Muscle activity during leg strengthening exercise using free weights and elastic resistance: Effects of ballistic vs controlled contractions

► Lunges with elastic resistance could be an effective leg strengthening exercise. ► Ballistic muscle contraction with medium load are as effective as slow contraction with heavy load. ► Lunges with elastic resistance and isoinertial resistance induces only slightly different muscle activity patterns. The present study’s aim was to evaluate muscle activity during leg exercises using elastic vs. isoinertial resistance at different exertion and loading levels, respectively. Twenty-four women and eighteen men aged 26–67years volunteered to participate in the experiment. Electromyographic (EMG) activity was recorded in nine muscles during a standardized forward lunge movement performed with dumbbells and elastic bands during (1) ballistic vs. controlled exertion, and (2) at low, medium and high loads (33%, 66% and 100% of 10 RM, respectively). The recorded EMG signals were normalized to MVC EMG. Knee joint angle was measured using electronic inclinometers. The following results were obtained. Loading intensity affected EMG amplitude in the order: low