Spinal Shrinkage Research Articles

Cadence matters: Influence of cadence on spinal load during running

BackgroundRunning exposes the body to physiological and mechanical stresses that generate musculoskeletal injuries, such as low back pain due to large spinal loading. Increasing running cadence may reduce impact forces and spinal shrinkage. Research questionThis study aimed to determine the relationship between spinal loading and running cadence. MethodsThis cross-sectional study included 15 runners from the local community (36 ± 11 years; 23 ± 2 kg.m−2, and 8 ± 9 years of running experience) who ran for 30 min (R30) and 60 min (R60) at a constant speed (10 km.h−1). The spinal loading was assessed via fine stature variation measurements before the run (baseline) at R30 and R60. Cadence was monitored via a wristwatch. The cadence ranged from 150 to 180 steps.min−1. A t-test was used to compare stature loss between R30 and R60 (relative to baseline), and a stepwise linear regression equation was used to identify the relationship between cadence and stature variation in each instant. ResultsThere was a stature loss throughout the race (R30 = 5.27 ± 1.92 mm and R60 =7.51 ± 2.51 mm). A linear regression analysis revealed a negative relationship between stature loss and cadence, indicating that running at a faster cadence produces smaller spinal loading than running at slower cadences after R60 (R2 = 0.38; p<0.05). SignificanceIncreasing running cadence might cause less spinal loading than running with a slower cadence, which may reduce the risk of injury and back disorders in runners.

The effect of low back pain on neuromuscular control in cyclists

ABSTRACT This study was designed to identify neuromuscular adaptations of low back pain (LBP) cyclists , and the impact of a cycling effort on spinal shrinkage. Forty-eight trained cyclists rode their road bike on a smart trainer for 1-hour. Surface electromyography (EMG) recorded muscle activity of the lumbar erector spinae (LES), 3D motion analysis system recorded kinematic of the trunk, and stadiometry measured spinal height. Statistical comparisons were made using repeated measure ANOVAs. The LBP group presented increase in pain levels throughout the effort (p < 0.001). A significant group difference was only observed for the thoracic angle (p = 0.03), which was less flexed for LBP. The one-hour cycling effort (time effect) significantly increased the trunk flexion (p < 0.001) and thoracic flexion (p < 0.001) for both groups. Significant lower LES activation (35% less) was observed at the end of the effort as well as a decrease in spinal height (p = 0.01) for both groups. Neuromuscular adaptations to cycling effort is identified by a decrease in LES EMG amplitude and an increase flexion of the trunk. Adaptation to pain is seen by an increase in thoracic flexion. Despite these adaptations, LBP cyclists could not ride their bike pain-free.

Use of a Spinal Traction Device during Work Shift in Assembly Line Workers.

Increasing back discomfort and spinal shrinkage during the workday is a problem that affects assembly line workers. The aim of this research was to analyze the effect of a spinal traction system on discomfort, spinal shrinkage, and spinal sagittal alignment in assembly line workers, who are in prolonged standing conditions during a workday. A total of 16 asymptomatic males were recruited to assess spinal shrinkage, spinal sagittal alignment, and back discomfort during the workday. The measurement was carried out in two days of work, a normal day, and the other using a spinal traction device utilized in two breaks during the workday. Assembly line workers lost height significantly on both control and intervention days. No differences were found between days. No changes were found in spinal sagittal alignment on the control day. Lumbar lordosis angle increased significantly at the end of the intervention day. The use of a spinal traction device during the workday in two breaks time did not significantly reduce the spinal shrinkage of healthy workers. Lumbar lordosis angle increased significantly at the end of the spinal traction intervention day. Prospective studies would be necessary to clarify the possible benefits of the traction device.

A cross-sectional analysis of the muscle strength, spinal shrinkage, and recovery during a working day of military police officers.

ObjectiveMilitary personnel has a large prevalence of back pain, especially those involved in patrolling routines, as they wear heavy protective equipment. Patrolling includes long periods of sustaining the protective equipment in a sitting or in a motor vehicle (motorcycle or car). Thus, understanding spinal loading of military police officers after patrolling by car (CAR; n = 14), motorcycle (MOT; n = 14), and administrative (ADM; n = 14) routines is relevant to establish preventive strategies.MethodsThe torque of the trunk and working and anthropometric characteristics were assessed to explain spinal loading using stature variation measures. Precise stature measures were performed before and after a 6 h journey (LOSS) and 20 min after a resting posture (RECOV). The trunk extensor (PTE BM−1) and flexor (PTF BM−1) muscles' isometric peak torque were measured before the working journey.ResultsThe LOSS was similar between CAR and MOT (4.8 and 5.8 mm, respectively) after 6 h of patrolling. The ADM presented the lowest LOSS (2.8 mm; P < .05). No changes in RECOV between groups were observed (P > .05). Vibration may explain the greater spinal loading involved in patrolling in comparison to the ADM. A GLM analysis revealed that BMI was the only explanatory factor for stature loss. No independent variables explained RECOV. The ability of the trunk muscles to produce force did not influence LOSS or RECOV.ConclusionsMilitary police officers involved in patrolling may require greater post‐work periods and strategies designed to reduce the weight of the protective apparatus to dissipate spinal loading. The external load used in patrolling is a relevant spinal loading factor.

Spinal sagittal alignment, spinal shrinkage and back pain changes in office workers during a workday

Purpose. Prolonged sitting is a risk factor for the appearance of lower back pain during work. The aim of this study was to observe changes in spinal sagittal alignment, height and the perception of back pain in office workers during a workday. Materials and methods. Forty-one office workers (20 women) were enrolled into a cross-sectional study. Height, sitting height and degrees of thoracic kyphosis and lumbar lordosis as well as perceived neck pain, lower back pain and upper back pain were determined, before and after an 8-h workday. Results. At the end of the day, workers had a significant decrease (p = 0.000) in height and sitting height, and upper back pain increased significantly (p = 0.023). In men, spinal shrinkage correlated with neck pain (r = 0.410, p = 0.027), and lumbar lordosis degrees in women correlated negatively with upper back pain at the end of the day (r = −0.440, p = 0.012). Conclusions. Spinal shrinkage equally affects men and women who perform the same work. There are no changes in spinal sagittal alignment throughout the workday in office workers. Office workers show significantly increased pain in the upper back at the end of the day.

Spinal shrinkage, sagittal alignment and back discomfort changes in manufacturing company workers during a working day

Prolonged standing and lifting heavy loads are risk factors for the appearance of low back pain in work. The aim of this study was to observe changes in the height, spinal sagittal alignment, and the lumbar and dorsal discomfort perception in assembly line workers. Cross-sectional study, 40 assembly line workers (6 females). Height, sitting height, grades of thoracic kyphosis and lumbar lordosis and perceived spine discomfort, before and after the working day, were determined. Thoracic and lumbar sagittal alignment was compared between discomfort developers and no developers. There was a significant decrease in the height and sitting height of the workers at the end of the day. Thoracic and lumbar curvature increased significantly, as did the perceived lumbar discomfort. Workers on the assembly line, in a prolonged standing work, suffer an increase in lumbar discomfort, and changes in height and thoracic and lumbar curvatures. Practitioner summary: Spinal shrinkage, sagittal alignment and back discomfort (upper and lower back), were analysed in assembly line workers in prolonged standing during a workday. Assembly line workers suffer a decrease in height, an increase in their thoracic and lumbar curvature, and in lumbar discomfort throughout their workday.

Spinal Shrinkage Response to Shoulder Loading Posture

The aim of this study is to investigate effects of shoulder loading posture on spinal shrinkage. Twenty two university students (including five women and seventeen men) participated in the study. Each performed 10 min static standing with a load of 20% body weight on shoulder in two loading postures: front and back loading. One-way ANOVA was utilized to test the effect of loading posture. It was found that the loading posture has a significant effect on spinal shrinkage. The shrinkage in front posture is significantly larger than that in back one. It was suggested that the front loading posture could be more likely to developing LBP than the back posture during prolonged compressive loading.

An investigation into four different sit–stand workstation use schedules

Twelve office workers participated in a study investigating effects of four sit/stand schedules (90-min sit/30-min stand, 80/40, 105/15, and 60/60) via several objective and subjective measures (muscle fatigue, foot swelling, spinal shrinkage, and self-reported discomfort). Results showed that there were no significant differences in shoulder and low back static muscle activities between sitting and standing. Muscle fatigue was developed during workday under all schedules. The longest standing schedule seemed to have a tendency of reducing muscle fatigue. None of the schedules helped or worsened foot swelling and spinal shrinkage. More active break-time activities seemed reducing muscle fatigue and foot swelling. While the self-reported bodily discomfort levels were generally low, the preferred schedules among the participants were varied, although the least standing schedule was the least preferred. We may conclude that effects of using sit–stand workstation to improve musculoskeletal health may be limited but promoting more active break-time activities can help.Practitioner Summary: Sit–stand workstations are used to reduce work-related musculoskeletal disorders. This study shows that office workers prefer sit/stand durations in the range between 1:1 and 3:1. Longer standing may have the potential to reduce muscle fatigue. However, active break-time activities may be more effective in reducing muscle fatigue and foot swelling.

Assessment of Physiological Health Status in Relations to Different Anthropometric and Cardio-Respiratory Measures of Head-Supported Load Carrying Male Porters of Sikkim, India

Background: Carrying heavy loads in the hilly region, porters face extreme ranges in terrain condition, sloped path that is very steep and lack of oxygen due to altitude. The porters in Sikkim, India, routinely carry head-supported loads, which often exceed their body weight, over long distances up and down the steep mountain footpaths which prompted us to assess occupational health status of these head supported load carrying porters. Objective: We aimed our study to evaluate physical and physiological status of male porters of Gangtok, Sikkim. Methods: Seventeen male porters and twenty one healthy as well as age matched (Age: 37 – 52 years) control subjects were selected for the study. Different physical, anthropometric and physiological parameters were studied. Students “t” test was performed to find out the significant difference (P less than 0.05), if any, between the selected variables. Results: Results of this study on male porters suggest that they are physically healthy but having spinal shrinkage along with lower hand grip strength and PEFR. Conclusion: This study supports the hypothesis that the male porters are associated with decreased lung function and increased spinal shrinkage. To develop an effective intervention strategy, the treatment seeking behavior of individuals would also need to be improved through awareness program

Safe backpack weight limit for secondary school students in Ibadan, Southwestern Nigeria

The aim of the study was to determine the safe limit of backpack weight that students in secondary schools should carry.This study considered a sample of 324 secondary school students (both boys and girls) that were randomly selected from both private and public secondary schools located in the city of Ibadan, the capital of Oyo State. A model was developed using strain energy principle of the spine in terms of chest width, chest depth, Young Modulus of Elasticity of articular cartilage, maximum permissible spinal shrinkage, length of spine and leg length of the students. The 5th, 50th, and 95th percentiles of the data obtained were computed using a SPSS 16.0 statistical package.The safe weight of backpack to be carried by male and female secondary students was 2.87kg (5.18% of body weight) and 2.53kg (4.91% of body weight) respectively.The study confirmed that the model may be used to determine the safe weight of backpack that should be carried out by the students.

Muscle activity patterns and spinal shrinkage in office workers using a sit–stand workstation versus a sit workstation

Reducing sitting time by means of sit–stand workstations is an emerging trend, but further evidence is needed regarding their health benefits. This cross-sectional study compared work time muscle activity patterns and spinal shrinkage between office workers (aged 24–62, 58.3% female) who used either a sit–stand workstation (Sit–Stand group, n = 10) or a traditional sit workstation (Sit group, n = 14) for at least the past three months. During one typical workday, muscle inactivity and activity from quadriceps and hamstrings were monitored using electromyography shorts, and spinal shrinkage was measured using stadiometry before and after the workday. Compared with the Sit group, the Sit–Stand group had less muscle inactivity time (66.2 ± 17.1% vs. 80.9 ± 6.4%, p = 0.014) and more light muscle activity time (26.1 ± 12.3% vs. 14.9 ± 6.3%, p = 0.019) with no significant difference in spinal shrinkage (5.62 ± 2.75 mm vs. 6.11 ± 2.44 mm). This study provides evidence that working with sit–stand workstations can promote more light muscle activity time and less inactivity without negative effects on spinal shrinkage.Practitioner Summary: This cross-sectional study compared the effects of using a sit–stand workstation to a sit workstation on muscle activity patterns and spinal shrinkage in office workers. It provides evidence that working with a sit–stand workstation can promote more light muscle activity time and less inactivity without negative effects on spinal shrinkage.

Recovery from Spinal Shrinkage

Recovery from Spinal Shrinkage

The effect of dynamic sitting on trunk muscle activation: A systematic review

The purpose of this systematic review was to investigate the effect of dynamic sitting on trunk muscle activation in sitting. Electronic databases were searched by two independent reviewers. Studies were included if they compared the effect of dynamic sitting on trunk muscle activation to a more static sitting condition. Seven studies were eligible for inclusion, six of which were rated as “high-quality” using the PEDro scale. Five studies reported no difference in trunk muscle activation. Two studies reported a difference in trunk muscle activation, yet this was associated with increased discomfort, increased fatigue and greater spinal shrinkage. Furthermore, the changes reported in these two studies may be more related to the absence of a backrest rather than dynamic sitting. Therefore, the findings of this review suggest dynamic sitting does not significantly change trunk muscle activation. No randomised clinical trials or longitudinal design studies were found which evaluated the effect of dynamic sitting on trunk muscle activation, limiting the ability to make definitive conclusions about causality. The implications of the results, and recommendations for future research, are discussed.

Does work stress make you shorter? An ambulatory field study of daily work stressors, job control, and spinal shrinkage.

Body height decreases throughout the day due to fluid loss from the intervertebral disk. This study investigated whether spinal shrinkage was greater during workdays compared with nonwork days, whether daily work stressors were positively related to spinal shrinkage, and whether job control was negatively related to spinal shrinkage. In a consecutive 2-week ambulatory field study, including 39 office employees and 512 days of observation, spinal shrinkage was measured by a stadiometer, and calculated as body height in the morning minus body height in the evening. Physical activity was monitored throughout the 14 days by accelerometry. Daily work stressors, daily job control, biomechanical workload, and recreational activities after work were measured with daily surveys. Multilevel regression analyses showed that spinal disks shrank more during workdays than during nonwork days. After adjustment for sex, age, body weight, smoking status, biomechanical work strain, and time spent on physical and low-effort activities during the day, lower levels of daily job control significantly predicted increased spinal shrinkage. Findings add to knowledge on how work redesign that increases job control may possibly contribute to preserving intervertebral disk function and preventing occupational back pain.

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

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. 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. 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). 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.

Flexion relaxation of erector spinae response to spinal shrinkage

The purpose of the study was to investigate the effect of spinal shrinkage on the characteristic of flexion relaxation phenomenon in erector spinae muscle. Twelve male university students volunteered for this study. The spinal shrinkage was created with a load of 20% body weight on shoulder in 10min. Each performed three trials of lumbar flexion–extension with the cycle of 5s flexion and 5s extension in standing before and after shrinkage. Surface electromyography from right erector spinae muscle as well as trunk flexion performance was recorded synchronously in video camera. A one-way ANOVA with repeated measures was used to evaluate the effect of shrinkage. The results showed that there was a significant (p<0.001) stature change with mean magnitude of shrinkage 5.9mm. The erector spinae was active through a significantly larger angle during flexion and began activity significantly earlier during extension after shrinkage. It was concluded that shrinkage caused by prolonged compressive loading will elicit the change of flexion relaxation characteristic, which may be closely related to low back disorder.

Change in spine height measurements following sustained mid-range and end-range flexion of the lumbar spine

Workers lose height during the day. Flexion-based exercises and body positions are commonly prescribed to unload the spine and prevent back pain. Lumbar extension positions have been researched and result in an increase in spine height. End-range lumbar extension postures increase spine height to a greater extent than mid-range lumbar extension postures, but these positions are not always tolerated by patients with lumbar conditions. No study to date has investigated the effect of end-range versus mid-range lumbar flexion postures on spine height changes. The purpose of this study was to investigate the effects of two techniques commonly used in clinical settings to unload the lumbar intervertebral disc (IVD) segments through increasing spine height in: (1) a sidelying mid-range lumbar flexion position; and (2) a sidelying end-range lumbar flexion position. A total of 20 asymptomatic women and 21 asymptomatic men with a mean age of 23.8 years (±2.5) participated in the study. Subjects were randomized systematically into 2 groups to determine the order of testing position. Measurements were taken with a stadiometer in the sitting position to detect change in spine height after each position. Results of the paired t-tests indicated that compared to the spine height in sitting, the sidelying end-range lumbar flexion position resulted in a statistically significant ( p < .001) mean spine height gain of 4.78 mm (±4.01) while the sidelying mid-range lumbar flexion position resulted in a statistically significant ( p < .001) mean spine height gain of 5.84 mm (±4.4). No significant difference between the height changes observed following the two sidelying positions was found ( p = .22). Sidelying lumbar flexion positions offer valuable alternatives to lumbar extension positions to increase spine height, possibly through increasing hydration levels of the lumbar IVD and could be proposed as techniques to offset spinal shrinkage and the biomechanical consequences of sustained loads.

Change in stature by walking and running at a preferred transition speed

This study aimed to measure stature changes during and after walking and running at a preferred transition speed (PTS) and the recovery period, and to examine differences caused by loads imposed on the spinal column. Seven males and three females aged 22-41 years took part in this study. Subjects The subjects underwent 15 minutes of walking or running on a treadmill in a random order. Stature changes were measured during each exercise at intervals of 5 minutes and after a 20 minute standing recovery period within units of 0.01 mm. Two- way ANOVA revealed that both main factors, gait (F = 5.250, P < 0.05) and elapsed time (F = 14.409, P < 0.05), had a significant effect on stature. In the post hoc test, stature shrank with time and its loss was found to be greater in running than in walking, but recovered after both exercises. In conclusion, the spinal load increases with time during both walking and running at PTS, but is greater in running than in walking. After both exercises, spinal shrinkage shows a similar recovery process and recovers faster in walking to its pre-exercise level.

Car driving with and without a movable back support: Effect on transmission of vibration through the trunk and on its consequences for muscle activation and spinal shrinkage

The aim of this study was to test the effect of a movable backrest on vibration transmission through the trunk during driving and on the physiological consequences thereof. Eleven healthy male subjects drove for about 1 h on normal roads with a movable and with a fixed backrest while surface electromyography (EMG) was measured at the level of the fifth lumbar vertebra (L5) and vertical accelerations were measured at the seat, backrest and at the spine at the levels of the second sacral vertebra (S2) and seventh cervical vertebra (C7). The movable backrest significantly reduced accelerations at C7 by up to 11.9% at the 5 Hz frequency band. The movable backrest also significantly reduced the coherence and transmission between S2 and C7 accelerations, but not the differential motion between these sensors. EMG at both sides of L5 was on average 28% lower when using the movable backrest. Spinal shrinkage was unaffected by backrest type. It is concluded that a movable backrest reduces the transmission of vibration through the trunk and that it reduces low back EMG. Car driving is associated with the risk of developing low back pain and this may be related to exposure to whole body vibration. This study found an effect of a simple ergonomics measure on the transmission of vibration through the trunk as well as on back muscle activation.

Assessment of the Effect of a Pivoting Backrest and Activity Level on Spinal Shrinkage

Spinal shrinkage is commonly used as a measure of spinal loading. Spinal shrinkage has been shown to be affected by design features of chair backrests. A freely reclining (dynamic) backrest, passive movement of the lumbar spine via means of a cyclically inflated bladder and passive side-to-side rotation of the spine through a very small angle about its vertical axis at a low frequency via motion of the seat pan have all been shown to produce decreased spinal shrinkage. In the current study we investigated the effect of two independent variables (pivoting backrest and activity level) on spinal shrinkage. The first variable was a pivoting backrest design with two use conditions, locked vs. unlocked. A locked backrest could recline but not pivot while an unlocked backrest could do both. Activity level consisted of an active condition during which the participant typed for 25 minutes and then moused for 25 minutes, which was interspersed every five minutes with a maximum forward reach to touch targets located at about 30, 60, 120, 150 180 degrees relative to the participant's centerline. During the passive activity condition, the participant only sat and typed. It was hypothesized that the pivoting backrest would flex and extend the lumbar spine and/or stabilize the pelvis during the subjects' normal movement patterns and that it would have an effect similar to the previous spinal motion studies, which had found decreased spinal shrinkage as an effect of passive spinal motion. It was further hypothesized that the more active conditions would work synergistically with the pivoting backrest to retard spinal shrinkage. Five individuals participated in the study, three males and two females. Spinal shrinkage was statistically significantly less when the backrest pivot action was unlocked (t = 0.044) and nearly so during the active condition (t = 0.059). The pivoting backrest condition was also significantly preferred to the locked condition.