Reviewing the current methods of assessing hydration in athletes

Background Despite a substantial body of research, no clear best practice guidelines exist for the assessment of hydration in athletes. Body water is stored in and shifted between different sites throughout the body complicating hydration assessment. This review seeks to highlight the unique strengths and limitations of various hydration assessment methods described in the literature as well as providing best practice guidelines. Main body There is a plethora of methods that range in validity and reliability, including complicated and invasive methods (i.e. neutron activation analysis and stable isotope dilution), to moderately invasive blood, urine and salivary variables, progressing to non-invasive metrics such as tear osmolality, body mass, bioimpedance analysis, and sensation of thirst. Any single assessment of hydration status is problematic. Instead, the recommended approach is to use a combination, which have complementary strengths, which increase accuracy and validity. If methods such as salivary variables, urine colour, vital signs and sensation of thirst are utilised in isolation, great care must be taken due to their lack of sensitivity, reliability and/or accuracy. Detailed assessments such as neutron activation and stable isotope dilution analysis are highly accurate but expensive, with significant time delays due to data analysis providing little potential for immediate action. While alternative variables such as hormonal and electrolyte concentration, bioimpedance and tear osmolality require further research to determine their validity and reliability before inclusion into any test battery. Conclusion To improve best practice additional comprehensive research is required to further the scientific understanding of evaluating hydration status

Nutrition and hydration implications for trained athletes

Lifestyle choices threaten to compromise health and performance of trained athletes. This thesis presents a series of studies which broadly investigated the impact of nutritional and physical challenges to human health and performance. The potential causes and effects of fluid imbalances on physical health, immune function and athletic performance were investigated. Certain populations experience chronic low-level hypohydration and athletes often fail to rehydrate sufficiently between exercise sessions. The long-term implications of hypohydration are not fully understood, but are suggested to be associated with chronic disease. In this thesis, maintenance of fluid balance was observed in healthy males, despite a caffeine intervention thought to cause diuresis. Furthermore, when mild hypohydration was induced by 24-h fluid restriction, there was little impact on mucosal immunity during endurance exercise compared with euhydration. The impact of intensified training (IT) on the physical, mental, hormonal and immunological status of well-trained athletes was investigated. A performance-specific nutritional intervention was implemented to investigate the effects of nutrient availability during prolonged exercise training sessions. Phases of IT are a regular feature of a periodised training programme. However, an imbalance between training and recovery can have significant implications for long-term athletic performance and general wellbeing. Changes in neuroendocrine, neurobiological and mucosal immune function were observed during IT and some potential markers of overreaching and were identified. Further research is required before practical application of these markers can be used effectively in the field. A relatively short period of IT resulted in significant disruptions to mood state and sleep quality. Minor changes in exercise performance were observed. Markers of overreaching were highly individual, as were responses to training

Predicting Hydration Status Using Machine Learning Models From Physiological and Sweat Biomarkers During Endurance Exercise: A Single Case Study

Improper hydration routines can reduce athletic performance. Recent studies show that data from noninvasive biomarker recordings can help to evaluate the hydration status of subjects during endurance exercise. These studies are usually carried out on multiple subjects. In this work, we present the first study on predicting hydration status using machine learning models from single-subject experiments, which involve 32 exercise sessions of constant moderate intensity performed with and without fluid intake. During exercise, we measured four noninvasive physiological and sweat biomarkers including heart rate, core temperature, sweat sodium concentration, and whole-body sweat rate. Sweat sodium concentration was measured from six body regions using absorbent patches. We used three machine learning models to determine the percentage of body weight loss as an indicator of dehydration with these biomarkers and compared the prediction accuracy. The results on this single subject show that these models gave similar mean absolute errors, while in general the nonlinear models slightly outperformed the linear model in most of the experiments. The prediction accuracy of using the whole-body sweat rate or heart rate was higher than using core temperature or sweat sodium concentration. In addition, the model trained on the sweat sodium concentration collected from the arms gave slightly better accuracy than from the other five body regions. This exploratory work paves the way for the use of these machine learning models to develop personalized health monitoring together with emerging, noninvasive wearable sensor devices

Endurance races effects in non-elite runners by clinical biomarkers and bioimpedance measurements

Participation in marathons and ultra-endurance races is growing every day, but it is worrisome that these types of races are becoming mass events, where many runners are not sufficiently prepared. For example, in the 2017 Barcelona marathon there were 19.740 runners, whereas in the 2007 marathon there were 7.430_ runners (Zurich Barcelona Marathon). In the age of social media everyone wants to put his/her photo and comment on instagram, facebook, twitter, etc., about the achievement reached, without caríng if his/her healt.h has been compromised. A marathon or longer distance races, require significant exertions and result in impact to our bodies and bring short and long-term consequences for our health. Never befare has running been so fashionable, but to what extent is it done in a healthy manner? The motivation and merit of this thesis líes in the fact of finding the impact of a 42km run on our body and evaluate the risk of muscle and cardiac damage, inflammation and infection, and renal impairment. The results embodied in the different research articles of this thesís, due to the small number of runners are subjective and show a tendency to be validated in other studies with more athletes. More than 80 non-elite runners were studied during 4 years (from 2016 to 2019). The changes evaluated in pre-race conditions {baseline), at the end, and 48h post-race were through blood and saliva biomarkers. Additionally, other variables were assessed before the race, like nutrition balance and sorne specific supplement intake, and it was proved how the body weight, recovery time, and amount of training done can directly affect the runner's performance and health. The highest elevations in biomarkers associated to muscle damage (CK), inflammation (CRP), and cardiovascular health (Hs-TnT, NT-proBNP, ST2) were seen in the runners with the worse performance time and less training hours before-race. Also, the marathon provoked changes in the salivary immunity and increased the risk of developing a respiratory tract infection. In addition, supplementation actions like polysaccharide-based ones, positively affected on the immune response initiated during a 42 km effort. By BIVA methodogly, a correlation can be made with a displacement ofthe vector impedance at 24 h and 48 h post-race on the tolerance ellipses of a European Caucasian reference population with biomarkers of renal damage. Transient values of acute kidney injury (AKI) stage 1, more related to inflammatory factors rather than muscle damage, were found in many marathoners which recovered mostly 48 h post-race. · Regarding diet, a correct mono- and poly-unsaturated fatty acid, potassium, and magnesium intake befare the marathon influenced better performance and better cardiovascular health. But, what are the negative long-term effects of these acute changes in clinical biomarkers and bioimpedance measurements after 42 km? How does it affect an inadequate diet and preparation? This thesis is based on five original publications, three accepted and two under review, separated in three chapters ordered from 2 to 4, starting with cardidVascular biomarkers, immunity, and supplements. In Appendix 1, renal function and bioimpedance vector displacement, and in Appendix 2, diet effects on performance and cardiac health. An introduction in Chapter 1, describes the rationale of the published work and its place within the whole topic of this thesis. As an elite runner for many years and already a veteran, this thesis is my "grain of sand" in the fasciriating world of metabolic responses while running.La participació en maratons i curses d'ultra resistència creix cada dia, però és preocupant que aquest tipus de curses es converteixin en esdeveniments massius, on molts corredors no estan prou preparats. Per exemple, a la marató Barcelona del 2017 hi havía 19.740 corredors, mentre que a la marató del 2007 hi havia 7.430 corredors (Zurich Barcelona Marató). En l'era de les xarxes socials, tots volen posar la seva foto i comentar a lnstagram, Facebook, Twitter, etc., sobre l'assoliment aconseguit, independentment de si la seva salut s'ha vist compromesa. Una marató o cursa de llarga distància, requereix esforços sígnificatius i té un impacte en el nostre cos amb unes conseqüències a curt i llarg termini pera la nostra salut. Mai abans havia¿ estat tan de moda córrer, però fins a quin punt es fa de manera saludable? La motivació i el mèrit d'aquesta tesi rau en el fet de veure !'impacte d'una carrera de 42 km en el nostre cos i avaluar el risc de dany muscular i cardíac, d'inflamació i infecció, i d'insuficiència renal. Els resultats exposats en els diferents articles d'investigació d'aquesta tesi, a causa del petit nombre de corredors, són subjectius i mostren una tendència a ser validats en altres estudis amb més atletes. Es van estudiar més de 80 corredors no elit durant 4 anys (del 2016 al 2019). Els canvis avaluats en les condicions prèvies a la cursa (estat basal), al final i 48 hores després de la cursa, es van realitzar a través de biomarcadors en sang i saliva. A més a més, es van avaluar altres variables abans de la cursa, corn l'equilibri nutricional i una suplementació específica, i es va demostrar com el pes corporal, el temps de recuperació i la quantitat d'entrenament realitzat poden afectar directament el rendiment i la salut del corredor. Les elevacions més altes en els biomarcadors associats amb el dany muscular (CK), la inflamació (CRP) i la salut cardiovascular (Hs-TnT, NT-proBNP, ST2) es van observar en els corredors amb pitjor rendiment en carrera i amb menys hores d'entrenament abans de la cursa. A més, la marató va provocar canvis en la immunitat salival i va augmentar el risc de desenvolupar una infecció del tracte respiratori. Així mateix, les accions de suplementació com les basades en polisacàrids van afectar positivament la resposta immune iniciada durant l'esforç de córrer 42 km. Segons el mètode BIVA, es pot fer una correlació del desplaçament del vector impedància a les 24 h i 48 h després de la carrera sobre les el·lipses de tolerància d'una població de referencia caucàsica europea, amb els biomarcadors de dany renal. Els valors transitoris de la lesió renal aguda (AKI) tipus 1, més relacionats amb factors inflamatoris que amb el dany muscular, es van trobar en molts maratonians que van recuperar a les 48 h després de la cursa. Pel que fa a la dieta, una correcta ingesta d'àcids grassos monoinsaturats i poliinsaturats, potasi i magnesi abans de la marató va influir en un millar rendiment i una millar salut cardiovascular. Però quins són els efectes negatius a llarg termini d'aquests canvis aguts en els bíomarcadors clínics i en les mesures de bioimpedància després de 42 km? Com afecta una dieta i una preparació inadequades? Aquesta tesi es basa en cinc publicacions originals, 3 acceptades i dos en revisió, separades en tres capítols ordenats del 2 al 4, començant amb biomarcadors cardiovasculars, infecció, immunitat i suplementació. En l'Annex 1, la funció renal i el desplaçament del vector de bioimpedància, i l'Annex 2, els efectes de la dieta sobre el rendiment í la salut cardíaca. Una introducció al Capital 1 descriu la justificació del treball publicat i el seu lloc dins el tema general d'aquesta tesi. Com a corredora d'elit durant molts anys i ja veterana, aquesta tesi és el meu "gra de sorra" en el fascinant món de les respostes metabòliques mentre correm.La participación en maratones y carreras de ultra resistencia crece cada día, pero es preocupante que este tipo de carreras se conviertan en eventos masivos, donde muchos corredores no están lo suficientemente preparados. Por ejemplo, en la maratón Barcelona de 2017 había 19.740 corredores, mientras que en la maratón de 2007 había 7.430 corredores (Zurich Barcelona Marathon). En la era de las redes sociales, todos quieren subir su foto y comentar en Instagram, Facebook, Twitter, etc., sobre el logro alcanzado, sin importar si su salud se ha visto comprometida. Una maratón o carrera de larga distancia, requiere esfuerzos significativos y tiene un impacto en nuestro cuerpo con unas consecuencias a corto y largo plazo para nuestra salud. Nunca antes había estado tan de moda correr, pero ¿hasta qué punto se hace de manera saludable? La motivación y el mérito de esta tesis radica en el hecho de ver el impacto de una carrera de 42 km en nuestro cuerpo y evaluar el riesgo de daño muscular, daño cardíaco, inflamación, cambios inmunológicos, infección, e insuficiencia renal. Un total de 234 corredores no elite se estudiaron durante 4 años (del 2016 al 2019). Los artículos presentados en esta tesis se basan en los corredores que participaron en la maratón del 2016. En el artículo “The Dynamics of Cardiovascular Biomarkers in non-Elite Marathon Runners” se analizaron 79 corredores, en el de “Salivary immunity and lower respiratory tract infections in non-elite marathon runners” se analizaron 47 corredores y en el de “Effects of a polysaccharide-based multiingredient supplement on salivary immunity in non-elite marathon runners” se analizaron 41 corredores. Los cambios evaluados en las condiciones previas a la carrera (estado basal), al final y 48 horas después de la carrera, se realizaron a través de biomarcadores de sangre y saliva. Además, se evaluaron otras variables antes de la carrera, como el equilibrio nutricional y una suplementación específica, y se demostró como el peso corporal, el tiempo de recuperación y la cantidad de entrenamiento realizado pueden afectar directamente el rendimiento y la salud del corredor. Las elevaciones más altas en los biomarcadores asociados con el daño muscular (CK), la inflamación (CRP) y la salud cardiovascular (Hs-TnT, NT-proBNP, ST2) se observaron en los corredores con peor rendimiento en carrera y con menos horas de entrenamiento antes de la misma. Además, la maratón provocó cambios en la inmunidad salival y aumentó el riesgo de desarrollar una infección del tracto respiratorio. A su vez, las acciones de suplementación como las basadas en polisacáridos afectaron positivamente la respuesta inmune iniciada durante el esfuerzo de correr 42 km. Según el método BIVA, se puede hacer una correlación del desplazamiento del vector impedancia a las 24 h y 48 h después de la carrera sobre las elipses de tolerancia de una población de referencia caucásica europea, con los biomarcadores de daño renal. Los valores transitorios de la lesión renal aguda (AKI) tipo 1, más relacionados con factores inflamatorios que con el daño muscular, se encontraron en muchos maratonianos que recuperaron a las 48 h después de la carrera. Con respecto a la dieta, una correcta ingesta de ácidos grasos monoinsaturados y poliinsaturados, potasio y magnesio antes de la maratón influyó en un mejor rendimiento y una mejor salud cardiovascular. ¿Pero cuáles son los efectos negativos a largo plazo de estos cambios agudos en los biomarcadores clínicos y las mediciones de bioimpedancia después de 42 km? ¿Cómo afecta una dieta y una preparación inadecuadas? Esta tesis se basa en cinco publicaciones originales, tres aceptadas y dos en revisión, separadas en tres capítulos ordenados del 2 al 4, comenzando con biomarcadores cardiovasculares, infección, inmunidad y suplementación. En el Anexo 2, la función renal y el desplazamiento del vector de bioimpedancia, y en el Anexo 3, los efectos de la dieta sobre el rendimiento y la salud cardíaca. Una introducción en el Capítulo 1 describe la justificación del trabajo publicado y su lugar dentro del tema general de esta tesis. Como corredora de élite durante muchos años y ya veterana, esta tesis es mi "grano de arena" en el fascinante mundo de las respuestas metabólicas que hace nuestro cuerpo mientras corremo

Effects of beet juice supplementation in different concentrations and the importance of nitric oxide in endurance runners

More and more beetroot has been highlighted in sports, mainly in long-term aerobic modalities, due to its high concentration of nitrate (NO3- ), being an important precursor of nitric oxide (NO), providing an improvement in sports performance. The main objective of this study was to investigate the effects of acute ingestion of beetroot juice (BR), rich in NO3- in different concentrations in endurance exercise, evaluating performance, glycemic, cardiorespiratory and urinary responses of amateur runners. We hypothesized that BR would increase glucose uptake, minimize VO2max (maximum oxygen uptake), improve exercise economy and runners' performance. Nineteen male amateur runners were exposed to two conditions, ingestion of BR and PL (placebo), the individuals were divided into three groups (minimum, average and maximum concentration), being submitted to a 30-minute running test at maximum intensity, on a racetrack. Pre and posttest blood and urine samples were collected to determine glucose uptake, NO2- (nitrite) excretion, urinary pH and urinary density. Cooper's test also performed in order to assess VO2max. The main posttest results showed that through nitrite excretion there was a reduction of nitrate to nitric oxide (0 ± 0 vs 0.94 ± 0.23, P <0.05 (pre vs post)), increase in glucose uptake (139.94 ± 35.02 vs 122.88 ± 37.69, P <0.05 (PL vs BR)) and VO2max improvement(54.96 ± 6.87 vs 55.99 ± 6.88, P <0.05 (PL vs BR))], coinciding with the increase in physical performance (2972.63 ± 308.84 vs 3018.95 ± 309.29, P <0.05 (PL vs BR))]. The results found observed that beet supplementation in amateur runners increased glucose uptake, improved VO2max and running performance

A Comparison Between UK and Cyprus Based Male Football Athletes in Terms of Dietary Intake, Markers of Physiological Stress, and Training Load

Few studies have examined the relationship of nutritional intake and training load between different football teams. Additionally, there are not any comparison studies regarding training load in terms of energy cost and whether this is sufficiently balanced with energy intake. The present study aimed to examine if there was a difference in nutrition intake and training load between teams from different geographical locations across football training season, and how both influence training stress markers regarding training sessions. Methods: Following ethical approval, participants (n=45; age 24.47 ± 6.07 years; height 1.75 ± 0.08 m; mass 74.86 ± 9.57 kg) were male footballers from three different teams; one UK based professional team and two Cyprus based teams; professional (UKpro), semi-professional (CYsem) and recreational (CYrec). Data was collected from all teams at three time points across an annual training programme (pre, mid, end season). A food recall 4-day diary was used to record nutritional intake and metabolic equivalent (MET) values of physical activities method was used to quantify the energy cost of training. Saliva samples were collected during a standard training week on a fixed day pre- and post-training, and at rest 24hours post training. Samples were analysed in duplicate via enzyme linked immunoassay (ELISA) for secretory IgA, cortisol and testosterone. Results: It was found that across all three testing blocks none of the groups received inadequate nutritional energy intake. All groups showed consumption of the investigated micronutrients in higher than recommended daily amounts (RDA) but only vitamin C was significantly higher (> 20%) for UKpro compared to Cyprus groups . Furthermore, findings showed that pre-season average daily energy cost was not the highest across season and neither difference between blocks was significant. In parallel, both average daily energy intake and s-IgA did not show important changes. Conclusions: The collected results revealed that energy expenditure for UK based professional players was not significantly higher neither regarding the average daily or training day energy cost between all three testing blocks and with balanced nutritional energy intake. Monitoring Salivary IgA in football athletes may be an effective way to monitoring recovery

National Athletic Trainers\u27 Association Position Statement: Safe Weight Loss and Maintenance Practices in Sport and Exercise

Objective: To present athletic trainers with recommendations for safe weight loss and weight maintenance practices for athletes and active clients and to provide athletes, clients, coaches, and parents with safe guidelines that will allow athletes and clients to achieve and maintain weight and body composition goals. Background: Unsafe weight management practices can compromise athletic performance and negatively affect health. Athletes and clients often attempt to lose weight by not eating, limiting caloric or specific nutrients from the diet, engaging in pathogenic weight control behaviors, and restricting fluids. These people often respond to pressures of the sport or activity, coaches, peers, or parents by adopting negative body images and unsafe practices to maintain an ideal body composition for the activity. We provide athletic trainers with recommendations for safe weight loss and weight maintenance in sport and exercise. Although safe weight gain is also a concern for athletic trainers and their athletes and clients, that topic is outside the scope of this position statement. Recommendations: Athletic trainers are often the source of nutrition information for athletes and clients; therefore, they practices, and methods to change body composition. Body composition assessments should be done in the most scientifically appropriate manner possible. Reasonable and individualized weight and body composition goals should be identified by appropriately trained health care personnel (eg, athletic trainers, registered dietitians, physicians). In keeping with the American Dietetics Association (ADA) preferred nomenclature, this document uses the terms registered dietitian or dietician when referring to a food and nutrition expert who has met the academic and professional requirements specified by the ADA\u27s Commission on Accreditation for Dietetics Education. In some cases, a registered nutritionist may have equivalent credentials and be the commonly used term. All weight management and exercise protocols used to achieve these goals should be safe and based on the most current evidence. Athletes, clients, parents, and coaches should be educated on how to determine safe weight and body composition so that athletes and clients more safely achieve competitive weights that will meet sport and activity requirements while also allowing them to meet their energy and nutritional needs for optimal health and performance

The influence of habitual fluid intake on energy balance

Epidemiologic data have linked chronic low fluid intake (i.e., underhydration) with greater incidence of obesity, but the underlying mechanisms behind this association are unclear. No study has assessed the direct effect of underhydration on energy balance (EB), which is inclusive of energy consumed from food or fluid (EI) and energy expended from resting metabolism (RMR), the thermic effect of food (TEF), and physical activity (PAEE). Underhydration increases release of the fluid regulatory hormone arginine vasopressin (AVP) to conserve total body water. However, chronic elevations in AVP may cause metabolic changes including alterations in cortisol release that could influence one’s propensity toward developing obesity and metabolic disease. Thus, the purpose of the present study was to characterize the associations between habitual fluid intake and behavioral, perceptual, and physiologic factors influencing energy balance to inform the development of effective intervention strategies promoting adequate hydration for metabolic health. Healthy male participants with low, moderate, and high habitual fluid intake completed measures of EI and fluid intake (TFI), PAEE for seven days, as well as measures of hydration status for four of these days. Participants also came to the lab for assessments of RMR, TEF, fasting and postprandial changes in appetite and thirst, food reward, and salivary and hematological measures of hormonal responses to hydration status. Higher habitual fluid intake was associated with higher RMR and increased PAEE, but there was no effect on overall EB. There was no association between habitual fluid intake and appetite ratings. Lower habitual fluid intake and a flatter diurnal cortisol slope were independently associated with liking of high fat sweet foods and wanting of high fat savory foods, respectively, but twenty-four-hour urinary osmolality was not associated with salivary cortisol dynamics (peak cortisol, cortisol awakening response, diurnal cortisol slope). These data suggest increased fluid intake is a promising target for future interventions to aid with weight maintenance from both a physiologic and behavioral standpoint