Acute Recovery after a Fatigue Protocol Using a Recovery Sports Legging: An Experimental Study.

Enhancing recovery is a fundamental component of high-performance sports training since it enables practitioners to potentiate physical performance and minimise the risk of injuries. Using a new sports legging embedded with an intelligent system for electrostimulation, localised heating and compression (completely embodied into the textile structures), we aimed to analyse acute recovery following a fatigue protocol. Surface electromyography- and torque-related variables were recorded on eight recreational athletes. A fatigue protocol conducted in an isokinetic dynamometer allowed us to examine isometric torque and consequent post-exercise acute recovery after using the sports legging. Regarding peak torque, no differences were found between post-fatigue and post-recovery assessments in any variable; however, pre-fatigue registered a 16% greater peak torque when compared with post-fatigue for localised heating and compression recovery methods. Our data are supported by recent meta-analyses indicating that individual recovery methods, such as localised heating, electrostimulation and compression, are not effective to recover from a fatiguing exercise. In fact, none of the recovery methods available through the sports legging tested was effective in acutely recovering the torque values produced isometrically.

Nonlinear Analysis of the Hand and Foot Force-Time Profiles in the Four Competitive Swimming Strokes.

Human locomotion on water depends on the force produced by the swimmer to propel the body forward. Performance of highly complex motor tasks like swimming can yield minor variations that only nonlinear analysis can be sensitive enough to detect. The purpose of the present study was to examine the nonlinear properties of the hand/feet forces and describe their variations across the four competitive swimming strokes performing segmental and full-body swimming. Swimmers performed all-out bouts of 25 m in the four swimming strokes, swimming the full-body stroke, with the arm-pull only and with the leg kicking only. Hand/foot force and swimming velocity were measured. The Higuchi's fractal dimension (HFD) and sample entropy (SampEn) were used for the nonlinear analysis of force and velocity. Both the arm-pull and leg kicking alone were found to produce similar peak and mean hand/foot forces as swimming the full-body stroke. Hand force was more complex in breaststroke and butterfly stroke; conversely, kicking conditions were more complex in front crawl and backstroke. Moreover, the arm-pull and kicking alone tended to be more complex (higher HFD) but more predictable (lower SampEn) than while swimming the full-body stroke. There was no loss of force production from segmental swimming to the full-body counterpart. In conclusion, the number of segments in action influences the nonlinear behavior of the force produced and, when combining the four limbs, the complexity of the hand/foot force tends to decrease.

Secular Trends in Anthropometrics and Physical Fitness of Young Portuguese School-Aged Children.

INTRODUCTION: The purpose of this study was to analyze secular trends in anthropometrics and physical fitness of Portuguese children. MATERIAL AND METHODS: A group of 1819 students (881 boys and 938 girls) between 10 and 11 years old was assessed in their 5th and 6th scholar grade throughout a 20 years' time-frame. ANCOVA models were used to analyze variations in anthropometrics (height, weight and body mass index) and physical fitness (sit and reach, curl-up, horizontal jump and sprint time) across four quinquennials (1993 - 1998; 1998 - 2003; 2003 - 2008; 2008 - 2013). RESULTS: Secular trends showed the presence of heavier boys and girls with higher body mass index in the 5th and 6th grade throughout the last 20 years. There was also a presence of taller girls but just until the 3rd quinquennial. Both boys and girls were able to perform better on the core strength test and sprint time but become less flexible over the years. Mean jumping performance remained unchanged for both genders. DISCUSSION: The present study provides novel data on anthropometrics and physical fitness trends over the last two decades in young Portuguese children, consistent with the results reported in other developed countries. CONCLUSION: Evidence for the start of a positive secular trend in body mass index and in some physical fitness components over the last two decades among the Portuguese youth.

Introdução: Analisar as tendências seculares ao nível da antropometria e aptidão física das crianças portuguesas. Material e Métodos: Um grupo de 1819 crianças (881 rapazes e 938 raparigas) entre os 10 e os 11 anos de idade, foi avaliado no 5º e 6º ano de escolaridade durante 20 anos. A ANCOVA foi usada para analisar as variações de antropometria (índice de massa corporal, peso e altura) e aptidão física (sentar e alcançar, força abdominal, salto horizontal e corrida de velocidade) durante quatro quinquénios (1993 - 1998; 1998 - 2003; 2003 - 2008 e 2008 - 2013). Resultados: As tendências seculares mostraram a presença de crianças mais pesadas e com um índice de massa corporal mais elevado ao longo dos últimos 20 anos. Verificou-se também a presença de raparigas mais altas, mas só até ao terceiro quinquénio. Ambos os géneros melhoraram o desempenho nos testes de força abdominal e corrida de velocidade mas pioram a sua capacidade de flexibilidade ao longo dos anos. O desempenho no salto horizontal permaneceu inalterado em ambos os géneros. Discussão: Este estudo fornece novos dados sobre a tendência dos registos antropométricos e de aptidão física nos últimos 20 anos em crianças Portuguesas, sendo consistente com as tendências reportadas sobre outros países desenvolvidos. Conclusão: Os resultados sugerem uma tendência positiva nos últimos 20 anos no índice de massa corporal e em alguns componentes da aptidão física em crianças Portuguesas.

Validação de equações preditivas da área de secção transversa do tronco / Validation of predictive equations of the cross-sectional area of the human trunk

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 < 0,01). No processo de validação entre as áreas de secção transversal do tronco medida e estimada, não se verificaram diferenças significativas entre valores médios (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.

The objective of this study was to develop and validate predictive equations of the cross-sectional area of the human trunk. The models were developed for males according to their level of expertise. The sample comprised 152 male subjects, all of them with a background in competitive or recreational swimming. Their ages ranged between 10 and 32 years. Two different groups of subjects were used to estimate and validate the equation. The following anthropometric characteristics were assessed: (i) body weight, (ii) height, (iii) biacromial diameter, (iv) sagittal thoracic diameter, (v) chest circumference, and (vi) cross-sectional area of the trunk. Predictive models were developed using stepwise multiple linear regression analysis. One of the models used level of expertise as a dummy variable. All models included sagittal thoracic diameter and chest circumference as independent variables (0.32 ≤ R² ≤ 0.48; P < 0.01). The validation process of the measured and estimated cross-sectional area of the trunk did not reveal any significant differences between the mean values (P > 0.05). The simple linear regressions were moderate (0.23 ≤ R² ≤ 0.55; 0.01 ≤ P ≤ 0.001), and the Bland-Altman criterion was met in all cases. Therefore, our findings suggest that the models developed for male swimmers according to their level of expertise are able to provide a valid prediction of the cross-sectional area of the trunk.