People who develop low back pain during standing (standing-intolerant) are a subclinical group at risk for clinical low back pain. Standing-intolerant individuals respond favorably to stabilization exercise and may be similar to people with sacroiliac joint dysfunction that respond to stabilization approaches including sacroiliac joint (SIJ) bracing. The purpose was to characterize muscle activation and response to SIJ bracing in standing-tolerant and standing-intolerant individuals during forward flexion and unilateral stance. Trunk and hip electromyography data were collected from 31 participants (17 standing-tolerant and 14 standing-intolerant) while performing these tasks with and without SIJ bracing. Kinematics were captured concurrently and used for movement phase identification. Cross-correlation quantified trunk coactivation and extensor timing during return-to-stand from forward flexion; root mean square amplitude quantified gluteal activity during unilateral stance. The standing-intolerant group had elevated erector spinae–external oblique coactivation without bracing, and erector spinae–internal oblique coactivation with bracing during return-to-stand compared with standing-tolerant individuals. Both groups reversed extensor sequencing during return-to-stand with bracing. Standing-tolerant individuals had higher hip abductor activity in nondominant unilateral stance and increased hip extensor activity with bracing. SIJ bracing could be a useful adjunct to other interventions targeted toward facilitating appropriate muscle activation in standing-intolerant individuals.
Kristi Edgar, Aimee Appel, Nicholas Clay, Adam Engelsgjerd, Lauren Hill, Eric Leeseberg, Allison Lyle and Erika Nelson-Wong
Daniel Viggiani, Erin M. Mannen, Erika Nelson-Wong, Alexander Wong, Gary Ghiselli, Kevin B. Shelburne, Bradley S. Davidson and Jack P. Callaghan
People developing transient low back pain during standing have altered control of their spine and hips during standing tasks, but the transfer of these responses to other tasks has not been assessed. This study used video fluoroscopy to assess lumbar spine intervertebral kinematics of people who do and do not develop standing-induced low back pain during a seated chair-tilting task. A total of 9 females and 8 males were categorized as pain developers (5 females and 3 males) or nonpain developers (4 females and 5 males) using a 2-hour standing exposure; pain developers reported transient low back pain and nonpain developers did not. Participants were imaged with sagittal plane fluoroscopy at 25 Hz while cyclically tilting their pelvises anteriorly and posteriorly on an unstable chair. Intervertebral angles, relative contributions, and anterior–posterior translations were measured for the L3/L4, L4/L5, and L5/S1 joints and compared between sexes, pain groups, joints, and tilting directions. Female pain developers experienced more extension in their L5/S1 joints in both tilting directions compared with female nonpain developers, a finding not present in males. The specificity in intervertebral kinematics to sex-pain group combinations suggests that these subgroups of pain developers and nonpain developers may implement different control strategies.
Liana M. Tennant, Erika Nelson-Wong, Joshua Kuest, Gabriel Lawrence, Kristen Levesque, David Owens, Jeremy Prisby, Sarah Spivey, Stephanie R. Albin, Kristen Jagger, Jeff M. Barrett, James D. Wong and Jack P. Callaghan
Spinal stiffness and mobility assessments vary between clinical and research settings, potentially hindering the understanding and treatment of low back pain. A total of 71 healthy participants were evaluated using 2 clinical assessments (posteroanterior spring and passive intervertebral motion) and 2 quantitative measures: lumped mechanical stiffness of the lumbar spine and local tissue stiffness (lumbar erector spinae and supraspinous ligament) measured via myotonometry. The authors hypothesized that clinical, mechanical, and local tissue measures would be correlated, that clinical tests would not alter mechanical stiffness, and that males would demonstrate greater lumbar stiffness than females. Clinical, lumped mechanical, and tissue stiffness were not correlated; however, gradings from the posteroanterior spring and passive intervertebral motion tests were positively correlated with each other. Clinical assessments had no effect on lumped mechanical stiffness. The males had greater lumped mechanical and lumbar erector spinae stiffness compared with the females. The lack of correlation between clinical, tissue, and lumped mechanical measures of spinal stiffness indicates that the use of the term “stiffness” by clinicians may require reevaluation; clinicians should be confident that they are not altering mechanical stiffness of the spine through segmental mobility assessments; and greater resting lumbar erector stiffness in males suggests that sex should be considered in the assessment and treatment of the low back.