Spinal Shrinkage Research Articles

Spinal shrinkage with three different types of chair whilst performing video display unit work

The aim of the study was to investigate the magnitude of spinal shrinkage during video display unit (VDU) work when subjects were sitting on chairs with different design with forward-sloping seats with or without backrest, armrest or knee support and when using a conventional chair with horizontal seat. Three different chairs were investigated: A “Conventional chair” with horizontal seat, B “Ullman chair” with front half of seat sloping forward and back half horizontal, and C “Balans chair” with forward-sloping seat plus knee support. Eight healthy subjects used to professional VDU work volunteered to participate in this field study, which was performed at their own workplaces. The median shrinkage after a three-hour period was 1.3, 1.8 and 3.1 mm for chairs A, B and C, respectively. All subjects shrank more (p < 0.05) when sitting on the chair with knee support (C) than when sitting on the conventional chair. There was no statistically significant difference in shrinkage between chairs A and B, or between chairs B and C.

Posture, acceptability and energy consumption on a tiltable and a knee-support chair

Sitting postures on a knee-support (Balans®) chair and a tiltable chair were investigated with 12 healthy subjects during office work and simulated assembly work. After at least 3 weeks' adaptation to each chair, the subjects were investigated for 1 hour on each chair in stratified sequence. Postures were evaluated by means of a statometric method. Spinal load was further estimated by measuring stature shrinkage over each sitting period. Energy consumption was roughly assessed by pulse measurements. Finally, subjective acceptability was rated by a 5-point scale. Posture effects of the Balans® chair, taken in relation to the tiltable chair, were primarily a forward tilt of the pelvis and a change toward lumbar lordosis. Secondly, the trunk was vertical compared to the slightly backward-inclined position in the tiltable chair. The head was most vertical in the Balans® chair. No effect on spinal shrinkage or pulse was observed. The subjective rating seemed to favour the tiltable chair if used over longer periods. However, the Balans ® chair may be a good alternative for some seated periods and special tasks.

Spinal shrinkage in females: circadian variation and the effects of circuit weight-training : Wilby J, Linge K, Reilly T, Troup JDG. Ergonomics 1987; 30: 47–54

Spinal shrinkage in females: circadian variation and the effects of circuit weight-training : Wilby J, Linge K, Reilly T, Troup JDG. Ergonomics 1987; 30: 47–54

Spinal loading during circuit weight-training and running : Leatt P, Reilly T, Troup JDG. Br J Sports Med 1986;20: 119–124

Spinal shrinkage wasusedasanindicant ofloading onthespine incircuit weight-training andrunning regimes. Theloss of stature during twosetsofacircuit ofweight-training (n= 10), a6kmrunbynovices (n=9)anda-25 kmrunbytrained runners (n= 7)wasassessed inmalesubjects. Shrinkage wasnotsignificantly different between theweight-training regime andthe 6kmrunbynovices, meanlosses being5.4and3.25mm respectively. Therate ofheight loss intheexperienced runners was 2.35mm over6kmrunat12.2km.h-1, representing 0.4mm.km-1overthe6kmrun,this shrinkage ratebeing continued over thelast 19kmrunat14.7km.h-1. Thelossofheight could notbepredicted fromasetofcovariates. Themagnitude ofthe circadian variation, mean14.4mm,exceeded thechange inheight during the25kmrun.Thediurnal variation conformed toa cosine function, though abetter fit wasobtained withapowerfunction equation. Amarkeddiurnal pattern wasalso observed inlumbarextension. Thoughreversal ofspinal shrinkage wasobserved during anight's sleep, nosignificant recovery occurred during a20minresting period immediately following theexercise regimes. Theseresults haveimplications forthe warm-upandtiming ofexercise regimes thatimpose significant loading onthespine.

Spinal shrinkage in females: circadian variation and the effects of circuit weight-training.

Compressive loading of the spine leads to spinal shrinkage and a loss of stature. The aim of this study was to measure the circadian variation in the stature of females and to examine differential effects of spinal loading with the time of day. Ten females aged 20–30 years were studied in nine measurements on a 24-hour period. Between rising and retiring to bed, the mean peak-to-trough variation was 15·4 mm (0·92% of stature). Subjects underwent two sequences of 20 min circuit-training with weights, followed by 20 min reclining in Fowler's position and 20 min standing erect, these being first thing in the morning after 7 hours of sleep and before retiring at midnight. Mean loss of height from circuit-training was 5·4 mm in the morning and 4·3 mm in the evening (P < 0·001): mean height regained in Fowler's position was 4·5 mm and 3·4 mm respectively (P<0·05). There were significant height losses in the subsequent standing posture but no time of day effect. Height losses with exercise were related to the is...

Spinal loading during circuit weight-training and running.

Spinal shrinkage was used as an indicant of loading on the spine in circuit weight-training and running regimes. The loss of stature during two sets of a circuit of weight-training (n = 10), a 6 km run by novices (n = 9) and a 25 km run by trained runners (n = 7) was assessed in male subjects. Shrinkage was not significantly different between the weight-training regime and the 6 km run by novices, mean losses being 5.4 and 3.25 mm respectively. The rate of height loss in the experienced runners was 2.35 mm over 6 km run at 12.2 km.h-1, representing 0.4 mm.km-1 over the 6 km run, this shrinkage rate being continued over the last 19 km run at 14.7 km.h-1. The loss of height could not be predicted from a set of covariates. The magnitude of the circadian variation, mean 14.4 mm, exceeded the change in height during the 25 km run. The diurnal variation conformed to a cosine function, though a better fit was obtained with a power function equation. A marked diurnal pattern was also observed in lumbar extension. Though reversal of spinal shrinkage was observed during a night's sleep, no significant recovery occurred during a 20 min resting period immediately following the exercise regimes. These results have implications for the warm-up and timing of exercise regimes that impose significant loading on the spine.