Delayed trunk muscle reflex responses increase the risk of low back injuries.

Study Design: Prospective observational study with a 2- to 3-year follow-up.

Objectives: To determine whether delayed muscle reflex response to sudden trunk loading is a result of or a risk factor for sustaining a low back injury (LBI).

Summary Of Background Data: Differences in motor control have been identified in individuals with chronic low back pain and in athletes with a history of LBI when compared with controls.

Sustained orbital shear stress stimulates smooth muscle cell proliferation via the extracellular signal-regulated protein kinase 1/2 pathway.

Objective: Nonlaminar shear stress stimulates smooth muscle cell (SMC) proliferation and migration in vivo, especially after an endothelial-denuding injury. To determine whether sustained shear stress directly stimulates SMC proliferation in vitro, the effect of orbital shear stress on SMC proliferation, phenotype, and extracellular signal-regulated protein kinase 1/2 (ERK1/2) phosphorylation was examined.

Methods: Bovine SMCs were exposed to orbital shear stress (210 rpm) for up to 10 days, with and without the ERK1/2 upstream pathway inhibitor PD98059 (10 microM) or the p38 pathway inhibitor SB203580 (10 microM).

Comparison of motion restriction and trunk stiffness provided by three thoracolumbosacral orthoses (TLSOs).

The amounts of thoracic and lumbar spine motion restriction and passive trunk stiffness provided by three thoracolumbosacral orthoses (TLSOs) (Aspen TLSO, Boston Body Jacket, and CAMP TLSO) were compared. Ten subjects executed maximum trunk flexion, extension, and lateral bending motions. The spine motion was measured noninvasively with a thin strain gauge device (Flexducer), and passive trunk stiffness around the neutral posture was estimated from an electromyography-assisted biomechanical model.