Muscle activation patterns of the lumbo-pelvic-hip complex during walking gait before and after exercise.

The lumbo-pelvic-hip core complex consists of musculoskeletal structures that stabilize the spine and pelvis, however fatigue may affect muscle recruitment, active muscle stiffness and trunk kinematics, compromising trunk stability. The purpose of this study was to compare trunk muscle activation patterns, and trunk and lower extremity kinematics during walking gait before and after exercise. Surface electrodes were placed over the rectus abdominis, external oblique, erector spinae, gluteus medius, vastus lateralis, and vastus medialis of twenty-five healthy inidviduals. Means and 95% confidence intervals for muscle amplitude, muscle onsent and kinematics for 0-100% of the gait cycle were compared before and after exercise. Mean differences (MD) and standard deviations were calculated for all significant differences. The amplitude increased in the rectus abdominis during loading (MD=0.67±0.11), midstance (MD=0.75±0.04), terminal stance (MD=0.58±0.04), and late swing (MD=0.75±0.07) after exercise. Amplitude also increased during swing phase in the erector spinae (MD=0.92±0.11), vastus lateralis (MD=1.12±0.30), and vastus medialis (MD=1.80±0.19) after exercise. There was less trunk and hip rotation from initial contact to midstance after exercise. Neuromuscular fatigue significantly influenced the activation patterns of superficial musculature and kinematics of the lumbo-pelvic-hip complex during walking. Increased muscle activation with decreased movement in a fatigued state may represent an effort to increase trunk stiffness to protect lumbo-pelvic-hip structures from overload.