The effects of upper limb loading on spinal shrinkage during treadmill walking

Abstract

Introduction 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. Materials and 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). Conclusion 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.

Influence of Shopping Bags Carrying on Human Responses While Walking

“…The study found an evidence of favoring the two-hands carrying to the one-hand carrying in general based on the investigated physiological responses in the form of lower cardiac cost and lower %MVC and subjective response in the form of lower discomfort rating. This finding is in support of other studies, which investigated different responses such as trunk kinematics [ 3 , 6 , 7 ], trunk loading [ 8 , 15 ], and gait analysis [ 4 , 10 , 11 , 16 ].…”

“…Participants were asked to walk steadily at their normal walking speed and avoid any sudden or aggressive moves that might result in sudden loading of the spine [ 3 , 37 – 39 ]. After 90 seconds of walking, PPPs and 15-second sEMG muscular activities were recorded one time every minute for three minutes.…”

“…Whether it is in one hand or in both hands, the carrying style of shopping bags varies from person to person depending on the weight, shape, and type of handles of the carried bags. This daily activity might be associated with risk factors contributing to the development of low back pain (LBP) due to the compression forces on the lumbar spine [ 1 – 3 ]. In addition, other risks such as strains and sprains in the fingers, wrists, elbows, and shoulders are present [ 2 , 3 ].…”

“…Daily walking and carrying tasks cause spinal shrinkage, reduce the height of the intervertebral discs, and might produce abnormal compressive loads on the lumbar spine due to trunk muscles' contraction [ 4 , 5 ]. Carrying loads causes height loss due to intervertebral discs' compression along with spinal curvature increase, which might result in LBP [ 3 , 6 , 7 ]. According to the Work Practices Guide for Manual Lifting published by the National Institute for Occupational Safety and Health, loads carried that resulting in developing of 6400 Newton, or more, of the compression load on the lumbosacral joint (L5/S1) are considered hazardous [ 8 ].…”

“…Researchers investigated the problem of walking while carrying loads through different approaches such as the investigation of trunk kinematics [ 3 , 6 , 7 ], investigation of trunk loading [ 9 , 15 ], gait analysis [ 4 , 10 , 11 , 16 ], and cardiovascular response [ 2 ]. In their approaches, researchers attempted to investigate various situations of carrying that are likely to represent real-life situations, whether it is two-hands or one-hand carrying, in front of the body or beside the body, or carrying a backpack.…”