An Exploration of the Influence of Non-Biomechanical Factors on Lifting-Related LBP.

Objective: The primary objective was to compare non-biomechanical factors between manual workers with and without a history of LBP related to lifting. A secondary objective was to investigate associations between the change in pain intensity during repeated lifting (termed pain ramp) and non-biomechanical factors tested in the LBP group. Methods: Manual workers currently in lifting occupations with and without a history of lifting-related LBP were recruited (21 LBP and 20 noLBP) and took part in a repeated (100) lift task. A series of non-biomechanical factors, including psychological, work-related, lifestyle, whole health and psychophysical factors, were collected. Psychophysical factors (pressure pain thresholds (PPTs) and fatigue) were also measured at different time points. Associations between pain ramp during lifting and non-biomechanical factors were investigated with linear regression. Results: The LBP group reported worse perceived sleep quality, more musculoskeletal pain sites other than LBP and greater symptoms related to gastrointestinal complaints and pseudo-neurology compared to the group with no history of LBP. The group with LBP were also slightly more worried about the lifting task and felt more fatigued at the end of the lifting task. The feeling of fatigue during lifting was positively associated with pain ramp in the LBP group. Anxiety and gastrointestinal complaints were weakly negatively associated with pain ramp during lifting. Conclusions: The group differences of poorer perceived sleep, greater non-specific health complaints, slightly more worry about the lifting task and more perceived fatigue in the LBP group highlight the complex and multi-factorial nature of LBP related to lifting. The feeling of fatigue was positively associated with pain ramp in the LBP group, suggesting a close relationship with pain and fatigue during lifting that requires further exploration.

Concurrent validity of DorsaVi wireless motion sensor system Version 6 and the Vicon motion analysis system during lifting.

BACKGROUND: Wearable sensor technology may allow accurate monitoring of spine movement outside a clinical setting. The concurrent validity of wearable sensors during multiplane tasks, such as lifting, is unknown. This study assessed DorsaVi Version 6 sensors for their concurrent validity with the Vicon motion analysis system for measuring lumbar flexion during lifting. METHODS: Twelve participants (nine with, and three without back pain) wore sensors on T12 and S2 spinal levels with Vicon surface markers attached to those sensors. Participants performed 5 symmetrical (lifting from front) and 20 asymmetrical lifts (alternate lifting from left and right). The global-T12-angle, global-S2-angle and the angle between these two sensors (relative-lumbar-angle) were output in the sagittal plane. Agreement between systems was determined through-range and at peak flexion, using multilevel mixed-effects regression models to calculate root mean square errors and standard deviation. Mean differences and limits of agreement for peak flexion were calculated using the Bland Altman method. RESULTS: For through-range measures of symmetrical lifts, root mean squared errors (standard deviation) were 0.86° (0.78) at global-T12-angle, 0.90° (0.84) at global-S2-angle and 1.34° (1.25) at relative-lumbar-angle. For through-range measures of asymmetrical lifts, root mean squared errors (standard deviation) were 1.84° (1.58) at global-T12-angle, 1.90° (1.65) at global-S2-angle and 1.70° (1.54) at relative-lumbar-angle. The mean difference (95% limit of agreement) for peak flexion of symmetrical lifts, was - 0.90° (-6.80 to 5.00) for global-T12-angle, 0.60° (-2.16 to 3.36) for global-S2-angle and - 1.20° (-8.06 to 5.67) for relative-lumbar-angle. The mean difference (95% limit of agreement) for peak flexion of asymmetrical lifts was - 1.59° (-8.66 to 5.48) for global-T12-angle, -0.60° (-7.00 to 5.79) for global-S2-angle and - 0.84° (-8.55 to 6.88) for relative-lumbar-angle. CONCLUSION: The root means squared errors were slightly better for symmetrical lifts than they were for asymmetrical lifts. Mean differences and 95% limits of agreement showed variability across lift types. However, the root mean squared errors for all lifts were better than previous research and below clinically acceptable thresholds. This research supports the use of lumbar flexion measurements from these inertial measurement units in populations with low back pain, where multi-plane lifting movements are assessed.

Does intra-lumbar flexion during lifting differ in manual workers with and without a history of low back pain? A cross-sectional laboratory study.

Advice to limit or avoid a flexed lumbar curvature during lifting is widely promoted to reduce the risk of low back pain (LBP), yet there is very limited evidence to support this relationship. To provide higher quality evidence this study compared intra-lumbar flexion in manual workers with (n = 21) and without a history of LBP (n = 21) during a repeated lifting task. In contrast to common expectations, the LBP group demonstrated less peak absolute intra-lumbar flexion during lifting than the noLBP group [adjusted difference -3.7° (95%CI -6.9 to -0.6)]. The LBP group was also further from the end of range intra-lumbar flexion and did not use more intra-lumbar range of motion during any lift condition (both symmetrical and asymmetrical lifts and different box loads). Peak absolute intra-lumbar flexion was more variable in the LBP group during lifting and both groups increased their peak absolute intra-lumbar flexion over the lift repetitions. This high-quality capture of intra-lumbar spine flexion during repeated lifting in a clinically relevant cohort questions dominant safe lifting advice.Practitioner summary: Lifting remains a common trigger for low back pain (LBP). This study demonstrated that people with LBP, lift with less intra-lumbar flexion than those without LBP. Providing the best quality in-vivo laboratory evidence, that greater intra-lumbar flexion is not associated with LBP in manual workers, raising questions about lifting advice.

Exploring lumbar and lower limb kinematics and kinetics for evidence that lifting technique is associated with LBP.

PURPOSE: To investigate if lumbar and lower limb kinematics or kinetics are different between groups with and without a history of LBP during lifting. Secondly, to investigate relationships between biomechanical variables and pain ramp during repeated lifting. METHODS: 21 LBP and 20 noLBP participants completed a 100-lift task, where lumbar and lower limb kinematics and kinetics were measured during lifting, with a simultaneous report of LBP intensity every 10 lifts. Lifts were performed in a laboratory setting, limiting ecological validity. RESULTS: The LBP group used a different lifting technique to the noLBP group at the beginning of the task (slower and more squat-like). Kinetic differences at the beginning included less peak lumbar external anterior shear force and greater peak knee power demonstrated by the LBP group. However, at the end of the task, both groups lifted with a much more similar technique that could be classified as more stoop-like and faster. Peak knee power remained greater in the LBP group throughout and was the only kinetic difference between groups at the end of the lifting task. While both groups lifted using a more comparable technique at the end, the LBP group still demonstrated a tendency to perform a slower and more squat-like lift throughout the task. Only one of 21 variables (pelvic tilt at box lift-off), was associated with pain ramp in the LBP group. Conclusions: Workers with a history of LBP, lift with a style that is slower and more squat-like than workers without any history of LBP. Common assumptions that LBP is associated with lumbar kinematics or kinetics such as greater lumbar flexion or greater forces were not observed in this study, raising questions about the current paradigm around 'safe lifting'.

To Flex or Not to Flex? Is There a Relationship Between Lumbar Spine Flexion During Lifting and Low Back Pain? A Systematic Review With Meta-analysis.

OBJECTIVE: To evaluate whether lumbar spine flexion during lifting is a risk factor for low back pain (LBP) onset/persistence or a differentiator of people with and without LBP. DESIGN: Etiology systematic review with meta-analysis. LITERATURE SEARCH: Database search of ProQuest, CINAHL, MEDLINE, and Embase up to August 21, 2018. STUDY SELECTION CRITERIA: We included peer-reviewed articles that investigated whether lumbar spine position during lifting was a risk factor for LBP onset or persistence or a differentiator of people with and without LBP. DATA SYNTHESIS: Lifting-task comparison data were tabulated and summarized. The meta-analysis calculated an n-weighted pooled mean ± SD of the results in the LBP and no-LBP groups. If a study contained multiple comparisons (ie, different lifting tasks that used various weights or directions), then only 1 result from that study was included in the meta-analysis. RESULTS: Four studies (1 longitudinal study and 3 cross-sectional studies across 5 articles) included in meta-analysis measured lumbar flexion with intralumbar angles and found no difference in peak lumbar spine flexion when lifting (1.5°; 95% confidence interval [CI]: -0.7°, 3.7°; P = .19 for the longitudinal study and -0.9°; 95% CI: -2.5°, 0.7°; P = .29 for the cross-sectional studies). Seven cross-sectional studies measured lumbar flexion with thoracopelvic angles and found that people with LBP lifted with 6.0° less lumbar flexion than people without LBP (95% CI: -11.2°, -0.9°; P = .02). Most (9/11) studies reported no significant between-group differences in lumbar flexion during lifting. The included studies were of low quality. CONCLUSION: There was low-quality evidence that greater lumbar spine flexion during lifting was not a risk factor for LBP onset/persistence or a differentiator of people with and without LBP. J Orthop Sports Phys Ther 2020;50(3):121-130. Epub 28 Nov 2019. doi:10.2519/jospt.2020.9218.