Activation of latissimus dorsi muscle in patients with sacroiliac joint dysfunction when lifting a load

Abstract

BACKGROUND: Sacroiliac Joint Dysfunction (SIJD) may be observed in 13% to 30% people with idiopathic low back pain (LBP). Latissimus dorsi (LD) muscle works by stabilizing the SIJ, providing a pathway for force transmission through the thoraco lumbar fascia. Literature has shown that muscles can change their activation pattern in response to pain, altering motor control. However, to date, there have been no studies evaluating the EMG activity of LD in people with SIJD while lifting a load, this could guide for a better understanding about how muscle activation occurs in this group of patients. AIM: To evaluate and compare activation of LD in people with LBP, SIJD and without LBP in load lifting. METHODS: One hundred fourteen people were evaluated and divided into 3 groups: LBP, SIJD and Control group. EMG signals were recorded from LD while the subjects lifted a load in a symmetrical posture. Subjects started in an upright position, grasped the box from the floor and returned to the initial position with flexed elbows. Root Mean Square (RMS) amplitude and latency were calculated. The Kruskal-Wallis and the post hoc Dunn’s tests were used to compare groups. RESULTS: Results showed that left LD in SIJD group is activated 26.21% more than in the control group and 23.98% than the LBP group (p = 0.02). Besides, right LD has a delayed onset in SIJD by 0.68 ms compare with the control group and 0.29 ms with LBP group (p = 0.03). CONCLUSION: In a specific group of individuals with SIJD, alterations in LD muscle activation, could be evidenced by an increased RMS amplitude which is accompanied with a delay in activation in the opposite side during lifting a load in a symmetrical posture.