Cinemática do nado crawl em velocidade sustentada até a exaustão / Kinematics of the front crawl in sustained speed to exhaustion

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)

Direct Medical Cost of Stroke: Findings from a Tertiary Hospital in Malaysia

This study aimed to estimate cost of in-patient medical care due to stroke in a tertiary hospital in Malaysia. A retrospective analysis of stroke patients admitted to Universiti Kebangsaan Malaysia Medical Centre (UKMMC) between January 2005 and December 2008 were conducted. Cost evaluation was undertaken from the health provider’s perspective using a top-down costing approach. Mean length of stay (LOS) was 6.4 ± 3.1 days and mean cost of care per patient per admission was MYR 3,696.40 ± 1,842.17 or 16% of per capita GDP of the country. Human resources made up the highest cost component (MYR 1,343.90, SD: 669.8 or 36% of the total cost), followed by medications (MYR 867.30, SD:432.40) and laboratory services (MYR 337.90, SD:168.40). LOS and cost of care varied across different stroke severity levels (p<0.01). A regression analysis shown significant influence of stroke severity on cost of care, with the most severe stroke consumed MYR 1,598.10 higher cost than the mild stroke (p<0.001). Cost of medical care during hospital admission due to stroke is substantial. Health promotion and primary prevention activities need to take priority to minimise stroke admission in future.

Análise descritiva do desempenho em uma prova de 100 m nado livre feminino baseada em variáveis biomecânicas / Descriptive analysis of performance in the female 100 meters free swimming based on biomechanics variables

Na natação, atualmente, a avaliação do desempenho dos nadadores, apóiam-se em diversas metodologias de observação da competição. As variáveis biomecânicas representam um importante recurso para análise da performance esportiva por serem indicadores da eficiência do nado, com aplicação simples e objetiva. O objetivo deste estudo foi realizar uma análise descritiva do desempenho na prova de 100 metros nado Livre feminino, baseada nas variáveis: comprimento de braçada (CB), frequência de braçada (FB), velocidade de nado (VN), índice de nado (IN), velocidade média escalar (Vm), tempo de saída (Ts) e tempo de virada (Tv), a fim de observar o comportamento e influências na performance. Foram capturadas imagens por uma câmera mini-DV, analisadas por um "software" editor de vídeo. As variáveis CB, VN e IN foram encontradas indiretamente, sem considerar as fases de saída e virada. Ts e Tv foram obtidos através da linha do tempo do software. A análise de dados mostra para atleta 1: CB 2,00 m, FB 0,89 Hz, VN 1,78 m/s e IN 3,56 m²/s; atleta 2: CB 1,82 m, FB 0,97 Hz, VN 1,76 m/s, IN 3,20 m²/s; atleta 3: CB 1,91 m, FB 0,92 Hz, VN 1,75 m/s, IN 3,32 m²/s. Conclui-se que: o desempenho final apresentou comportamentos similares nos três primeiros trechos da prova indicando uma influência semelhante dessas variáveis sobre o desempenho das atletas. No último quarto da prova as variáveis apresentam maior interferência na performance final, sendo este decorrente de uma possível diminuição da eficiência mecânica do nado devido ao aumento do arrasto e redução da força propulsiva.

The performance evaluation of swimmers is based on many methodologies of watching the competition. Biomechanical variables represent an important resource for analyzing the performance of swimmers because they are simple and objective indicators of swimming efficiency. The objective of this research was to observe how biomechanical variables affect swimmers' performance in of the female 100 meters freestyle in order to observe the behavior and influence stroke length (SL), stroke frequency (SF), swimming velocity (SV), swimming index (SI), average speed (AS), time of departure (Td), time of turning (Tt). On swimming performance images were captured using a mini-DV camera, which were subsequently analyzed with the help of a software video editor. The variables SL, SV and SI were indirectly measured, without considering start and turning phases. Td and Tt were obtained through the timeline of the software. Data analysis shows for athlete 1: SL = 2.00 m, SF = 0.89 hz, SV = 1.78 m/s, SI = 3.56 m²/s, athlete 2: SL = 1.82 m, SF = 0,97Hz, SV = 1.76 m/s, SI = 3.20 m²/s, athlete 3: SL = 1.91 m, SF = 0.92 Hz, SV = 1.75 m/s, SI = 3.32 m²/s. We concluded that the final performance presented similar behavior in the first three parts of the race, indicating a similar influence of these variables on the performance of athletes. In the last quarter of the race showed that variables have greater interference in the final performance, this probably due to a possible decrease in mechanical efficiency of swimming due to increase in drag and reduction in propulsive force.

RELATIONSHIP BETWEEN CHANGES OF SWIMMING VELOCITY, STROKE RATE, STROKE LENGTH AND MUSCLE ACTIVITIES IN FRONT CRAWL SWIMMING / 体力科学

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.

Índices técnicos correspondentes à velocidade crítica e à máxima velocidade de 30 minutos em nadadores com diferentes níveis de performance aeróbia / Technical indexes corresponding to the critical speed and the maximal speed of 30 minutes in swimmers with different aerobic performance levels

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.