Análise eletromiográfica e força do grupo muscular extensor do punho durante isquemia induzida

Abstract

Objective: To analyze the effect of induced ischemia on the parameters of electromyographic signals and the strength of the wrist extensor muscle group (WEMG) in healthy women. Methods: Thirteen right-handed sedentary subjects aged 23.38±2.32 years old, with body mass index (BMI) of 20.68±1.87kg/ m2, took part. To determine WEMG strength, three maximal voluntary isometric contractions (MVIC) were performed using a load cell for 15 seconds, with 2 minutes intervals between contractions. The entire procedure was repeated on three nonconsecutive days. Ischemia was induced for 5 minutes using a sphygmomanometer placed on the dominant arm and inflated until blood flow was absent, as confirmed by Doppler ultrasound. The EMG1000 module (Lynx®) was used with differential surface electrodes (Lynx®) to record the electromyographic signal of the WEMG. Three MVIC were recorded for 15 seconds, with 30 seconds intervals between them, under the following conditions: pre-ischemia, ischemia, immediate post-ischemia (post-1) and later post-ischemia (post-2: 10 minutes after the onset of ischemia). The MATLAB 6.5.1 software was used to analyze the parameters for the electromyographic signal, the root mean square (RMS) and the median frequency of the signal power spectrum. For statistical analysis, two-way ANOVA and the Friedman test were used. Results: Ischemia caused a significant reduction (p<0.05) in WEMG strength. However, there were no significant changes in the RMS electromyographic parameters (p=0.05) or the median frequency of the signal power spectrum (p=0.09). Conclusion: Induced ischemia caused WEMG fatigue in relation to muscle strength production. However, it did not cause electromyographic fatigue in the evaluated muscle group. © Revista Brasileira de Fisioterapia.