A.J. van der Beek

Episodes of Low Back Pain : A Proposal for Uniform Definitions to Be Used in Research

Study Design. Literature review and group discussions. Objective. To propose uniform definitions for low back pain episodes to be used in research. Background. Different definitions of episodes have been used in low back pain studies. This hampers comparison of study results. Definitions are proposed for episodes of low back pain, care for low back pain, and work absence because of low back pain. Methods. In a Medline search, we identified about 1200 papers, of which 81 possibly contained a definition of episodes. In group discussions, we decided which definitions to propose and discussed their applicability. Results. We found few definitions in the literature. In the group discussions we decided to define an episode of LBP as a period of pain in the lower back lasting for more than 24 hours, preceded and followed by a period of at least 1 month without low back pain. An episode of care for low back pain was defined as a consultation or a series of consultations for low back pain, preceded and followed by at least 3 months without consultation for low back pain. An episode of work absence due to low back pain was defined as a period of work absence due to low back pain, preceded and followed by a period of at least 1 day at work. Conclusions. In many studies, episodes of low back pain are mentioned without a clear definition. We consider our proposed definitions of episodes to be arbitrary but well considered. We advise that they be tested for use in future research.

The influence of work characteristics on the need for recovery and experienced health: a study on coach drivers

Work characteristics, occupationally-induced fatigue, and health complaints were investigated on the basis of questionnaire data from 363 randomized coach drivers. The hypothesis was tested that, apart from high job demands and low job control, need for recovery is an indicator of occupationally-induced health complaints. Multiple linear regression analyses showed that need for recovery was a major predictor of psychosomatic complaints, sleep complaints, and complaints of emotional exhaustion in coach drivers. The influence of job demands and job control on health problems was moderately confirmed. The results of this study draw attention to the role of the need for recovery, as a sign of occupationally-induced fatigue and predictor of health complaints, in future research on occupational stress.

Assessment of mechanical exposure in ergonomic epidemiology

In recent years several different methods have been developed to assess mechanical exposures, which are related to musculoskeletal disorders in ergonomic epidemiology. Each of these methods is capable of measuring one or more aspects of risk factors, but has drawbacks as well. Improper application of methods might result in biased exposure estimates, which has serious consequences for risk estimates arising from epidemiological studies. The aim of this paper was to systematically evaluate the usefulness of different measurement methods in terms of accuracy and applicability. Assessment of external exposure measures by subjective judgements (from experts or self reports from workers), observational methods (on site or afterwards from video recordings), and direct measurements methods (at work or during laboratory simulations) are discussed for each of the dimensions of exposure level, duration, and frequency. It is concluded that expert judgements and self reports give only limited insight into the occurrence of tasks and activities. Further information can be obtained from observations, which can best be combined with direct measurements of exposure to posture, movement, and exerted forces to achieve exposure profiles by occupational task. Internal exposures estimated by biomechanical modelling mostly consider the low back and require information on postures of the different body segments and exerted forces, completed with movement data in the case of dynamic models. Moreover, electromyography (EMG) and measurements of intra-abdominal pressure might be used for this purpose. Both biomechanical models and EMG are useful methods to assess internal exposure, but biomechanical models should not be restricted to the level of compressive forces on the lower back. Finally, current problems and future directions in measurement strategies and methods are discussed.

A one season prospective cohort study of volleyball injuries

Objective: To estimate the overall incidence of acute and overuse volleyball injuries, and to describe factors associated with ankle sprains. Methods: 486 players from the second and third Dutch national volleyball divisions participated in the study and were followed prospectively during a whole season. Three measurements were made during the season (baseline, follow up 1, and follow up 2), where all players completed a questionnaire on demographic variables (only at baseline), sports participation, use of preventive measures, and previous injuries. Volleyball exposure during training and matches was recorded for each individual player by the coach on a weekly exposure form. In case of injury the coach provided the injured player with an injury registration form, which had to be completed within one week after the onset of injury. Results: 100 injuries were reported, resulting in an overall injury incidence of 2.6 injuries/1000 hours. The incidence of acute injuries was 2.0/1000 hours. Ankle sprains (n = 41) accounted for most of the acute injuries, and 31 (75%) of all players with an ankle sprain reported a previous ankle sprain. Twenty five overuse injuries were reported. The overall incidence of overuse injuries was 0.6/1000 hours; the back and the shoulder were the most common sites. Conclusions: Ankle sprain is the most common injury in volleyball, accounting for 41% of all volleyball related injuries. Previous injury seems to be an important risk factor for an ankle sprain. Injury prevention programmes should focus on ankle sprains and concentrate on players with previous ankle sprains.

Should office workers spend fewer hours at their computer? A systematic review of the literature

Worldwide, millions of office workers use a computer. Reports of adverse health effects due to computer use have received considerable media attention. This systematic review summarises the evidence for a relationship between the duration of work time spent using the computer and the incidence of hand–arm and neck–shoulder symptoms and disorders. Several databases were systematically searched up to 6 November 2005. Two reviewers independently selected articles that presented a risk estimate for the duration of computer use, included an outcome measure related to hand–arm or neck–shoulder symptoms or disorders, and had a longitudinal study design. The strength of the evidence was based on methodological quality and consistency of the results. Nine relevant articles were identified, of which six were rated as high quality. Moderate evidence was concluded for a positive association between the duration of mouse use and hand–arm symptoms. For this association, indications for a dose–response relationship were found. Risk estimates were in general stronger for the hand–arm region than for the neck–shoulder region, and stronger for mouse use than for total computer use and keyboard use. A pathophysiological model focusing on the overuse of muscles during computer use supports these differences. Future studies are needed to improve our understanding of safe levels of computer use by measuring the duration of computer use in a more objective way, differentiating between total computer use, mouse use and keyboard use, attaining sufficient exposure contrast, and collecting data on disability caused by symptoms.

Pushing and pulling in relation to musculoskeletal disorders: a review of risk factors

The objective was to review the literature on risk factors for musculoskeletal disorders related to pushing and pulling. The risk factors have been described and evaluated from four perspectives: epidemiology, psychophysics, physiology, and biomechanics. Epidemiological studies have shown, based on cross-sectional data, that pushing and pulling is associated with low back pain. Evidence with respect to complaints of other parts of the musculoskeletal system is lacking. Risk factors have been found to influence the maximum (acceptable) push or pull forces as well as the physiological and mechanical strain on the human body. The risk factors have been divided into: (a) work situation, such as distance, frequency, handle height, and cart weight, (b) actual working method and posture/movement/exerted forces, such as foot distance and velocity, and (c) workers characteristics, such as body weight. Longitudinal epidemiological studies are needed to relate pushing and pulling to musculoskeletal disorders.

An economic evaluation of a proprioceptive balance board training programme for the prevention of ankle sprains in volleyball

Objectives: To evaluate the cost effectiveness of a proprioceptive balance board training programme for the prevention of ankle sprains in volleyball. Methods: A total of 116 volleyball teams participated in this study which was carried out during the 2001–2002 volleyball season. Teams were randomly allotted to an intervention group (66 teams, 628 players) or a control group (52 teams, 494 players). Intervention teams followed a prescribed balance board training programme as part of their warm up. Control teams followed their normal training routine. An ankle sprain was recorded if it occurred as a result of volleyball and caused the subject to stop volleyball activity. The injured player completed a cost diary for the duration of the ankle sprain. Analyses were performed according to the intention to treat principle. Mean direct, indirect, and total costs were calculated and were compared between the two groups. Results: The total costs per player (including the intervention material) were significantly higher in the intervention group (€36.99 (93.87)) than in the control group (€18.94 (147.09)). The cost of preventing one ankle sprain was approximately €444.03. Sensitivity analysis showed that a proprioceptive balance board training programme aimed only at players with previous ankle sprains could be cost effective over a longer period of time. Conclusions: Positive effects of the balance board programme could only be achieved at certain costs. However, if broadly implemented, costs associated with the balance board programme would probably be lower.

Psychosocial work characteristics in relation to neck and upper limb symptoms

&NA; The aim of this study was to investigate the relationship between psychosocial work characteristics and neck and upper limb symptoms and to examine to what extent this relationship could be explained by other risk factors. Data were used from a prospective cohort study in a working population, with a follow‐up period of 3 years. The 3‐year cumulative incidence rates of neck or upper limb symptoms, neck/shoulder symptoms and elbow/wrist/hand symptoms were 32, 24 and 15%, respectively. After adjustment for potential confounders high job demands was identified as a risk factor for neck/shoulder symptoms (RR: 2.1; CI: 1.2–3.6) and elbow/wrist/hand symptoms (RR: 1.9; CI: 1.0–3.7), and low social support of co‐workers was identified as a risk factor for elbow/wrist/hand symptoms (RR: 2.2; CI: 1.0–4.9). Partly, but not exclusively, these relationships were intermediated by an increased exposure to physical risk factors and increased stress symptoms. Personal characteristics did not considerably influence the main effects of the identified risk factors.

The effectiveness of physical and organisational ergonomic interventions on low back pain and neck pain: a systematic review

Ergonomic interventions (physical and organisational) are used to prevent or reduce low back pain (LBP) and neck pain among workers. We conducted a systematic review of randomised controlled trials (RCTs) on the effectiveness of ergonomic interventions. A total of 10 RCTs met the inclusion criteria. There was low to moderate quality evidence that physical and organisational ergonomic interventions were not more effective than no ergonomic intervention on short and long term LBP and neck pain incidence/prevalence, and short and long term LBP intensity. There was low quality evidence that a physical ergonomic intervention was significantly more effective for reducing neck pain intensity in the short term (ie, curved or flat seat pan chair) and the long term (ie, arm board) than no ergonomic intervention. The limited number of RCTs included make it difficult to answer our broad research question and the results should be interpreted with care. This review, however, provides a solid overview of the high quality epidemiological evidence on the (usually lack of) effectiveness of ergonomic interventions on LBP and neck pain.

Reactivity and recovery from different types of work measured by catecholamines and cortisol: a systematic literature overview

OBJECTIVES To review occupational health, laboratory, and sports literature on neuroendocrine reactivity and recovery from mental, combined mental and physical, or physical tasks. METHODS A systematic literature search was performed in eight databases. Studies with catecholamines or cortisol as effect variables measured in blood, urine, or saliva were included. RESULTS After application of inclusion and exclusion criteria, 77 studies from the initial 559 identified were taken into account. In occupational settings it was found that relatively few studies were conclusive about recovery, which formed a contrast with sports research. For reactivity and recovery up to 1 hour after performing the task, half of the studies considered physical tasks and more than two thirds showed incomplete recovery compared with baseline excretion of catecholamines and cortisol. Recovery extending to 3 days after the task was performed was often incomplete for cortisol after combined mentally and physically demanding tasks, and less often after solely mental or physical tasks. This type of recovery was more often incomplete for adrenaline (epinephrine) than for noradrenaline (norepinephrine), which was the case after mental as well as combined mental and physical tasks. CONCLUSIONS The results from laboratory and sports research may be transferable to some occupations, but more research is needed on the course of recovery relative to health effects in occupational settings.