Shoulder Pain in Persons With Tetraplegia and the Association With Force Application During Manual Wheelchair Propulsion.

Objective: To investigate the association between propulsion biomechanics, including force application and spatio-temporal characteristics, and shoulder pain in persons with tetraplegia. Design: Cross-sectional, observational study. Setting: Non-university research institution. Participants: 16 community dwelling, wheelchair dependent persons with a chronic tetraplegia between C4 and C7, with and without shoulder pain (age, 49.1±11.7 years; 94% men, 23.4±9.5 years past injury). Interventions: Not applicable. Main Outcome Measures: Force application and spatio-temporal characteristics of wheelchair propulsion on a treadmill (0.56 m/s, 10W and 0.83 m/s, 15W). Participants were stratified in groups with low, moderate, and high pain based on their Wheelchair User Shoulder Pain Index (WUSPI) score on the day of measurement. Results: The mixed-effect multilevel analysis showed that wheelchair users with high levels of shoulder pain applied propulsion force more effectively (and with a lower medial component) and over a longer push angle, thus shortening the recovery time as compared with persons with low or moderate levels of shoulder pain. Conclusions: In contrast with previous results from persons with a paraplegia, persons with tetraplegia and high levels of shoulder pain propel their wheelchair more optimal with regard to risk factors for shoulder pain. Our results therefore affirm that there is a different interaction of shoulder pain and propulsion biomechanics in persons with a tetraplegia which should be considered when further analyzing risk factors for shoulder pain in wheelchair users or applying literature results to different patient populations.

Association Between the Availability of Mobility Assistive Products and Participation Outcomes in Individuals With Spinal Cord Injury in Switzerland.

Objectives: This study investigated the association between the reported availability of mobility assistive products and the perceived frequency, restriction, and satisfaction of participation in individuals with spinal cord injury in Switzerland. Methods: This study was based on a cross-sectional analysis based on questionnaire data collected from the Swiss SCI Cohort Study community survey in 2012 (N = 492). The availability of 12 mobility assistive products were analyzed as the main predictor variable. The outcomes of interest were the frequency, restriction, and satisfaction of participation scales as measured by the 32-item Utrecht Scale for Evaluation of Rehabilitation-Participation (USER-P). The association between availability of mobility assistive products and participation was investigated using linear regressions analyses. All mobility assistive products were ranked in terms of relevance to improve participation by means of an importance performance plot. Results: The availability of a sports wheelchair or a hand bike were both significant in reducing the restriction to participation. Having an adapted car increased the frequency of participation. Conclusion: The availability of a sports wheelchair or a hand bike was significantly associated with less restriction in participation. With an unmet need of up to 36%, the known health benefits of regular physical activity and thereby cost-saving potential for the health care system, external support in the acquiring or use of these sports-related mobility assistive products could be an easy target for intervention.

Real-Life Wheelchair Mobility Metrics from IMUs.

Daily wheelchair ambulation is seen as a risk factor for shoulder problems, which are prevalent in manual wheelchair users. To examine the long-term effect of shoulder load from daily wheelchair ambulation on shoulder problems, quantification is required in real-life settings. In this study, we describe and validate a comprehensive and unobtrusive methodology to derive clinically relevant wheelchair mobility metrics (WCMMs) from inertial measurement systems (IMUs) placed on the wheelchair frame and wheel in real-life settings. The set of WCMMs includes distance covered by the wheelchair, linear velocity of the wheelchair, number and duration of pushes, number and magnitude of turns and inclination of the wheelchair when on a slope. Data are collected from ten able-bodied participants, trained in wheelchair-related activities, who followed a 40 min course over the campus. The IMU-derived WCMMs are validated against accepted reference methods such as Smartwheel and video analysis. Intraclass correlation (ICC) is applied to test the reliability of the IMU method. IMU-derived push duration appeared to be less comparable with Smartwheel estimates, as it measures the effect of all energy applied to the wheelchair (including thorax and upper extremity movements), whereas the Smartwheel only measures forces and torques applied by the hand at the rim. All other WCMMs can be reliably estimated from real-life IMU data, with small errors and high ICCs, which opens the way to further examine real-life behavior in wheelchair ambulation with respect to shoulder loading. Moreover, WCMMs can be applied to other applications, including health tracking for individual interest or in therapy settings.

Machine-Learning-Based Methodology for Estimation of Shoulder Load in Wheelchair-Related Activities Using Wearables.

There is a high prevalence of shoulder problems in manual wheelchair users (MWUs) with a spinal cord injury. How shoulder load relates to shoulder problems remains unclear. This study aimed to develop a machine-learning-based methodology to estimate the shoulder load in wheelchair-related activities of daily living using wearable sensors. Ten able-bodied participants equipped with five inertial measurement units (IMU) on their thorax, right arm, and wheelchair performed activities exemplary of daily life of MWUs. Electromyography (EMG) was recorded from the long head of the biceps and medial part of the deltoid. A neural network was trained to predict the shoulder load based on IMU and EMG data. Different cross-validation strategies, sensor setups, and model architectures were examined. The predicted shoulder load was compared to the shoulder load determined with musculoskeletal modeling. A subject-specific biLSTM model trained on a sparse sensor setup yielded the most promising results (mean correlation coefficient = 0.74 ± 0.14, relative root-mean-squared error = 8.93% ± 2.49%). The shoulder-load profiles had a mean similarity of 0.84 ± 0.10 over all activities. This study demonstrates the feasibility of using wearable sensors and neural networks to estimate the shoulder load in wheelchair-related activities of daily living.

Classification of Wheelchair Related Shoulder Loading Activities from Wearable Sensor Data: A Machine Learning Approach.

Shoulder problems (pain and pathology) are highly prevalent in manual wheelchair users with spinal cord injury. These problems lead to limitations in activities of daily life (ADL), labor- and leisure participation, and increase the health care costs. Shoulder problems are often associated with the long-term reliance on the upper limbs, and the accompanying "shoulder load". To make an estimation of daily shoulder load, it is crucial to know which ADL are performed and how these are executed in the free-living environment (in terms of magnitude, frequency, and duration). The aim of this study was to develop and validate methodology for the classification of wheelchair related shoulder loading ADL (SL-ADL) from wearable sensor data. Ten able bodied participants equipped with five Shimmer sensors on a wheelchair and upper extremity performed eight relevant SL-ADL. Deep learning networks using bidirectional long short-term memory networks were trained on sensor data (acceleration, gyroscope signals and EMG), using video annotated activities as the target. Overall, the trained algorithm performed well, with an accuracy of 98% and specificity of 99%. When reducing the input for training the network to data from only one sensor, the overall performance decreased to around 80% for all performance measures. The use of only forearm sensor data led to a better performance than the use of the upper arm sensor data. It can be concluded that a generalizable algorithm could be trained by a deep learning network to classify wheelchair related SL-ADL from the wearable sensor data.

A Scoping Review on Shoulder Injuries of Wheelchair Tennis Players: Potential Risk-Factors and Musculoskeletal Adaptations.

Wheelchair tennis players are prone to develop shoulder injuries, due to the combination of wheelchair propulsion, overhead activities and daily wheelchair activities. A methodical literature search was conducted to identify articles on shoulder complaints in wheelchair tennis, wheelchair sports and tennis. The aims were to identify (1) type of shoulder complaints; (2) possible risk factors for the development of shoulder injuries; (3) musculoskeletal adaptations in the shoulder joint in wheelchair tennis players. Fifteen papers were included in this review, five on wheelchair tennis, three on wheelchair sports and seven on tennis. Type of shoulder complaints were acromioclavicular pathology, osteoarthritic changes, joint effusion and rotator cuff tears. Possible risk factors for the development of shoulder injuries in wheelchair tennis are overhead movements, repetitive activation of the anterior muscle chain and internal rotators, as well as a higher spinal cord injury level. Muscular imbalance with higher values for the internal rotators, increase in external range of motion, decrease in internal range of motion and reduced total arc of motion were the most common proposed musculoskeletal adaptations due to an unbalanced load. These presented risk factors and musculoskeletal adaptations might help researchers, coaches and wheelchair tennis players to prevent shoulder injuries.

MRI evaluation of shoulder pathologies in wheelchair users with spinal cord injury and the relation to shoulder pain.

OBJECTIVE: To describe the number, specifics and co-occurrence of shoulder pathologies detected by MRI in manual wheelchair users with spinal cord injury and to evaluate the association between shoulder pathologies and presence of shoulder pain. DESIGN: Cross-sectional observation study. SETTING: Community. PARTICIPANTS: Fifty-one wheelchair-dependent persons with spinal cord injury (44 males, 7 females, median age 50 years (IQR 14), median time since injury 24 years (IQR 16)) were allocated to pain or no-pain group based on the Wheelchair User Shoulder Pain Index. INTERVENTIONS: Not applicable. OUTCOME MEASURES: All persons underwent shoulder MRI. Pathologies were scored blinded by two experienced radiologists. Participant characteristics, number and severity of shoulder pathologies were analyzed descriptively. Logistic regression was performed to evaluate the association between MRI findings and shoulder pain. RESULTS: The median number of co-occurring MRI findings per person ranged from 0 to 19 (out of 31 possible findings). The cluster of MRI findings occurring most often together were tendon tears of supraspinatus (present in 84%), subscapularis (69%) and biceps (67%) and osteoarthritis of acromioclavicular joint (80%). When correcting for age and time since injury, the logistic regression showed no statistically significant correlation between the individual pathologies and shoulder pain. CONCLUSION: MRI findings of shoulder pathology are very frequent in persons with and without shoulder pain. Therefore, when diagnosing the cause of shoulder pain and planning interventions, health care professionals should keep this finding in mind and MRI should not be interpreted without careful consideration of clinical history and functional testing.

Change in mobility independence over 5 years for persons with chronic spinal cord injury.

OBJECTIVES: To evaluate change in mobility independence (MI) in community dwelling persons with spinal cord injury (SCI). PARTICIPANTS: Community Survey. DESIGN: Cohort study. Rasch analysis was applied to the mobility subscale of the Spinal Cord Independence Measure - Self-Report data from years 2012 to 2017, resulting in a Rasch Mobility Independence Score (RMIS). We employed multilevel modeling to examine RMIS and its change over 5 years, adjusting for demographics and SCI severity; random forest regression was applied to determine the impact of modifiable factors (e.g. environmental factors, home-support) on its change. RESULTS: The analysis included 728 participants. The majority (≈85%) of participants demonstrated little or no change in RMIS from 2012 to 2017; however, a smaller proportion (15%) showed considerably large change of more than 10 on the 100-point scale. A mixed-effects model with random slopes and intercepts described the dataset very well (conditional R2 of 0.95) in terms of demographics and SCI severity. Age was the main predictor of change in RMIS. Considering SCI severity, change in RMIS was related to age for the subgroup with paraplegia, and to time since injury for the subgroup with tetraplegia. No impact of modifiable factors was found. CONCLUSION: RMIS in persons with SCI changes over a period of 5 years, especially in elder patients with paraplegia and persons with incomplete tetraplegia with more than 15 years of time since injury. During routine follow-up change in mobility independence should be assessed in order to timely intervene and prevent mobility loss and participation limitations.

Shoulder Pain Is Associated With Rate of Rise and Jerk of the Applied Forces During Wheelchair Propulsion in Individuals With Paraplegic Spinal Cord Injury.

OBJECTIVE: To investigate the association between propulsion biomechanics, including variables that describe smoothness of the applied forces, and shoulder pain in individuals with spinal cord injury (SCI). DESIGN: Cross-sectional, observational study. SETTING: Non-university research institution. PARTICIPANTS: Community dwelling, wheelchair dependent participants (N=30) with chronic paraplegia between T2 and L1, with and without shoulder pain (age, 48.6±9.3y; 83% men). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Rate of rise and jerk of applied forces during wheelchair propulsion. Participants were stratified in groups with low, moderate, and high pain based on their Wheelchair User Shoulder Pain Index score on the day of measurement. RESULTS: A mixed-effect multilevel analysis showed that wheelchair users in the high pain group propelled with a significantly greater rate of rise and jerk, measures that describe smoothness of the applied forces, compared with individuals with less or no pain, when controlling for all covariables. CONCLUSIONS: Individuals with severe shoulder pain propelled with less smooth strokes compared to individuals with less or no pain. This supports a possible association between shoulder pain and rate of rise and jerk of the applied forces during wheelchair propulsion.

Compensation Strategies in Response to Fatiguing Propulsion in Wheelchair Users: Implications for Shoulder Injury Risk.

OBJECTIVE: The aims of the study were to examine whether fatigue-inducing wheelchair propulsion changes neuromuscular activation and propulsion biomechanics and to determine predictor variables for susceptibility to fatigue. DESIGN: This study with a quasi-experimental, one-group, pretest-posttest design investigates a population-based sample of wheelchair users with a spinal cord injury (n = 34, age: 50.8 ± 9.7 yrs, 82% males). Neuromuscular activation and propulsion biomechanics during treadmill propulsion at 25 W and 45 W were assessed before and after a protocol designed to cause fatigue. RESULTS: With the induced fatigue, wheelchair users propelled with increased neuromuscular activation in the pectoralis major pars sternalis, deltoideus pars acromialis and upper trapezius (45 W, P < 0.05), and a slightly reduced push angle (25 W: 75-74 degrees, P < 0.05, 45 W: 78-76 degrees, P < 0.05). Wheelchair users susceptible to fatigue (47%) were more likely to have a complete lesion, to be injured at an older age, and had less years since injury. This group propelled in general with shorter push angle and greater maximum resultant force, had a greater anaerobic capacity, and had less neuromuscular activation. CONCLUSIONS: Compensation strategies in response to fatiguing propulsion could increase the risk for shoulder injury. Predictor variables for susceptibility to fatigue inform interventions preserving shoulder health and include lesion characteristics, propulsion technique, anaerobic capacity, and neuromuscular activation. TO CLAIM CME CREDITS: Complete the self-assessment activity and evaluation online at http://www.physiatry.org/JournalCME CME OBJECTIVES: Upon completion of this article, the reader should be able to: (1) Explain a neuromuscular compensation strategy and the corresponding muscles in response to fatiguing wheelchair propulsion; (2) Recommend propulsion biomechanics associated to reduced susceptibly to fatiguing wheelchair propulsion; and (3) List examples of predictor variables of susceptibility to fatigue. LEVEL: Advanced. ACCREDITATION: The Association of Academic Physiatrists is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.The Association of Academic Physiatrists designates this journal-based CME activity for a maximum of 1.0 AMA PRA Category 1 Credit(s)™. Physicians should only claim credit commensurate with the extent of their participation in the activity.

Changes in propulsion technique and shoulder complex loading following low-intensity wheelchair practice in novices.

BACKGROUND: Up to 80% of wheelchair users are affected by shoulder pain. The Clinical Practice Guidelines for preservation of upper limb function following spinal cord injury suggest that using a proper wheelchair propulsion technique could minimize the shoulder injury risk. Yet, the exact relationship between the wheelchair propulsion technique and shoulder load is not well understood. OBJECTIVE: This study aimed to examine the changes in shoulder loading accompanying the typical changes in propulsion technique following 80 min of low-intensity wheelchair practice distributed over 3 weeks. METHODS: Seven able-bodied participants performed the pre- and the post-test and 56 min of visual feedback-based low-intensity wheelchair propulsion practice. Kinematics and kinetics of propulsion technique were recorded during the pre- and the post-test. A musculoskeletal model was used to calculate muscle force and glenohumeral reaction force. RESULTS: Participants decreased push frequency (51→36 pushes/min, p = 0.04) and increased contact angle (68→94°, p = 0.02) between the pre- and the post-test. The excursion of the upper arm increased, approaching significance (297→342 mm, p = 0.06). Range of motion of the hand, trunk and shoulder remained unchanged. The mean glenohumeral reaction force per cycle decreased by 13%, approaching significance (268→232 N, p = 0.06). CONCLUSIONS: Despite homogenous changes in propulsion technique, the kinematic solution to the task varied among the participants. Participants exhibited two glenohumeral reaction force distribution patterns: 1) Two individuals developed high force at the onset of the push, leading to increased peak and mean glenohumeral forces 2) Five individuals distributed the force more evenly over the cycle, lowering both peak and mean glenohumeral forces.

Scapular kinematics during manual wheelchair propulsion in able-bodied participants.

BACKGROUND: Altered scapular kinematics have been associated with shoulder pain and functional limitations. To understand kinematics in persons with spinal cord injury during manual handrim wheelchair propulsion, a description of normal scapular behaviour in able-bodied persons during this specific task is a prerequisite for accurate interpretation. The primary aim of this study is to describe scapular kinematics in able-bodied persons during manual wheelchair propulsion. METHODS: Sixteen able-bodied, novice wheelchair users without shoulder complaints participated in the study. Kinematic and kinetic data were collected during a standardized pose in the anatomic posture, frontal-plane arm elevation and low-intensity steady-state handrim wheelchair propulsion and upper-body Euler angles were calculated. FINDINGS: Scapulothoracic joint orientations in a static position were 36.7° (SD 5.4°), 6.4° (SD 9.1°) and 9.1° (SD 5.7°) for respectively protraction, lateral rotation and anterior tilt. At 80° of arm elevation in the frontal plane, the respective values of 33.4° (SD 8.0°), 23.9° (SD 5.4°) and 4.1° (SD 11.3°) were found. During the push phase of manual wheelchair propulsion, the mean scapular rotations were respectively 32.7° (SD 7.1°), 7.1° (SD 9.2°) and 9.8° (SD 8.3°). INTERPRETATION: The orientation of the scapula in a static pose, during arm elevation and in manual wheelchair propulsion in able-bodied participants showed similar patterns to a previous study in persons with para- and tetraplegia. These values provide a reference for the investigation of the scapular movement pattern in wheelchair-dependent persons and its relation to shoulder complex abnormalities.

Effect of power-assisted hand-rim wheelchair propulsion on shoulder load in experienced wheelchair users: A pilot study with an instrumented wheelchair.

This study aims to compare hand-rim and power-assisted hand-rim propulsion on potential risk factors for shoulder overuse injuries: intensity and repetition of shoulder loading and force generation in the extremes of shoulder motion. Eleven experienced hand-rim wheelchair users propelled an instrumented wheelchair on a treadmill while upper-extremity kinematic, kinetic and surface electromyographical data was collected during propulsion with and without power-assist. As a result during power-assisted propulsion the peak resultant force exerted at the hand-rim decreased and was performed with significantly less abduction and internal rotation at the shoulder. At shoulder level the anterior directed force and internal rotation and flexion moments decreased significantly. In addition, posterior and the minimal inferior directed forces and the external rotation moment significantly increased. The stroke angle decreased significantly, as did maximum shoulder flexion, extension, abduction and internal rotation. Stroke-frequency significantly increased. Muscle activation in the anterior deltoid and pectoralis major also decreased significantly. In conclusion, compared to hand-rim propulsion power-assisted propulsion seems effective in reducing potential risk factors of overuse injuries with the highest gain on decreased range of motion of the shoulder joint, lower peak propulsion force on the rim and reduced muscle activity.

Effects of an implantable two-channel peroneal nerve stimulator versus conventional walking device on spatiotemporal parameters and kinematics of hemiparetic gait.

OBJECTIVE: The aims of this study were: (i) to compare the neuro-prosthetic effect of implantable peroneal nerve stimulation to the orthotic effect of a standard of care intervention (no device, shoe or ankle foot orthosis) on walking, as assessed by spatiotemporal parameters; and (ii) to examine whether there is evidence of an enhanced lower-limb flexion reflex with peroneal nerve stimulation and compare the kinematic effect of an implantable peroneal nerve stimulation device vs standard of care intervention on initial loading response of the paretic limb, as assessed by hip, knee and ankle kinematics. DESIGN: Randomized controlled trial. SUBJECTS: A total of 23 chronic stroke survivors with drop foot. METHODS: The intervention group received an implantable 2-channel peroneal nerve stimulator for correction of drop foot. The control group continued using a conventional walking device. Spatiotemporal parameters and hip, knee and ankle kinematics were measured while subjects walked with the device on using a 3-dimensional video camera system during baseline and after a follow-up period of 26 weeks. RESULTS: Peroneal nerve stimulation normalized stance and double support of the paretic limb and single support of the non-paretic limb, in comparison with using a conventional walking device. In addition, peroneal nerve stimulation is more effective to provide ankle dorsiflexion during swing and resulted in a normalized initial loading response. CONCLUSION: Although peroneal nerve stimulation and ankle foot orthosis are both prescribed to correct a drop foot in the same patient population, spatiotemporal parameters, dorsiflexion during swing and loading response are influenced in a functionally different way.

Feasibility of pulse oximetry in the initial prehospital management of victims of drowning: a preliminary study.

AIM: Immediate delivery of oxygen is the most important treatment for victims of drowning at the rescue site. Monitoring oxygen saturation with pulse oximetry is potentially useful, but its use may be limited by poor peripheral perfusion due to hypothermia. This preliminary study explores the feasibility of pulse oximetry in simulated minor drowning scenarios. MATERIALS AND METHODS: Six different pulse oximeters were tested on ten healthy volunteers after brief submersion, after ten minutes of swimming in a swimming pool (warm water, temperature 21°C), and in the sea (cold water, temperature 16°C). A measured oxygen saturation reading ≤ 94% was assumed to be incorrect. RESULTS: There was considerable variability between each pulse oximeter. In warm water, 5.8% of measurements were outside the predicted range (8.3% after submersion, 3.3% after swimming), compared to 34% in cold water (20% after submersion, 48% after swimming). The spurious measurements came from two pulse oximeters in warm water, but from all six in cold water. The best and worst performing pulse oximeters showed 5% and 33% measurements respectively outside the predicted range. CONCLUSION: The performance of pulse oximeters varies considerably in healthy volunteers submersed or immersed in warm or cold water. Further studies are needed to understand these differences.

Comparison of instructor-led automated external defibrillation training and three alternative DVD-based training methods.

BACKGROUND: Self-directed BLS-training, using a personal training manikin with video has been shown to be as effective as instructor-led training. This has not previously been investigated for AED-training. MATERIALS AND METHODS: This prospective, randomized study with a non-inferiority design compared traditional instructor-led training with three DVD-based AED-training methods (2.5min DVD without practice; 4.5min DVD with manikin practice; 9min DVD with manikin practice and scenario training). After DVD BLS-training, 396 participants were assigned to one of the four AED-training methods by randomization stratified for age. Participants were tested immediately after the training (post-test) and 2 months later (retention-test) using modified Cardiff criteria. The primary endpoint was the percentage of providers scoring 70% or higher on testing. The secondary endpoints were the mean scores and differences per item per age group. RESULTS: Comparison non-inferiority could not be accepted for the post-test or retention-test. Relative risk (RR) and 95% confidence interval (CI) of passing for DVD without practice, with manikin practice and with manikin practice and scenario training compared to instructor-led training were 0.36 (0.25-0.53), 0.35 (0.24-0.51), 0.55 (0.38-0.79), respectively for the post-test, and 0.82 (0.68-0.97), 0.82 (0.68-0.97), and 0.84 (0.70-1.00), respectively for the retention-test. The performance of participants in all DVD-based training groups was significantly higher on the retention-test than on the post-test. Those receiving scenario training scored higher on the post-test compared to the other DVD-training groups (p<0.001). CONCLUSIONS: DVD-based AED-training without scenario is not recommended. Scenario training is a useful addition, but instructor-facilitated training remains the best method.

Instructor retraining and poster retraining are equally effective for the retention of BLS and AED skills of lifeguards.

INTRODUCTION: More than a million people in the USA and Europe suffer a sudden cardiac arrest each year. Thousands of people have to be trained in delivering help in such a situation. This cluster-randomized study compared two refresher training methods for basic life support and use of an automated external defibrillation: a traditional instructor-led course, and self-instruction by poster. METHODS: One hundred and thirty-nine lifeguards were assigned to one of the two groups. Group A (n=79) received a 1.5 h, instructor-led refresher training course, whereas group B (n=60) was advised to refresh their own knowledge with a poster, a manikin, and an automated external defibrillation training device. The lifeguards were assessed 3, 6, and 12 months after the initial training. RESULTS: Seventy-five percent of the lifeguards in each group were deemed competent after 3 months. After 6 months, 78% lifeguards in group A and 75% in group B were considered competent. After 12 months, this was 71 and 76%, respectively. Young, less experienced lifeguards performed better than older, more experienced lifeguards. CONCLUSION: Refresher self-training by the use of a poster was as effective as, and more flexible than, scheduled, instructor-led refresher training.

Effect of lifting height and load mass on low back loading.

The objective of this study was to quantify the effect of lifting height and mass lifted on the peak low back load in terms of net moments, compression forces and anterior-posterior shear forces. Ten participants had to lift a box using four handle heights. Low back loading was quantified using a dynamic 3-D linked segment model and a detailed electromyographic driven model of the trunk musculature. The effects of lifting height and lifting mass were quantified using a regression technique (GEE) for correlated data. Results indicate that an increase in lifting height and a decrease in lifting mass were related to a decrease in low back load. It is argued that trunk flexion is a major contributor to low back load. For ergonomic interventions it can be advised to prioritise optimisation of the vertical location of the load to be lifted rather than decreasing the mass of the load for handle heights between 32 cm and 155 cm, and for load masses between 7.5 and 15 kg. Lifting height and load mass are important determinants of low back load during manual materials handling. This paper provides the quantitative effect of lifting height and mass lifted, the results of which can be used by ergonomists at the workplace to evaluate interventions regarding lifting height and load mass.

Self-training in the use of automated external defibrillators: the same results for less money.

PURPOSE: To compare the educational benefits and cost-effectiveness of initial AED training for nurses, already trained in basic life support, by a 3-h, instructor-based course, with self-training by means of an instructional poster, a resuscitation manikin, and a training AED. METHODS: Thirty general ward nurses from a single regional hospital were randomly allocated to one of two groups for training in the use of an AED. Fifteen nurses were trained by a certified instructor and 15 nurses participated in self-training using a poster, manikin, and training AED. Each nurse was assessed on 17 aspects of performance between 13 and 16 days after training. RESULTS: The two groups were comparable for gender, seniority, and experience in resuscitation. No significant differences in performance were found between the groups for 14 of the skills tested. For three skills, there were statistical differences, but these were not considered to be of clinical relevance. If poster self-training were to be used instead of instructor-based courses, it was calculated that there would be a saving in costs of up to 47 euros for each nurse trained.