Exploring the Effect of Attachment Position of Electrodes for EMG-Based Detection of Minimum Effective Load on Muscles

Isokinetic training leads to rapid skeletal muscle hypertrophy, while slow-speed resistance training is effective for promoting muscle hypertrophy. It is essential to use an effective resistance load that minimizes injury risk in skeletal muscle hypertrophy interventions. Previous studies have indicated that surface electromyogram (EMG) measurements are useful for detecting the load threshold (minimum effective load). However, the attachment position of the electrodes affects the characteristics of the EMG signal readings. It remains unclear whether the system for detecting the load threshold functions correctly when the electrode attachment position shifts. The objective of this study is to explore how the attachment position of EMG electrodes affects the detection of the load threshold. We hypothesized that frequency analysis of EMG signals might be a reliable method for checking the electrode attachment position, given the alternating current nature of EMG signals. As a result, as long as the EMG electrode is placed on the muscle, slight positional shifts are not very critical for detecting the load threshold. In addition, results show that we can verify whether the electrode attachment position is appropriate for detecting the load threshold and make adjustments by examining the magnitude data of the EMG signal frequency bands.