Abdominal bracing increases ground reaction forces and reduces knee and hip flexion during landing

STUDY DESIGN: Controlled laboratory study. 

BACKGROUND: Abdominal bracing (AB) is a widely advocated method of increasing spine stability, yet the influence of AB on the execution of sporting movements has not been quantified. Landing is a common task during sporting endeavors; therefore, investigating the effect of performing AB during a drop-landing task is relevant. 

OBJECTIVE: To quantify the effect of AB on kinematics (ankle, knee, hip, and regional lumbar spine peak flexion angles) and peak vertical ground reaction force (vGRF) during a droplanding task. 

METHODS: Sixteen healthy adults (7 female, 9 male; mean ± SD age, 27 ± 7 years; height, 170.6 ± 8.1 cm; mass, 68.0 ± 11.3 kg) were assessed using 3-D motion analysis, electromyography (EMG), and a force platform while performing a drop-landing task with and without AB. Abdominal bracing was achieved with the assistance of real-time internal oblique EMG feedback. Lower-limb and regional lumbar spine kinematics, peak vGRF, and normalized EMG of the left and right internal obliques and lumbar multifidus were quantified. Paired-samples t tests were used to compare variables between the AB and no-AB conditions. 

RESULTS: Abdominal bracing resulted in significantly reduced knee and hip flexion and increased peak vGRF during landing. No differences in lumbar multifidus EMG or lumbar spine kinematics were observed. 

CONCLUSION: Abdominal bracing reduces impact attenuation during landing. These altered biomechanics may have implications for lowerlimb and spinal injury risk during dynamic tasks.