Spinal Shrinkage Research Articles

Using “spinal shrinkage” as a trigger for motivating students to learn about obesity and adopt a healthy lifestyle

Obesity is a global problem; however, relatively little attention is directed toward preparing and inspiring students of medicine and allied medical sciences to address this serious matter. Students are not routinely exposed to the assessment methods for obesity, its overall prevalence, causative factors, short- and long-term consequences, and its management by lifestyle modification. This physiology laboratory exercise involving students of medicine (n = 106) was developed to 1) introduce medical students to methods of obesity assessment and to differentiate between general and abdominal obesity, 2) generate an interest and sensitivity about obesity, and 3) stimulate thinking about modification of their lifestyle in relation to eating habits, weight control, and physical activity. Spinal shrinkage (the difference between the standing height of a person and his/her recumbent length) was used as an immediate observable parameter to demonstrate the effect of adiposity. Spinal shrinkage is recognized as an index of the compressive forces acting on the spine and is related to body mass index. A positive correlation (r = 0.365, P < 0.05) was observed between body mass index and spinal shrinkage. A questionnaire was used to assess student responses to this exercise. Students were motivated to engage in more physical activity (74%), adopt healthier eating (63%), and enhance their knowledge about obesity (67%). They expressed keen interest in the laboratory exercise and found the sessions enjoyable (91%). The laboratory exercise proved to be a success in motivating the students to actively learn and inquire about obesity and to adopt a healthier lifestyle.

Effects of Type of Work and Age on Spinal Shrinkage

Spinal shrinkage has been confirmed to be a result of loads imposed on the human spine. The present study was aimed at studying the effects of different types of work on spinal shrinkage. Moreover, the relationship between age and spinal shrinkage was also studied. The heights just before the start and after the close of work were measured in order to determine the spinal shrinkage. The study confirmed that there was no correlation between age and spinal shrinkage at 5% level of significance. It also confirmed that significant differences (at 5% level of significance) exist between spinal shrinkages due to heavy and light workloads. This suggests that inter individual variation in spinal shrinkage may be as a result of the types of work undertaken. Keywords: Spinal shrinkage, Spine, age, workloads, visco-elasticity. Journal of Applied Science, Engineering and Technology Vol. 6 (1) 2006 pp. 8-15

Static and dynamic postural loadings during computer work in females: Sitting on an office chair versus sitting on an exercise ball

Seated computer work results in prolonged static loading, which has been associated with the development of musculoskeletal disorders. A popular alternative to sitting on an office chair while performing computer work is to sit on an exercise ball. Sitting on an exercise ball might affect static and dynamic aspects of working posture. We monitored posture, muscle activation and spinal shrinkage in 10 females performing a 1-h typing task, while sitting on an office chair with armrests and while sitting on an exercise ball. Sitting on an exercise ball resulted in 33% more trunk motion and in 66% more variation in lumbar EMG. Both of these findings can be considered to be an advantage for the exercise ball. However, the fifth percentile and average lumbar EMG were also higher when sitting on an exercise ball, with 38% and 78%, respectively. In addition, more spinal shrinkage occurred when sitting on an exercise ball than when sitting on an office chair. Arm flexion was reduced, but trapezius activation was unaffected when sitting on an exercise ball. It is concluded that the advantages with respect to physical loading of sitting on an exercise ball may not outweigh the disadvantages.

Under-arm partial body weight unloading causes spinal elongation and vibration attenuation during treadmill walking

Whilst exercise is beneficial to those suffering from low back pain (LBP), spinal shrinkage and vibration during walking may aggravate the condition. This study investigates the effects of spinal unloading, by means of body-weight unloading (BWU), on spinal length and vibration response. Under-arm partial BWU (40% of bodyweight) was performed on 8 healthy males whilst walking on a treadmill for 1 h, and compared to a control condition in the same participants. Motion analysis was used to track four reflective markers attached to the spine between C7 and the lumbar concavity at 100 Hz, in 7 s samples at regular intervals during the walk. A quintic polynomial was fitted to the coordinates in the sagittal plane, and sub-sectioned into three regions: the upper thoracic (UT), lower thoracic (LT) and upper lumbar (UL). The lengths of the curves were analysed in the time and frequency domains. The length of the spine increased by 4 ± 2% (18 mm) during the unloading condition with all regions showing an increase in length. The UL and LT regions lost length in the control condition, thereby exhibiting a significant interaction between unloading and time on region length (both P < 0.05). In addition, compared to the control condition, the frequencies of the length changes were attenuated between 3 and 6 Hz with unloading. Therefore, under-arm BWU facilitates spinal elongation, attenuates the frequency response of the spine in its resonant frequency regime and thus has potential benefits to the LBP population.

Sitting versus standing: Does the intradiscal pressure cause disc degeneration or low back pain?

Studies of lumbar intradiscal pressure (IDP) in standing and upright sitting have mostly reported higher pressures in sitting. It was assumed clinically that flexion of the lumbar spine in sitting relative to standing, caused higher IDP, disc degeneration or rupture, and low back pain. IDP indicates axial compressive load upon a non-degenerate disc, but provides little or no indication of shear, axial rotation or bending. This review is presented in two main parts. First, in vivo IDP data in standing and upright sitting for non-degenerate discs are comprehensively reviewed. As methodology, results and interpretations varied between IDP studies, in vivo studies measuring spinal shrinkage and spinal internal-fixator loads to infer axial compressive load to the discs are also reviewed. When data are considered together, it is clear that IDP is often similar in standing and sitting. Secondly, clinical assumptions related to IDP in sitting are considered in light of basic and epidemiologic studies. Current studies indicate that IDP in sitting is unlikely to pose a threat to non-degenerate discs, and sitting is no worse than standing for disc degeneration or low back pain incidence. If sitting is a greater threat for development of low back pain than standing, the mechanism is unlikely to be raised IDP.

SPINAL SHRINKAGE UNDER LOADING - A NOVEL APPROACH USING SURFACE BACK CONTOUR ANALYSIS STEREOPHOTOGRAMMETRY

Exposure of the body to impact loads has been associated with spinal shrinkage, and several studies have investigated changes due to loading on stature and specifically spinal shrinkage. Currently the instrument of choice is the stadiometer, which has proven to be cumbersome, requiring patient or subject training, thereby limiting its compliance and use in the work place, sports field or clinic. The two-dimensional, static nature of stadiometer measurement also eliminates the ability to measure the effect of change of posture on spinal shrinkage. The other choice is planar or multi-axial X-ray, which has its obvious limitations. In a contact sport like rugby union, there is growing evidence of spinal degeneration in both the lumbar and cervical spines, particularly those involved in the 'tight' positions in the scrum. These players are exposed to moderately high and relatively sustained forces of up to a third of a tonne on front-row players [1] that are coupled with torsional and lateral shearing. Insidious onset non-specific back pain is also reported in triathletes [2], cricket bowlers [3], and ultra-endurance athletes [4]. However, surprisingly little is known about spinal shrinkage or postural change in athletic performance, and its role in the development of clinical symptoms.

Effects of loading on spinal shrinkage in males of different age groups

A reduction in stature (shrinkage) has been used as a measure of the load on the spine. Musculoskeletal effects of ageing may influence individual responses to compressive loading on the spine and the resultant loss in stature. The aim was to apply the technique of precision stadiometry for assessment of spinal shrinkage in a comparison of responses of two different age groups performing a regimen of circuit weight training. In all, 20 subjects (10 aged 18–25 and 10 aged 47–60 years) participated in the study. Each performed two sets of a 12-station circuit of exercises, the loading being established relative to individual capabilities. Recovery procedures using a semi-supine posture intervened between the two sets and again post-exercise; altogether seven measures of change in stature were obtained using precision stadiometry. The two groups showed a similar pattern of spinal shrinkage, losses in stature being greater for the first set compared to the later set of exercises. Subjects gained height whilst in the formal recovery posture, but responses were inconsistent during warm-up, cool-down and active recovery. Irrespective of age, the spine was less responsive to loading as the duration of activity was increased. It was concluded that provided loading is related to individual capability, healthy older operators are not necessarily compromised by their age in activities that include handling and lifting weights.

Body mass as a factor in stature change

Back pain is a common condition which has been described as a serious public health problem. Spinal shrinkage has been used as an index of spinal loading in a range of tasks. Epidemiological evidence shows that body mass index (BMI: 30 kg/m(2)) is related to the development of low back pain however, no studies have described the stature change patterns of obese individuals. This study aimed to compare changes in stature after an exercise task in obese and non-obese individuals. Twenty volunteers were divided into two equal groups; obese: BMI>30 kg/m(2), non-obese: BMI<25 kg/m(2). Stature was measured at 3 min intervals during a 30 min walking task and a 30 min standing recovery period. Tests were performed on two occasions, once with participants loaded during the walking task (10% body mass) and once unloaded. The influence of obesity and load condition on the magnitude and rate of stature change were compared by a two-way ANOVA: In both groups the stature loss was greater in the loaded than unloaded condition (mean (SD)) (6.52 (1.45)mm and 3.55 (0.93)mm non-obese; 8.49 (1.75)mm and 7.02 (1.32)mm obese: P=0.016). The obese presented a greater reduction in stature in both task conditions. The obese group were unable to recover stature regardless of the task condition during the recovery period (loaded: 0.06 (0.3)mm; unloaded: 0.32 (0.6)mm; P=0.013). It was concluded that the acute response of the spine to loading may represent a risk factor for low back pain in the obese, in addition to the chronic adaptations previously reported. A greater period of recovery may be necessary for obese individuals to re-establish intervertebral disc height. These findings may help to explain the high incidence of back disorders in obese individuals.

7.14 Modulations of anticipatory postural adjustment (apa) associated with different heel-up movements and with different standing postures

Studies of lumbar intradiscal pressure (IDP) in standing and upright sitting have mostly reported higher pressures in sitting. It was assumed clinically that flexion of the lumbar spine in sitting relative to standing, caused higher IDP, disc degeneration or rupture, and low back pain. IDP indicates axial compressive load upon a non-degenerate disc, but provides little or no indication of shear, axial rotation or bending. This review is presented in two main parts. First, in vivo IDP data in standing and upright sitting for non-degenerate discs are comprehensively reviewed. As methodology, results and interpretations varied between IDP studies, in vivo studies measuring spinal shrinkage and spinal internal-fixator loads to infer axial compressive load to the discs are also reviewed. When data are considered together, it is clear that IDP is often similar in standing and sitting. Secondly, clinical assumptions related to IDP in sitting are considered in light of basic and epidemiologic studies. Current studies indicate that IDP in sitting is unlikely to pose a threat to non-degenerate discs, and sitting is no worse than standing for disc degeneration or low back pain incidence. If sitting is a greater threat for development of low back pain than standing, the mechanism is unlikely to be raised IDP.

Relationship between everyday activities and spinal shrinkage

Background. Purpose of this study was to determine the spinal shrinkage in several activities of daily life and to assess a relationship with intradiscal pressure during these activities. Low back pain is thought to be related to spinal load. In a clinical evaluation of low back pain as provoked by everyday activities, we found a relationship between the amount of complaints during static activities and intradiscal pressure. However, because invasive intradiscal pressure measurements during dynamic activities like walking and cycling are complicated and hardly done before, an analogue relationship between low back complaints and dynamic activities is lacking. Methods. Therefore spinal load was ascertained by stadiometric measurement of the decrease in standing height, so-called “spinal shrinkage”, quantified by the exposure of a 1-h adopted posture or activity. Ten subjects performed five daily life activities: standing, sitting, walking, cycling and lying down. Findings. By doing different activities during 1 h, immediate after getting up in the morning, following average values for shrinkage were measured: standing −7.4 mm (SD 0.5); sitting −5.0 mm (SD 0.6); walking −7.9 mm (SD 0.5); cycling −3.7 mm (SD 0.4) and lying down +0.4 mm (SD 0.5). Interpretation. Overall, good correlation was found between spinal shrinkage and intradiscal pressure. The use of spinal shrinkage measurement seems a good alternative for intradiscal pressure measurement in static situations, but is still questionable in dynamic situations.

Spinal shrinkage and recovery in women with and without low back pain

Fowler NE, Rodacki CdeL, Rodacki AL. Spinal shrinkage and recovery in women with and without low back pain. ObjectivesTo assess the behavior of the spinal column after loading in participants with and without low back pain (LBP) using spinal shrinkage measurements as a criterion and to analyze the relations among spinal shrinkage, recovery, and LBP. DesignA case-control study with repeated measures. SettingUniversity department with recruitment from primary care. ParticipantsConvenience sample of 31 women (15 with chronic, nondisabling LBP [LBP group]; 16 with no history of low back disorders [control group]). InterventionsNot applicable. Main outcome measureChanges in body length as determined by using a stadiometer. ResultsThe spinal shrinkage induced by the exercise was similar (P>.05) in both groups (control group, mean ± standard deviation of −3.99±1.13mm; LBP group, −4.16±1.54mm). Differences in spinal length were found after 20 minutes in the recovery position (P<.05). The control group was able to recover stature to a greater extent (111.2%±13.6%) than the LBP group (P<.05), which was unable to regain stature beyond baseline (57.5%±25.1%). A negative correlation was found between regaining stature and low back pain (r=−.52, P<.05). ConclusionsParticipants with LBP were unable to recover stature to the same extent as controls. We suggest that LBP is related to the diminished ability to recover rather than to the magnitude of the spinal shrinkage imposed during the task.

Associations between serum markers of collagen metabolism and spinal shrinkage

Objectives. To explore whether serum concentrations of the carboxyterminal propeptide of type I collagen and the carboxyterminal telopeptide region of type I collagen as biomarkers of the metabolic condition of spinal tissues are associated with spinal shrinkage as a measure of tissue response to physical loading. Design. Association of biomarker concentrations in blood and spinal shrinkage in healthy young nurses. Background. Certain biomarkers of type I collagen metabolism may be considered potential instruments to assess the biochemical condition of spinal tissues and alterations thereof in response to physical loading. Correlation of the serum concentrations of the biomarkers with spinal shrinkage, as a measure of the response of spinal tissues to physical loading, provides information on the validity of the biomarkers. Methods. Concentrations of biomarkers of type I collagen synthesis and degradation have been monitored during a period of six months in 25 young nurses. Spinal shrinkage was assessed on a representative working day and related to shrinkage on a rest day. Results. Larger relative spinal shrinkage was associated with a lower rate of collagen turnover and a higher relative synthesis. Conclusions. These results support the assumption that biomarkers of type I collagen metabolism are associated with structural and material properties of spinal tissues. Relevance Assessment of the response to physical loading at the level of biochemical and compositional changes in tissues will enhance the understanding of the associations between exposure to physical load factors and back disorders. In this paper, the validity of potential biomarkers to assess these tissue changes is explored.

Stature loss and recovery in pregnant women with and without low back pain

Rodacki CL, Fowler NE, Rodacki AL, Birch K. Stature loss and recovery in pregnant women with and without low back pain. Arch Phys Med Rehabil 2003;84:507-12. Objectives: To assess the loss of stature and its recovery in normal and pregnant women with and without low back pain (LBP) and to examine the relations between spinal shrinkage, recovery, and LBP. Design: Stature changes were measured before and after physical activity in each group and differences in response compared between groups. Setting: A laboratory environment. Participants: Thirty-one women (7 pregnant without LBP, 8 pregnant with LBP, 16 nonpregnant with no history of low back disorders) were recruited using convenience sampling. Controls were recruited from the general community; subjects in the pregnant groups were recruited from local primary care groups. Interventions: Not applicable. Main Outcome Measures: Stature change was assessed as the main outcome measure. Changes in stature were interpreted with respect to the woman[apos]s stature at the start of the trial. Results: Stature loss induced by a moderate physical activity was similar ( P[gt].05) in all groups (control, [minus]3.99[plusmn]1.13mm; pregnant no back pain, [minus]4.23[plusmn]1.23mm; pregnant with back pain, [minus]4.57[plusmn]1.53mm). Differences were found after 20 minutes in a recovery position ( P[lt].05): the controls were able to recover stature to a greater extent (111.2%[plusmn]13.6%) than the other groups ( P[lt].05). A negative correlation was found between regain in stature and LBP in pregnant subjects ( r[equals][minus].81, P[lt].05). Conclusions: The pregnant women with LBP were unable to recover stature to the same extent as the controls and pregnant women without LBP. Results suggest that LBP in pregnancy may be related to the woman[apos]s diminished ability to recover, rather than the magnitude of the spinal shrinkage imposed during the task.

Head posture and loading of the cervical spine

Calculations by Colombini et al. (Ergonomics of Working Postures. Taylor & Francis, London, 1985) showed that a line of gaze below the horizontal would load the cervical spine more than a horizontal gaze. Precision stadiometer tests were run, using seven subjects, to measure the effects on spinal length of different angles of gaze. After 1 h exposure whilst sitting in a controlled posture, there were significant differences in the shrinkage of the spine between the horizontal gaze and the 20° and 40° angles below the horizontal. The increased spinal loading demonstrated by the increase in spinal shrinkage calls into question the recommendations for angle of gaze recommended in textbooks.

Spinal shrinkage during a seated break and standing break during simulated nursing tasks

Prevalence rates for back pain in nurses are comparable to rates of workers in heavy industry. Spinal loading is one factor thought to be associated with the onset of back problems (Spine 9(2) (1984) 189). Loading can be measured indirectly using precision stadiometry, with changes in stature indicating the magnitude of the loading over time. Ten female subjects completed 4 h of simulated nursing activities on two separate occasions. The two trials were identical except that subjects were asked to sit for a 20-min break in one and stand for a 20-min break in the other trial. Heart rate, discomfort, rating of perceived exertion and spinal shrinkage were recorded at various intervals throughout testing. Spinal shrinkage was significantly less during the seated trial than the standing trial ( p<0.05). It is suggested that a seated break during a nursing shift may reduce the potential of suffering back problems resulting from spinal loading.

Effects of dynamic office chairs on trunk kinematics, trunk extensor EMG and spinal shrinkage

Effects of dynamic office chairs on trunk kinematics, trunk extensor EMG and spinal shrinkage

Effects of dynamic office chairs on trunk kinematics, trunk extensor EMG and spinal shrinkage

Seated work has been shown to constitute a risk factor for low-back pain. This is attributed to the prolonged and monotonous low-level mechanical load imposed by a seated posture. To evaluate the potential health effects with respect to the low back of office chairs with a movable seat and back rest, trunk kinematics, erector spinae EMG, spinal shrinkage and local discomfort were assessed in 10 subjects performing simulated office work. On three separate occasions subjects performed a 3 h task consisting of word processing, computer-aided design and reading. Three chairs were used, one with a fixed seat and back rest and two dynamic chairs, one with a seat and back rest movable in a fixed ratio with respect to each other, and one with a freely movable seat and back rest. Spinal shrinkage measurements showed a larger stature gain when working on the two dynamic chairs as compared with working on the chair with fixed seat and back rest. Trunk kinematics and erector spinae EMG were strongly affected by the task performed but not by the chair type. The results imply that dynamic office chairs offer a potential advantage over fixed chairs, but the effects of the task on the indicators of trunk load investigated were more pronounced than the effects of the chair.

Spinal shrinkage during repetitive controlled torsional, flexion and lateral bend motion exertions

This experiment analysed the spinal shrinkage due to repetitive exertions confined to each of three separate axes (twist, lateral bend, flexion). While the experiment was performed twice with small technique modifications in the twisting task (and thus two data collections were performed), the essential components were as follows. A total of 20 subjects were loaded with an equal moment of 20 Nm in each of the three axes, on 3 separate days (one axis per day). Subjects performed each task for 20 min at 10 repetitions min-1, where stadiometer measurements of standing height were taken prior to and immediately following the 20 min exertion. The twisting task demonstrated significant spinal shrinkage (1.81 and 3.2 mm in the two experiments) between the pre- and post-stature measurements while no clear effect emerged for the other two tasks. These data suggest that repetitive torsional motions impose a larger cumulative loading on the spine when compared with controlled lateral or flexion motion tasks of a similar moment.

Effects of activity-rest schedules on physiological strain and spinal load in hospital-based porters

Workers in physically demanding occupations require rest breaks to recover from physiological stress and biomechanical loading. Physiological stress can increase the risk of developing musculoskeletal disorders and repeated loading of the spine may increase the potential for incurring back pain. The aim of the study was to assess the impact of an altered activity-rest schedule on physiological and spinal loading in hospital-based porters. An existing 4-h activity-rest schedule was obtained from observations on eight male porters. This schedule formed the normal trial, which included two 5- and one 15-min breaks. An alternative 4-h schedule was proposed (experimental condition) that had two breaks each of 12.5 min. It was hypothesized that the experimental trial is more effective in promoting recovery from physiological strain and spinal shrinkage than the normal trial, due to the 5-min breaks being insufficient to allow physiological variables to return to resting levels or the intervertebral discs to reabsorb fluid. Ten males performed both test conditions and oxygen uptake VO2, heart rate, minute ventilation VE, perceived exertion and spinal shrinkage were recorded. There were no significant differences in any of the measured variables between the two trials (p >0.05). Median heart rates were 78 (range 71–93) and 82 (71–90) beats.min - 1 for the normal trial and the experimental trial respectively, indicating that the activity was of low intensity. The light intensity was corroborated by the oxygen uptakes (0.75, range 0.65-0.94 l.min - 1. Spinal shrinkage occurred to the same extent in the two trials (2.12±3.16 mm and 2.88±2.92 mm in the normal trial and the experimental trial respectively). Varying the length and positioning of the rest breaks did not significantly affect the physiological responses or magnitude of spinal shrinkage between the two trials. More physically demanding work than the porters' schedule should induce greater physiological fatigue and spinal shrinkage. The ratio between activity and rest breaks would then become more important.

Stadiometer Measurements of Driver'S Spinal Response to Steering Force and Vibration

The effects on spinal loading of two aspects of the driving task - force exertion while steering and exposure to 4 Hz 1ms−2 peak vertical seat vibration - were investigated with a group of six male subjects seated in a driving simulator. In addition, the effect of the combination of the two aspects was tested. Spinal shrinkage was measured with a precision seated stadiometer over a 40 minute period. Analysis of variance showed that both steering actions and vibration had a significant effect on spinal loading (p&lt;0.05 and p&lt;0.025 respectively), even though the steering torque (5Nm) was moderate. The response was significantly greater in all three experimental conditions than in static sitting (in the same posture). There appeared to be a tendency for the mean spinal shrinkage to increase from 6.0 mm when steering to 7.1mm under vibration and 8.7mm when steering and vibration were combined, but the only difference which was statistical significant was that between the combined condition and steering alone (t test, p&lt;0.01).