Análise da confiabilidade de um método de mensuração do ângulo de pico de torque ativo dos isquiossurais / Analysis of the reliability of a method for measuring hamstring active peak torque angle

INTRODUÇÃO: O comprimento muscular pode ser inferido através da determinação da relação comprimento-tensão do músculo. Essa relação é tradicionalmente investigada por meio da medida do torque máximo produzido pelo músculo e do ângulo em que esse torque é gerado. OBJETIVO: O presente estudo verificou a confiabilidade teste-reteste de um método de mensuração do ângulo de pico de torque ativo dos isquiossurais em jovens saudáveis. MÉTODO: Vinte e cinco indivíduos saudáveis (22,88 ± 1,67 anos) foram avaliados duas vezes em um intervalo de três semanas. Um dinamômetro isocinético foi utilizado no modo passivo para avaliar o torque passivo dos isquiossurais. A atividade muscular foi monitorada para garantir silêncio eletromio-gráfico. O dinamômetro foi utilizado no modo concêntrico para determinar o torque total dos isquiossurais. O torque ativo foi obtido subtraindo-se o torque passivo do torque total. O ângulo do pico de torque ativo foi utilizado para a análise. RESULTADO: Não houve diferença estatisticamente significativa entre as duas medidas realizadas (t= 1,009; p= 0,323). O Coeficiente de Correlação Intraclasse para os valores obtidos do ângulo de pico de torque ativo foi de 0,948 (p= 0,0001; IC 95 por cento 0,881 - 0,977). CONCLUSÃO: O presente estudo demonstrou que o método descrito é confiável para a quantificação deste ângulo, sugerindo que este método pode ser utilizado para avaliar mudanças da curva torque-ângulo promovidas por alterações de comprimento muscular.

INTRODUCTION: Muscle length can be inferred from the length-tension relationship of the muscle. This relationship is traditionally investigated by measuring the peak torque produced by the muscle and the angle at which it is generated. OBJECTIVE: The present study investigated the test-retest reliability of a method for measuring hamstring active peak torque angle in healthy young adults. METHOD: Twenty-five healthy individuals (22.88 ± 1.67 years) were assessed twice with an interval of three weeks. An isokinetic dynamometer was used in passive mode to assess hamstring passive torque. Muscle activity was monitored to ensure electromyographic silence. The dynamometer was also used in concentric mode to determine hamstring total torque. The active torque was obtained as the difference between total torque and passive torque. The active peak torque angle was used for the analysis. RESULTS: There was no significant difference between the two measurements (t= 1.009; p= 0.323). The intraclass correlation coefficient for the active peak torque angle values obtained was 0.948 (p= 0.0001; 95 percent CI: 0.883 - 0.977). CONCLUSION: This study has shown that the method described is reliable for the quantification of active peak torque angle, thus suggesting that this method can be used to evaluate shifts in the torque-angle curve produced by muscle length changes.

Incomplete dominance of the low antibody response to Cryptosporidium parvum antigens in mice selected for high and low antibody responsiveness

The humoral antibody response to Cryptosporidium was investigated in mice genetically selected for high (H) and low (L) antibody responsiveness. Groups of 4-5 mice from two different selections, general primary (GP) and general secondary (GS), were studied. Following immunization with Cryptosporidium parvum antigens, the maximum levels of IgG in the HGP, (X ñ SD = 1.13 ñ 0.35, N = 5) and in the HGS (0.42 ñ 0.15, N = 4) lines, and of IgM in the HGP line (0.86 ñ 0.53, N = 5) were significantly higher than those in their L counterparts (0.04 ñ 0.02, N = 5;0.05 ñ 0.02, N = 4 and 0.24 ñ 0.07, N = 5, respectively). These findings were similar to those reported for other immunogens. However, the IgG (0.22 ñ 0.05, N = 4) and the IgM (0.33 ñ 0.08, N = 4) responses to immunization of F1 (LGP x HGP) hybrids indicated an incomplete dominance of the low response, in contrast to the incomplete dominance of the high response described for many other antigens and representing an important exception. In addition, the H, L and F1 mice did not develop detectable infections when inoculated with live Cryptosporidium oocysts, supporting the view that a reduced or zero antibody production itself is not enough to permit the establishment of Cryptosporidium infection in adult mice.