| Objective: To investigate the change of kinematic parameters in healthy subjectswhose trunk stiffness were increased under experimental condition, and explore thereason of this change under the biomechanical view. Moreover, we try to find out thechange of trunk coordination in healthy subjects whose trunk stiffness are increasedand compare the results in low back pain patients that reported in the literature.Method: Thirteen healthy male volunteers (median age29years, ranged from25-32years, mean height171.61±4.29cm, mean weight67.08±10.14kg) participated in thestudy. The markers were attached to the segments of the body. They walked intreadmill in3velocities×2step widths, while they walked naturally, co-contractedtheir trunk muscles or wear the corset. The walking speed will be set in3modesincluding0.5m/s、1.0m/s、1.5m/s. In total,18conditions were set randomly. Thekinematic parameters of every segment were collected, and calculated bythree-dimensional gait analysis computational program. The difference of intersegmental movement with different conditions were compared.Results: When healthy subjects walked with their trunk muscles co-contracted theirerector spinae (high and the low) surface EMG enhanced significantly. Total trunktransverse rotation amplitudes (TTRA) were reduced when subjects increased theirtrunk stiffness.(Decrease level: wear a corset> co-contracted their trunk muscles>walked naturally). Thorax-pelvis relative Fourier phase (RFP) was significantlydecreased when trunk stiffness was increased (P=0.018). Healthy subjects who hadincreased their trunk stiffness generated higher pelvis-leg RFP compared with thenatural trunk walking (P <0.01).Conclusions: Our result of trunk coordination in walking is different from that inliterature about the patients with low back pain. Patients with low back pain may be adopting more complex control strategies to achieve trunk movement coordination.The increased trunk stiffness may be a secondary strategy for low back pain patients. |
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