The effect of hand dominance has not been considered in great detail regarding low back muscles in patients with chronic low back pain. The different response characteristics, in which left-sided spinal muscle responses for right-handed patients will be the same as right-sided spinal muscle responses for left-handed patients, should be considered. Statistically significant and clinically relevant differences in muscle response times and muscle fatigue were observed for right- and left-handed patients. Importantly, these differences were not observed when subject handedness was not considered in the model. The long-term preferential use of the dominant side of the back may alter physiologic properties of the back muscles.