Swiss ball abdominal crunch with added elastic resistance is an effective alternative to training machines

Background: Swiss ball training is recommended as a low intensity modality to improve joint position,posture, balance, and neural feedback. However, proper training intensity is difficult to obtain during Swissball exercises whereas strengthening exercises on machines usually are performed to induce high level ofmuscle activation.Purpose:To compare muscle activation as measured by electromyography (EMG) of global core and thighmuscles during abdominal crunches performed on Swiss ball with elastic resistance or on an isotonic trainingmachine when normalized for training intensity.Methods:42 untrained individuals (18 men and 24 women) aged 28-67 years participated in the study.EMG activity was measured in 13 muscles during 3 repetitions with a 10 RM load during both abdominalcrunches on training ball with elastic resistance and in the same movement utilizing a training machine(seated crunch, Technogym, Cesena, Italy). The order of performance of the exercises was randomized,and EMG amplitude was normalized to maximum voluntary isometric contraction (MVIC) EMG.Results: When comparing between muscles, normalized EMG was highest in the rectus abdominis (P