Editorial: advances in wearable devices for sports

In sports, coaches and support staff spend considerable time analyzing athletes’ technique. It is well known that athletes who can perform movements associated with their sport of choice using a better technique are more likely to present better performances. Video-based analysis has traditionally been the most used procedure to assess athletes’ technique [1,2]. This consists of recording sports skills and the subsequent computation of meaningful parameters describing the movement from raw data [3]. However, this data acquisition and handling is a time-consuming process. Consequently, coaches and support staff are looking for less time-consuming procedures that lead to real-time outputs and that they themselves can also use and handle. The use of wearables allows the acquisition of kinematic [4], kinetic [5], or physiological variables [6] that are of paramount importance for coaches and athletes. For instance, Lim et al. [7] aimed to predict the lower limb kinetics and kinematics during walking with a single inertial measurement unit (IMU) placed on the lower back. In the specific case of the aquatic environment, cable handling makes data collection more difficult. Thus, wearable usage is a solid alternative in aquatic sports. Besides kinematic data, swimming researchers can also measure kinetic parameters, such as propulsive force, that are key determinants for performance enhancement [5,8]. Regarding physiological parameters, these can also be measured or estimated with the data collected with wearables. A study by Dasa et al. [9] aimed to assess the accuracy of commonly used global positioning systems/accelerometer-based tracking devices to estimate energy expenditure during high-intensity intermittent exercise in soccer. The authors noted an underestimation of the energy expenditure since these gears do not account for anaerobic energy production during high-intensity exercise [9]. Nonetheless, and despite the deviations observed in energy expenditure that should be considered by practitioners and researchers, it was argued that the devices tested can still provide useful information, but with the limitations addressed.This research was funded by the FCT Portuguese Foundation for Science and Technology, grant number UIDB/DTP/04045/2020.info:eu-repo/semantics/publishedVersio

Relationship between oxygen uptake reserve and heart rate reserve in young male tennis players: implications for physical fitness monitoring

The aims of this study were to (i) verify the relationship between reserve oxygen uptake (VOreserve) and reserve heart rate (HRreserve) in young male tennis players, and (ii) understand the relationship between oxygen uptake (VO2) measured at the end of a tennis drill and recovery heart rate (HRrecovery) after the tennis drill. Ten young male tennis players (16.64 1.69 years; 62.36 6.53 kg of body mass; 175.91 5.26 cm of height) were recruited from the National Tennis Association. Players were instructed to perform a tennis drill based on an incremental intensity protocol. Afterward, three levels of intensity were used based on VO2reserve and HRreserve. A significant variance was observed between levels (VO2reserve and HRreserve = p < 0.001). VO2reserve presented a significant and high agreement with HRreserve. The mean data revealed non-significant differences (p > 0.05), a very high relationship of linear regression (R2 = 82.4%, p < 0.001), and high agreement in Bland Altman plots. VO2, at the highest level of intensity (>93%), presented a significant correlation with HRrecovery during the immediate 30 s after the drill (rs = 0.468, p = 0.028). Tennis coaches or instructors must be aware of the differences between monitoring or prescribing training intensities based on HRreserve or HRmax. They can also use HRrecovery for 30 s immediately after exercise to verify and understand the variation in their players’ cardiorespiratory capacities.This research was funded by the Portuguese Foundation for Science and Technology (FCT) under the grant number UIDB/DTP/04045/2020info:eu-repo/semantics/publishedVersio

Longitudinal modeling of young swimmers’ performance and biomechanics: identification, development and follow-up

Os programas de identificação de talentos estão a tornar-se de extrema utilidade, fornecendo dados importantes sobre os determinantes da performance em nadadores jovens, e como esta evolui ao longo do tempo. Esta informação pode ajudá-los a atingirem um nível de elite. No entanto, a literatura baseia-se estudos transversais ou em estudos longitudinais de curto prazo. Os principais objetivos desta tese foram: (i) identificar os principais determinantes da performance em nadadores jovens (estudo #1); (ii) observar e entender a evolução da performance em nadadores jovens, e os fatores determinantes associados, durante uma época (estudo #2); (iii) identificar, classificar e acompanhar nadadores jovens, com base na sua performance e fatores determinantes, bem como a sua estabilidade durante uma época (estudo #3); (iv) e desenvolver um modelo preditor da performance, durante três épocas consecutivas com base no perfil biomecânico dos nadadores (estudo #4). No estudo #1 desenvolveu-se um modelo de equações estruturais para a performance, com base em variáveis cinemáticas, antropométricas, eficiência e hidrodinâmicas. Verificou-se que a performance depende de um conjunto de fatores antropométricos, cinemáticos, eficiência e hidrodinâmicos. No estudo #2 foi desenvolvido um modelo de crescimento latente. A performance melhorou significativamente, e com uma inter-variabilidade significativa. Diferentes fatores determinantes foram responsáveis por essa melhoria em cada um dos momentos de avaliação. No estudo #3 foi utilizada a análise de clusters para classificar, identificar e acompanhar a performance e os seus fatores determinantes. Verificou-se em nadadores pré-púberes, existirem três subgrupos com características biomecânicas semelhantes. No estudo #4, foi desenvolvido um modelo preditivo, durante três épocas consecutivas, com base em fatores biomecânicos. O modelo preditivo incluiu uma variável antropométrica, uma cinemática e uma de eficiência, evidenciando que a natação competitiva é um fenómeno multifatorial. As principais conclusões foram que variáveis antropométricas, cinemáticas, eficiência e hidrodinâmicas caracterizaram o perfil dos nadadores jovens e a sua performance, mostrando uma melhoria nos períodos de tempo avaliados.The Portuguese Science and Technology Foundation (FCT) funded this thesis, under the Human Potential Operating Program, supported by the European Social Found (ESF), grant SFRH/BD/76287/2011

Desenvolvimento e validação de equações preditivas da área de secção transversa do tronco baseadas em determinadas características antropométricas

Foi objectivo desta dissertação desenvolver e validar equações com maior capacidade preditiva da área de secção transversa do tronco baseadas em determinadas características antropométricas. Os modelos foram desenvolvidos por sexo, e de acordo com o nível competitivo por sexo. A amostra foi composta por 264 sujeitos, entre os quais 112 do sexo feminino e 152 do sexo masculino. Da totalidade, 71 das nadadoras pertenciam à categoria das experts e 41 à das não experts, 60 dos nadadores pertenciam à categoria dos experts e 92 à dos não experts. Todos eles eram praticantes de actividades aquáticas, nomeadamente de Natação Pura Desportiva. Foi utilizado um grupo para estimar os modelos e outro grupo para validar os mesmos. Foram avaliadas as características antropométricas área de secção transversa do tronco, massa corporal, estatura, diâmetro bi-acromial, diâmetro tóraco-sagital e perímetro peitoral. Os modelos preditivos foram desenvolvidos através de análise de regressão linear múltipla passo-a-passo. Todos os modelos desenvolvidos respeitaram os processos de validação e foram considerados significativos (0,28 ≤ R2 ≤ 0,48; p 0,05), a regressão linear simples entre a área de secção transversa do tronco avaliada e medida foi moderada (0,23 ≤ R2 ≤ 0,55; 0,01 ≤ p ≤ 0,001) e o critério de Bland Altman foi cumprido. Pode concluir-se que os modelos desenvolvidos por sexo e de acordo com o nível competitivo predizem significativamente a área de secção transversa do tronco.The purpose of this thesis was to develop and validate prediction equations of the trunk transverse surface area based on selected anthropometric characteristics. The models were developed by gender and the expertise level sexing each gender. The overall sample was composed by 264 subjects, including 112 females and 152 males. Seventy one female swimmers were included in the cohort group of experts and 41 in non-experts ones; 60 of the male swimmers were in the cohort group of the experts and 92 in the non-experts. All subjects have a background in competitive or recreational swimming. One group was used to estimate the models and another one to validate them. The trunk transverse surface area, body weight, height, bi-acromial diameter, chest sagital diameter and chest circunference were the anthropometrical variables assessed. Predictive models were developed using multiple linear regression analysis step by step. All models comply with the procedures developed for validation and were considered significant (0.28 ≤ R2 ≤ 0.48, p 0.05), the linear regression between measured and the estimated trunk transverse surface area was moderate (0.23 ≤ R2 ≤ 0.55, 0.01 ≤ p ≤ 0.001) and Bland Altman criterion was accomplished in all situations. It is concluded that the models developed by gender and according to the expertise level sexing each gender predict with validation the trunk transverse surface area

The influence of kineanthropometrical profile in deep-water tethered running

The purpose of this study was to identify the kineanthropometrical parameters that best predict the maximal horizontal propulsive force during deep-water tethered running. 21 young and healthy males with large experience in aquatic exercises (24.3+/-2.7 years old, 191.9+/-82.6 minutes physical activity per week) performed 3 repetitions of maximal deep-water running for 10-s, using a flotation vest (Golfinho, H-906, Coimbra, Portugal). The subjects were connected to a strain gauge (Globus, Ergo Meter, Codigné, Italy) by a cable of steel with reduced elastic properties. The other end of the cable was fasted to a rubber band and this to a swimming starting block. Dynamometrical data was exported and processed with Matlab v. 6.0. It was evaluated the maximal propulsive force (Fx-max) and computed the maximal horizontal propulsive force through a trigonometric correction, as suggested by Taylor et al. (2003). Body mass (SECA, 884, Hamburg, Germany), height (SECA, 242, Hamburg, Germany), body mass index (BMI) and fat mass (BIA 101, RJL Systems, Florence, Italy) were also measured. Surface area (SA) was calculated according to the procedure of Du Bois and Du Bois (Shuter and Aslani, 2000). The forearms (Globus, Ergo Meter, Codigné, Italy) and hands (TSD 121C, Biopac Systems, California, USA) maximal isometric forces were also measured. Intra-cyclic variation of the Fx-max presented a tetra-modal profile. Computing a stepby- step regression equation, for prediction of the Fx-max, the kineanthropometrical variables that entered the model were the forearms maximal isometric force, the BMI, the body mass and the SA (r^2=0.57, p=0.01). The purpose of the study was achieved. Evidences revealed that some kineanthropometrical parameters related to buoyancy force (e.g., fat mass), to drag force (e.g., SA and height), to weight force (e.g., body mass) and to propulsive force (e.g., segmental forces) predicted the Fx-max. This means that, besides physical fitness and technical level, often described in the literature, kineanthropometrical characteristics of the runner also affect significantly his performance during a training session. The main conclusion is that tethered running is significantly associated to kineanthropometrical profile of the runner. So, instructors should pay attention to kineanthropometrical characteristics of runners and how it affects their performance

Estimating the trunk transverse surface area to assess swimmer's drag force based on their competitive level

The aim of this study was to compute and validate trunk transverse surface area (TTSA) estimation equations to be used assessing the swimmer’s drag force according to competitive level by gender. One group of 130 swimmers (54 females and 76 males) was used to compute the TTSA estimation equations and another group of 132 swimmers (56 females and 76 males) were used for its validations. Swimmers were photographed in the transverse plane from above, on land, in the upright and hydrodynamic position. The TTSA was measured from the swimmer’s photo with specific software. It was also measured the height, body mass, biacromial diameter, chest sagital diameter (CSD) and the chest perimeter (CP). With the first group of swimmers it was computed the TTSA estimation equations based on stepwise multiple regression models from the selected anthropometrical variables. The TTSA prediction equations were significant and with a prediction level qualitatively considered as moderate. All equations included only the CP and the CSD in the final models. In all prediction models there were no significant differences between assessed and estimated mean TTSA. Coefficients of determination for the linear regression models between assessed and estimated TTSA were moderate and significant. More than 80% of the plots were within the 95% interval confidence for the Bland-Altman analysis in both genders. So, TTSA estimation equations that are easy to be computed by coached and researchers were developed. All equations accomplished the validation criteria adopted

The influence of kineanthropometrical profile in deep-water tethered running

Aquatic jogging is a variant of head-out aquatic exercises characterised by the walking and/or running of a subject in aquatic environment. The main goal of this aquatic program is to promote an increase of physical fitness, specially the cardiorespiratory component

Validação de equações preditivas da área de secção

O objectivo do estudo foi desenvolver e validar equações para estimar a área de secção transversa do tronco (ASTT), em ambos os sexos, de acordo com o nível competitivo, que habitualmente são usadas para avaliar o arrasto hidrodinâmico. Para o sexo feminino, na condição de experts, foi utilizado um grupo de 33 sujeitos para estimar a equação e um grupo de 38 sujeitos para validar a equação, na condição de não experts foi utilizado um grupo de 23 sujeitos para estimar a equação e um grupo de 18 sujeitos para validar a mesma. No caso do sexo masculino, na condição de experts, foi utilizado um grupo de 28 sujeitos para estimar a equação e um grupo de 32 sujeitos para a validar, na condição de não experts, foi utilizado um grupo de 48 sujeitos para estimar a equação e um grupo de 44 sujeitos para validar a equação. Os sujeitos foram fotografados (DSC-T7, Sony, Tóquio, Japão) num plano superior transversal, no meio terrestre, simulando a posição hidrodinâmica. A ASTT foi medida através da foto digital do sujeito com um software específico (Universal Desktop Ruler, v3.3.3268, AVPSoft, E.U.A.). Foram ainda medidas as variáveis antropométricas massa corporal (SECA, 884, Hamburgo, Alemanha), a estatura (SECA, 242, Hamburgo, Alemanha), os diâmetros bi-acromial (DBC) e tóraco-sagital (DTS) com um clip antropométrico (Campbell, 20, RossCraft, Canadá), assim como, o perímetro peitoral (PP) com fita métrica (RossCraft, Canadá). Para sexo feminino experts ASTT=16,498*DTS+10,875*PP-504,705 (R2=0,28; Ra=0,24; p<0,01). Para sexo feminino não experts ASTT=14,836*PP-26,825*DTS-33,149 (R2=0,28; Ra=0,21; p<0,01). Para sexo masculino experts ASTT=19,216*DTS+10,505*PP-575,496 (R2=0,33; Ra=0,27; p<0,01). Para sexo masculino não experts ASTT=30,453*DTS+5,030*PP-371,404 (R2=0,48; Ra=0,45; p<0,01). Em todas as condições, por sexo e nível competitivo, não se verificaram diferenças estatisticamente significativas entre a média da ASTT medida e da estimada. Os coeficientes de determinação, calculados através da análise de regressão linear, entre a ASTT medida e estimada foram moderados. Para todas as condições, por sexo e nível competitivo, mais de 80% dos plots, na análise de Bland-Altman, encontram-se dentro dos 95% do intervalo de confiança

Validação de equações preditivas da área de secção transversa do tronco

O objectivo do estudo foi desenvolver e validar equações preditivas da área de secção transversa do tronco humano, Os modelos foram desenvolvidos para o sexo masculino e de acordo com o nível competitivo, A amostra foi composta por 152 sujeitos, todos praticantes de Natação Pura desportiva, com idades entre os 10 e os 32 anos de idade. Para o desenvolvimento dos modelos foi utilizado um grupo de sujeitos para estimar a equação e um outro para validar. Foram avaliadas as seguintes características antropométricas: (i) massa corporal; (ii) estatura; (iii) diâmetro bi-acromial; (iv) diâmetro tóraco-sagital; (v) perímetro peitoral e (vi) área de secção transversal do tronco. Os modelos preditivos foram desenvolvidos através de análise de regressão linear múltipla passo-a-passo e num dos casos, com recurso ao nível competitivo enquanto variável dummy. Todos os modelos desenvolvidos incluíram como variáveis independentes o diâmetro tóraco-sagital e o perímetro peitoral (0,32 ≤ R2 ≤ 0,48; P 0,05), as regressões lineares simples foram moderadas (0,23 ≤ R2 ≤ 0,39; 0,01 ≤ P ≤ 0,001) e o critério de Bland Altman foi em todos os casos cumprido. Pode concluir-se que os modelos desenvolvidos para nadadores masculinos, e de acordo com o nível competitivo, predizem com validade a área de secção transversa do tronco de nadadores

Computing and validating trunk transverse surface area equations to assess swimmers drag force

A couple of methods to assess drag force (i.e., computer fluid dynamics and velocity perturbation method) need to include in the data input the trunk transverse surface area (TTSA). TTSA is measured with a planimeter, on screen measure area software of plane 2D digital images or body scan. However the data collection and its treatment are somewhat time consuming and/or expensive