Cheng, Chih-Hsiu

Background/Objectives: Limited spinal range of motion (ROM) is linked to low back disorders, emphasizing the need to maintain mobility in the elderly. This study measured maximum spinal ROM, asymmetrical patterns, and the effects of age and muscle activation on spinal mobility. Methods: Forty healthy participants aged 50 and older were recruited. An optical motion capture system recorded three-dimensional coordinates of reflective markers placed on spinal landmarks. Asymmetry was analyzed in sidebending and axial rotation. Electromyography (EMG) data were collected bilaterally from paraspinal muscles at L3 during flexion, extension, sidebending, and axial rotation. Results: Trunk ROM averaged 111° in flexion, 38° in extension, 46° in sidebending, and 87° in axial rotation. Kinematic asymmetry was observed in sidebending and axial rotation. ROM decreased with age in flexion motion (p ≤ 0.04). EMG activity was significantly correlated with ROM data for all combined motions (p = 0.0002). The strongest EMG signal was recorded during flexion, whereas the weakest signal was observed during extension. EMG activity also correlated with kinematic asymmetry (p ≤ 0.03). Conclusions: Age and muscle activation significantly influence spinal ROM in the elderly. Lumbar kinematic asymmetry can be partially attributed to paraspinal muscle activation, underscoring the importance of analyzing asymmetrical motions in conjunction with EMG activity.