Effect of a Fast-Skin 'Body' Suit on drag during front crawl swimming

The effect on drag of a Speedo Fast‐skin suit compared to a conventional suit was studied in 13 subjects (6 males, 7 females) swimming at different velocities between 1.0 and 2.0 m•

When is a lifting movement too asymmetric to identify low back loading by 2D analysis

In ergonomics research, two-dimensional (2-D) biomechanical models are often used to study the mechanical loading of the low back in lifting movements. When lifting movements are asymmetric, errors of unknown size may be introduced in a 2-D analysis. In the current study, an estimation of these errors was made by comparing the outcome of a 2-D analysis to the results of a recently developed and validated 3-D model. Four subjects made two repetitions of five lifting movements, differing in the amount of asymmetry. The results showed a significant underestimation of the peak torque by 20, 36 and 61% when the initial position of a box was rotated 30, 60 and 90°with respect to the sagittal plane of the subject. The main cause of this underestimation was a pelvic twist, resulting in an erroneous projection of a pelvic marker on to the sagittal plane due to pelvic twist. It is suggested that from 30°box rotation a 2-D analysis may easily lead to wrong conclusions when it is used to study asymmetric lifting

Efeito do uso do traje de neoprene sobre variáveis técnicas, fisiológicas e perceptivas de nadadores

Ao contrário do que ocorre em provas de piscina, competições em águas abertas estão sujeitas as condições ambientais, sendo uma delas as baixas temperaturas. Em determinadas circunstâncias é permitido o uso de roupas especiais para evitar hipotermia. O objetivo do estudo foi verificar os efeitos do uso da roupa de neoprene em um grupo composto por triatletas e nadadores, comparado ao uso de vestimentas convencionais (sunga) sobre variáveis cinemáticas e psicofisiológicas do nado. Participaram 20 homens (12 triatletas e oito nadadores) de idade 22,0 ± 6,6 anos com desempenhos que correspondem a 75 ± 7,7% do melhor tempo brasileiro na prova de 400 m. Os atletas realizaram duas repetições máximas e duas submáximas de 400 m em nado "crawl", com e sem o uso da roupa de neoprene. Foram comparadas a velocidade média (VM), comprimento de braçada (CB), frequência de braçada (FB), índice de nado (IN), percepção subjetiva de esforço (PSE), frequência cardíaca (FC), e concentração de lactato sanguíneo (LAC). Um conjunto de ANOVAs com medidas repetidas do tipo "two-way" foi aplicado. Quando diferenças foram encontradas o teste de Tukey foi empregado. Com o traje de neoprene, em máxima intensidade, o tempo para nadar a distância foi 6,4% menor, com manutenção da FB e aumento da CB, as variáveis psicofisiológicas não diferiram estatisticamente. Em esforço submáximo, o uso do traje de neoprene resultou em menor FB, maior CB, maior IN e em menores valores de FC, LAC e PSE (p In open water swimming competitions, athletes are prone to environmental conditions and are frequently exposed to low temperatures, in contrast to what occurs in indoor competitions. In some circumstances the use of special swimming suits is allowed to avoid hypothermia. The aim of this study was to verify the effects of the use of a neoprene swimming suit in comparison to a conventional swimming suit on a number of cinematic and psychophysiological variables. Twenty athletes experienced in swimming competitions (12 triathletes and 8 swimmers; 22.0± 6.6 yearsold), whose the performance was 75 ± 7.7% of the National record. Athletes performed two maximal and two submaximal 400m crawl simulated competition with a whole body neoprene swimming suit and with a conventional swimming suit. Mean speed (VM) stroke length (CB), stroke frequency (FB), swimming index (IN), rate of perceived effort (PSE), heart rate, and blood lactate concentration (LAC) were compared between conditions. The time to perform maximal trials with the use of the neoprene swimming suit was 6.4% shorter than when wearing the traditional swimming suit. FB and the psychophysiological variables remained unchanged, while CB increased in response to the use of the neoprene swimming suit. The use of the neoprene swimming suit in submaximal trials provided smaller FB, FC, LAC and PSE and larger CB and IN in comparison to the use of the traditional swimming suit. The results indicated that the neoprene swimming suit increases performance in biomechanical, physiological and perceptive aspects. The VM increase in maximal efforts does not depend exclusively on changes in FB and CB. Possibly, increments of the parameters related to the swimming may have improved the mechanical efficiency of the movement, which may have provided a movement economy that resulted in a better performance