The effects of upper limb loading on spinal shrinkage during treadmill walking.
BACKGROUND
Everyday activities such as walking may elicit spinal shrinkage in an order of magnitude that has been related to lower back pain. The present study aims to compare the effects of unloaded treadmill walking with walking carrying loads representing everyday shopping tasks.


METHODS
Walking tasks were performed on seven healthy males and motion analysis was used to track four reflective markers at 100 Hz, dividing the spine into three segments. Static data was collected in 5-min intervals over a 30-min period.


RESULTS
Total spinal length and lumbar segment decreased with respect to time (p < 0.001). Load affected the percentage length change at each spinal segment (p < 0.005), with the lumbar segment showing greatest height loss at the highest load. The upper and lower thoracic segments showed greater anterior lean with the heavier loads (p = 0.000) and the lumbar segment showed the opposite trend (p = 0.000).


CONCLUSIONS
Results suggest that the body adopts less anterior lean with an immediate load-bearing demand, to decrease the necessary extension moment generated by the spinal extensors for spinal stability. Further postural alteration in the same direction is observed with prolonged loading. In combination with lumbar spinal shrinkage, such postural changes are likely to increase the loading on the facet joints and subsequently unload the discs which may be beneficial for those with low back pain.
Health and Exercise Sciences Research Unit, University of the West of Scotland, Hamilton, ML3 0JB, UK. hugh.watson@uws.ac.uk
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Watson
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Simpson
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Riches
D000222:Adaptation, Physiological / Q000502:physiology*; D001696:Biomechanical Phenomena; D006801:Humans; D007403:Intervertebral Disc / Q000502:physiology; D008297:Male; D011187:Posture / Q000502:physiology*; D013131:Spine / Q000502:physiology*; D034941:Upper Extremity; D016138:Walking / Q000502:physiology*; D016474:Weight-Bearing / Q000502:physiology*; D055815:Young Adult