Objectives: Contraction of the transversus abdominis (TrA) plays an important role in lumbar stability. Ultrasonography can be used to measure muscle elasticity and lateral slide for a noninvasive evaluation of TrA contraction. However, no reports have verified the relationship between these indexes and lumbar stability. Therefore, the objectives of this study were to clarify the contribution of the elasticity and lateral slide of the TrA to lumbar stability and to identify an effective exercise for stabilizing the lumbar vertebrae.
Measurements of lumbar stability and muscle elasticity and lateral slide of the TrA were performed in 29 healthy males. Lumbar stability was measured with the participant’s pelvis in a neutral position and body in the crook lying position, and a pressure biofeedback unit was placed under the lumbar vertebrae. The participant then fully extended the knee joints while maintaining the original hip joint angle, and the examiner measured changes in pressure on the biofeedback unit. Muscle elasticity and lateral slide of the TrA were measured at rest and during hollowing with maximum effort, and the amount of change between rest and hollowing was calculated. Potential relationships among lumbar stability, muscle elasticity, and lateral slide of the TrA were verified using Pearson's correlation coefficient. The significance level was set to p < 0.05.
As an index of TrA contraction during hollowing, improving the elasticity of the TrA, not the lateral slide, may help stabilize the lumbar vertebrae in healthy individuals. Moreover, hollowing with maximum effort may be an effective training exercise for stabilizing the lumbar vertebrae.
Itsuroh Shimizu– Mr, Fukui General Clinic
Hiroichi Miaki– Mr, Kanazawa University
Katsunori Mizuno– Dr, Fukui General Hospital
Nobuhide Azuma– Faculty of Health Science, Department of Rehabilitation Physical Therapy, Fukui Health Science University
Takao Nakagawa– Prof, Kanazawa University