ABSTRACT
O objetivo deste estudo foi verificar as respostas da frequência média de ciclos de braçadas (FB) e da distância média percorrida por ciclo de braçada (DC) no nado crawl ao longo de série de natação na intensidade de 95% da velocidade média dos 400 m (V400), até a exaustão. Onze nadadores realizaram 400 m em máxima intensidade para determinação da V400, e, posteriormente, uma série a 95% da V400 (95v) com média de 2,88 ± 1,37 repetições de 400 m e intervalos de 40 s de repouso passivo, quarenta e oito horas após a V400. A duração da série a 95% da V400 foi normalizada a 100%, de modo individual, e posteriormente, foi dividida em cinco momentos (0, 25, 50, 75 e 100%) para a análise de FB e DC, que foram comparadas ao longo da série. Resultados: houve manutenção dos parâmetros cinemáticos apenas entre os momentos 0 e 25%. Ocorreram aumento da FB e diminuição da DC nos últimos momentos (75 e 100%) em comparação aos demais momentos da série 95v. Ao nadar nesta intensidade, que está situada o domínio de intensidade severa, nadadores não são capazes de manter a técnica constante ao longo da duração total da série...(AU)
The objective of this study was to investigate the stroke rate (SR) and the stroke length (SL) responses in front crawl along swimming training series in the intensity of 95% of the average velocity of 400 m (V400) until exhaustion. Eleven swimmers performed 400 m at maximum intensity for determining V400, and subsequently, a series of 95% the V400 (95v) with average 2.88 ± 1.37 trials of 400 m and intervals of 40 s of passive rest, 48 hours after the V400. The duration of the 95V was normalized to 100%, individually, and, later, it was divided into five moments (0, 25, 50, 75, and 100%) for the SR and SL analysis, which were compared over the series. Results: there was maintenance of kinematic parameters only between moments 0 and 25%, The SR increased and the SL decreased in the end of the series (75 and 100%) compared to other moments. When swimming at this intensity, which is situated in severe intensity domain, swimmers are not able to keep constant the technique over the entire duration of the series...(AU)
Subject(s)
Humans , Male , Young Adult , Physical Education and Training , Swimming , Energy MetabolismABSTRACT
The aim of this study was to investigate the relationship between changes in swimming velocity (SV), stroke rate (SR), stroke length (SL) and muscle activities during a 4×50m swimming test to simulate a 200m freestyle race. A total of 20 male collegiate swimmers participated in this study. The electromyography (EMG) signals of 11 muscles, 7 muscles in the upper half of the body and 4 muscles in the lower half, were recorded with surface electrodes. SV, SR and SL were analyzed for each 50m (S1, S2, S3 and S4) from side view recordings of swimmers taken with an underwater camera.SV and SR for S1 were significantly higher than for S2 and S3. SL for S1 was significantly longer than for S3. The averaged EMGs (aEMGs) for S1 were significantly higher than for S2 or for S3 in 5 muscles (flexor carpi ulnaris, biceps brachii, triceps brachii, deltoideus posterior and rectus femoris). There were no significant changes between S3 and S4 in SV, SR, SL and aEMG of all muscles except pectoralis major which showed the highest aEMG in S4. Significant correlations were observed between changes of (Δ) aEMG and ΔSV, especially in upper half muscles (<i>r</i>=0.485-0.939, <i>p</i><0.05).These results suggested that decline in muscle activities of the five muscles mentioned earlier caused a decrease in SV from S1 to S3; and an increase in muscle activity of the pectoralis major led preventing a decline in SV by maintaining the SR in S4.
ABSTRACT
O principal objetivo deste estudo foi verificar o efeito do nível de performance aeróbia na relação entre os índices técnicos correspondentes à velocidade crítica (VC) e à velocidade máxima de 30 minutos (V30) em nadadores. Participaram deste estudo, 23 nadadores do gênero masculino com características antropométricas similares, divididos segundo o nível de performance aeróbia em grupo G1 (maior performance) (n = 13) e G2 (menor performance) (n = 10). Os indivíduos tinham pelo menos quatro anos de experiência no esporte e treinavam um volume semanal de 30.000 a 45.000m. A VC foi determinada através do coeficiente angular da regressão linear entre as distâncias (200 e 400m) e seus respectivos tempos. A V30 foi determinada através da máxima distância realizada em um teste de 30 minutos. Todas as variáveis foram determinadas no nado crawl. A VC foi significantemente maior do que a V30 no grupo G1 (1,30 ± 0,04 vs. 1,23 ± 0,06m.s-1) e no G2 (1,17 ± 0,08 vs. 1,07 ± 0,06m.s-1). As duas variáveis foram maiores no grupo G1. As taxas de braçada correspondentes à VC (TBVC) e à V30 (TBV30) obtidas nos grupos G1 (33,07 ± 4,34 vs. 31,38 ± 4,15 ciclos.min-1) e G2 (35,57 ± 6,52 vs. 33,54 ± 5,89 ciclos.min-1) foram similares entre si. A TBVC foi significantemente menor no grupo 1 do que no grupo 2, enquanto que a TBV30 não foi diferente entre os grupos. Os comprimentos de braçada correspondentes à VC (CBVC) e à V30 (CBV30) foram significantemente maiores no grupo G1 (2,41 ± 0,33 vs. 2,38 ± 0,30m.ciclo-1) do que no G2 (2,04 ± 0,43 vs. 1,97 ± 0,40m.ciclo-1), e similares entre si nos dois grupos. As correlações (r) entre a VC e a V30 e as variáveis técnicas correspondentes às duas velocidades foram significantes em todas as comparações (0,68 a 0,91). Portanto, a relação entre a velocidade e as variáveis técnicas correspondentes à VC e à V30 não é modificada pelo nível de performance aeróbia.
The main objective of this study was to verify the effect of aerobic performance level on the relationship between the technical indexes corresponding to critical speed (CS) and maximal speed of 30 minutes (S30) in swimmers. Participated of this study 23 male swimmers with similar anthropometric characteristics, divided by aerobic performance level in groups G1 (n = 13) and G2 (n = 10). They had at least four years of experience in the modality and a weekly training volume between 30,000 to 45,000 m. The CS was determined through the angular coefficient of the linear regression line between the distances (200 and 400 m) and respective times. The S30 was determined through the maximal distance covered in a 30 minutes test. All variables were determined in front crawl. CS was higher than S30 in G1 (1.30 ± 0.04 vs. 1.23 ± 0.06 m.s-1) and G2 (1.17 ± 0.08 vs. 1.07 ± 0.06 m.s -1). These variables were higher in group G1. The stroke rate corresponding to CS (SRCS) and S30 (SRS30) obtained in group G1 (33.07 ± 4.34 vs. 31.38 ± 4.15 cycles.min-1) and G2 (35.57 ± 6.52 vs. 33.54 ± 5.89 cycles.min-1) were similar. The SRCS was significantly lower in group G1 than G2, while SRS30 was not different between groups. The stroke length corresponding to CS (SLCS) and S30 (SLS30) was significantly higher in group G1 (2.41 ± 0.33 vs. 2.38 ± 0.30 m.cycle-1) than in G2 (2.04 ± 0.43 vs. 1.97 ± 0.40 m.cycle-1), and had similar values in both groups. The correlation (r) between CS and S30 and technical variables corresponding to CS and S30 were significant in all comparisons (0.68 to 0.91). Thus, the relationship between the speed and technical variables corresponding to CS and S30 was not modified by the aerobic performance level.