Spinal loading during manual materials handling in a kneeling posture

Kneeling trunk kinematics during simulated sloped roof shingle installation

Trunk musculoskeletal disorders are common among residential roofers. Addressing this problem requires a better understanding of the movements required to complete working tasks, such as affixing shingles on a sloped residential roof. We analyzed the extent to which the trunk kinematics during a shingling process are altered due to different angles of roof slope. Eight male subjects completed a kneeling shingle installation process on three differently sloped roof surfaces. The magnitude of the trunk kinematics was significantly influenced by both slope and task phase of the shingling process, depending on the metric. The results unequivocally point to roof slope and task phase as significant factors altering trunk kinematics. However, extension of the results to roofing workers should be done carefully, depending on the degree to which the study protocol represents the natural setting. Future studies on shingle installation in residential roofing should absolutely consider capturing a wider array of shingling procedures in order to encapsulate all the possible methods that are used due to the lack of a standardized procedure.

Spinal loading and lift style in confined vertical space

The objective of this study was to investigate biomechanical loads on the lumbar spine as a function of working in a confined vertical space, consistent with baggage handling inside the baggage compartment of an airplane. Ten male subjects performed baggage handling tasks using confined (kneeling, sitting) and unconfined (stooping) lifting styles. Dependent measures of torso flexion and three-dimensional spinal loads were assessed with an electromyography-driven biomechanical model. Lifting exertions typical to airline baggage handling posed significant risk to the lumbar spine, regardless of lifting style. Statistically significant differences attributable to lift style (stooping, kneeling, sitting) were not observed for peak compressive, lateral shear, or resultant spinal loads, but lifting while kneeling decreased anterior/posterior (A/P) shear spinal loads relative to stooping (p = 0.02). Collectively, kneeling offers the greatest benefit when lifting in confined spaces because of the ability to keep the torso upright, subsequently reducing shear forces on the lumbar spine.

Determination of maximum acceptable and comfortable height during one-handed lifting

BACKGROUND

One-handed lifting commonly occurs in the industry. Specific guidelines of proper heights during one-handed lifting could be valuable information to design or to assess the risk of work environment.

OBJECTIVE

The objective of this study was to determine the maximum acceptable height and comfortable height during one-handed vertical lifting by gender, participant height, hand, and object weight.

METHODS

Based on the psychophysical method, 72 males and 50 females, divided into four different height groups, determined their maximum acceptable and comfortable heights by each hand (left and right) and various object weights (1 kg, 3 kg, 5 kg, and 8 kg).

RESULTS

Males revealed significantly greater maximum acceptable heights (males: 157 cm; females: 135 cm) and higher comfortable heights (males: 104 cm; females: 96 cm) compared to females. The participants' heights, which hand was used to lift, and the object weight were significant factors in determining the maximum acceptable height for both males and females. The multiple linear regression model of the maximum acceptable height showed more robust predictive power (R2 = 0.55) compared to the comfortable height (R2 = 0.20) as a function of gender, participant height, hand, and object weight.

CONCLUSIONS

Results suggest that gender, participant height, hand, and object weight are important variables to consider when determining the proper surface height of one-handed vertical lifting. Using the robust predictive model, an appropriate maximum acceptable height could be suggested based on the material handler's anthropometric information and object weight.

Obesity effects on muscular activity during lifting and lowering tasks

Obesity is an emerging health problem and its incidence has been increasing throughout the workforce. In industrial workstations, vertical handling tasks (VHT), including lifting and lowering, are very common and can cause a significant muscular overload for the involved workers. During these tasks, muscular activity may be considerably affected by workers' body conditions. This study aims to analyze and compare the muscular activity in subjects with different obesity levels, using surface electromyography (EMG), during predefined VHT. Six different VHT (combining 5, 10 and 15-kg loads with two task styles) were performed. EMG data normalization was based on the percentage of maximum contraction during each task (MCT%). The results show that obesity influences the MCT%, which in turn increases the muscular effort during VHT. The current investigation demonstrates that obesity is a relevant musculoskeletal risk factor regarding VHT. The engineering analysis and design implications of this work can thus be perceived.

Daily Shoulder Pain Among Flight Baggage Handlers and its Association With Work Tasks and Upper Arm Postures on the Same Day

Objectives

This study of flight baggage handlers aimed at examining the extent to which shoulder pain developed during single work shifts, and whether a possible development was associated with biomechanical exposures and psychosocial factors during the same shift.

Methods

Data were collected during, in total, 82 work shifts in 44 workers. Right and left shoulder pain intensity was rated just before and just after the shift (VAS scale 0–100 mm). Objective data on ‘time in extreme’ and ‘time in neutral’ upper arm postures were obtained for the full shift using accelerometers, and the baggage handlers registered the number of ‘aircrafts handled’ in a diary. During half of the shift, workers were recorded on video for subsequent task analysis of baggage handling. ‘Influence’ at work and ‘support’ from colleagues were measured by use of Copenhagen Psychosocial Questionnaire (COPSOQ). Associations between exposures and the increase in pain intensity during the shift (‘daily pain’) were analysed for the right and left shoulder separately using Generalized Estimating Equations (GEE).

Results

‘Daily pain’ was observed in approximately one third of all shifts. It was significantly associated with the number of ‘aircrafts handled’ for both the right and left shoulder. In multivariate models including both biomechanical exposures and the psychosocial factors ‘influence’ at work and ‘support’ from colleagues, ‘aircrafts handled’ was still significantly associated with ‘daily pain’ in both shoulders, and so was ‘influence’ and ‘support’, however in opposite directions.

Conclusions

‘Daily pain’ was, in general, associated with biomechanical exposures during the same shift and with general ‘influence’ and ‘support’ in the job. In an effort to reduce pain among flight baggage handlers, it may therefore be justified to consider a reduction of biomechanical exposures during handling of aircrafts, combined with due attention to psychosocial factors at work.

Psychosocial Work Factors and Musculoskeletal Pain: A Cross-Sectional Study among Swedish Flight Baggage Handlers

OBJECTIVE

Flight baggage handlers sort and load luggage to airplanes. This study aimed at investigating associations between psychosocial exposures and low back and shoulder musculoskeletal disorders (MSDs) among Swedish flight baggage handlers.

METHODS

A questionnaire addressing MSDs (Standardized Nordic Questionnaire) and psychosocial factors (Copenhagen Psychosocial Questionnaire, COPSOQ) was answered by 525 baggage handlers in six Swedish airports.

RESULTS

Low back (LBP) and shoulder pain (SP) were reported by 70% and 60%, respectively. Pain was reported to interfere with work (PIW) by 30% (low back) and 18% (shoulders), and intense pain (PINT) occurred in 34% and 28% of the population. Quality of leadership was the most dissatisfying psychosocial factor, while the most positive was social community at work. Low ratings in the combined domain Work organization and job content were significantly associated with PIW in both low back and shoulders (Adjusted Hazard Ratios 3.65 (95% CI 1.67-7.99) and 2.68 (1.09-6.61)) while lower ratings in the domain Interpersonal relations and leadership were associated with PIW LBP (HR 2.18 (1.06-4.49)) and PINT LBP and SP (HRs 1.95 (1.05-3.65) and 2.11 (1.08-4.12)).

CONCLUSION

Severity of pain among flight baggage handlers was associated with psychosocial factors at work, suggesting that they may be a relevant target for intervention in this occupation.

Improving transfer task practices used with air travelers with mobility impairments: a systematic literature review

Manual lifting in healthcare and air transportation is a high-risk activity and a primary cause of musculoskeletal injuries for workers who are required to provide transfer assistance to people with mobility impairments. In the healthcare industry, safe patient-handling programs and policies are accepted as effective ways to prevent worker injury and to improve patient safety. We reviewed evidence-based studies and several websites for disability groups and the airline industry. Seven studies found significant improvements in musculoskeletal comfort levels and declines in musculoskeletal injuries. One study found significant improvements in every musculoskeletal group surveyed. Our review of websites revealed that there were no published research studies or policies about safe handling practices for air travelers. It is evident that passengers with mobility impairments have different expectations for assistance, not congruent with existing services offered by the airline industry.

A history of low back pain affects pelvis and trunk mechanics during a sustained lift/lower task

This study compared three-dimensional trunk and pelvis range of motion (ROM) during a sustained asymmetric box lift/lower task between a group with a history of low back pain (HBP, n = 9) and a group with no history of low back pain (NBP, n = 9). Participants lifted an 11-kg box for 10 min at 12 cycles/min from ankle height in front to shelves 45 deg off-centre at waist height. Kinematic data were collected at the beginning (min1), middle (min5) and end of the bout (min9). Two-way analyses of variance were performed for all variables. Pelvis and trunk transverse ROM were similar at min1. By min9, HBP group did not change (31.9 ± 9 deg); however, ROM decreased in NBP group (21.6 ± 6 deg, p < 0.05). Therefore, despite no current pain, the HBP group demonstrated protective lifting mechanics compared to controls. Also discussed are implications for studying lifting paradigms at sub-maximal effort over longer periods of time.

PRACTITIONER SUMMARY

Differences between groups over time demonstrate residual consequences of low back pain (LBP) in a manual materials handling scenario. Individuals with a history of LBP (pain free for 6 months) demonstrated more conservative lifting mechanics towards the end of the bout compared to controls with no history of LBP.