Analysis of head movements coupled with trunk drift in healthy subjects

Abstract

Accelerometers were used to measure sequential head tilt and trunk drift in 14 healthy young subjects while they performed three kinds of head task. First, maximum inclination angles in anterior, posterior, right and left directions were measured to estimate cervical ranges of motion for flexion-extension and lateral bending. The inclination angles measured (61.2 degrees on average for flexion, 51.7 degrees for extension, 42.7 degrees for right bending and 43.9 degrees for left bending) were consistent with previous findings. Secondly, cross-correlation analysis was applied to evaluate the degree of functional coupling between the head and trunk during flexion-extension and lateral bending. Significantly higher correlation coefficients were found between head tilt and trunk drift when these movements were in the same (iso-) directional condition than in a different (allo-) directional condition. The coupled trunk drift in flexion-extension for the iso-directional condition (10.3 degrees on average) was much larger than for the allodirectional condition (2.3 degrees). Finally, head turning was recorded as oval traces in a biaxial plane. In both clockwise and counter-clockwise head turning conditions, the maximum inclination angles of the traces were larger in the anterior-posterior direction (59.8 degrees anterior and 58.2 degrees posterior, in the clockwise condition, and 47.4 degrees and 47.4 degrees in the counter-clockwise condition) than in the right-left direction (36.3 degrees right and 39.0 degrees left, in the clockwise condition, and 40.5 degrees and 36.7 degrees in the counter-clockwise condition), and the angles in the four directions were almost equal to flexion-extension and lateral bending. The characteristics of the traces recorded and a possible application of the present recording system are discussed.

Relationship between biomechanical changes at adjacent segments and number of fused bone grafts in multilevel cervical fusions: a finite element investigation

“…Both corpectomy and discectomy models were previously validated and compared well with the literature findings. 17 The moments were chosen within the in vivo physiological range: flexion (45°)/extension (35°), [7][8][9]14,25,29,37,49 axial rotation on each side (20°), 20,28,38 and lateral bending on each side (25°). 21,37 Next, these moment loads in 3 planes were applied to the C-3 vertebra under a compressive preload of 73.6 N.…”

Constancy of Head Turning Recorded in Healthy Young Humans

“…After attaching the two accelerometers, individual participants were asked to perform three tasks of head movements: flexionextension, lateral bending, and head turning. 16 In the present study, data collected during the head turning task under clockwise (CW) and counter-clockwise (CCW) conditions were analyzed. Each session consisted of a 5-s period of gazing at a fixed point determined freely by each participant and of a 15-s task performance period.…”

“…16 In brief, 14 healthy young volunteers (seven men and seven women, 20.7 years old on average) participated in the experiment after providing informed consent. Two accelerometers located in the center of eye glasses and just above the center point between the scapulae recorded head movement and trunk drift, respectively.…”

“…16 Since the recording system depicted trajectories of head turning in two-dimensional space, we were able to perform 'quantitative' analysis of head turning well. However, we obtained no information about such 'qualitative' properties as constancy and smoothness of head turning.…”

Accelerometry for the motion analysis of the lateral plane of the human body during gait

“…Accelerometers have been used to measure a wide range of physiological characteristics [3][4][5][6][7], with emphasis on motor activities [8][9][10][11][12], such as walking and running [5,6,[13][14][15][16][17][18], as well as on some studies of small movements, such as those in the temporomandibular region, mainly related to jaw opening and closing movements [19][20][21], in the characterization of respiratory disorders, such as apneas [3], [22,23], in the study of human body impact and vibration [24,25], its characterization posture [26,27], and movements performed during sleep [28,29].…”