mass Index (P = 0.03), fat-free mass (P = 0.000), and maximum thigh circumference (P = 0.000). However, no significant changes were observed in certain physical characteristics such as sex, field, and weight (P = 1.000). Interval and power training also resulted in significant improvements in various physiological characteristics, including 400 m sprint performance (P = 0.000), 1.5 km Kosmin test (P = 0.000), 3 km maximum speed TT (P = 0.000), LS (P = 0.000), Sprint Bounding Index (SBI) (P = 0.000), and maximum exercise heart rate (P = 0.000). In contrast, the post-test (POT) results for the ITG and PTG groups, when compared to the CTG, showed no significant differences in certain areas of physiological characteristics, including Balke V̇O2Max (P = 0.000), leg press (P = 0.000), and squat (p = 0.000). Regarding the third subgroup analysis of training characteristics, all POT results showed a decrease, except for the habit of sleeping (P = 0.04). In general, the POT results of the CTG demonstrated less change in all subgroup analyses of performance indices compared to the ITG and PTG. Conclusions: Our key findings emphasize the importance of combined interval and power training in improving V̇O2Max, overall strength endurance, speed endurance, running economy (RE), and muscle adaptation compared to the control group. These factors are vital for enhancing physical and physiological characteristics. Future research should explore additional factors, such as nutrition and psychological needs, which may influence athletic performance.
This chapter delves into the intricate relationship between dietary strategies and athletic performance, focusing on the pivotal role of nutrition in achieving optimal body composition and readiness for competition. It explores the principles and methodologies behind eating plans designed to reduce body fat percentage while simultaneously promoting muscle gain, a delicate balance crucial for enhancing athletic performance. The chapter investigates the roles of numerous nutrients required for a healthy diet, such as carbohydrates, proteins, lipids, water, vitamins, and minerals, emphasizing their overall impact on health and athletic performance. Furthermore, the chapter discusses the dietary requirements for athletic competition preparation, including diet adjustment for weight class aims, pre- and post-competition meals, and the critical importance of staying hydrated during the competing cycle.
Purpose
Citrulline (CIT) and beetroot extract (BR) supplements positively impacts exercise performance in elite rowers. However, its influence on metabolic outcomes such as whole-body volumes of oxygen consumption (VO2) and carbon dioxide production (VCO2), substrate oxidation, energy expenditure (EE), and gross efficiency remains unknown. We studied the effects of 1 week of daily co-supplementation of 3.5 g BR (500 mg NO3⁻) plus 6 g CIT on VO2 and VCO2 kinetics, substrate utilization, EE, and gross efficiency in elite male rowers compared to a placebo and to a BR supplementation.
Methods
Twenty elite rowers participated in this randomized, double-blind, placebo-controlled crossover trial completing 1 week of supplementation in each group of study: Placebo (PLAG); BRG; and BR-CITG. Efficiency (70% VO2max) and performance (incremental maximal) tests were performed, and gas-exchange data were collected via indirect calorimetry.
Results
Analysis of covariance (ANCOVA) showed no mean between-condition differences on respiratory exchange ratio (RER), EE, and gross efficiency in the efficiency test (all P > 0.06), and in the performance test (all P > 0.28). Moreover, in both tests no interaction Time × Supplement effects were observed for VO2, VCO2, RER, EE, substrate oxidation, and, gross efficiency (all P > 0.12).
Conclusion
After 1 week, no effects on energy metabolism and substrate utilization were observed after the daily co-ingestion of BR extract plus CIT supplement, therefore longer (> 7 days) and higher doses of supplementation might be needed to influence metabolism.
Carbohydrate (CHO) metabolism is crucial for short-duration, high-intensity exercise performance, but the effects of variations in glycogen availability have not been investigated in field trials of trained athletes. This study was designed to test how 1500 m time trial (TT) performance is affected by the manipulation of pre-race glycogen reserves. Competitive middle-distance runners (n = 11 (4 females)) completed a 1500 m individually paced indoor TT after abundant (high, >5 g/kg/d) or restricted (low, <1.5 g/kg/d) dietary CHO intake for 2 days after a glycogen-depleting session. Stride pattern, heart rate (HR), capillary blood lactate, and glucose and plasma malondialdehyde (MDA) response were determined. The TT was slower in low vs. high condition by 4.5 (4.5) s (~2%; p < 0.01), with a tendency toward shorter stride length. Blood lactate and glucose were lower before the TT in low vs. high condition (1.8 (0.5) vs. 2.2 (0.7) mmol/L and 5.4 (0.7) vs. 5.9 (0.8) mmol/L, p = 0.022 and 0.007, respectively), and peak lactate was higher in high vs. low condition (16.8 (3.1) vs. 14.5 (4.2) mmol/L, p = 0.039). Plasma MDA was the same before the TT, and 15 min after the TT, it increased similarly by 15% in low (p = 0.032) and high (p = 0.005) conditions. The restriction of pre-test CHO intake impaired 1500 m TT performance and reduced baseline and peak blood lactate concentrations but not blood glucose or MDA response.
Ultra-marathons are running events that exceed the traditional marathon distance of 42.2 km (26.2 miles), and involve various distances, durations and environmental conditions. Considering the varying physiological characteristics and types of races, nutrition plays a crucial role in achieving optimal performance. Based on the literature, during the preparation period for these athletes, a daily energy intake of 40-70 kcal/kg/day, a carbohydrate intake of 5-8 g/kg/day, and a protein intake ranging from at least 1.65 to 2.1 g/kg/day are recommended. Nutrition during races is one of the fundamental challenges of ultra-marathons, so, careful planning is highlighted. For ultra-marathon runners, it is suggested to consume 150-300 kcal/h of energy during 81 km races, and 200-400 kcal/h during longer races, with a carbohydrate intake of 30-50 g/h. It is also noted that fat intake can be effective during long-duration ultra-marathons, and a protein intake of 5-10 g/h is recommended. Regarding hydration, the recommendations include consuming 450-750 ml/h or 150-250 ml of fluid every 20 min, with the fluid containing 500-700 mg/L or 300-600 mg/h of sodium (equivalent to 1000-2000 mg of salt), particularly in hot weather. In addition, pre-race caffeine intake of 3-6 mg/kg or 1-2 mg/kg during the race may be beneficial. However, it is essential to remember that all these recommendations are general sports nutrition guidelines adapted to the physiology of ultra-marathon running, and it is important to develop individualized nutrition strategies specific to each athlete.
This research is a literature study that aims to explore the relationship between carbohydrate consumption and athlete performance and health, especially female athletes who run long distances. This study uses the method of literature study or literature review using secondary data from scientific journal articles. Article searches are conducted through various platforms such as Google Scholar, EBSCO, ScienceDirect, and Proquest using keywords related to carbohydrate consumption in female long-distance runners. The inclusion criterion for articles is that they must be scientific journal research articles conducted in the UK with the main subject female athletes long-distance runners and the topic relates to carbohydrates. Articles that meet these criteria are then further analyzed Through an analysis of 8 scientific journal articles, it was concluded that carbohydrate intake has a crucial role in improving athletes' performance and endurance, as well as preventing the risk of low energy availability that can have a negative impact on health. In addition, research also highlights the need for adjustments in carbohydrate intake based on environment and stress to maximize athletes' training and recovery abilities. These findings affirm the importance of designing a balanced diet of carbohydrates and protein to achieve the desired results in improving athlete performance and supporting healthy weight loss. This study provides a deep understanding of the importance of carbohydrate intake in supporting the performance and health of female long-distance runners, and emphasizes the need for more inclusive research to develop better nutritional interventions.
The widespread use of sports supplements (SS) to enhance athletic performance extends to cyclists, although little research has been conducted on this subject within this sport. This descriptive and cross-sectional study involved 1688 federated road cyclists, aiming to analyse the pattern of SS consumption concerning the degree of scientific evidence and different categories. This study categorised SS based on the groups and subgroups established by the Australian Sport Institute (AIS, 2023) based on the level of evidence. Our results showed that 62.5% of the sample cyclists used SS, with an average of 12.2 ± 8.6 supplements consumed per participant. Health status (78.2%), pharmacies (62.5%), and medical doctors (45.7%) were the main reasons, purchase sites, and sources of information for SS consumption, respectively. The most prevalent SS consumed were Sports Gels (94%), Sports Bars (89.3%), and Sports Drinks (73.8%). Notably, 80% of the top ten most consumed SS belonged to the group with the highest level of evidence according to the AIS, with an average of 6.9 ± 3.2 supplements per participant. However, 23.3% of the total SS consumers used prohibited substances. In conclusion, while the prevalence of SS consumption among road cyclists is considerable and the primary sources for purchasing SS and obtaining advice are reliable, there is a notable prevalence of prohibited substance use within the sample.
Equestrian sport is under-researched within the sport science literature, creating a possible knowledge vacuum for athletes and support personnel wishing to train and perform in an evidence based manner. This review aims to synthesise available evidence from equitation, sport, and veterinary sciences to describe the pertinent rider physiology of equestrian disciplines. Estimates of energy expenditure and the contribution of underpinning energy systems to equestrian performance are used to provide nutrition and hydration recommendations for competition and training in equestrian disciplines. Relative energy deficiency and disordered eating are also considered. The practical challenges of the equestrian environment, including competitive, personal, and professional factors, injury and concussion, and female participation, are discussed to better highlight novelty within equestrian disciplines compared to more commonly studied sports. The evidence and recommendations are supported by example scenarios, and future research directions are outlined.
The Constrained Model of Total Energy Expenditure predicts that increased physical activity may not influence total energy expenditure, but instead, induces compensatory energetic savings in other processes. Much remains unknown, however, about concepts of energy expenditure, constraint and compensation in different populations, and it is unclear whether this model applies to endurance athletes, who expend very large amounts of energy during training and competition. Furthermore, it is well-established that some endurance athletes consciously or unconsciously fail to meet their energy requirements via adequate food intake, thus exacerbating the extent of energetic stress that they experience. Within this review we A) Describe unique characteristics of endurance athletes that render them a useful model to investigate energy constraints and compensations, B) Consider the factors that may combine to constrain activity and total energy expenditure, and C) Describe compensations that occur when activity energy expenditure is high and unmet by adequate energy intake. Our main conclusions are as follows: A) Higher activity levels, as observed in endurance athletes, may indeed increase total energy expenditure, albeit to a lesser degree than may be predicted by an additive model, given that some compensation is likely to occur; B) That while a range of factors may combine to constrain sustained high activity levels, the ability to ingest, digest, absorb and deliver sufficient calories from food to the working muscle is likely the primary determinant in most situations and C) That energetic compensation that occurs in the face of high activity expenditure may be primarily driven by low energy availability i.e., the amount of energy available for all biological processes after the demands of exercise have been met, and not by activity expenditure per se.
Hoy en día es incuestionable la influencia de la alimentación en el deporte, de tal forma que la nutrición deportiva se reconoce como parte fundamental del bienestar, rendimiento y de las adaptaciones propias de la carga de entrenamiento planificada.
Endurance athletes are defined as those who take part in competitive events and workouts that last more than 30 minutes. The high physical demand in this type of event, as well as the possibility that any small gain obtained may provide a real improvement in sports performance, encourages athletes to consider the use of various tools and/or strategies, among which we find the use of sports supplements. Sports supplements are defined as a food, food component, nutrient, or non-food compound that is purposefully ingested in addition to the habitually consumed diet, to obtain a specific health and/or performance benefit. It is important to know and compare the benefits of consuming sports supplements in specific sports situations using evidence-based protocols. As part of dietary-nutritional planning for training and competition, a nutritional chronology should be established for ingesting food, liquids and/or sports supplements for each hour of physical exercise, considering the sports equipment of the athlete, characteristics of the training or competition, and nutritional needs. This chapter describes potentially beneficial sports supplements for endurance athletes, and their possible use, through examples according to best practice protocols.
Relative Energy Deficiency in Sport (REDs) was first introduced in 2014 by the International Olympic Committee’s expert writing panel, identifying a syndrome of deleterious health and performance outcomes experienced by female and male athletes exposed to low energy availability (LEA; inadequate energy intake in relation to exercise energy expenditure). Since the 2018 REDs consensus, there have been >170 original research publications advancing the field of REDs science, including emerging data demonstrating the growing role of low carbohydrate availability, further evidence of the interplay between mental health and REDs and more data elucidating the impact of LEA in males. Our knowledge of REDs signs and symptoms has resulted in updated Health and Performance Conceptual Models and the development of a novel Physiological Model. This Physiological Model is designed to demonstrate the complexity of either problematic or adaptable LEA exposure, coupled with individual moderating factors, leading to changes in health and performance outcomes. Guidelines for safe and effective body composition assessment to help prevent REDs are also outlined. A new REDs Clinical Assessment Tool-Version 2 is introduced to facilitate the detection and clinical diagnosis of REDs based on accumulated severity and risk stratification, with associated training and competition recommendations. Prevention and treatment principles of REDs are presented to encourage best practices for sports organisations and clinicians. Finally, methodological best practices for REDs research are outlined to stimulate future high-quality research to address important knowledge gaps.
The reported prevalence of low energy availability (LEA) in female and male track and field athletes is between 18% and 58% with the highest prevalence among athletes in endurance and jump events. In male athletes, LEA may result in reduced testosterone levels and libido along with impaired training capacity. In female track and field athletes, functional hypothalamic amenorrhea as consequence of LEA has been reported among 60% of elite middle- and long-distance athletes and 23% among elite sprinters. Health concerns with functional hypothalamic amenorrhea include impaired bone health, elevated risk for bone stress injury, and cardiovascular disease. Furthermore, LEA negatively affects recovery, muscle mass, neuromuscular function, and increases the risk of injuries and illness that may affect performance negatively. LEA in track and field athletes may occur due to intentional alterations in body mass or body composition, appetite changes, time constraints, or disordered eating behavior. Long-term LEA causes metabolic and physiological adaptations to prevent further weight loss, and athletes may therefore be weight stable yet have impaired physiological function secondary to LEA. Achieving or maintaining a lower body mass or fat levels through long-term LEA may therefore result in impaired health and performance as proposed in the Relative Energy Deficiency in Sport model. Preventive educational programs and screening to identify athletes with LEA are important for early intervention to prevent long-term secondary health consequences. Treatment for athletes is primarily to increase energy availability and often requires a team approach including a sport physician, sports dietitian, physiologist, and psychologist.
The main focus of this review is illness among elite athletes, how and why it occurs, and whether any measures can be taken to combat it or to prevent its onset. In particular, there is particular interest in exercise-induced immunodepression, which is a result of the immune system regarding exercise (e.g., prolonged, exhaustive exercise) as a challenge to its function. This promotes the inflammatory response. There is often a high incidence of illness in athletes after undertaking strenuous exercise, particularly among those competing in endurance events, not only mainly in terms of upper respiratory tract illness, but also involving gastrointestinal problems. It may well be that this high incidence is largely due to insufficient recovery time being allowed after, for example, a marathon, a triathlon, or other endurance events. Two examples of the incidence of upper respiratory tract illness in moderate versus endurance exercise are provided. In recent years, increasing numbers of research studies have investigated the origins, symptoms, and incidence of these bouts of illness and have attempted to alleviate the symptoms with supplements, sports foods, or immunonutrition. One aspect of the present review discusses iron deficiency, which has been primarily suggested to have an impact upon cell-mediated immunity. Immunonutrition is also discussed, as are new techniques for investigating links between metabolism and immune function.
Athletes should achieve event-specific physiological requirements through careful periodization of training, underpinned by individualized and targeted nutrition strategies. However, evidence of whether, and how, elite endurance athletes periodize nutrition is scarce. Accordingly, elite international female (n = 67) and male (n = 37) middle/long-distance athletes (IAAF score: 1129 ± 54, corresponds to 13:22.49 [males] and 15:17.93 [females] in the 5000 m) completed an online survey (February–May 2018) examining self-reported practices of dietary periodization for micro (within/between-days), meso (weeks/months) and macro (across the year) contexts. Data are shown as the percentage of all athletes practicing a given strategy followed by the % of athletes reporting various beliefs or practices within this strategy. Differences according to sex, event (middle-distance [800 m/1500 m] vs. track-distance [3000 m-10000 m] vs. road-distance [marathon/race walks]), caliber (high [major championship qualifier] vs. lower), and training volume (low/moderate/high male and female tertiles) were analyzed using Chi-square test or Kruskal–Wallis Test and indicated statistically different when p ≤ 0.05. Most athletes reported eating more on hard training days (92%) and focusing on nutrition before (84%; carbohydrate intake [63%] and timing [58%]) and after (95%; protein goals [59%], timing [55%], carbohydrate goals [50%]) key sessions. Road-distance were the most (62 and 57%), and middle-distance the least (30 and 30%) likely to train fasted (p = 0.037) or restrict carbohydrates periodically (p = 0.050), respectively. Carbohydrate intake during training (58% of total) was more common in males (79%; p = 0.004) and road-distance (90%; p < 0.001) than females (53%) or middle/track-distance (48 and 37%). Most athletes (83%) reported following a specific diet before and during race day, with half of the athletes focusing on carbohydrates. Nearly all (97%) road-distance athletes reported following a during-race nutrition plan (carbohydrates/fluids:89%). Only 32% reported taking advice from a dietitian/nutritionist. Based on our analysis: (1) Road-distance athletes periodize carbohydrate availability while track/middle-distance avoid low carbohydrate availability; (2) Middle-distance runners emphasize physique goals to guide their nutrition strategies; (3) Females seem to be more cautious of increasing energy/carbohydrate intake; (4) Among all athletes, nutrition strategies are chosen primarily to improve performance, followed by reasons related to physique, adaptation and health outcomes. Overall, these athletes appear to possess good knowledge of nutrition for supporting training and competition performance.
The exploits of elite athletes delight, frustrate, and confound us as they strive to reach their physiological, psychological, and biomechanical limits. We dissect nutritional approaches to optimal performance, showcasing the contribution of modern sports science to gold medals and world titles. Despite an enduring belief in a single, superior “athletic diet,” diversity in sports nutrition practices among successful athletes arises from the specificity of the metabolic demands of different sports and the periodization of training and competition goals. Pragmatic implementation of nutrition strategies in real-world scenarios and the prioritization of important strategies when nutrition themes are in conflict add to this variation. Lastly, differences in athlete practices both promote and reflect areas of controversy and disagreement among sports nutrition experts.
Caffeine use is widespread among athletes following its removal from the World Anti-Doping Agency banned list, with approximately 75% of competitive athletes using caffeine. While literature supports that caffeine has a small positive ergogenic effect for most forms of sports and exercise, there exists a significant amount of inter-individual difference in the response to caffeine ingestion and the subsequent effect on exercise performance. In this narrative review, we discuss some of the potential mechanisms and focus on the role that genetics has in these differences. CYP1A2 and ADORA2A are two of the genes which are thought to have the largest impact on the ergogenicity of caffeine. CYP1A2 is responsible for the majority of the metabolism of caffeine, and ADORA2A has been linked to caffeine-induced anxiety. The effects of CYP1A2 and ADORA2A genes on responses to caffeine will be discussed in detail and an overview of the current literature will be presented. The role of these two genes may explain a large portion of the inter-individual variance reported by studies following caffeine ingestion. Elucidating the extent to which these genes moderate responses to caffeine during exercise will ensure caffeine supplementation programs can be tailored to individual athletes in order to maximize the potential ergogenic effect.
Low energy availability (LEA) is a key element of the Female Athlete Triad. Causes of LEA include failure to match high exercise energy expenditure (unintentional) or pathological behaviors of disordered eating (compulsive) and overzealous weight control programs (misguided but intentional). Recognition of such scenarios in male athletes contributed to the pronouncement of the more inclusive Relative Energy Deficiency in Sport (RED-S) syndrome. This commentary describes the insights and experience of the current group of authors around the apparently heightened risk of LEA in some populations of male athletes: road cyclists, rowers (lightweight and open weight), athletes in combat sports, distance runners, and jockeys. The frequency, duration, and magnitude of the LEA state appear to vary between populations. Common risk factors include cyclical management of challenging body mass and composition targets (including "making weight") and the high energy cost of some training programs or events that is not easily matched by energy intake. However, additional factors such as food insecurity and lack of finances may also contribute to impaired nutrition in some populations. Collectively, these insights substantiate the concept of RED-S in male athletes and suggest that a specific understanding of a sport, subpopulation, or culture may identify a complex series of factors that can contribute to LEA and the type and severity of its outcomes. This commentary provides a perspective on the range of risk factors that should be addressed in future surveys of RED-S in athletic populations and targeted for specific investigation and modification.
The human body requires energy for numerous functions including, growth, thermogenesis, reproduction, cellular maintenance, and movement. In sports nutrition, energy availability (EA) is defined as the energy available to support these basic physiological functions and good health once the energy cost of exercise is deducted from energy intake (EI), relative to an athlete's fat-free mass (FFM). Low EA provides a unifying theory to link numerous disorders seen in both female and male athletes, described by the syndrome Relative Energy Deficiency in Sport, and related to restricted energy intake, excessive exercise or a combination of both. These outcomes are incurred in different dose-response patterns relative to the reduction in EA below a "healthy" level of ∼45 kcal·kg FFM-1·day-1. Although EA estimates are being used to guide and monitor athletic practices, as well as support a diagnosis of Relative Energy Deficiency in Sport, problems associated with the measurement and interpretation of EA in the field should be explored. These include the lack of a universal protocol for the calculation of EA, the resources needed to achieve estimates of each of the components of the equation, and the residual errors in these estimates. The lack of a clear definition of the value for EA that is considered "low" reflects problems around its measurement, as well as differences between individuals and individual components of "normal"/"healthy" function. Finally, further investigation of nutrition and exercise behavior including within- and between-day energy spread and dietary characteristics is warranted since it may directly contribute to low EA or its secondary problems.
The purpose of this study was to investigate the effects of chronic beetroot juice (BRJ) supplementation on 10-km running performance in recreational runners. In a double-blind, placebo-controlled, crossover-designed study, 14 male recreational runners (age, 27.8 ± 3.4 years) performed three 10-km running tests, at baseline and under the conditions of BRJ supplementation and placebo (PLA). Supplementation was administered for 3 days, and on the days of the assessments, the ingestion occurred 2 h before the test and consisted of a dose of 420 mL of BRJ in natura (8.4 mmol inorganic nitrate (NO3⁻)·day⁻¹) or PLA with depleted NO3⁻ (0.01 mmol NO3⁻·day⁻¹). The mean velocity (MV) was calculated, and the following variables were determined: maximal heart rate, maximal rating of perceived exertion, blood glucose concentration (analyzed before and after the test), and lactate peak. There was no main effect between conditions regarding 10-km running time performance (BRJ: 50.1 ± 5.3 min; PLA: 51.0 ± 5.1 min; P = 0.391) and total MV (BRJ: 12.1 ± 1.3 km·h⁻¹; PLA: 11.9 ± 1.2 km·h⁻¹; P = 0.321) or in the other analyzed variables. The time to complete the first half of the test (5 km) was statistically lower in the BRJ group than in the PLA group (P = 0.027). In conclusion, chronic supplementation with BRJ increased MV in the first half of the test and improved the final test times of 10 of the 14 runners, although we did not find a statistically significant difference in the performance of the 10-km run.
Background:
Caffeine is a widely used ergogenic aid with most research suggesting it confers the greatest effects during endurance activities. Despite the growing body of literature around the use of caffeine as an ergogenic aid, there are few recent meta-analyses that quantitatively assess the effect of caffeine on endurance exercise.
Objectives:
To summarise studies that have investigated the ergogenic effects of caffeine on endurance time-trial performance and to quantitatively analyse the results of these studies to gain a better understanding of the magnitude of the ergogenic effect of caffeine on endurance time-trial performance.
Methods:
A systematic review was carried out on randomised placebo-controlled studies investigating the effects of caffeine on endurance performance and a meta-analysis was conducted to determine the ergogenic effect of caffeine on endurance time-trial performance.
Results:
Forty-six studies met the inclusion criteria and were included in the meta-analysis. Caffeine has a small but evident effect on endurance performance when taken in moderate doses (3-6 mg/kg) as well as an overall improvement following caffeine compared to placebo in mean power output (3.03 ± 3.07%; effect size = 0.23 ± 0.15) and time-trial completion time (2.22 ± 2.59%; effect size = 0.41 ± 0.2). However, differences in responses to caffeine ingestion have been shown, with two studies reporting slower time-trial performance, while five studies reported lower mean power output during the time-trial.
Conclusion:
Caffeine can be used effectively as an ergogenic aid when taken in moderate doses, such as during sports when a small increase in endurance performance can lead to significant differences in placements as athletes are often separated by small margins.
Nutrition usually makes a small but potentially valuable contribution to successful performance in elite athletes, and dietary supplements can make a minor contribution to this nutrition program. Nonetheless, supplement use is widespread at all levels of sport. Products described as supplements target different issues, including the management of micronutrient deficiencies, supply of convenient forms of energy and macronutrients, and provision of direct benefits to performance or indirect benefits such as supporting intense training regimens. The appropriate use of some supplements can offer benefits to the athlete, but others may be harmful to the athlete's health, performance, and/or livelihood and reputation if an anti-doping rule violation results. A complete nutritional assessment should be undertaken before decisions regarding supplement use are made. Supplements claiming to directly or indirectly enhance performance are typically the largest group of products marketed to athletes, but only a few (including caffeine, creatine, specific buffering agents and nitrate) have good evidence of benefits. However, responses are affected by the scenario of use and may vary widely between individuals because of factors that include genetics, the microbiome, and habitual diet. Supplements intended to enhance performance should be thoroughly trialed in training or simulated competition before implementation in competition. Inadvertent ingestion of substances prohibited under the anti-doping codes that govern elite sport is a known risk of taking some supplements. Protection of the athlete's health and awareness of the potential for harm must be paramount, and expert professional opinion and assistance is strongly advised before embarking on supplement use.
Cold water or ice slurry ingestion during exercise seems to be an effective and practical means to improve endurance exercise performance in the heat. However, transient reductions in sweating appear to decrease the potential for evaporative heat loss from the skin by a magnitude that at least negates the additional internal heat loss as a cold ingested fluid warms up to equilibrate with body temperature; thus explaining equivalent core temperatures during exercise at a fixed heat production irrespective of the ingested fluid temperature. Internal heat transfer with cold fluid/ice is always 100% efficient; therefore, when a decrement occurs in the efficiency that sweat evaporates from the skin surface (i.e. sweating efficiency), a net cooling effect should begin to develop. Using established relationships between activity, climate and sweating efficiency, the boundary conditions beyond which cold ingested fluids are beneficial in terms of increasing net heat loss can be calculated. These conditions are warmer and more humid for cycling relative to running by virtue of the greater skin surface airflow, which promotes evaporation, for a given metabolic heat production and thus sweat rate. Within these boundary conditions, athletes should ingest fluids at the temperature they find most palatable, which likely varies from athlete to athlete, and therefore best maintain hydration status. The cooling benefits of cold fluid/ice ingestion during exercise are likely disproportionately greater for athletes with physiological disruptions to sweating, such as those with a spinal cord injury or burn injuries, as their capacity for skin surface evaporative heat loss is much lower; however, more research examining these groups is needed.
Purpose:
This study investigated whether reported improvements in blood flow distribution, and the possible related effects on thermoregulation during exercise following supplementation with beetroot juice (BR), a rich source of dietary nitrate (NO3-), are mitigated in the heat.
Methods:
12 male endurance-trained cyclists (age 27 ± 6 years, VO2peak 68.6 ± 8.1 ml kg-1 min-1) completed two 60 min submaximal cycling trials at 60% of VO2peak power output. Trials were performed in hot environmental conditions (33.3 ± 0.4 °C, 48.8 ± 3.0% RH) following 3 days of supplementation with either NO3--rich BR (6.5 mmol NO3- for 2 days and 13 mmol NO3- on the final day) or NO3--depleted placebo (PLA). Salivary NO3- and nitrite (NO2-) were measured before and after the supplementation period. During exercise, cutaneous blood flow, blood pressure (MAP), core temperature (Tc), mean skin temperature (Tsk), indices of muscle oxygenation and oxygen (O2) consumption were measured.
Results:
Salivary NO3- and NO2- increased significantly following BR by 680 and 890%, respectively. There were no significant differences observed for cutaneous blood flow, MAP, Tc, Tsk, muscle oxygenation, or O2 consumption between BR and PLA.
Conclusion:
This investigation shows that the ergogenic effects and health benefits of BR supplementation, such as augmented cutaneous blood flow, reduced MAP, increased muscle oxygenation, and improved aerobic efficiency may be attenuated when exercise is performed in hot conditions.
Nitrate-rich beetroot juice (BR) supplementation has been shown to increase biomarkers of nitric oxide availability with implications for the physiological responses to exercise. We hypothesized that BR supplementation before and during prolonged moderate-intensity exercise would maintain an elevated plasma nitrite concentration ([[Formula: see text]]), attenuate the expected progressive increase in V̇o 2 over time, and improve performance in a subsequent time trial (TT). In a double-blind, randomized, crossover design, 12 men completed 2 h of moderate-intensity cycle exercise followed by a 100-kJ TT in three conditions: 1) BR before and 1 h into exercise (BR + BR); 2) BR before and placebo (PL) 1 h into exercise (BR + PL); and 3) PL before and 1 h into exercise (PL + PL). During the 2-h moderate-intensity exercise bout, plasma [[Formula: see text]] declined by ~17% in BR + PL but increased by ~8% in BR + BR such that, at 2 h, plasma [[Formula: see text]] was greater in BR + BR than both BR + PL and PL + PL ( P < 0.05). V̇o 2 was not different among conditions over the first 90 min of exercise but was lower at 120 min in BR + BR (1.73 ± 0.24 l/min) compared with BR + PL (1.80 ± 0.21 l/min; P = 0.08) and PL + PL (1.83 ± 0.27 l/min; P < 0.01). The decline in muscle glycogen concentration over the 2-h exercise bout was attenuated in BR + BR (~28% decline) compared with BR + PL (~44% decline) and PL + PL (~44% decline; n = 9, P < 0.05). TT performance was not different among conditions ( P > 0.05). BR supplementation before and during prolonged moderate-intensity exercise attenuated the progressive rise in V̇o 2 over time and appeared to reduce muscle glycogen depletion but did not enhance subsequent TT performance.
NEW & NOTEWORTHY We show for the first time that ingestion of nitrate during exercise preserves elevated plasma [nitrite] and negates the progressive rise in O 2 uptake during prolonged moderate-intensity exercise.
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.
The gastrointestinal (GI) tract plays a critical role in delivering carbohydrate and fluid during prolonged exercise and can therefore be a major determinant of performance. The incidence of GI problems in athletes participating in endurance events is high, indicating that GI function is not always optimal in those conditions. A substantial body of evidence suggests that the GI system is highly adaptable. Gastric emptying as well as stomach comfort can be “trained” and perceptions of fullness decreased; some studies have suggested that nutrient-specific increases in gastric emptying may occur. Evidence also shows that diet has an impact on the capacity of the intestine to absorb nutrients. Again, the adaptations that occur appear to be nutrient specific. For example, a high-carbohydrate diet will increase the density of sodium-dependent glucose-1 (SGLT1) transporters in the intestine as well as the activity of the transporter, allowing greater carbohydrate absorption and oxidation during exercise. It is also likely that, when such adaptations occur, the chances of developing GI distress are smaller. Future studies should include more human studies and focus on a number of areas, including the most effective methods to induce gut adaptations and the timeline of adaptations. To develop effective strategies, a better understanding of the exact mechanisms underlying these adaptations is important. It is clear that “nutritional training” can improve gastric emptying and absorption and likely reduce the chances and/or severity of GI problems, thereby improving endurance performance as well as providing a better experience for the athlete. The gut is an important organ for endurance athletes and should be trained for the conditions in which it will be required to function.
The curvilinear relationship between power output and the time for which it can be sustained is a fundamental and well-known feature of high-intensity exercise performance. This relationship ‘levels off’ at a ‘critical power’ (CP) that separates power outputs that can be sustained with stable values of, for example, muscle phosphocreatine, blood lactate, and pulmonary oxygen uptake (), from power outputs where these variables change continuously with time until their respective minimum and maximum values are reached and exercise intolerance occurs. The amount of work that can be done during exercise above CP (the so-called W′) is constant but may be utilized at different rates depending on the proximity of the exercise power output to CP. Traditionally, this two-parameter CP model has been employed to provide insights into physiological responses, fatigue mechanisms, and performance capacity during continuous constant power output exercise in discrete exercise intensity domains. However, many team sports (e.g., basketball, football, hockey, rugby) involve frequent changes in exercise intensity and, even in endurance sports (e.g., cycling, running), intensity may vary considerably with environmental/course conditions and pacing strategy. In recent years, the appeal of the CP concept has been broadened through its application to intermittent high-intensity exercise. With the assumptions that W′ is utilized during work intervals above CP and reconstituted during recovery intervals below CP, it can be shown that performance during intermittent exercise is related to four factors: the intensity and duration of the work intervals and the intensity and duration of the recovery intervals. However, while the utilization of W′ may be assumed to be linear, studies indicate that the reconstitution of W′ may be curvilinear with kinetics that are highly variable between individuals. This has led to the development of a new CP model for intermittent exercise in which the balance of W′ remaining () may be calculated with greater accuracy. Field trials of athletes performing stochastic exercise indicate that this model can accurately predict the time at which W′ tends to zero and exhaustion is imminent. The model potentially has important applications in the real-time monitoring of athlete fatigue progression in endurance and team sports, which may inform tactics and influence pacing strategy.
Abstract
Purpose This study evaluated the effects of dietary nitrate (NO3-) supplementation on physiological functioning and exercise performance in trained runners/ triathletes conducting short and longer distance treadmill running time-trials (TT).
Method Eight trained male runners or triathletes completed four exercise performance tests comprising a 10 minute warm up followed by either a 1500 m or 10,000 m treadmill TT. Exercise performance tests were preceded 3 hours before the exercise by supplementation with either 140 ml concentrated nitrate-rich (~ 12.5 mmol nitrate) (BRJ) or nitrate-deplete (~ 0.01 mmol nitrate) (PLA) beetroot juice.
Results BRJ supplementation significantly elevated plasma [NO2-] (P < 0.05). Resting blood pressure and exercise V̇O2 were not significantly different between BRJ and PLA (P > 0.05). However, post-exercise blood [lactate] was significantly greater in BRJ following the 1500 m TT (6.6 ± 1.2 vs. 6.1 ± 1.5 mM; P < 0.05), but not significantly different between conditions in the 10,000 m TT (P > 0.05). Performance in the 1500 m TT was significantly faster in BRJ versus PLA (319.6 ± 36.2 vs. 325.7 ± 38.8 s; P < 0.05). Conversely, there was no significant difference in 10,000 m TT performance between conditions (2643.1 ± 324. 1 vs. 2649.9 ± 319.8 s, P > 0.05).
Conclusion Acute BRJ supplementation significantly enhanced 1500 m but not 10,000 m TT performance. These findings suggest that BRJ might be ergogenic during shorter-distance TTs which allow for a high work rate, but not during longer-distance TTs, completed at a lower work rate.
Due to gastrointestinal tract adaptability, the study aimed to determine the impact of gut-training protocol over 2 weeks on gastrointestinal status, blood glucose availability, fuel kinetics, and running performance. Endurance runners (n = 25) performed a gut-challenge trial (GC1), consisting of 2 h running exercise at 60% V̇O2max whilst consuming gel-discs containing 30 g carbohydrates (2:1 glucose/fructose, 10% w/v) every 20 min and a 1 h distance test. Participants were then randomly assigned to a carbohydrate gel-disc (CHO-S), carbohydrate food (CHO-F), or placebo (PLA) gut-training group for 2 weeks of repetitive gut-challenge intervention. Participants then repeated a second gut-challenge trial (GC2). Gastrointestinal symptoms reduced in GC2 on CHO-S (60%; p = 0.008) and CHO-F (63%; p = 0.046); reductions were greater than PLA (p < 0.05). H2 peak was lower in GC2 on CHO-S (mean (CI): 6 (4–8) ppm) compared with CHO-F (9 (6–12) ppm) and PLA (12 (2–21) ppm) (trial × time: p < 0.001). Blood glucose concentration was higher in GC2 on CHO-S (7.2 (6.3–8.1) mmol·L⁻¹) compared with CHO-F (6.1 (5.7–6.5) mmol·L⁻¹) and PLA (6.2 (4.9–7.5) mmol·L⁻¹) (trial × time: p = 0.015). No difference in oxidation rates, plasma I-FABP, and cortisol concentrations were observed between groups and trials. Distance test improved on CHO-S (5.2%) and CHO-F (4.3%) in GC2, but not on PLA (–2.1%) (trial × time: p = 0.009). Two weeks of gut-training with CHO-S and CHO-F improved gastrointestinal symptoms and running performance compared with PLA. CHO-S also reduced malabsorption and increased blood glucose availability during endurance running compared with PLA.
The application of menthol has recently been researched as a performance-enhancing aid for various aspects of athletic performance including endurance, speed, strength and joint range of motion. A range of application methods has been used including a mouth rinse, ingestion of a beverage containing menthol or external application to the skin or clothing via a gel or spray. The majority of research has focussed on the use of menthol to impart a cooling sensation on athletes performing endurance exercise in the heat. In this situation, menthol appears to have the greatest beneficial effect on performance when applied internally. In contrast, the majority of investigations into the external application of menthol demonstrated no performance benefit. While studies are limited in number, menthol has not yet proven to be beneficial for speed or strength, and only effective at increasing joint range of motion following exercise that induced delayed-onset muscle soreness. Internal application of menthol may provoke such performance-enhancing effects via mechanisms related to its thermal, ventilatory, analgesic and arousing properties. Future research should focus on well-trained subjects and investigate the addition of menthol to nutritional sports products.
Maximal oxygen uptake (VO2max), fractional utilization of VO2max during running and running economy (RE) are crucial factors for running success for all endurance athletes. Although evidence is limited, investigations of these key factors indicate that the East Africans superiority in distance running is to a large exent due to a unique combination of these factors. East African runners appear to have a very high level of RE most likely associated, at least partly, with anthropometric characteristics rather than with any specific metabolic property of the working muscle. That is, evidence suggest that anthropometrics and body composition might have important parameters as determinants of superior performance of East African distance runners. Regrettably, this role is often overlooked and mentioned as a descriptive parameter rather than explanatory one in many research studies. This brief review article provides an overview of the evidence to support the critical role anthropometrics and body composition has on the distance running success of East African athletes. The structural form and shape of these athletes also has a downside, as having very low BMI or body fat increases the risk for Relative Energy Deficiency in Sport (RED-S) conditions in both, male and female runners which can have serious health consequences.
Background
Recent research into the use of dietary nitrates and their role in vascular function has led to it becoming progressively more popular amongst athletes attempting to enhance performance. Objective
The objective of this review was to perform a systematic review and meta-analysis of the literature to evaluate the effect of dietary nitrate (NO3−) supplementation on endurance exercise performance. An additional aim was to determine whether the performance outcomes are affected by potential moderator variables. Data sourcesRelevant databases such as Cochrane Library, Embase, PubMed, Ovid, Scopus and Web of Science were searched for the following search terms ‘nitrates OR nitrate OR beetroot OR table beet OR garden beet OR red beet AND exercise AND performance’ from inception to October 2015. Study selectionStudies were included if a placebo versus dietary nitrate-only supplementation protocol was able to be compared, and if a quantifiable measure of exercise performance was ≥30 s (for a single bout of exercise or the combined total for multiple bouts). Study appraisal and synthesisThe literature search identified 1038 studies, with 47 (76 trials) meeting the inclusion criteria. Data from the 76 trials were extracted for inclusion in the meta-analysis. A fixed-effects meta-analysis was conducted for time trial (TT) (n = 28), time to exhaustion (TTE) (n = 22) and graded-exercise test (GXT) (n = 8) protocols. Univariate meta-regression was used to assess potential moderator variables (exercise type, dose duration, NO3− type, study quality, fitness level and percentage nitrite change). ResultsPooled analysis identified a trivial but non-significant effect in favour of dietary NO3− supplementation [effect size (ES) = −0.10, 95 % Cl = −0.27 to 0.06, p > 0.05]. TTE trials had a small to moderate statistically significant effect in favour of dietary NO3− supplementation (ES = 0.33, 95 % Cl = 0.15–0.50, p < 0.01). GXT trials had a small but non-significant effect in favour of dietary NO3− supplementation in GXT performance measures (ES = 0.25, 95 % Cl = −0.06 to 0.56, p > 0.05). No significant heterogeneity was detected in the meta-analysis. No statistically significant effects were observed from the meta-regression analysis. Conclusion
Dietary NO3− supplementation is likely to elicit a positive outcome when testing endurance exercise capacity, whereas dietary NO3− supplementation is less likely to be effective for time-trial performance. Further work is needed to understand the optimal dosing strategies, which population is most likely to benefit, and under which conditions dietary nitrates are likely to be most effective for performance.
It is common for athletes in weight category sports to try to gain a theoretical advantage by competing in weight divisions that are lower than their day-to-day body mass (BM). Weight loss is achieved not only through chronic strategies (body fat losses) but also through acute manipulations prior to weigh-in ("making weight"). Both have performance implications. In this review we focus on Olympic combat sports, noting that the varied nature of regulations surrounding the weigh-in procedures, weight requirements and recovery opportunities among these sports provide opportunity for a wider discussion of factors that can be applied to other weight category sports. We summarise previous literature that has examined the performance effects of "weight making" practices before investigating the physiological nature of these BM losses. Practical recommendations in the form of a decision tree are provided to guide the achievement of acute BM loss while minimising performance decrements.
Exertional heat stress (EHS) disturbs the integrity of the gastrointestinal tract leading to endotoxaemia and cytokinaemia, which have symptomatic and health implications. This study aimed to determine the effects of carbohydrate and protein intake during EHS on gastrointestinal integrity, symptoms, and systemic responses. Eleven (male, n = 6; female, n = 5) endurance runners completed 2 h of running at 60% maximal oxygen uptake in 35 °C ambient temperature on 3 occasions in randomised order, consuming water (WATER), 15 g glucose (GLUC), or energy-matched whey protein hydrolysate (WPH) before and every 20 min during EHS. Rectal temperature and gastrointestinal symptoms were recorded every 10 min during EHS. Blood was collected pre- and post-EHS, and during recovery to determine plasma concentrations of intestinal fatty-acid binding protein (I-FABP) as a marker of intestinal epithelial injury, cortisol, endotoxin, and inflammatory cytokines. Urinary lactulose/l-rhamnose ratio was used to measure small intestine permeability. Compared with WATER, GLUC, and WPH ameliorated EHS associated intestinal epithelial injury (I-FABP: 897 ± 478 pg·mL⁻¹ vs. 123 ± 197 pg·mL⁻¹ and 82 ± 156 pg·mL⁻¹, respectively, p < 0.001) and small intestine permeability (lactulose/l-rhamnose ratio: 0.034 ± 0.014 vs. 0.017 ± 0.005 and 0.008 ± 0.002, respectively, p = 0.001). Endotoxaemia was observed post-EHS in all trials (10.2 pg·mL⁻¹, p = 0.001). Post-EHS anti-endotoxin antibodies were higher (p < 0.01) and cortisol and interleukin-6 lower (p < 0.05) on GLUC than WATER only. Total and upper gastrointestinal symptoms were greater on WPH, compared with GLUC and WATER (p < 0.05), in response to EHS. In conclusion, carbohydrate and protein intake during EHS ameliorates intestinal injury and permeability. Carbohydrate also supports endotoxin clearance and reduces stress markers, while protein appears to increase gastrointestinal symptoms, suggesting that carbohydrate is a more appropriate option.
Muscle glycogen availability can limit endurance exercise performance. We previously demonstrated 5 days of creatine (Cr) and carbohydrate (CHO) ingestion augmented post-exercise muscle glycogen storage compared to CHO feeding alone in healthy volunteers. Here we aimed to characterise the time-course of this Cr-induced response under more stringent and controlled experimental conditions and identify potential mechanisms underpinning this phenomenon. Fourteen healthy, male volunteers cycled to exhaustion at 70% VO2peak. Muscle biopsies were obtained at rest immediately post-exercise and after 1, 3 and 6 days of recovery, during which Cr or placebo supplements (20g.day-1) were ingested along with a prescribed high CHO diet (37.5 kcal.kg body mass-1.day-1, >80% calories CHO). Oral-glucose tolerance tests (oral-GTT) were performed pre-exercise and after 1, 3 and 6 days of Cr and placebo supplementation. Exercise depleted muscle glycogen content to the same extent in both treatment groups. Creatine supplementation increased muscle total-Cr, free-Cr and phosphocreatine (PCr) content above placebo following 1, 3 and 6 days of supplementation (all P<0.05). Creatine supplementation also increased muscle glycogen content noticeably above placebo after 1 day of supplementation (P<0.05), which was sustained thereafter. This study confirmed dietary Cr augments post-exercise muscle glycogen super-compensation, and demonstrates this occurred during the initial 24 h of post-exercise recovery (when muscle total-Cr had increased by <10%). This marked response ensued without apparent treatment differences in muscle insulin sensitivity (oral-GTT, muscle GLUT4 mRNA), osmotic stress (muscle c-fos and HSP72 mRNA) or muscle cell volume (muscle water content) responses, such that another mechanism must be causative.
The hyperbolic form of the power-duration relationship is rigorous and highly conserved across species, forms of exercise and individual muscles/muscle groups. For modalities such as cycling, the relationship resolves to two parameters, the asymptote for power (critical power, CP) and the so-called W' (work doable above CP), which together predict the tolerable duration of exercise above CP. Crucially, the CP concept integrates sentinel physiological profiles - respiratory, metabolic and contractile - within a coherent framework that has great scientific and practical utility. Rather than calibrating equivalent exercise intensities relative to metabolically distant parameters such as the lactate threshold or V˙O2 max, setting the exercise intensity relative to CP unifies the profile of systemic and intramuscular responses and, if greater than CP, predicts the tolerable duration of exercise until W' is expended, V˙O2 max is attained, and intolerance is manifested. CP may be regarded as a 'fatigue threshold' in the sense that it separates exercise intensity domains within which the physiological responses to exercise can (<CP) or cannot (>CP) be stabilized. The CP concept therefore enables important insights into 1) the principal loci of fatigue development (central vs. peripheral) at different intensities of exercise, and 2) mechanisms of cardiovascular and metabolic control and their modulation by factors such as O2 delivery. Practically, the CP concept has great potential application in optimizing athletic training programs and performance as well as improving the life quality for individuals enduring chronic disease.
Purpose:
We investigated the effect of a chronic dietary periodization strategy on endurance performance in trained athletes.
Methods:
21 triathletes (V[Combining Dot Above]O2max: 58.7 ± 5.7 mL·min·kg) were divided into 2 groups: a "sleep-low"