As a result of the pain , it triggered a defense mechanism that results in a change in motor recruitment deficit represented by the generation of muscle strength and increased agonist antagonist activation ( DIEEN ; SELEN ; CHOLEWICHI , 2003; Larivière et al . , 2003; BASSANI et al . , 2008) . Aimed at quantifying motor function becomes useful a resource as surface electromyography , which enables the recording of muscle electrical activity in real time , allowing the identification of abnormal patterns of response ( Portney , 2004) . The device comprises electrodes reference surface and connected to the unit via cables sealed , and sensor preamplifiers information leading to electrical activity , and also biofeedback unit . The collected data are stored in the computer for further analysis , normally made by means of the square root of the mean square value (RMS ) comprising the result of the signal amplitude by means of the average power in the time interval considered , containing information about the number of motor units fired at a given motion ( Hamill , Knutzen , 1999; DE LUCA , 2002; MACHADO , 2008; O ' SULLIVAN , SCHMITZ , 2010) .