Related Experiment Videos
Trunk positioning accuracy in the frontal and sagittal planes
K McGlashen1, J A Ashton-Miller, M Green
1Department of Mechanical Engineering and Applied Mechanics, University of Michigan, Ann Arbor 48109-2125.
Summary
Healthy adults can accurately sense their trunk position, with frontal plane accuracy being slightly better than sagittal. Lateral trunk shifts over 12 mm may indicate abnormalities in young adults.
Area of Science:
- Biomedical Engineering
- Human Biomechanics
- Kinesiology
Background:
- Accurate head and spine positioning relative to the pelvis is crucial for maintaining balance and posture.
- Understanding trunk proprioception is essential for diagnosing and treating musculoskeletal disorders.
Purpose of the Study:
- To quantify the accuracy of head and spine positioning in the frontal and sagittal planes relative to the pelvis in healthy adults.
- To compare positioning accuracy under different sensory and motor conditions.
Main Methods:
- Ten healthy adult males stood with eyes closed and pelvis restrained.
- Markers on the head and spinous processes (T1, T6, T11, L3) were measured using strain-gaged flexible beam transducers.
- Subjects performed active and passive trunk positioning tasks to a neutral reference.
Main Results:
- Positioning accuracy was 16-45% better in the frontal plane compared to the sagittal plane, though not statistically significant.
- T1 (first thoracic vertebra) could be centered within 7 mm (frontal) and 10 mm (sagittal).
- Active and passive positioning accuracies were not significantly different; external trunk moments caused systematic overshoot.
Conclusions:
- Healthy young adults exhibit reliable trunk repositioning accuracy, particularly in the frontal plane.
- Lateral trunk shifts exceeding 12 mm may be considered abnormal in this population.
- Findings contribute to understanding postural control and identifying potential deviations from normal trunk alignment.