The clinical significance of electromyography normalisation techniques in subjects with anterior cruciate ligament injury during treadmill walking

This study investigated the clinical interpretation of three electromyographic (EMG) normalisation techniques to detect neuromuscular alterations in patients diagnosed with anterior cruciate ligament knee injury during treadmill walking. The EMG signal was normalised using the mean value during the gait cycles (MEA), the maximum value during the gait cycles (MAX), and a maximum voluntary isometric contraction (MVC) test in 16 male and female subjects. The MAX method detected an increase in total muscle activity in the injured limb rectus femoris (11.6%; P = 0.02) while the MVC method detected decreased injured limb gastrocnemius medialis (GM) overall muscle activity (34.4%; P = 0.02). The MAX method identified decreased GM activity in three portions of the gait cycle. This study indicates the importance of choosing the appropriate normalisation technique since its choice will change outcome measures and subsequent clinical interpretation. (C) 2002 Elsevier Science B.V. All rights reserved.