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This study was to quantitatively characterize the spatial, temporal, and neuromuscular activation patterns of Tai Chi gait (TCG). Ten healthy young subjects were tested. The kinematics of TCG and normal gait (NG) were measured using a marker-based motion analysis system and two biomechanical force plates. Surface electromyography (EMG) was recorded from six left-side muscles: tibialis anterior, soleus, peronaeus longus, rectus femoris, semitendinosus, and tensor fasciae latae. The results showed that TCG had (1) a longer cycle duration (11.9±2.4 vs. 1.3±0.2 s) and a longer duration of single-leg stance time (1.8±0.6 vs. 0.4±0.05 s); (2) a larger joint motion in ankle dorsi/plantar flexion (40±9° vs. 20±8°), knee flexion (82±8° vs. 53±10°), hip flexion (81±7° vs. 24±4°), and hip abduction (20±8° vs. 0±3°); (3) a larger lateral body shift (>25% vs. 5% body height); and (4) significant involvement of ankle dorsiflexors, knee extensors/hip flexors and hip abductors, as indicated by significantly higher peak (88±14%, 80±18% and 83±17% vs. 35±10%, 14±8% and 28±19% peak amplitude, respectively) and root-mean-square values of their EMG (37±6%, 32±7% and 33±7% vs. 23±7%, 11±8% and 22±11% peak amplitude, respectively), longer proportions of action (76±19%, 68±8% and 65±19% vs. 59±23%, 16±23% and 40±32% gait cycle duration, respectively), longer proportions of isometric and eccentric actions, and longer proportions of co-activations. These results demonstrate that the biomechanical characteristics of TCG can be quantified. The quantification of TCC movements is important for understanding its effect on balance, flexibility, strength, and health. [Copyright &y& Elsevier]

Abstract: There is increasing evidence that individuals with non-specific low back pain (LBP) have altered movement coordination. However, the relationship of this neuromotor impairment to recurrent pain episodes is unknown. To assess coordination while minimizing the confounding influences of pain we characterized automatic postural responses to multi-directional support surface translations in individuals with a history of LBP who were not in an active episode of their pain. Twenty subjects with and 21 subjects without non-specific LBP stood on a platform that was translated unexpectedly in 12 directions. Net joint torques of the ankles, knees, hips, and trunk in the frontal and sagittal planes as well as surface electromyographs of 12 lower leg and trunk muscles were compared across perturbation directions to determine if individuals with LBP responded using a trunk stiffening strategy. Individuals with LBP demonstrated reduced peak trunk torques, and enhanced activation of the trunk and ankle muscle responses following perturbations. These results suggest that individuals with LBP use a strategy of trunk stiffening achieved through co-activation of trunk musculature, aided by enhanced distal responses, to respond to unexpected support surface perturbations. Notably, these neuromotor alterations persisted between active pain periods and could represent either movement patterns that have developed in response to pain or could reflect underlying impairments that may contribute to recurrent episodes of LBP. [Copyright &y& Elsevier]