Influence of different stimuli on electromyographic variables of the biceps brachii

The objective of this study was to assess the influence of different stimuli on the muscular response of 30 young sedentary male and female subjects. A conditioning module with A/D 16/32 signals of 12 bits (LYNX), with band-pass filter of 10-500 Hz and sampling frequency of 1000 Hz was used. A bipolar active surface electrode (LYNX), a load cell (MM-100 KRATOS) and a pressure cuff were also used. The volunteers were submitted to four conditions: Without stimulus (WS), auditive stimulus (AS), visual stimulus (VS), and auditive + visual stimuli (AVS). Matlab 6.5.1 software was used to process the signals for analyzing RMS and median frequency (MF), as well as muscular force (F) and cuff pressure (P). Statistical analysis consisted of the Wilcoxon and Mann-Whitney test with a critical level of 5%. As to RMS, females presented a significant increase in all types of stimuli compared to WS. As to MF there was no significant difference between the different groups for either sex. P in both sexes presented a significant increase when submitted to VS and AVS. F was higher for AVS in males and for any of the stimuli in females when compared to WS. In all the variables analyzed, males presented significantly higher values than females for all types of stimuli.