An alternative test of electromyographic normalization in patients

The value of electromyography (EMG) in the interpretation of normal and pathological movement depends on recording, processing, and normalization procedures. Traditionally, maximum voluntary isometric contraction (MVIC) of individual muscles is commonly used for EMG normalization. However, this is a time- and energy-consuming procedure, especially in patients. The aim of the present study was to compare an alternative method of recording the MVIC of lower-limb muscles to the traditional method in healthy, young subjects as well as individuals with a stroke. The alternative method consisted of recording the maximum effort of several thigh and leg muscles simultaneously using two tasks on a dynamometer. Five healthy subjects and five individuals who had a stroke performed both MVIC tasks. The healthy group repeated the test 3 h later on the same day. In general, the method of computing maximum EMG from the alternative MVIC test yielded values that were equal or greater than those from the traditional test in both groups. In the healthy group, muscles showed similar EMGs in the two sessions, indicating that the test was reliable. These results suggest that the less time-consuming alternative method of computing maximum EMG values used here provides a reasonable alternative when time and fatigue become issues, especially when testing patient populations.