Non-pain Developers Research Articles

Prolonged Standing-Induced Low Back Pain Is Linked to Extended Lumbar Spine Postures: A Study Linking Lumped Lumbar Spine Passive Stiffness to Standing Posture.

Postural assessments of the lumbar spine lack valuable information about its properties. The purpose of this study was to assess neutral zone (NZ) characteristics via in vivo lumbar spine passive stiffness and relate NZ characteristics to standing lumbar lordosis. A comparison was made between those that develop low back pain during prolonged standing (pain developers) and those that do not (nonpain developers). Twenty-two participants with known pain status stood on level ground, and median lumbar lordosis angle was calculated. Participants were then placed in a near-frictionless jig to characterize their passive stiffness curve and location of their NZ. Overall, both pain developers and nonpain developers stood with a lumbar lordosis angle that was more extended than their NZ boundary. Pain developers stood slightly more extended (in comparison to nonpain developers) and had a lower moment corresponding to the location of their extension NZ boundary. Overall, in comparison to nonpain developers, pain developers displayed a lower moment corresponding to the location of their extension NZ boundary which could correspond to greater laxity in the lumbar spine. This may indicate why pain developers have a tendency to stand further beyond their NZ with greater muscle co-contraction.

Distinctive characteristics of prolonged standing low back pain developers’ and the associated risk factors: systematic review and meta-analysis

Pain developers (PDs) are considered a pre-clinical low back pain (LBP) population at risk of clinical LBP development and thus exacting great social and economic costs. Therefore, it is necessary to comprehensively investigate their distinctive characteristics and the risk factors of standing-induced LBP based on which appropriate preventive measures can be planned. Scopus, Web of Science, and PubMed databases as well as Google Scholar and ProQuest were systematically searched from inception through 14 July 2022 using a combination of terms relevant to ‘standing’ and ‘LBP’. Studies with low risk of bias in English and Persian using a methodological quality scoring system were deemed eligible for inclusion if they were laboratory studies using prolonged standing duration greater than 42 min to classify adult PDs and non-pain developers (NPDs) without a history of LBP. PDs were compared with NPDs in demographics, biomechanical, and psychological outcomes. Weighted or standardized mean differences, and Hedge’s g were generated to determine the pooled effect sizes using STATA software version 17. 52 papers and theses involving 1070 participants (528 PDs and 542 NPDs) were eligible for inclusion in the systematic review 33 of which were used in meta-analyses. Significant differences between PDs and NPDs in terms of movement patterns, muscular, postural, psychological, structural, and anthropometric variables were evidenced. The following factors were found to have a statistically significant association with standing-induced LBP: lumbar fidgets (Hedge’s g − 0.72, 95% CI − 1.35 to − 0.08, P = 0.03), lumbar lordosis in participants over 25 years (Hedge’s g 2.75, 95% CI 1.89–3.61, P < 0.001), AHAbd test (WMD 0.7, 95% CI 0.36–1.05, P < 0.001), GMed co-activation (Hedge’s g 4.24, 95% CI 3.18–5.3, P < 0.001), and Pain Catastrophizing Scale (WMD 2.85, 95% CI 0.51–5.19, P = 0.02). Altered motor control displayed in AHAbd test and higher lumbar lordosis in individuals over 25 years seem to be probable risk factors for standing-induced LBP. In order to detect standing-induced LBP risk factors, future researchers should investigate the association of the reported distinctive characteristics to the standing-induced LBP and that whether they are manipulable through various interventions.

Does a break from sitting change biomechanical outcome measures or transient pain? A laboratory-based experimental study.

Sitting can induce transient low back pain (LBP) in healthy individuals. A rest from sitting should provide relief, however, the parameters of breaks (activity type, intensity, duration, and timing) are not currently known. The purpose of this study was to examine the effect of 2-minute walking breaks at 40-minute intervals on sitting-induced LBP. Thirty-two healthy participants were recruited for a within-control study: two randomly presented sessions of sitting for 2 hours with and without breaks. Outcome measures were compared between condition and pain group using a three-way ANOVA with significance atp > 0.05. Walking breaks at 40-minute intervals result in significantly lower pain ratings than those taken immediately before the break for sitting-induced back pain developers. However, this relief is short lived (<10 minutes), with ratings increasing to pre-break levels once the sitting exposure resumes. There were no differences in biomechanical factors between sessions. Regardless of session type, pain developers displayed higher spine fidget frequency than non-pain developers, females sat with less spine flexion, with greater gluteal activation levels, and with their center of pressure approximately half a centimeter to the left and forward compared to males, and males had significantly greater peak pressures over a smaller area compared to females. Walking breaks at 40-minute intervals provide significant, but temporary, relief of sitting-induced back pain for pain developers. Future work should optimize break parameters and examine the longer-term benefit of breaks, especially for individuals that are not able to tolerate sitting for extended durations.

Effect of office chair design features on lumbar spine posture, muscle activity and perceived pain during prolonged sitting

Chair design features are typically compared using multiple seats, which can lead to confounding effects. Using a single chair, configurable to four designs (control, lumbar support, seat pan tilt and scapular relief), we investigated the effect of chair design on spine posture and movement, muscle activity and perceived pain in a sample of 31 asymptomatic adults. A total of 39% of the population were classified as pain developers, having significantly higher peak pain levels across most body regions. The lumbar support and seat pan tilt condition resulted in more neutral spine and pelvic postures. Greater muscle activity was found in the seat pan condition and non-pain developers displayed lower spine muscle activation levels overall. Despite some improvements in spine posture, sitting-induced pain was present in the study sample at similar proportions to those reported previously. Future studies may consider investigating interventions targeted to sitting-induced pain developers as opposed to the general population. Practitioner summary: Four office chair configurations were tested. The lumbar support and seat pan tilt conditions resulted in the most neutral back posture but did not mitigate the clinically significant levels of sitting-induced pain experienced by a large portion of the tested sample. Future work should target interventions to these individuals.

Anti-fatigue mats can reduce low back discomfort in transient pain developers

Complaints of musculoskeletal pain are common among employees who stand for prolonged periods. This study sought to determine if an anti-fatigue mat (AFM) could uniquely affect low back pain (LBP), low back posture, and foot-floor interface responses in individuals prone to developing LBP (termed pain developers (PDs)) during prolonged standing experiments compared to those who do not develop LBP under the same exposures (termed non pain developers (NPDs)). Sixteen volunteers (8 PDs and 8 NPDs) were recruited based on their pain-development tendencies, which were established in previous standing experiments. They visited the laboratory on two separate days for 60 min of light manual work while standing on either a rigid floor or AFM. All participants were asymptomatic at the beginning of each experimental session. The amount of LBP experienced during the standing exposure, measured via a visual analogue scale, was reduced (p = 0.03) in the PD group when on the AFM (3.6 ± 6 mm) compared to the rigid floor (6.8 ± 7 mm). LBP levels remained low and unchanged (p = 0.5) between the AFM (2.4 ± 5 mm) and rigid floor (1.6 ± 2 mm) conditions for the NPD group. Neither postural nor foot-floor interface measures correlated with this unique reduction of LBP for the PD group when standing on the AFM. The AFM did, however, increase centre of pressure excursion (NPD 55% increase; PD 35% increase) and tended to increase the number of body weight shifts (NPD 116% increase; PD 54% increase) in both the PD and NPD groups. These findings suggest that AFMs may selectively benefit individuals prone to developing standing-induced back pain by facilitating subtle movements at the foot-floor interface.

A comparison of functional movement patterns between female low back pain developers and non-pain developers.

Distinctive features of low back pain-developers (LBPDs) as pre-clinical low back pain (LBP) population have been evidenced in three areas of alignment, muscle activation, and movement patterns. To clarify whether the reported altered functional movement patterns in chronic LBP patients result from or result in LBP disorders, LBPDs' functional movement patterns should be investigated. This study aimed to compare female LBPDs' functional movement patterns with non-pain developers' (NPDs). Sixty female LBPDs and NPDs were recruited based on the research requirements. The Functional Movement Screen (FMS) was used to investigate movement quality. Data were compared between groups via Mann-Whitney U tests and correlation analyses examined association between pain intensity and onset during prolonged standing and the FMS score. Receiver Operating Characteristic Curves and Chi Squares were conducted to find the best cutoff points. An alpha level of p≤0.05 was used to establish statistical significance. LBPDs scored significantly lower, or rather worse than NPDs in the FMS composite score (12.06±1.33 vs. 16.43±1.59, U = 3, P < 0.001). Moreover, the optimal cutoff scores of≤14 on the FMS, 2 on the push-up, and 1 on the deep squat discriminated between female LBPDs and NPDs. The FMS composite score was correlated negatively with LBP intensity (r (60) = -0.724, p < 0.001) and positively with LBP onset (r (60) = 0.277, p = 0.032) during prolonged standing. Finally, the results indicated that female LBPDs presented with at least one bilateral asymmetry on the FMS had 10 times (95% CI, 2.941-34.008) and with at least two bilateral asymmetries on the FMS had 15.5 times (95% CI, 3.814-63.359) higher odds of developing LBP during prolonged standing than NPDs. Female LBPDs, who are at higher risk for developing LBP in the future, have significantly lower quality of functional movement patterns compared to NPDs. Moreover, the FMS appears to show promise for predicting individuals who are at risk for LBP development during prolonged standing.

The impact of a progressive sit-stand rotation exposure duration on low back posture, muscle activation, and pain development

This study evaluated early and frequent seated breaks from standing work to reduce low back pain (LBP) in known pain developers (PD). Twenty-four participants, classified as either PD or non-PD during a separate 2-hour standing session, performed 124 minutes of standing work with seated breaks at a 3:1 stand-sit ratio with increasing durations from 3:1 minute to 48:16 minutes. Back pain and spine posture measures showed no differences between PD and non-PD. Females had greater left glutaeus medius activation (8.4%MVC) than males (4.5%MVC) and greater glutaeus medius co-contraction. This protocol was successful at reducing LBP in PD to the level of non-PD, with mean pain scores (13 mm) only slightly exceeding the clinical LBP threshold of 10 mm. Early and frequent breaks within the first hour of standing work appear to be an effective solution to reduce the LBP that often occurs at the beginning of standing work. Practicioner Summary: Sit-stand workstations may be an effective solution to reduce static occupational low back postures. This experimental study demonstrated that early and frequent seated breaks from standing work may be an effective solution to reduce tissue aggravation that often occurs within the first 45 minutes of a standing work exposure. Abbreviations: LBP: low back pain; PD: pain developer; NPD: non-pain developer; VAS: visual analog scale; EMG: electromyography; LES: lumbar erector spinae; TES: thoracic erector spinae; GMD: glutaeus medius; IOB: internal oblique; MVC: maximum voluntary contraction; CCI: co-activation coefficient; FDA: functional data analysis

What Psychosocial and Physical Characteristics Differentiate Office Workers Who Develop Standing-Induced Low Back Pain? A Cross-Sectional Study.

This study examines demographic, physical and psychosocial factors associated with an increase in low back pain (LBP) during a one-hour standing task. A cross-sectional survey with 40 office workers was conducted. The primary outcome was pain severity during a one-hour standing task recorded every 15 min using a 100 mm Visual Analogue Scale (VAS). Participants were defined as pain developers (PD), if they reported a change in pain of ≥10 mm from baseline, or non-pain developers (NPD). Physical outcomes included participant-rated and examiner-rated trunk and hip motor control and endurance. Self-report history of LBP, physical activity, psychosocial job characteristics, general health and pain catastrophising were collected. Fourteen participants were PD. Hip abduction, abdominal and spinal muscle endurance was lower for PD (p ≤ 0.05). PD had greater self-reported difficulty performing active hip abduction and active straight leg raise tests (p ≤ 0.04). Those reporting a lifetime, 12 month or 7-day history of LBP (p < 0.05) and lower self-reported physical function (p = 0.01) were more likely to develop LBP during the standing task. In conclusion, a history of LBP, reduced trunk and hip muscle endurance and deficits in lumbopelvic/hip motor control may be important to consider in office workers experiencing standing-induced LBP.

Lumbar Intervertebral Kinematics During an Unstable Sitting Task and Its Association With Standing-Induced Low Back Pain.

People developing transient low back pain during standing have altered control of their spine and hips during standing tasks, but the transfer of these responses to other tasks has not been assessed. This study used video fluoroscopy to assess lumbar spine intervertebral kinematics of people who do and do not develop standing-induced low back pain during a seated chair-tilting task. A total of 9 females and 8 males were categorized as pain developers (5 females and 3 males) or nonpain developers (4 females and 5 males) using a 2-hour standing exposure; pain developers reported transient low back pain and nonpain developers did not. Participants were imaged with sagittal plane fluoroscopy at 25Hz while cyclically tilting their pelvises anteriorly and posteriorly on an unstable chair. Intervertebral angles, relative contributions, and anterior-posterior translations were measured for the L3/L4, L4/L5, and L5/S1 joints and compared between sexes, pain groups, joints, and tilting directions. Female pain developers experienced more extension in their L5/S1 joints in both tilting directions compared with female nonpain developers, a finding not present in males. The specificity in intervertebral kinematics to sex-pain group combinations suggests that these subgroups of pain developers and nonpain developers may implement different control strategies.

A comparison of trunk control in people with no history, standing-induced, and recurrent low back pain during trunk extension

ABSTRACTObjectives: This study compares people with recurrent low back pain (rLBP) and people with pre-clinical low back pain (standing-induced low back pain developers; PDs) to each other and back-healthy controls (non-pain developers; NPDs). Movement variability and muscular co-activity related to coordination are important for both rLBP and PDs, and these two groups also have altered static spine extension.Methods: Eleven participants with recurrent low back pain, and twenty-one asymptomatic participants, categorized as PDs (11) and NPDs (10) through an established standing protocol, volunteered for this study. Three phases of standing extension motion (lean, hold, and return to neutral) were analyzed. Root mean square angular jerk was calculated from trunk and pelvis kinematics, co-activation of the trunk and hip musculature were assessed in four-muscle sets.Results: Root-mean-square jerk was greater when returning to neutral than when leaning back during standing extension in all three groups. People with rLBP had reduced co-activity in their trunk extensors, people classified as PD had more co-activity in their hip extensors compared with the other groups, and anterior trunk co-activity was phase-dependent, and similar between groups.Discussion: Movement control alterations with low back pain may start as an over-protective co-activation strategy in those with standing-induced LBP and progress to an under-protective strategy in those with recurrent low back pain. Level of Evidence: 3.

Transient perceived back pain induced by prolonged sitting in a backless office chair: are biomechanical factors involved?

It is not currently known if biomechanical factors contribute to low back pain (LBP) during prolonged sitting. Thus, this study recruited 90 participants (61 with no history of LBP, and 29 with) to sit for 1 hour where back electromyography, spine posture, and perceived pain ratings (PPR) were collected. Participants were classified as Pain Developers (PD) or Non-Pain Developers (NPD) based on their maximum PPR. PDs had significantly higher PPR (p = 0.000) and lower number of spine fidgets (p = 0.004) than NPDs. There was a significant interaction between clinical health history and pain group (p = 0.037) for PPR. Besides fidget frequency, there were no biomechanical differences between pain groups. Therefore, sitting-induced back pain does not appear to be due to posture or muscle activity; however, it may be related to micro-movement strategies. Future work should explore fidgeting further and whether healthy PDs are at risk for clinical LBP in the future. Practitioner summary: We have replicated the differential transient sitting-induced pain response observed in previous studies. Pain developers do not sit differently than non-pain developers, although they do appear to move less. More research is warranted to better understand these groups and the relationship between pain developers and future cases of back pain. Abbreviations: LBP: low back pain; PG: pain group; PD: pain developer; NPD: non-pain developer; +veHx: positive clinical history for low back pain; -veHx: negative clinical history for low back pain; RTS: right thoracic erector spinae; LTS: left thoracic erector spine; RLM: right lumbar multifidus; LLM: left lumbar multifidus; MVC: maximum voluntary contraction; Pelvic N: normalized pelvic angle; ANOVA: analysis of variance; SD: standard deviation

Does proactive cyclic usage of a footrest prevent the development of standing induced low back pain?

Various interventions, such as standing intermittently with one leg on a footrest, have been suggested to prevent low back pain (LBP) development during prolonged standing. To assess this standing intervention twelve participants stood for 80 min while cycling through three minute periods of level-ground standing divided by one minute periods with either the right or left leg elevated onto a platform. All participants had previously participated in a prolonged level standing protocol and were classified as pain (PD) or non-pain developers (NPD). Out of the six known PDs, only one PD developed LBP by the end of the standing intervention. The intervals of elevated leg standing resulted in increased lumbar spine flexion in comparison to level standing. In addition, over time there was an increase in lumbar spine flexion during the level standing intervals. This change in lumbar spine posture in standing pain developers likely contributed to the reduced LBP development during this prolonged standing intervention

Walking breaks can reduce prolonged standing induced low back pain

Standing is commonly recommended to reduce sedentary behavior in the workplace; however, constrained prolonged standing has also been linked to musculoskeletal symptoms, such as low back pain (LBP). Light physical activity breaks, such as walking, may change lumbar spine posture enough to reduce LBP during standing. This study assessed the effectiveness of inserting 5-minute walking breaks every 25 min for reducing prolonged standing-induced LBP development. Nineteen participants completed two bouts of standing lasting 2 h – one with a 5-minute walking break every 25 min and one with no breaks. Pain measures were completed throughout the trial to categorize participants as pain developers (PDs) or non-pain developers (non-PDs). Lumbar region kinematics angle and range of motion were measured continuously. In standing, 58% (11/19) of participants were PDs, compared to just 26% when walking breaks were inserted. Seventy-three percent (8/11) were categorized as non-PDs with walking breaks. Median lumbar flexion increased during walking compared to standing. Lumbar region range of motion in the coronal and transverse planes also increased during walking. The intermittent lumbar flexion may help decrease LBP during prolonged standing. These results demonstrate that walking breaks may help promote lumbar movement and reduce prolonged standing-induced LBP.

(157) Humans with Inducible Symptoms of Low Back Pain Show Intervertebral Disc Changes in the Lumbar Spine during Prolonged Standing

LBP symptoms can be induced in back-healthy individuals in prolonged standing and are relieved upon exiting standing [1]. These individuals who develop LBP (pain developers -PDs) are 3 times more likely to develop a clinical episode of LBP within two years than their non-pain developer (NPD) counterparts [2]. Yet the specific anatomical changes that provoke these LBP symptoms remain unknown. We hypothesized that PDs have distinct adaptations in each intervertebral disc (IVD) level compared to NPDs. We investigated the changes in spinal alignment (Cobb angle) and local IVD structure over time in PDs. Forty human subjects (age 18-30, BMI

Lumbar spine posture and spinopelvic parameters change in various standing and sitting postures.

This study aimed to compare differences in lumbosacral and spinopelvic parameters between pain developers and non-pain developers as well as the effects of various posture changes. A total of 38 consecutive participants, 20 standing-induced low back pain developers (mean age: 27.7 ± 5.3; mean BMI: 22.64 ± 2.95) and 18 non-pain developers (mean age: 29.0 ± 7.5; mean BMI: 24.2 ± 1.87) (p > 0.05), were prospectively evaluated. Six sagittal plane radiographs were taken. Upright standing posture was used as the reference posture. Lumbar lordosis, lumbosacral lordosis, L1/L2 and L5/S1 intervertebral (IV) joint angles, pelvic incidence, pelvic tilt and sacral slope were measured on each radiograph. There were no significant differences in terms of age, BMI, SF-36 score, or Oswestry Disability Index scores between pain developer and non-pain developer groups (p > 0.05). Pain developers had significantly larger lumbar lordosis, larger L1/L2 intervertebral angles, larger pelvic incidences and sacral slopes in all postures (p < 0.05). The contribution of L5/S1 intervertebral angle to lumbar flexion was higher than that of the L1/L2 intervertebral angle during stair descent, the sitting and the leaning forward while sitting postures (p < 0.05). The current study supports the assertion that increased lumbar lordosis is associated with increased pain. Lumbar spine angles change in various postures. The changes were more prominent in pain developers than in non-pain developers. Larger lumbar lordosis due to larger pelvic incidence may be a risk factor for the development of standing-induced low back pain. These slides can be retrieved under Electronic Supplementary Material.

The distribution of lumbar intervertebral angles in upright standing and extension is related to low back pain developed during standing

BackgroundLumbar lordosis measures are poorly related to clinical low back pain, however using a controlled exposure such as prolonged standing to identify pain groups may clarify this relationship. The purpose of this study was to determine the distribution of lumbar intervertebral angles in asymptomatic persons who do (pain developers) and do not (non-pain developers) develop low back pain during standing. MethodsSagittal plane lumbar spine radiographs of eight pain developers and eight non-pain developers were taken in three poses: upright standing, full extension and full flexion. Measures of vertebral end plate orientations from L1 to S1 were taken in each pose to compute: intervertebral angles, contribution of each level to the total curve, total lordosis, ranges of motion, relative pose positioning within the range of motion, vertebral shape, and lumbar spine recurve. Measures were compared between pain groups and lumbar levels. FindingsPain group differences in intervertebral angles and level contributions were greatest in the full extension pose, with pain developers having greater contributions from higher lumbar levels and fewer contributions from lower levels than non-pain developers. Pain group differences in intervertebral angle distributions were less pronounced in upright standing and non-existent in full flexion. No other measures differentiated pain groups. InterpretationsAlthough participants had similar gross-lumbar spine curvature characteristics, non-pain developers have more curvature at lower levels in upright standing and full extension. These differences in regional vertebral kinematics may partially be responsible for standing-induced low back pain.

Low back pain development differentially influences centre of pressure regularity following prolonged standing

Occupations requiring prolonged periods of static standing are associated with the development of low back pain (LBP). Certain individuals are susceptible to LBP development during prolonged standing (pain developers, PDs) while others are not (non-pain developers, NPDs). Linear centre of pressure (COP) measures suggest that standing balance control is negatively influenced following prolonged standing, and that PDs and NPDs may be differentially affected. The objective of this study was to determine if nonlinear standing balance control, quantified on COP, using sample entropy, is altered after 2-h of standing. Thirty two participants stood for 2-h. Separate 2-min standing trials, performed with eyes open and eyes closed, were collected before and after the 2-h standing protocol. Sample entropy, median power frequency and RMS amplitude of the COP time-series, was calculated from the 2-min standing trials for all participants. For comparison, participants were classified, post hoc, as PDs or NPDs according to visual analog scale pain scores. Sample entropy decreased after 2-h of standing for both PDs and NPDs, however, the decrease for NPDs was only 21% of the decrease observed in PDs. This study demonstrated that nonlinear control of upright standing changes after 2- hours of standing, resulting in an increase in COP regularity post 2- hours of standing for both PDs and NPDs. PDs displayed a greater change in COP regularity, which is supported by the theory that increased COP regularity occurs with pain/pathology

A hip abduction exercise prior to prolonged standing increased movement while reducing cocontraction and low back pain perception in those initially reporting low back pain

Persons who develop low back pain from prolonged standing exhibit increased muscle cocontraction, decreased movement and increased spine extension. However, it is unclear how these factors relate to pain development. The purpose of this study was to use hip abductor fatigue to manipulate muscle activity patterns and determine its effects on standing behaviours and pain development. Forty participants stood for two hours twice, once following a hip abductor fatigue exercise (fatigue), and once without exercise beforehand (control). Trunk and gluteal muscle activity were measured to determine cocontraction. Lumbo-pelvic angles and force plates were used to assess posture and movement strategies. Visual analog scales differentiated pain (PDs) and non-pain developers (NPDs). PDs reported less low back pain during the fatigue session, with females having earlier reductions of similar scale than males. The fatigue session reduced gluteal and trunk cocontraction and increased centre of pressure movement; male and female PDs had opposing spine posture compensations. Muscle fatigue prior to standing reduced cocontraction, increased movement during standing and reduced the low back pain developed by PDs; the timing of pain reductions depended on spine postures adopted during standing.

A radiographic assessment of lumbar spine posture in four different upright standing positions

BackgroundApproximately 50% of a sample population will develop prolonged standing induced low back pain. The cause of this pain may be due to their lumbar spine posture. The purpose of this study was to investigate differences in lumbar posture between 17 participants categorized as a pain or non-pain developers during level ground standing. A secondary purpose was to evaluate the influence of two standing aids (an elevated surface to act as a foot rest and declined sloped surface) on lumbopelvic posture. MethodsFour sagittal plane radiographs were taken: a normal standing position on level ground, when using an elevated foot rest, using a declined sloped surface, and maximum lumbar spine extension as a reference posture. Lumbosacral lordosis, total lumbar lordosis, and L1/L2 and L5/S1 intervertebral joint angles were measured on each radiograph. FindingsThere was a significant difference between the lumbosacral lordosis angle and L5/S1 angles in upright versus maximum extension; however, this was independent of pain group. The elevated surface was most effective at causing lumbosacral spine flexion. InterpretationPotentially successful postures for eliminating low back pain during prolonged standing mainly influence the lower lumbar lordosis. Future work should assess the influence of hip posture on low back pain development during standing.

Psychological Factors Are Related to Pain Intensity in Back-Healthy People Who Develop Clinically Relevant Pain During Prolonged Standing: A Preliminary Study

BackgroundAn induced-pain paradigm has been used to examine risk factors for the development of low back pain (LBP) during prolonged standing in back-healthy people (standing paradigm). Previous studies that used induced-pain methods suggest that pain intensity may be related to psychologic factors. It is not currently known, however, whether pain intensity reported during the standing paradigm is related to psychologic factors. ObjectiveTo examine the relationship between LBP symptom intensity and psychological factors (fear of pain and pain catastrophizing) in back-healthy people who develop LBP during prolonged standing. We hypothesized that symptom intensity during standing would be positively related to initial levels of fear of pain and pain catastrophizing in people who developed LBP during standing. DesignCross-sectional. SettingMovement science research center at an academic medical center. ParticipantsFifty seven back-healthy participants. MethodsParticipants completed the Fear of Pain Questionnaire-III (FPQ-III) and Pain Catastrophizing Scale (PCS) before a 2-hour standing protocol. Participants rated LBP intensity on a 100-mm visual analogue scale (VAS) throughout standing and were classified as pain developers (PDs) or nonpain developers (NPDs). Relationships between LBP intensity and psychological measures were examined in PDs that did and did not have a ≥20 mm maximum VAS score. Main Outcome MeasurementsFPQ-III and PCS total scores, maximum and average VAS scores during standing. ResultsThere were 24 (42%) PDs. Five PDs reported a maximum VAS score ≥20 mm. For PDs with a maximum VAS score <20 mm, correlations between average VAS scores and each psychological measure were small and nonsignificant (FPQ-III: r = 0.16, P = .50; PCS: r = 0.27, P = .26). For PDs with a maximum VAS score ≥20 mm, correlation between average VAS scores and FPQ-III was large and significant (r = 0.91, P = .03), and large for PCS but nonsignificant (r = 0.87, P = .06). ConclusionThese preliminary data suggest that if pain exceeds a clinically meaningful threshold (20 mm) during standing, pain intensity is related to psychological factors. Understanding factors that modulate acute pain response can inform early intervention strategies. Level of EvidenceII