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Diurnal variation in trunk kinematics during a typical work shift
F A Fathallah1, W S Marras, P L Wright
1Department of Industrial and Systems Engineering, Ohio State University, Columbus 43210, USA.
Journal of Spinal Disorders
|February 1, 1995
Summary
Trunk flexibility does not change throughout the day, but dynamic trunk motion (velocity and acceleration) does. This suggests diurnal variation in injury risk is more complex than previously understood.
Area of Science:
- Biomechanics
- Human Movement Science
- Occupational Health
Background:
- Diurnal variation in trunk flexibility (range of motion) is known.
- Decreased disk height and slackened ligaments are hypothesized to increase flexibility and reduce injury risk as the day progresses.
- Dynamic spinal motions may accentuate injury risk.
Purpose of the Study:
- To investigate diurnal changes in dynamic trunk mobility.
- To assess if trunk range of motion or dynamic parameters vary with time of day.
- To re-evaluate the "slack ligaments" hypothesis in relation to diurnal trunk mobility.
Main Methods:
- Trunk motions of 21 men were measured using a triaxial electrogoniometer at three times daily.
- Static range of motion in cardinal planes was assessed.
- Dynamic parameters including velocity and acceleration in the sagittal plane were analyzed.
Main Results:
- No significant diurnal variation was found in trunk range of motion across any cardinal plane.
- Significant diurnal variations were observed in trunk velocity and acceleration, particularly in the sagittal plane.
- These findings challenge the "slack ligaments" hypothesis based solely on static range of motion.
Conclusions:
- Static range of motion provides incomplete information on diurnal variations in spinal mobility.
- Diurnal changes in dynamic trunk mobility, not just static flexibility, are crucial for understanding spinal health.
- Early morning industrial injuries may relate to insufficient dynamic trunk mobility, indicating complex diurnal risk factors.