RESUMO
STUDY DESIGN: Randomized, blinded, controlled crossover trial. OBJECTIVE: To determine if thrust joint manipulation (TJM) to the lumbar spine would result in changes to the resting and contraction thickness of transversus abdominis (TrA) in healthy individuals. BACKGROUND: Recent studies have demonstrated an immediate decrease in resting thickness and an increase in contraction thickness in TrA following lumbar TJM in patients with low back pain (LBP) who met a clinical prediction rule (CPR) for spinal manipulation. This observed phenomenon has not been investigated in healthy individuals. METHODS: Thirty-five healthy participants were randomly assigned to receive a TJM or sham manipulation treatment. All participants received instruction on how to produce an isolated concentric contraction of the TrA that involved visual ultrasound imaging biofeedback. Data were analyzed using ultrasound imaging to measure changes in thickness of the TrA at rest and during contraction, following the administration of each treatment. RESULTS: There were no interactions observed between treatment and time for TrA muscle thickness at rest (P = .351) and during the contracted state (P = .761). CONCLUSION: Our results indicate that TJM to the lumbar spine does not appear to affect the resting or contraction thickness of TrA in healthy individuals. These findings are in contrast to previous research in which patients with LBP who met a CPR demonstrated an immediate decrease in resting thickness and an increase in contraction thickness in TrA following lumbar TJM.