Abstract
Context: Individuals with low back pain (LBP) are thought to benefit from interventions that improve motor control of the lumbopelvic region. It is unknown if therapeutic exercise can acutely facilitate activation of lateral abdominal musculature. Objective: To investigate the ability of 2 types of bridging-exercise progressions to facilitate lateral abdominal muscles during an abdominal drawing-in maneuver (ADIM) in individuals with LBP. Design: Randomized control trial. Setting: University research laboratory. Participants: 51 adults (mean ± SD age 23.1 ± 6.0y, height 173.6 ± 10.5cm, mass 74.7 ± 14.5kg, and 64.7% female) with LBP. All participants met 3 of 4 criteria for stabilization-classification LBP or at least 6 best-fit criteria for stabilization classification. Interventions: Participants were randomly assigned to either traditional-bridge progression or suspension-exercise-bridge progression, each with 4 levels of progressive difficulty. They performed 5 repetitions at each level and were progressed based on specific criteria. Main Outcome Measures: Muscle thickness of the external oblique (EO), internal oblique (IO), and transversus abdominis (TrA) was measured during an ADIM using ultrasound imaging preintervention and postintervention. A contraction ratio (contracted thickness:resting thickness) of the EO, IO, and TrA was used to quantify changes in muscle thickness. Results: There was not a significant increase in EO (F 1,47 = 0.44, P =.51) or IO (F 1,47 =.30, P =.59) contraction ratios after the exercise progression. There was a significant (F 1,47 = 4.05, P =.05) group-bytime interaction wherein the traditional-bridge progression (pre = 1.55 ± 0.22; post = 1.65 ± 0.21) resulted in greater (P =.03) TrA contraction ratio after exercise than the suspension-exercise-bridge progression (pre = 1.61 ± 0.31; post = 1.58 ± 0.28). Conclusion: A single exercise progression did not acutely improve muscle thickness of the EO and IO. The magnitude of change in TrA muscle thickness after the traditional-bridging progression was less than the minimal detectable change, thus not clinically significant.