Morten Villumsen

Physical activities at work and risk of musculoskeletal pain and its consequences: protocol for a study with objective field measures among blue-collar workers

BackgroundAmong blue-collar workers, high physical work demands are generally considered to be the main cause of musculoskeletal pain and work disability. However, current available research on this topic has been criticised for using self-reported data, cross-sectional design, insufficient adjustment for potential confounders, and inadequate follow-up on the recurrent and fluctuating pattern of musculoskeletal pain. Recent technological advances have provided possibilities for objective diurnal field measurements of physical activities and frequent follow-up on musculoskeletal pain.The main aim of this paper is to describe the background, design, methods, limitations and perspectives of the Danish Physical Activity cohort with Objective measurements (DPhacto) investigating the association between objectively measured physical activities capturing work and leisure time and frequent measurements of musculoskeletal pain among blue-collar workers.Methods/designApproximately 2000 blue-collar workers are invited for the study and asked to respond to a baseline questionnaire, participate in physical tests (i.e. muscle strength, aerobic fitness, back muscle endurance and flexibility), to wear accelerometers and a heart rate monitor for four consecutive days, and finally respond to monthly text messages regarding musculoskeletal pain and quarterly questionnaires regarding the consequences of musculoskeletal pain on work activities, social activities and work ability for a one-year follow-up period.DiscussionThis study will provide novel information on the association between physical activities at work and musculoskeletal pain. The study will provide valid and precise documentation about the relation between physical work activities and musculoskeletal pain and its consequences among blue-collar workers.

Are forward bending of the trunk and low back pain associated among Danish blue-collar workers?: a cross- sectional field study based on objective measures

The aim of this cross-sectional study was to investigate the association between the duration of objectively measured forward bending of the trunk and low back pain (LBP) intensity among 198 Danish blue-collar workers (male = 115; female = 83). The duration of forward bending of ≥ 30°, ≥ 60° and ≥ 90° was divided into high (the highest tertile) and low–moderate (the remaining tertiles) categories. High (>5) and low ( ≤ 5) pain intensities were categorised from a self-reported 0–9 scale. Results of multi-adjusted logistic regressions indicated no significant positive associations between forward bending and LBP intensity. On the contrary, higher duration of forward bending of ≥ 30° was associated with lower LBP intensity during all day (OR = 0.40; 95% CI, 0.15–1.02; p = 0.05) and work (OR = 0.44; 95% CI, 0.17–1.15; p = 0.09). This indication of a negative association may be explained by fear-avoidance behaviour of the blue-collar worker, job crafting or healthy worker effect. Practitioner Summary: Ergonomics practice often relies on observations and subjective assessments. This study indicates that higher duration of forward bending of the trunk may be associated with lower low back pain intensity among blue-collar workers. Therefore, practitioners should take care in basing recommendations for action on concurrent measures of workload and pain.

Social support modifies association between forward bending of the trunk and low-back pain: Cross-sectional field study of blue-collar workers

OBJECTIVES This study aimed to investigate the association between forward bending of the trunk and low-back pain intensity (LBPi) among blue-collar workers in Denmark as well as whether the level of social support modifies the association. METHODS In total, 457 workers were included in the study. The forward bending of ≥ 30° was computed from accelerometer recordings for several consecutive days during work, categorized into long (highest tertile) and short-moderate (remaining tertiles) duration. LBPi was measured on a 0-10 scale and categorized into low (≤ 5) and high (>5) pain. Self-reported social support was categorized into low, moderate, and high levels. Multi-adjusted logistic regressions estimated the association between forward bending and LBPi and the effect modification by social support. RESULTS Forward bending and LBPi were not significantly associated but modified by social support. Workers with low social support and long duration of forward bending had higher likelihood of high LBPi [odds ratio (OR) 2.97, 95% confidence interval (95% CI) 1.11-7.95] compared to workers with high social support and long duration of forward bending. Among workers with low social support, workers with long duration of forward bending had higher likelihood of high LBPi (OR 3.28, 95% CI 0.99-10.90) compared to workers with short-moderate duration of forward bending. Among workers with high social support, workers with long duration of forward bending had reduced likelihood of high LBPi (OR 0.39, 95% CI 0.16-0.95) compared to workers with short-moderate duration of forward bending. CONCLUSIONS Social support modifies the association between objectively measured forward bending and LBPi among blue-collar workers.

Comparison between Mother, ActiGraph wGT3X-BT, and a hand tally for measuring steps at various walking speeds under controlled conditions

Introduction Walking is endorsed as health enhancing and is the most common type of physical activity among older adults. Accelerometers are superior to self-reports when measuring steps, however, if they are to be used by clinicians the validity is of great importance. The aim of this study was to investigate the criterion validity of Mother and ActiGraph wGT3X-BT in measuring steps by comparing the devices to a hand tally under controlled conditions in healthy participants. Methods Thirty healthy participants were fitted with a belt containing the sensor of Mother (Motion Cookie) and ActiGraph. Participants walked on a treadmill for two minutes at each of the following speeds; 3.2, 4.8, and 6.4 km/h. The treadmill walking was video recorded and actual steps were subsequently determined by using a hand tally. Wilcoxon’s signed ranks test was used to determine whether Mother and ActiGraph measured an identical number of steps compared to the hand tally. Intraclass correlation coefficients were calculated to determine the relationship and Root Mean Square error was calculated to investigate the average error between the devices and the hand tally. Percent differences (PD) were calculated for between-instrument agreement (Mother vs. the hand tally and ActiGraph vs. the hand tally) and PDs below 3% were interpreted as acceptable and clinically irrelevant. Results Mother and ActiGraph under-counted steps significantly compared to the hand tally at all walking speeds (p < 0.001). Mother had a median of total differences of 9.5 steps (IQR = 10) and ActiGraph 59 steps (IQR = 77). Mother had smaller PDs at all speeds especially at 3.2 km/h (2.5% compared to 26.7%). Mother showed excellent ICC values ≥0.88 (0.51–0.96) at all speeds whilst ActiGraph had poor and fair to good ICC values ranging from 0.03 (−0.09–0.21) at a speed of 3.2 km/h to 0.64 (0.16–0.84) at a speed of 6.4 km/h. Conclusion Mother provides valid measures of steps at walking speeds of 3.2, 4.8, and 6.4 km/h with clinically irrelevant deviations compared to a hand tally while ActiGraph only provides valid measurements at 6.4 km/h based on the 3% criterion. These results have significant potential for valid objective measurements of low walking speeds. However, further research should investigate the validity of Mother in patients at even slower walking speeds and in free-living conditions.

Ergonomics in sports and at work

This paper addresses issues related to ergonomics in sports and at work. Ergonomics and sports science disciplines are interrelated. Workers and athletes operate in demanding environments requiring a high level of performance. Thus, a branch of ergonomics focuses on quantifying motor strategies in order to optimize human performance and prevent injuries. These goals can be pursued by (i) assessing human characteristics and capabilities in relation to certain motor tasks, (ii) achieving optimal efficiency and improving the overall level of performance, (iii) reducing discomfort level, and (iv) ensuring safety. This paper reviews recent studies and presents novel methods used to assess human performance.

Measurements of rearfoot acceleration during walking and running: a pilot study

In healthy, older adults, peak pressure FRR asymmetry exists and faster gait speeds show greater FRR asymmetry. These results agree with the theory that each limb may a specific functional task during gait (Hirasawa 1981). As gait speed is a predictor of future disability in older adults (Abellan van Kan et al. 2009), understanding the mechanisms that promote healthy gait and foot function is imperative. Future work should examine asymmetry as it relates to balance, fall risk, and activities of daily living to evaluate the effects of lower limb asymmetry in older adult populations.

Comparison of rearfoot motion assessments from 3D motion capture and the Achillex® system

Extensive rearfoot movement and high impact forces have been linked to overuse injuries in running. However, several prospective studies indicated that the occurrence of injuries is not directly related to the amount of rearfoot movement during ground contact or the impact magnitude at touch-down (Nigg 2001). However, it may be that individuals adapt differently to alterations of running footwear. If that is the case the factor ageing of the shoe becomes important to consider. Recently, a fast and easy to use mobile system was presented to allow for such assessments with providing an automated data analysis and the possibility of comparing between repeated measurements by providing fast feedback.

Differences between accelerometry measurements of heel counter and calcaneus movement during treadmill running

Abnormal pronation of the foot has been implicated in numerous lower extremity pathologies (Genova and Gross 2000), thus screening for abnormal pronation is crucial in order to prevent overloading. Presently, screening methods consist of clinical subjective evaluation, planar video analysis or 3D Motion Capture technology (MoCap). Common to these methods is that they measure movement of the shoe and equate this to actual foot kinematics. However, the validity of this assumption may be questionable (Reinschmidt et al. 1992, Stacoff et al. 1992). The movement of the heel counter and the movement of the calcaneus are similar but not identical as the heel typically moves with a smaller amplitude than the shoe (Stacoff et al. 1992, Reinschmidt et al. 1997). These differences are likely to increase at higher running velocities or during lateral change in direction tasks (Reinschmidt et al. 1992). These noticeable differences fuel the question of validity and clinical relevance of shoe-related measurements. The authors have in pilot studies found that rearfoot movements can be measured by in-shoe accelerometry. This entails the possibility of ambulant, low-cost measurements of rearfoot movement in natural settings (Kavanagh and Menz 2008).