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The market for wrist-worn devices is growing at previously unheard-of speeds. A consequence of their fast commercialization is a lack of adequate studies testing their accuracy on varied populations and pursuits. To provide an understanding of wearable sensors for sports medicine, the present study examined heart rate (HR) measurements of four popular wrist-worn devices, the (Fitbit Charge (FB), Apple Watch (AW), Tomtom runner Cardio (TT), and Samsung G2 (G2)), and compared them with gold standard measurements derived by continuous electrocardiogram examination (ECG). Eight athletes participated in a comparative study undergoing maximal stress testing on a cycle ergometer or a treadmill. We analyzed 1,286 simultaneous HR data pairs between the tested devices and the ECG. The four devices were reasonably accurate at the lowest activity level. However, at higher levels of exercise intensity the FB and G2 tended to underestimate HR values during intense physical effort, while the TT and AW devices were fairly reliable. Our results suggest that HR estimations should be considered cautiously at specific intensities. Indeed, an effective intervention is required to register accurate HR readings at high-intensity levels (above 150 bpm). It is important to consider that even though none of these devices are certified or sold as medical or safety devices, researchers must nonetheless evaluate wrist-worn wearable technology in order to fully understand how HR affects psychological and physical health, especially under conditions of more intense exercise.

Different rugby positions make different demands on players. It therefore follows that optimum body composition may vary according to the position played. Using anthropometry and bioimpedance analysis (BIA) to assess body composition, the present study aimed to compare the effect of sex and position on body composition variables using anthropometry and BIA methods. A total of 100 competitive rugby players (35 women and 65 men) competing in the First Spanish National League were recruited voluntarily and for convenience for this study. In the laboratory, body composition was assessed by anthropometry, following the recommendations established by the International Society for the Advancement of Kinanthropometry (ISAK), and by direct segmental multi-frequency BIA, following the guidelines established by the Spanish Group of Kinanthropome try (GREC) of the Spanish Federation of Sports Medicine (FEMEDE). We found sex-related differences in height, weight, body mass index and body fat (%) by anthropometry and in body lean mass (%) by DSM-BIA, in 4 of the 6 skinfolds assessed (p < 0.05). We also observed position-related differences in all the variables assessed (p < 0.05) except for lean body mass, as measured by both methods of determining body composition, and front thigh skinfold. Body composition and ∑6skinfolds differs according to sex and playing position, backs (16.6 ± 3.8% and 92.3 ± 33.9 mm,) vs. forwards (20.0 ± 6.7 and 115.3 ± 37.6 mm), and the muscle-adipose (meso-endomorphic somatotype) devel opment predominated in both sexes. Thus, forwards of both sexes are taller, heavier and fatter, possibly due to the specific demands of this position. In addition, body composition measurements vary according to the method used (DSM-BIA vs. anthropometry), indicating that anthropometry is probably the best body composition assessment method.

Purpose: Beetroot juice (BRJ) is considered an ergogenic aid with good to strong evidence for improving human performance in sport modalities with similar demands to rugby. However, most of the studies were realized in male athletes with limited evidence in female athletes. Thus, the aim of this study was to explore the acute ingestion of BRJ in female rugby players. Methods: Fourteen semi-professional female rugby players (25.0 ± 3.7 years) belonging to a team from the First Spanish Female Rugby Division participated in this study. Participants were randomly divided into two groups that realized a neuromuscular battery after BRJ (140mL, 12.8 mmol NO3−) or placebo (PLAC, 140 mL, 0.08 mmol NO3−) ingestion on two different days separated by one week between protocols. The neuromuscular test battery consisted of a countermovement jump (CMJ), isometric handgrip strength (i.e., dominant), 10-m and 30-m sprint, agility t-test and Bronco test. Afterwards, participants reported a rate of perception scale (6–20 points) and side effects questionnaire associated with BRJ or PLAC ingestion. Results: Statistically significant improvements were observed in CMJ (7.7%; p = 0.029; ES = 0.62), while no differences were reported in dominant isometric handgrip strength (−1.7%; p = 0.274; ES = −0.20); 10-m and 30-m sprint (0.5–0.8%; p = 0.441–0.588; ES = 0.03–0.18); modified agility t-test (−0.6%; p = 0.503; ES = −0.12) and Bronco test (1.94%; p = 0.459; ES = 0.16). Conclusions: BRJ ingestion could improve neuromuscular performance in the CMJ test, while no differences in sprint (10-m and 30-m sprint test), agility, isometric handgrip strength and endurance performance (i.e., Bronco test) were reported

Introduccion. El estudio analizo los niveles de actividad fisica cardiosaludable (AFCS) de los escolares de primaria en la jornada escolar y la jerarquia de factores predictores de dicha conducta activa. Metodologia. Estudio transversal, prospectivo, correlacional e inferencial. Se recabaron datos de diferente naturaleza (fenotipo sexual, tipologia ponderal, resistencia cardiaca, capacidad aerobica, expresividad emocional y social, ansiedad-rasgo, tipologia sociometrica, nivel de sedentarismo, tipo de centro y jornada) en un total de 58 sujetos (32 ninos y 26 ninas) (12 anos) de 24 centros. Tras registrar la FC durante 5 jornadas escolares, se analizo el tiempo invertido en AFCS en FC ≥50% FC de reserva. Posteriormente, se aplico analisis correlacional y tecnica arbol de decisiones determinando la relacion jerarquica de rasgos predictores de AFCS (α= 0,05). Resultados y conclusiones. Los varones alcanzarian en el recreo mas AFCS que las ninas (p min/sem =0,03; p % tiempo/sem =0,02). Los chicos populares acumularian mas AFCS que el resto (R 2 =38,85). Los escolares con una resistencia aerobica inferior a la media acumularian mas AFCS en Ed. Fisica que el resto (R 2 =8,39). Quienes muestran indices intermedios de expresividad emocional alcanzarian mas AFCS que el resto en Ed. Artistica y otras actividades escolares minoritarias, donde los introvertidos “activos y muy activos” alcanzarian mas AFCS que los introvertidos “poco activos y sedentarios” (R 2 =30,09). El supuesto ecologico es insuficiente para explicar el nivel de AFCS de los escolares durante la jornada escolar. Abstract. Introduction. The study analyzed the levels of cardio-healthy physical activity (CHPA) of elementary school children in the school day and the hierarchy of predictive factors. Methodology. A cross-sectional, prospective, correlational, and inferential study. Fifty-eight children (32 boys and 26 girls) (11.88 ± 0.32 years) enrolled in 24 schools provided data of sexual phenotype, weight type, cardiac endurance, aerobic capacity, social and emotional expressiveness, anxiety, sociometric type, sedentary level, type of center, and school day. After registering the subjects’ heart rate with Polar® monitors for 5 consecutive school days, the CHPA was analyzed (time spent in an effort of ≥50% HR reserve). Subsequently, correlational analysis and decision tree technique were carried out to determine the hierarchical relationship of CHPA predictive factors (α = 0.05). Results and conclusions. Boys would reach more CHPA than girls at recess (p min/sem = 0.03; p % time/sem = 0.02). Among the former, the popular ones would accumulate more CHPA than the rest (R 2 = 38.85). Schoolchildren with lower aerobic endurance would accumulate more CHPA in Physical Education than the rest (R 2 = 8.39). Those who show intermediate rates of emotional expressiveness would achieve more CHPA than the rest in Artistic and other minority school activities, where active and very active introverts would achieve more CHPA than little active and sedentary introverts (R 2 = 30.09). The ecological model is insufficient to explain the level of CHPA of school children during the school day.

Objective: The aim of this study was to investigate the effects of caffeine supplementation on: (i) psychological responses of subjective vitality and mood, (ii) performance through a Wingate test, and (iii) rate of perceived exertion (RPE) reported after a Wingate test. Methods: Fifteen male participants (22.60 &plusmn, 2.16 years) ingested 6 mg&middot, kg-1 of caffeine or placebo (sucrose) supplementation in two experimental sessions. After 60 min from supplement intake, participants fulfilled two questionnaires, which measured subjective vitality and mood state, respectively. Subsequently, participants&rsquo, performance was assessed through a Wingate test, which was followed by measurements of RPE at general, muscular, or cardiovascular level. Results: Caffeine supplementation increased some components of mood, as assessed by profile of mood states (POMS) (tension and vigor dimensions) and subjective vitality profiles, which were followed by a greater maximum power, average power, and lower time needed to reach maximum power during the Wingate test. Moreover, lower RPE, both at muscular and general levels were reported by participants after the Wingate test. Conclusions: These results suggest that caffeine supplementation exerts positive effects both in psychological and physical domains in trained subjects.

Background Martial arts are currently being practiced throughout the world by about 100 million people. Considering that sports injuries account for 20% of all emergencies treated in hospitals, this is an issue that should be further studied. Our objective was to determine the prevalence and type of injuries in wushu, judo, and karate practitioners in Community of Madrid, Spain. Methods A descriptive epidemiology study was carried out. A questionnaire was used to collect data from 457 men and women practicing karate, judo and/or wushu, including injuries from the past five years, type of injury and occurrence during training or competition. Results Injuries that disrupted training occurred in 56% of judokas, in 36.7% of karatekas and in 38.9% of wushu practitioners (WP). For judokas, the most common injury site was "shoulder/arm/elbow" (13.43%), for karatekas, it was "lower leg/foot/ankle" (9.95%), and for WP it was "groin/hip/thigh" (9.45%) (P=0.000). The most common injuries in judo and karate were "ankle sprains and joint injuries" (4.98% and 3.98%), while for WP the most common injury were "hamstring strains" (5.47%) (P=0.008). There was no relationship between occurrence of a first injury and sex, age or belt rank. Conclusions Judo is the martial art with the highest percentage of injuries, followed by wushu and then karate.

El zumo de remolacha (ZR) es una fuente nutricional rica en nitrato (NO3-) que, una vez ingerido, es reducido a óxido nítrico (ON). El ON posee efectos hipotensores, anti-inflamatorios y provoca mejoras en la eficiencia mitocondrial y en la regulación de la contractilidad muscular. Distintas investigaciones han comprobado que la suplementación con ZR presenta un efecto ergogénico en modalidades de resistencia cardiorrespiratoria y esfuerzos explosivos e intermitentes de alta intensidad. Sin embargo, dado que ninguna revisión ha valorado el efecto de la suplementación con ZR sobre la producción de fuerza muscular, el objetivo de la presente revisión sistemática es analizar el efecto de la suplementación con ZR sobre el rendimiento en la fuerza muscular. La búsqueda mediante palabras clave y conectores booleanos se realizó en las bases de datos Dialnet, Directory of Open Access Journals, Medline, Pubmed, Scielo, Scopus y SPORTDiscus. La estrategia de búsqueda empleada fue la siguiente: (nitrate OR beet*) AND (concepto 2) (supplement* OR nutr* OR diet*) AND (concepto 3) (strength OR "resistance exercise" OR "resistance training" OR "muscular power"). Tras la aplicación de los criterios de inclusión, un total de 14 artículos fueron seleccionados para la revisión. En la revisión se ha comprobado como la suplementación con ZR puede tener un efecto ergogénico sobre la producción de fuerza muscular bajo estimulación eléctrica, así como sobre la producción de potencia sobre contracciones isocinéticas únicamente a altas velocidades angulares, siendo el mecanismo explicativo una potenciación de la capacidad contráctil específicamente en las fibras musculares tipo II. Abstract. Beet juice (BJ) is a nutritional source rich in nitrate (NO3-) which, after ingestion, is reduced to nitric oxide (NO). NO has effects such as reduction in arterial pressure, anti-inflammatory effects, enhancement of mitochondrial efficiency, and regulation of muscle contractility. Different studies have reported that BJ supplementation has an ergogenic effect in modalities of cardiorespiratory endurance and explosive and intermittent high intensity efforts. Nevertheless, no review has assessed the effect of BJ supplementation on muscle strength production. Thus, the objective of this systematic review is to analyse the effect of BJ supplementation on muscle strength performance. The search using keywords and Boolean connectors was carried out in the databases Dialnet, Directory of Open Access Journals, Medline, Pubmed, Scielo, Scopus, and SPORTDiscus. The search strategy used was the following: (nitrate OR beet *) AND (concept 2) (supplement * OR nutr * OR diet *) AND (concept 3) (strength OR "resistance exercise" OR "resistance training" OR "muscular power "). After the application of the inclusion criteria, a total of 14 articles were selected for review. The review has shown how BJ supplementation can have an ergogenic effect on the production of muscle strength under electrical stimulation, as well as on the production of power over isokinetic contractions only at high angular speeds, the explanatory mechanism being a potentiation of the contractile capacity specifically in type II muscle fibers.

Purpose: the aim of the present study was to analyse the pattern of dietary supplements (DS) consumption on federated rugby players, including the analysis of differences based on the sex and competitive level (professional vs. amateurs). Material and methods: 144 rugby players (83 male and 61 female), of whom 69 were professionals and 75 amateurs, were recruited for the study. All the participants filled out a specific questionnaire about DS consumption including questions related to the consumption of DS and their effects on sport performance and health status. Results: 65.3% of participants declared consuming at least one DS, with a higher prevalence in males than females (77.1% vs. 49.2%) and in professionals thanin amateur players (79.7% vs. 52.0%). The main reason for consumption was to enhance sport performance (62.3%) with differences only based on sex (74.3% males vs. 43.2% females). The most common purchase sites were the Internet (45.6%) and specialised stores (39.8%). As to the moment of ingestion, professionals did this most frequently during competition and training (56.4% vs. 28.2%), whereas amateur players did so only during competition (20.5% vs. 3.6%). Moreover, professional player intake most frequently in post-exercise (65.5% vs. 35.9%), whereas amateur during pre-exercise (30.8% vs. 5.5%). The DS most consumed included whey protein (44%), caffeine (42%), sports drinks (38%), energy bars (34%) and creatine monohydrate (31%), with a higher prevalence in male and professional players of whey protein and creatine monohydrate. Conclusions: The main reason for DS consumption is for enhancing sports performance). Professional players more frequently purchase them on the Internet and consume DS during training and competition period and in the post-exercise, whereas amateur players consume during competition and pre-exercise. Related to the main form of DS consumption, it is observed that a moderate consumption of DS could be considered ergogenic, such as whey protein, sport bar and creatine, while an absence of other DS could be considered ergogenic.

La pulsioximetría sirve para determinar el porcentaje de saturación de oxígeno que hay en sangre. Su mayor característica es que se trata de un método no invasivo y relativamente económico. Existen pocos estudios que relacionen pulsioximetría con actividad física, y los estudios que más abundan son los clínicos. Los autores revisan la definición de la oximetría de pulso, los fundamentos en los cuales se basa. Se revisan la aplicación de la pulsioximetría a las pruebas de esfuerzo máximo, así como el comportamiento de la saturación de oxígeno en sangre durante la realización de pruebas de esfuerzo máximo. Además, se revisan los diferentes estudios acerca de los valores de saturación de oxígeno en sangre durante la realización de ejercicio físico y su correlación con otras variables ventilatorias. Se analizan las consecuencias del uso de la pulsioximetría en pruebas de esfuerzo máximo.

The measurement of the testosterone to epitestosterone ratio (T/E ratio) in urine is often used as a marker for testosterone administration in the doping control field. This study examines the frequencies of the different expression forms of the UGT2B17 gene, and assesses their effects on this marker in volunteer subjects. The sample for this descriptive study was composed of male and female athletes aged between 16 and 55 years old who practiced different sports disciplines. All participants underwent a sports‐medical physical examination, and subsequently provided 10 urine samples consecutively over a period of 48 h. The dependent variable examined was T/E and the main independent variable was the UGT2B17 gene polymorphism. During 1 year, 1410 urine samples were obtained from 141 athletes. The frequencies of the three genotypes were as follows: wt homozygotes (ins/ins) 48.2% (n = 68), mutant homozygotes (del/del) 12.1% (n = 17), and heterozygotes (ins/del) 39.7% (n = 56). Genotype distributions varied significantly (P

Photoplethysmography (PPG) is a non-invasive optical technique that enables to quantify the arterial blood pulse rate derived from the cardiac pumping action. Although this technique is widely used in the medical practice as part of pulse oximeters, the signal corruption by motion artifacts is a primary limitation in the practical accuracy and applicability of current instruments to monitor pulse rate during intense exercise. Here, we report on the application of transmittance PPG throughout maximal exercise tests in cycle ergometer in male athletes. A specifically developed algorithm has been applied to obtain PPG pulse rates similar to the reference heart rates.

The transmittance photoplethysmogramms recorded with multiple NIR laser diodes in an athlete along a maximal exercise test by treadmill ergometer and the results after processing, are presented and compared with the established reference techniques.

Photoplethysmography and pulse oximetry are widely used techniques for noninvasive monitoring of heart rate and peripheral oxygen saturation. Over the last years we have been working onto the application of near infrared range wavelengths to replace those of the classical pulse oximeters. The development of laser diodes based sensors, processing algorithms, a calibration procedure, and the comparison with a commercial pulse oximeter, have been followed by a set of experimental studies. The results exposed here demonstrate the applicability of transmittance photoplethysmography and pulse oximetry using laser diodes emitting at specific wavelengths for a wide range of situations.

Maximal effort tests are used to check the fitness of athletes and to assess their status of health. Measurements performed during the test are also useful to understand athlete physiology and to optimise the training protocols. One of the interesting measurements that can be performed is the oxygen saturation and desaturation in blood along with cardiac rate. The task is complicated by the fact that standard instrumentation (oximeters) are affected by movement artefact, and in the case of this kind of tests movements can be so strong and wide that the measurements is invalidated. In this paper, a novel algorithm is proposed which achieve meaningful measurements even in presence of very strong movement artefact.

Photoplethysmography (PPG) is a non-invasive optical technique that can be used to quantify the arterial blood pulse rate. Signal corruption by motion artifacts limits the practical accuracy and applicability of instruments for monitoring pulse rate during intense physical exercise. This study develops and validates an algorithm, which is based on linear filtering and frequency-domain and heuristic analyses, for extracting the heart rate from a PPG signal in the presence of severe motion artifacts. The basis of the hearth beat frequency selection is the observed high harmonic content of movement artifact signals with respect to the PPG-derived heartbeat. The algorithm, implemented in an experimental PPG measurement device, is developed by analyzing a set of PPG data recorded from a group of athletes exercising on a treadmill. An extensive set of tests is carried out during maximal exercise tests on a treadmill to validate the proposed algorithm by comparison with a reference electrocardiography measurement system. The Bland-Altman method is used to compare and evaluate PPG signals. The accuracy of the heartbeat measurement is better than ± 6.5 beats per minute (bpm) ( ≤ 4.2 %) even under maximal exercise conditions.