The effect of joint angle on surface electromyography amplitude of hamstring muscles

This thesis investigated the effect of knee angle position on the electrical signal of two hamstring muscles using a traditional technique (bipolar electromyography) and a modern technique (high-density electromyography). The results suggest that changes in knee position affect the electrical activity on bipolar electromyography and these changes are associated with the rotation of muscle fibers under the pair of electrodes. However, using high-density electromyography, there was no difference between different knee positions. These findings suggest that high-density electromyography has different responses compared to bipolar electromyography. Hence, studies using bipolar montages need to be interpreted with caution to avoid wrong conclusions.