Anticipatory postural control differs between low back pain and pelvic girdle pain patients in the absence of visual feedback

Purpose: The aim of this study was to examine the effect of vision on anticipatory postural control (APA) responses in two groups of clinically diagnosed chronic low back pain patients, those with Posterior Pelvic Girdle pain and those with Non-Specific Low Back Pain compared to a matched group of healthy controls during the modified Trendelenburg task. Methods: Seventy-eight volunteer participants (60 females and 18 males) gave informed consent to take part in this study. 39 with confirmed LBP or PGP lasting longer than 12 weeks and 39 healthy matched controls performed 40 single leg lift tasks (hip flexion to 90 degrees as quickly as possible) with their non-dominant lower limb. A force plate was used to determine the medial-lateral displacement of the center of pressure, and the initiation of weight shift; kinematics was used to determine initiation of leg lift; and electromyography was used to determine onset times from the external oblique CEO), internal oblique (JO) and lumbar multifidus (MF), gluteus maximus (GM) and biceps femoris (BF). Results: The PGP group showed significantly longer muscle onset latencies in the BF, BO MF with visual occlusion (F-2,F-746 = 4.51, p < .0001). Conclusion: The muscle onset delays identified between the two LBP sub-groups suggests that pain may not be the primary factor in alteration of APA response. The PGP group show a greater reliance on vision which may signal impairment in multiple feedback channels.