Quantification of lumbar stability by using 2 different abdominal activation strategies

Objective: To determine whether the abdominal hollowing technique is more effective for lumbar spine stabilization than a full abdominal muscle cocontraction. Design: Within-subject, repeated-measures analysis of variance was used to examine the effect of combining each of 4 loading conditions with either the hollow or brace condition on the dependent variables of stability and compression. A simulation was also conducted to assess the outcome of a person activating just the transversus abdominis during the hollow. Setting: Laboratory. Participants: Eight healthy men (age range, 20-33y). Interventions: Electromyography and spine kinematics were recorded during an abdominal brace and a hollow while supporting either a bilateral or asymmetric weight in the hands. Main Outcome Measures: Spine stability index and lumbar compression were calculated. Results: In the simulation "ideal case," the brace technique improved stability by 32%, with a 15% increase in lumbar compression. The transversus abdominis contributed .14% of stability to the brace pattern with a less than 0.1% decrease in compression. Conclusions: Whatever the benefit underlying low-load transversus abdominis activation training, it is unlikely to be mechanical. There seems to be no mechanical rationale for using an abdominal hollow, or the transversus abdominis, to enhance stability. Bracing creates patterns that better enhance stability.