Predictors of perceived effort in the shoulder during load transfer tasks

The mechanism of muscular effort perception in the shoulder was examined in this experiment. Two shoulder biomechanical models and experimental muscle activity data were used to assess physical exposure for a series of reaching tasks. Effort perception was quantitatively correlated to these measures of physical loading, both at the resultant torque (r² = 0.50) and muscle activity model-based muscle force predictions (MFPs): r² = 0.42, electromyography (EMG): r² = 0.26) levels. Muscle data did not explain variation in effort perception more fully than torque data. The inclusion of subject and task variables improved the ability of each model to explain variability in effort perception (torque: r² = 0.74; MFP: r² = 0.67, EMG: r² = 0.64). These results suggest that effort perception may not be fully explained by only an image of the motor command, but is rather a complex integrative quantity that is affected by other factors, such as posture and task goals, which may be dependent on sensory feedback.     

Little effect of transfer technique instruction and physical fitness training in reducing low back pain among nurses: a cluster randomised intervention study

The aim of this study was to evaluate the effect of a transfer technique education programme (TT) alone or in combination with physical fitness training (TTPT) compared with a control group, who followed their usual routine. Eleven clinical hospital wards were cluster randomised to either intervention (six wards) or to control (five wards). The intervention cluster was individually randomised to TT (55 nurses) and TTPT (50 nurses), control (76 nurses). The transfer technique programme was a 4-d course of train-the-trainers to teach transfer technique to their colleagues. The physical training consisted of supervised physical fitness training 1 h twice per week for 8 weeks. Implementing transfer technique alone or in combination with physical fitness training among a hospital nursing staff did not, when compared to a control group, show any statistical differences according to self-reported low back pain (LBP), pain level, disability and sick leave at a 12-month follow-up. However, the individual randomised intervention subgroup (transfer technique/physical training) significantly improved the LBP-disability (p = 0.001). Although weakened by a high withdrawal rate, teaching transfer technique to nurses in a hospital setting needs to be thoroughly considered. Other priorities such as physical training may be taken into consideration. The current study supports the findings of other studies that introducing transfer technique alone has no effect in targeting LBP. However, physical training seems to have an influence in minimising the LBP consequences and may be important in the discussion of how to prevent LBP or the recurrence of LBP among nursing personnel.     

The relationship between shoulder torques and the perception of muscular effort in loaded reaches

The objective of this study was to define the quantitative relationship between external dynamic shoulder torques and calibrated perceived muscular effort levels for load delivery tasks, for application in job analyses. Subjects performed a series of loaded reaches and, following each exertion, rated their perceived shoulder muscular effort. Motion and task physical requirements data were processed with a biomechanical upper extremity model to calculate external dynamic shoulder torques. Calculated torque values were then statistically compared to reported calibrated perceived muscular effort scores. Individual subject torque profiles were significantly positively correlated with perceived effort scores (r² = 0.45–0.77), with good population agreement (r² = 0.50). The accuracy of the general regression model improved (r² = 0.72) with inclusion of factors specific to task geometry and individual subjects. This suggests two major conclusions: 1) that the perception of muscular shoulder effort integrates several factors and this interplay should be considered when evaluating tasks for their impact on the shoulder region; 2) the torque/perception relationship may be usefully leveraged in job design and analysis.     

Satisfaction with health status among cyber patients: testing a mediation model of electronic coping support

There has been a growing interest among researchers about the Internet-based social support. However, not much is known about whether electronic support is associated with subjectively reported patient health outcomes. This study examines variation in satisfaction with physical health status among users of self-help groups for patients with cancer (N = 350). The analytical approach of the study differs from previous work in that satisfaction with physical health is modelled not as a predictor, but as an outcome variable. The study tested the hypothesis that perceived ability to cope with cancer mediates the association between electronic support and health satisfaction. Path analyses using ordinary least squares multiple regressions showed that there is an indirect association between electronic support and health satisfaction via perceived ability to cope with cancer. Electronic support increased perception of control over cancer, which in turn led to higher levels of satisfaction with health status. External health locus of control was associated with greater benefits derived from electronic support. This article concludes that the evaluation of physical health status includes not only clinical indicators but also subjective assessment of coping ability. Thus, the cyber social context in which health perceptions are developed has important medical implications for patient outcomes.     

Development of virtual reality proprioceptive rehabilitation system for stroke patients

In this study, the virtual reality (VR) proprioception rehabilitation system was developed for stroke patients to use proprioception feedback in upper limb rehabilitation by blocking visual feedback. To evaluate its therapeutic effect, 10 stroke patients (onset > 3 month) trained proprioception feedback rehabilitation for one week and visual feedback rehabilitation for another week in random order. Proprioception functions were checked before, a week after, and at the end of training. The results show the click count, error distance and total error distance among proprioception evaluation factors were significantly reduced after proprioception feedback training compared to visual feedback training (respectively, p = 0.005, p = 0.001, and p = 0.007). In addition, subjects were significantly improved in conventional behavioral tests after training. In conclusion, we showed the effectiveness and possible use of the VR to recover the proprioception of stroke patients.     

Virtual reality software package for implementing motor learning and rehabilitation experiments

Virtual reality games for rehabilitation are attracting increasing growth. In particular, there is a demand for games that allow therapists to identify an individual’s difficulties and customize the control of variables, such as speed, size, distance, as well as visual and auditory feedback. This study presents and describes a virtual reality software package (Bridge Games) to promote rehabilitation of individuals living with disabilities and highlights preliminary researches of its use for implementing motor learning and rehabilitation. First, the study presents seven games in the software package that can be chosen by the rehabilitation team, considering the patient’s needs. All game characteristics are described including name, function presentation, objective and valuable measurements for rehabilitation. Second, preliminary results illustrate some applications of two games, considering 343 people with various disabilities and health status. Based on the results, in the Coincident Timing game, there was a main effect of movement sensor type (in this instance the most functional device was the keyboard when compared with Kinect and touch screen) on average time reached by sample analyzed, F(2, 225) = 4.42, p < 0.05. Similarly, in the Challenge! game, a main effect was found for movement sensor type. However, in this case, touch screen provided better performance than Kinect and Leap Motion, F(2, 709) = 5.90, p < 0.01. Thus, Bridge Games is a possible software game to quantify motor learning. Moreover, the findings suggest that motor skills might be practiced differently depending on the environmental interface in which the game may be used.     

Improved design of polymeric composite electrothermal micro-actuator for high track density hard disk drives

Recently, we have developed a polymeric composite electrothermal micro-actuator for dual-stage applications in hard disk drives (HDDs). The polymer composite was demonstrated with a larger thermal expansion as compared to silicon. Yet, the previous design of polymeric composite thermal actuator was stiff, having a high mechanical resonant frequency at 33 kHz and a moderate static displacement stroke of 50 nm at 4 V. An even larger stroke above 100 nm is generally required to meet the need of HDD dual-stage systems. To meet the requirement for a large stroke, we presented an improved design of polymeric composite electrothermal micro-actuator by increasing flexibility of the composite thermal benders. As compared to the previous design, the new design doubled the displacement stroke up to 106 nm at 4 V while it maintained a high mechanical resonant frequency of 31 kHz, slightly below that of the previous design. In addition, a finite element analysis showed that electrothermal activation of the micro-actuator is rather localized and it causes only a small temperature rise of the neighbouring parts of head gimbal assembly. These good performances suggested that this improved design of thermal micro-actuator is promising for high bandwidth dual-stage positioning systems in future high track density HDDs.     

The influence of physical fitness training on the manual material handling capability of women

This study examined the influence of a generalized physical fitness training program on manual material handling (MMH) capability. Thirteen healthy women trained for 14 weeks, performing progressive resistance training three days per week and running with interval training two days per week. Subjects attended 85 ± 6% of the sessions. Compared to values obtained before training, subjects increased the maximum mass they could lift from floor to knuckle height by 19% (68–81 kg, p < 0.001) and from floor to chest height by 16% (49–57 kg, p < 0.001). They improved by 17% their ability to lift 15kg as many times as possible in 10 min(167–195 lifts, p < 0.001), while perception of effort (measured with the Borg Rating of Perceived Exertion) did not change. Total body mass did not change, but body fat mass was reduced by 9% (18.8–17.2 kg, p = 0.036) and fat-free mass increased by 6% (48.2–51.0 kg, p < 0.001). A short-term physical fitness program, conducted about 1 h per day, five days per week, can substantially improve women's MMH capability and provide favorable changes in body composition (increased fat-free mass and decreased body fat).     

Implementation of a participatory ergonomics program in the rehabilitation of workers suffering from subacute back pain

This paper describes a participatory ergonomics program aimed at early return to regular work of workers suffering from subacute occupational back pain and assesses the perceptions of the participants on the implementation of ergonomic solutions in the workplace. The participatory ergonomics program was used in the rehabilitation of workers suffering from subacute back pain for more than 6 weeks, a program that was associated with an increased rate of return to work. The perceptions of the participatory ergonomics participants were assessed 6 months after completion of the ergonomic intervention through a questionnaire sent to employer representatives, union representatives and injured workers of participating workplaces. About half of the ergonomic solutions were implemented according to the perception of the participants, with a substantial agreement between respondents.     

EEG analysis of mixed‐reality music rehabilitation system for post‐stroke lower limb therapy

Lots of evidence and guidelines recommended that stroke patients have to do the rehabilitation all the time, but in fact, the ratio of patients doing the rehabilitation is usually less than one third. In order to enhance the rehabilitation efficacy, we develop an innovative mixed‐reality music rehabilitation (MR²) system, which is consisted of an MR goggle, inertial measurement unit sensors, and an EEG system. Several music contents with different levels are implemented into the MR system. While doing the rehabilitation task, our system can monitor patient's both gait information and electroencephalographic (EEG) signals to understand the rehabilitation performance in both central and peripheral nervous systems. The MR² system has been pilot testing on two stroke patients and three healthy controls. Experiment results show that the patient's motor function is significantly activating when wearing the MR² system during the rehabilitation task. Furthermore, the gait analysis results also show that flexion angle of the hemiplegic knee during walking was significantly improved when following the tempo of the MR music content in the rehabilitation. The pilot testing results provide new insights into the understanding of complex brain functions of patients actively and continuously performing the rehabilitation ordinary tasks within the mixed‐reality applications.     

Metabolic demands of law enforcement personal protective equipment during exercise tasks

Many occupations require the use of personal protective equipment (PPE) but the added metabolic demands are unknown for certain professions. The purpose of this study was to quantify metabolic and perceptual differences between activity with and without the PPE ensemble required for police officers. Twelve participants were asked to complete experimental and control exercise sessions consisting of three modes of exercise (walking, jogging and stepping). A significant main effect (p < 0.01) for gear was found for heart rate (beats per minute) and VO₂ (L/min) between conditions. Dependent t-tests revealed significant differences for perceived effort, discomfort and session rating of perceived exertion between trials. Medium to large effect sizes for all variables with significant main effects between modes (p < 0.01, η² = 0.51–0.96, 1–β = 0.98–1.0, d = 0.42–2.7) were observed. These findings help to increase awareness of how PPE affects metabolic demands and perception of discomfort during exercise.     

The impact of different seats and whole-body vibration exposures on truck driver vigilance and discomfort

Laboratory studies have shown that exposure to whole-body vibration (WBV) increases physical and mental fatigue, which are common issues professional drivers face. The objective of this study was to determine whether altering WBV exposures had any effect on driver vigilance and discomfort. A repeated measures crossover design of five truck drivers with regular 10-h routes was used. Active and passive suspension truck seats were evaluated. For each seat, WBV exposures were measured. Participants completed a discomfort questionnaire and a reaction time task before and after their shift for two weeks, one week per seat. Compared with the passive seat, the active seat significantly reduced WBV exposures, decrements in the optimal and mean reaction times (p = 0.02, 0.047, respectively), and discomfort in the lower back and wrist(s)/forearm(s) (p < 0.01, 0.01, respectively). Study results indicated that reducing WBV helps reduce discomfort and maintain vigilance, which may improve drivers’ health and reduce the risk of truck collisions.

Practitioner Summary: The active suspension seat used in this study reduced truck drivers’ exposure to whole-body vibration (WBV) by over 33% in relation to their current industry standard passive suspension seat. This study demonstrated that reducing truck drivers’ exposure to WBV reduced fatigue and discomfort development over a workday.     

The vibration of inclined backrests: perception and discomfort of vibration applied parallel to the back in the z-axis of the body

This study determined how backrest inclination and the frequency of vibration influence the perception and discomfort of vibration applied parallel to the back (vertical vibration when sitting upright, horizontal vibration when recumbent). Subjects experienced backrest vibration at frequencies in the range 2.5 to 25 Hz at vibration magnitudes up to 24 dB above threshold. Absolute thresholds, equivalent comfort contours, and the principal locations for feeling vibration were determined with four backrest inclinations: 0° (upright), 30°, 60° and 90° (recumbent). With all backrest inclinations, acceleration thresholds and equivalent comfort contours were similar and increased with increasing frequency at 6 dB per octave (i.e. velocity constant). It is concluded that backrest inclination has little effect on the frequency dependence of thresholds and equivalent comfort contours for vibration applied along the back, and that the W _d frequency weighting in current standards is appropriate for evaluating z-axis vibration of the back at all backrest inclinations.

Statement of Relevance: To minimise the vibration discomfort of seated people, it is necessary to understand how discomfort varies with backrest inclination. It is concluded that the vibration on backrests can be measured using a pad between the backrest and the back, so that it reclines with the backrest, and the measured vibration evaluated without correcting for the backrest inclination.     

Self-reported musculoskeletal problems amongst professional truck drivers

Occupational driving has often been associated with a high prevalence of back pain. The factors that contribute to cause the pain are diverse and might include prolonged sitting, poor postures, exposure to whole-body vibration and other non-driving factors such as heavy lifting, poor diet or other psychosocial factors. In Europe, truck drivers are likely to be considered an ‘at risk’ group according to the Physical Agents (Vibration) Directive and therefore risks will need to be reduced. This questionnaire-based study set out to examine the relationship between musculoskeletal problems and possible risk factors for HGV truck drivers to help prioritize action aimed at risk reduction. Truck drivers (n = 192) completed an occupational questionnaire with two measures of vibration exposure (weekly hours and distance driven). Items on manual handling, relevant ergonomics factors and musculoskeletal problems were also included. Reported exposures to vibration ranged from 12 to 85 h per week, with a mean of 43.8 h. Distances driven ranged from 256 to 6400 km (mean 2469 km). Most of the respondents (81%) reported some musculoskeletal pain during the previous 12 months and 60% reported low back pain. Contrary to expectations, vibration exposures were significantly lower among those who suffered musculoskeletal symptoms when distance was used as an exposure measure. Manual handling and subjective ratings of seat discomfort were associated with reported musculoskeletal problems.     

Using a Tablet Device to Compensate for Underestimation of Cognitive Function due to Impaired Dominant Hand Function in Stroke Patients

This study aimed to investigate whether a touch-screen tablet device can be used to avoid underestimation of cognitive function due to hand disability in patients with stroke. Thirty patients with stroke and hemiplegia were divided according to whether the paretic side corresponded to their dominant or non-dominant hand. They were given the cube-copying task twice, once via paper and once via tablet. The results between paper- and tablet-based tasks were more likely to be concordant in participants with a non-paretic dominant hand (z = 2.80, p = 0.005) when the stroke type, education years, and sex were included in the model. All participants with discordant test results had a paretic dominant hand and showed lower muscle power in the wrist and hand muscles. In conclusion, cognitive function in patients with a paretic dominant hand may be underestimated in the cube-copying task, because it requires handwriting ability. This could be prevented by using a touch-screen device.     

Subjective evaluation of running footwear depends on country and assessment method: a bi-national study

This study examined (1) the perception of running shoes between China (Beijing) and Singapore and (2) whether running shoe preference depended on assessment methods. One hundred (n = 50 each country) Chinese males subjectively evaluated four shoe models during running by using two assessment procedures. Procedure 1 used a visual analogue scale (VAS) to assess five perception variables. Procedure 2 was a ‘head-to-head’ comparison of two shoes simultaneously (e.g. left foot: A and right foot: B) to decide which model was preferred. VAS scores were consistently higher in Beijing participants (p < .001), indicating a higher degree of liking. Singapore participants used the lower end but a wider range of the 15 cm scale for shoe discrimination. Moderate agreement was seen between the VAS and ‘head-to-head’ procedures, with only 14 out of 100 participants matched all 6 pairwise comparisons (median = 4 matches). Footwear companies and researchers should be aware that subjective shoe preference may vary with assessment methods.

Practitioner Summary: Footwear preference depends on country and assessment methods. Running shoe perception differed between Beijing and Singapore Chinese, suggesting that footwear recommendation should be country-specific. Individuals' shoe preference measured by visual analogue scale when wearing complete pairs may not reflect that when directly comparing different models in left and right feet.     

A cohort study of sciatic pain and measures of internal spinal load in professional drivers

In a prospective cohort study of 537 male professional drivers, the occurrence of sciatic pain showed stronger associations with measures of internal lumbar load expressed in terms of daily compressive dose, S_ed (MPa), and risk factor, R (non-dimensional), according to ISO/WD 2631-5 (2013), than with measures of daily vibration exposure calculated as either 8-h energy-equivalent frequency-weighted acceleration (ms^? 2 r.m.s.) or vibration dose value (ms^? 1.75) according to the EU Directive on mechanical vibration (2002). Herniated lumbar disc, previous lumbar trauma and physical work load were also powerful predictors of the occurrence of sciatic pain over time. Psychosocial work environment was poorly associated with sciatic pain. The boundary values of risk factor (R) for low and high probabilities of adverse health effects on the lumbar spine, as proposed by international standard ISO/WD 2631-5 (2013), tend to underestimate the health risk in professional drivers.     

Comparing data mining methods with logistic regression in childhood obesity prediction

The epidemiological question of concern here is “can young children at risk of obesity be identified from their early growth records?” Pilot work using logistic regression to predict overweight and obese children demonstrated relatively limited success. Hence we investigate the incorporation of non-linear interactions to help improve accuracy of prediction; by comparing the result of logistic regression with those of six mature data mining techniques. The contributions of this paper are as follows: a) a comparison of logistic regression with six data mining techniques: specifically, for the prediction of overweight and obese children at 3 years using data recorded at birth, 6 weeks, 8 months and 2 years respectively; b) improved accuracy of prediction: prediction at 8 months accuracy is improved very slightly, in this case by using neural networks, whereas for prediction at 2 years obtained accuracy is improved by over 10%, in this case by using Bayesian methods. It has also been shown that incorporation of non-linear interactions could be important in epidemiological prediction, and that data mining techniques are becoming sufficiently well established to offer the medical research community a valid alternative to logistic regression.     

Soft computing based intention reading techniques as a means of human-robot interaction for human centered system

 Friendly interaction between robot and human is vital in the design of a human centered system. Among several interaction technologies, the intention reading of the user plays an important role for the human centered system. We focus on the aspect of intention reading in rehabilitation robots, and implement its capability for the wheelchair-based robotic arm system, called KARES (KAIST Rehabilitation Engineering Service System) II. An effective intention reading scheme is proposed on the basis of several soft computing techniques to handle uncertainty of the user's intention. Two application examples of intention reading in KARES II are discussed: one is visual servoing of the user's face, and the other is emergency stop of the robot by using EMG signals of the user's arm. This work is partially supported by the Ministry of Science and Technology of Korea as a part of Critical Technology 21 Program on “Development of Service Robot Technology”.