Intra and interobserver reliability of the anterior trunk flexion angle measurements by the Whistance method

O objetivo do estudo foi avaliar a confiabilidade intra e interobservador damensuração do ângulo de Whistance por meio da análise cinemática angular. Participaram 50 voluntários, que foram submetidos a duas fotos: a primeira em ortostatismo e a segunda em flexão anterior máxima de tronco. O ângulo de flexão foi medido por dois avaliadores, analisando-se a confiabilidade intra e interobservadores da mensuração pelo método de Whistance com os testes estatísticos coeficiente de correlação intraclasse (CCI) e Bland & Altman. A média do ângulo de Whistance mensurado pelo avaliador 1 foi de 78,9º±11,4° e em seu re-teste, x=78,9°±10,9°. O avaliador 2 obteve média de 79,5°±11,1°. O CCI intra-observador foi de 0,94, com IC 95% [0,91;0,97]; e, no teste de Bland & Altman, foi de 0,04, com IC 95% [-0,99;1,07]. Os valores intra-observador foram de 0,98, com IC 95% [0,97;0,99] e -0,62 IC 95% [-1,09;-0,14], respectivamente. O presente estudo demonstrou alta confiabilidade intra e interobservadores para a mensuração do ângulo de flexão do tronco pelo método de Whistance.The purpose of this study was to evaluate intra and inter-rater reliability of the Whistance angle measurements through kinematic angular analysis. Two photographs of fifty subjects were registered: the first in standing position and the second performing trunk maximal anterior flexion. Two observers measured the trunk flexion angle. The intra and inter-rater reliability of the measurements made were analysed by two statistical analyses: intraclass correlation coefficient (ICC) and Bland & Altman’s. The mean Whistance angle measured by the first observer was 78.9º±11.4° and his testretest was x=78.9°±10.9°. The second evaluator obtained a mean of 79.5°±11.1°. The ICC for the intrarater was 0.94, with 95% CI [0.91;0.97] and for Bland and Altman, 0.04 with 95% CI [-0.99;1.07]. The inter-rater values were, respectively, 0.98 with 95% CI [0.97;0.99] and –0.62 95% CI [-1.09;- 0.14]. Both intra and inter-rater reliability thus was high for both statistical analyses. The present study showed high intra and inter-rater reliability for the Whistance method of measuring the trunk flexion angle

Analysis of erector spinae muscle fatigue in healthy subjects in the sitting position

The aim of this study was to evaluate the frequency and amplitude of surface electromyography during erector spinae fatigue in healthy subjects in the sitting position. Eleven healthy males without low back pain participated in the study. The electromyographic parameters were collected with a surface electromyograph. Four electrodes were positioned lateral to the first and fifth lumbar vertebrae. The electromyographic signals were recorded during isometric trunk extension against a load cell in the sitting position. Loads of 50% and 75% of maximal voluntary isometric contraction were applied for 25 seconds to induce muscle fatigue. The signals processed using a Fast Fourier Transform algorithm and root mean square were submitted to linear regression to determine the fatigue index. The median frequency of the power spectrum presented negative values and the root mean square presented positive values, indicating muscle fatigue. No significant differences were observed when comparing level and side, or between loads (P > 0.05). The sitting position provides a better pelvis fixation and reproduces the usual position of occupational activities. The protocol used did not cause pain. Although all subjects presented erector spinae fatigue, no differences were observed between lumbar regions. The concomitant use of median frequency and root mean square in fatigue studies is suggested

<b>Analysis of erector spinae muscle fatigue in healthy subjects in the sitting position</b>

The aim of this study was to evaluate the frequency and amplitude of surface electromyography during erector spinae fatigue in healthy subjects in the sitting position. Eleven healthy males without low back pain participated in the study. The electromyographic parameters were collected with a surface electromyograph. Four electrodes were positioned lateral to the first and fifth lumbar vertebrae. The electromyographic signals were recorded during isometric trunk extension against a load cell in the sitting position. Loads of 50% and 75% of maximal voluntary isometric contraction were applied for 25 seconds to induce muscle fatigue. The signals processed using a Fast Fourier Transform algorithm and root mean square were submitted to linear regression to determine the fatigue index. The median frequency of the power spectrum presented negative values and the root mean square presented positive values, indicating muscle fatigue. No significant differences were observed when comparing level and side, or between loads (P > 0.05). The sitting position provides a better pelvis fixation and reproduces the usual position of occupational activities. The protocol used did not cause pain. Although all subjects presented erector spinae fatigue, no differences were observed between lumbar regions. The concomitant use of median frequency and root mean square in fatigue studies is suggested