Balance recovery after trips is affected by the type of tripping obstacles.

Occupational falls are often initiated by trips. Mechanical perturbations applied onto the tripped foot are different for different types of tripping obstacles. The present study aimed to determine how different types of tripping obstacles affect balance recovery after trips. Sixty-four healthy adults participated in an experimental study. They were instructed to perform several walking trials, during which two trips were randomly induced, one by a pole-like obstacle and the other by a board-like obstacle. Balance recovery after trips was measured and compared between the two obstacles. Results showed that the board-like obstacle led to longer step-off time, shorter recovery step duration, and smaller minimum hip height, suggesting that the risk of trip-initiated falls could be higher with the board-like obstacle vs. the pole-like obstacle. This finding presents the need for future research to consider the influence of obstacle type when exploring mechanisms for trips and falls.

Occupational falls are often initiated by trips. For better knowledge about trips and falls, this study examined the effects of tripping obstacles on balance recovery after trips. Knowledge obtained here could be useful for improving workers' awareness and assessment of the risk of trip-initiated falls in their workplace.

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OBJECTIVES: To investigate the efficacy and required indicators of Children Neuropsychological and Behavioral Scale-Revision 2016 (CNBS-R2016) in the differential diagnosis of autism spectrum disorder (ASD) and global developmental delay (GDD). METHODS: A total of 277 children with ASD and 415 children with GDD, aged 18-48 months, were enrolled as subjects. CNBS-R2016 was used to assess the developmental levels of six domains, i.e., gross motor, fine motor, adaptive ability, language, social behavior, and warning behavior, and a total of 13 indicators on intelligence age and developmental quotient (DQ) were obtained as the input features. Five commonly used machine learning classifiers were used for training to calculate the classification accuracy, sensitivity, and specificity of each classifier. RESULTS: DQ of warning behavior was selected as the first feature in all five classifiers, and the use of this indicator alone had a classification accuracy of 78.90%. When the DQ of warning behavior was used in combination with the intelligence age of warning behavior, gross motor, and language, it had the highest classification accuracy of 86.71%. CONCLUSIONS: Machine learning combined with CNBS-R2016 can effectively distinguish children with ASD from those with GDD. The DQ of warning behavior plays an important role in machine learning, and its combination with other features can improve classification accuracy, providing a basis for the efficient and accurate differential diagnosis of ASD and GDD in clinical practice.

Classification of Children With Autism and Typical Development Using Eye-Tracking Data From Face-to-Face Conversations: Machine Learning Model Development and Performance Evaluation.

BACKGROUND: Previous studies have shown promising results in identifying individuals with autism spectrum disorder (ASD) by applying machine learning (ML) to eye-tracking data collected while participants viewed varying images (ie, pictures, videos, and web pages). Although gaze behavior is known to differ between face-to-face interaction and image-viewing tasks, no study has investigated whether eye-tracking data from face-to-face conversations can also accurately identify individuals with ASD. OBJECTIVE: The objective of this study was to examine whether eye-tracking data from face-to-face conversations could classify children with ASD and typical development (TD). We further investigated whether combining features on visual fixation and length of conversation would achieve better classification performance. METHODS: Eye tracking was performed on children with ASD and TD while they were engaged in face-to-face conversations (including 4 conversational sessions) with an interviewer. By implementing forward feature selection, four ML classifiers were used to determine the maximum classification accuracy and the corresponding features: support vector machine (SVM), linear discriminant analysis, decision tree, and random forest. RESULTS: A maximum classification accuracy of 92.31% was achieved with the SVM classifier by combining features on both visual fixation and session length. The classification accuracy of combined features was higher than that obtained using visual fixation features (maximum classification accuracy 84.62%) or session length (maximum classification accuracy 84.62%) alone. CONCLUSIONS: Eye-tracking data from face-to-face conversations could accurately classify children with ASD and TD, suggesting that ASD might be objectively screened in everyday social interactions. However, these results will need to be validated with a larger sample of individuals with ASD (varying in severity and balanced sex ratio) using data collected from different modalities (eg, eye tracking, kinematic, electroencephalogram, and neuroimaging). In addition, individuals with other clinical conditions (eg, developmental delay and attention deficit hyperactivity disorder) should be included in similar ML studies for detecting ASD.

Gait initiation differences between overweight and normal weight individuals.

Accidental falls often occur during gait initiation. Excess body weight has been identified as a risk factor for accidental falls. This study aimed to examine the differences of gait initiation between overweight and normal-weight individuals. Fourteen overweight and 14 normal-weight young adults participated in the study. They were instructed to perform the gait initiation task under single-task and dual-task conditions. Dependent variables for the assessment of gait initiation included spatial-temporal measures and postural stability measures. The results showed that overweight could compromise postural stability during gait initiation, primarily by decreasing margin of stability in the anterior-posterior direction. Cognitive task interference with gait initiation was found to be similar between the overweight and normal weight groups. The findings from the present study can aid in better understanding the mechanisms associated with increased fall risks among overweight individuals. They also highlight the importance of overweight control in fall prevention. Practitioner summary: Overweight was found to compromise postural stability during gait initiation, primarily by decreasing margin of stability in the anterior-posterior direction. The findings highlight the importance of overweight control in fall prevention. Abbreviations: ANOVA: analyses of variance; AP: anterior-posterior; APA: anticipatory postural adjustment; BOS: base of support; BW: Body weight; COM: centre-of-mass; COP: center-of-pressure; CT: cognitive task; GI: Gait initiation; GRF: ground reaction force; HC: heel-contact; HO: heel-off; ML: medial-lateral; MOS: margin of stability; SD: standard deviation; SE: step execution; SL: step length; SW: step width; VEL_COM: velocity of the COM; XCOM: extrapolated center of mass.

Basketball Activity Classification Based on Upper Body Kinematics and Dynamic Time Warping.

Basketball activity classification can help document players' statistics, allow coaches, trainers and the medical team to quantitatively supervise players' physical exertion and optimize training strategy, and further help prevent potential injuries. Traditionally, sports activity classification was done by manual notational, or through multi-camera systems or motion sensing technology. These methods were often erroneous and limited by space. This study presents a basketball activity classification model based on Dynamic Time Warping (DTW) and body kinematic measures. Twenty participants, including 10 experienced players and 10 novice players, were involved in an experimental study. The experienced and novice players differed in their years of playing basketball. Four basketball movements, including shooting, passing, dribbling, and lay-up were classified by kinematic measures. The results indicate that the proposed model can successfully classify different basketball movements with high accuracy and efficiency. Specifically, with the resultant acceleration of the hand, this model can achieve classification precision, recall, and specificity up to 0.984, 0.983 and 0.994, respectively. Findings from this study supported the feasibility of using DTW in real-time sports activity classification and provided insights into the optimal sensor placement for basketball activity classification applications.

Effects of Fatigue on Balance Recovery From Unexpected Trips.

OBJECTIVE: The objective was to examine how physical fatigue and mental fatigue affected balance recovery from unexpected trips. BACKGROUND: Trips are the leading cause for occupational falls that are a multifactorial problem. Recognizing risk factors is the first step in accident control. Fatigue is one of the most common task-related risk factors for occupational falls. Fatigue typically can be divided into physical fatigue and mental fatigue, both of which are common in occupational settings. METHOD: One hundred eight young volunteers participated in the experiment. They were evenly divided into three groups: no fatigue group, physical fatigue group, and mental fatigue group. Each participant performed four walking trials on a linear walkway at their self-selected normal speed. The first three trials were normal walking trials. A trip was induced to participants in the fourth walking trial using a metal pole. Balance recovery from unexpected trips was characterized by trunk flexion and first recovery step measures. RESULTS: Recovery step length was smaller and maximum trunk flexion became larger in the mental fatigue group compared with those in the no fatigue group. Physical fatigue did not significantly affect trunk flexion and first recovery step measures. CONCLUSION: Mental fatigue increased the likelihood of loss of balance. Thus, mental fatigue could be a risk factor for trips and falls. To prevent trip-related falls, interventions should be adopted to prevent prolonged exposures to cognitively demanding activities in occupational settings.

Age-Related Differences in the Relationships Between Lower-Limb Joint Proprioception and Postural Balance.

OBJECTIVE: In the present study we aimed to investigate the relationships between lower-limb joint proprioception and postural balance. Age-related differences in such relationships were also identified. BACKGROUND: Impaired postural balance is reportedly one of the most common risk factors for fall accidents. Interventions have been proposed to improve postural balance by enhancing proprioceptive feedback. However, there is still no consensus on the optimal design for these interventions; therefore, there is a need to better reveal the contributions of lower-limb joint proprioception to postural balance. METHOD: Twenty-eight young and 28 older adults participated. Lower-limb joint proprioception was assessed by joint position sense errors measured at the ankle, knee, and hip of the dominant side, respectively. Postural balance was assessed by using center-of-pressure measures during bilateral static stance. RESULTS: Ankle joint position sense error was positively correlated with root mean squared distance of the center of pressure in the anterior-posterior and medial-lateral directions in both young and older adults. Different from young adults, hip joint position sense error was positively correlated with root mean squared distance of the center of pressure in the anterior-posterior and medial-lateral directions in older adults only. CONCLUSION: Declined ankle and hip proprioception could be risk factors for falls in older adults. Age-related differences in the effects of hip proprioception suggests that hip proprioception is more important for maintaining balance in older adults. Ankle proprioception contributes the most to balance maintenance. Thus, ankle proprioception enhancement exercises should be considered in fall prevention interventions.

Estimation of Foot Plantar Center of Pressure Trajectories with Low-Cost Instrumented Insoles Using an Individual-Specific Nonlinear Model.

Postural control is a complex skill based on the interaction of dynamic sensorimotor processes, and can be challenging for people with deficits in sensory functions. The foot plantar center of pressure (COP) has often been used for quantitative assessment of postural control. Previously, the foot plantar COP was mainly measured by force plates or complicated and expensive insole-based measurement systems. Although some low-cost instrumented insoles have been developed, their ability to accurately estimate the foot plantar COP trajectory was not robust. In this study, a novel individual-specific nonlinear model was proposed to estimate the foot plantar COP trajectories with an instrumented insole based on low-cost force sensitive resistors (FSRs). The model coefficients were determined by a least square error approximation algorithm. Model validation was carried out by comparing the estimated COP data with the reference data in a variety of postural control assessment tasks. We also compared our data with the COP trajectories estimated by the previously well accepted weighted mean approach. Comparing with the reference measurements, the average root mean square errors of the COP trajectories of both feet were 2.23 mm (±0.64) (left foot) and 2.72 mm (±0.83) (right foot) along the medial-lateral direction, and 9.17 mm (±1.98) (left foot) and 11.19 mm (±2.98) (right foot) along the anterior-posterior direction. The results are superior to those reported in previous relevant studies, and demonstrate that our proposed approach can be used for accurate foot plantar COP trajectory estimation. This study could provide an inexpensive solution to fall risk assessment in home settings or community healthcare center for the elderly. It has the potential to help prevent future falls in the elderly.

Factors Affecting Consumer Acceptance of an Online Health Information Portal Among Young Internet Users.

Despite the proliferation of health and nursing informatics applications in the past decade, factors influencing consumer acceptance of the applications are not well understood. This study was conducted to investigate factors affecting acceptance of a consumer-used nursing informatics application (ie, online health information portal) within the framework of the Technology Acceptance Model. A cross-sectional study was conducted in which 201 Chinese young adults were invited to participate in usability testing with a typical health information portal and to complete a self-report questionnaire measuring the model's constructs and five hypothesized variables drawn from consumer and portal characteristics. Hierarchical regression analyses were used to test research hypotheses. Fifteen of the 22 research hypotheses were supported. Perceived ease of use and perceived usefulness predicted satisfaction and behavioral intention, respectively, over and above the portal and consumer characteristics examined in the study. All portal and consumer characteristics had significant, although varied, impacts on the original model constructs. This study demonstrated that an adapted Technology Acceptance Model, extended with portal and consumer characteristics, provides an effective means to understand consumer acceptance of health portals. The findings hold important implications for design and implementation strategies to increase the likelihood of acceptance of consumer-used nursing informatics applications.

Influence of drug colour on perceived drug effects and efficacy.

A drug's physical characteristics, such as colour, could be factors influencing its therapeutic effects. It is not well understood whether people's expectations on drug effects and efficacy are affected by colour, especially among Chinese population. This study was conducted to examine people's expectations on drug effects and efficacy on the basis of drug colour, and to reveal possible gender differences in colour-related drug expectations. Participants (n = 224) were asked to classify seven single-coloured and six two-coloured capsules into one of four categories of drug effects, and to indicate the strength of drug efficacy. It is found that all the coloured capsules yielded non-chance distributions in classifications of drug effects, with six single-coloured and four two-coloured capsules associated with specific drug effects. Colour also conveyed differential strengths of drug efficacy in general and in relation to specific drug effects. There were gender differences in drug expectations for some colours and colour combinations. Practitioner Summary: Drug colour was found to have impacts on perceived drug effects and efficacy. The findings from the present study can be used by ergonomics practitioners to design appropriate drug colours in support of drug differentiation, therapeutic effects and medication adherence.

Effects of Subsensory Noise and Fatigue on Knee Landing and Cross-over Cutting Biomechanics in Male Athletes.

The objective of this study was to examine the effects of subsensory noise and fatigue on knee biomechanics during the athletic task of landing followed by cross-over cutting. A total of 32 healthy male athletes participated in the study. They were evenly divided into 2 groups: no fatigue group and fatigue group. Fatigue was induced to the lower extremity by a repetitive squatting exercise in the fatigue group. Subsensory noise was generated by linear miniature vibrators bilaterally placed around the knee joints. During data collection, the participants were instructed to perform landing followed by cross-over cutting in both the subsensory on and off conditions. Dependent variables were selected to assess knee biomechanics in the phases of landing and cross-over cutting, separately. Results showed that fatigue resulted in larger knee flexion during landing and larger knee internal rotation during cross-over cutting. Subsensory noise was found to reduce knee rotation impulse during cross-over cutting. These findings suggest that cross-over cutting is more dangerous than landing in the fatigue condition, and subsensory noise may lead to changes in knee biomechanics consistent with reduced risk of anterior cruciate ligament injuries, but the changes may be task-specific.

Influence of affective auditory stimuli on balance control during static stance.

The main purpose of this study was to examine the effects of affective auditory stimuli on balance control during static stance. Twelve female and 12 male participants were recruited. Each participant completed four upright standing trials including three auditory stimuli trials and one baseline trial (ie no auditory stimuli). The three auditory stimuli trials corresponded to the pleasant, neutral and unpleasant sound conditions. Center of pressure (COP) measures were used to quantify balance control performance. It was found that unpleasant auditory stimuli were associated with larger COP amplitude in the AP direction compared to the rest testing conditions. There were no significant interaction effects between 'auditory stimuli' and gender. These findings suggested that some specificities presented by auditory stimuli are important for balance control, and the effects of auditory stimuli on balance control were dependent on their affective components. Practitioner Summary: Findings from this study can aid in better understanding of the relationship between auditory stimuli and balance control. In particular, unpleasant auditory stimuli were found to result in poorer balance control and higher fall risks. Therefore, to prevent fall accidents, interventions should be developed to reduce exposures to unpleasant sound.

Pre-impact fall detection.

Pre-impact fall detection has been proposed to be an effective fall prevention strategy. In particular, it can help activate on-demand fall injury prevention systems (e.g. inflatable hip protectors) prior to fall impacts, and thus directly prevent the fall-related physical injuries. This paper gave a systematical review on pre-impact fall detection, and focused on the following aspects of the existing pre-impact fall detection research: fall detection apparatus, fall detection indicators, fall detection algorithms, and types of falls for fall detection evaluation. In addition, the performance of the existing pre-impact fall detection solutions were also reviewed and reported in terms of their sensitivity, specificity, and detection/lead time. This review also summarized the limitations in the existing pre-impact fall detection research, and proposed future research directions in this field.

Benefits of Imperfect Conflict Resolution Advisory Aids for Future Air Traffic Control.

OBJECTIVE: The aim of this study was to examine the human-automation interaction issues and the interacting factors in the context of conflict detection and resolution advisory (CRA) systems. BACKGROUND: The issues of imperfect automation in air traffic control (ATC) have been well documented in previous studies, particularly in conflict-alerting systems. The extent to which the prior findings can be applied to an integrated conflict detection and resolution system in future ATC remains unknown. METHOD: Twenty-four participants were evenly divided into two groups corresponding to a medium- and a high-traffic density condition, respectively. In each traffic density condition, participants were instructed to perform simulated ATC tasks under four automation conditions, including reliable, unreliable with short time allowance to secondary conflict (TAS), unreliable with long TAS, and manual conditions. Dependent variables accounted for conflict resolution performance, workload, situation awareness, and trust in and dependence on the CRA aid, respectively. RESULTS: Imposing the CRA automation did increase performance and reduce workload as compared with manual performance. The CRA aid did not decrease situation awareness. The benefits of the CRA aid were manifest even when it was imperfectly reliable and were apparent across traffic loads. In the unreliable blocks, trust in the CRA aid was degraded but dependence was not influenced, yet the performance was not adversely affected. CONCLUSION: The use of CRA aid would benefit ATC operations across traffic densities. APPLICATION: CRA aid offers benefits across traffic densities, regardless of its imperfection, as long as its reliability level is set above the threshold of assistance, suggesting its application for future ATC.

Effects of neuromuscular fatigue on perceptual-cognitive skills between genders in the contribution to the knee joint loading during side-stepping tasks.

This study investigated whether neuromuscular fatigue affects the neuromuscular control of an athlete within a sports context setting and whether these effects were more pronounced in the females. Lower limb joint kinetics of 6 male and 6 female inter-varsity soccer players performing side-stepping tasks in non-fatigue versus fatigue and anticipated versus unanticipated conditions were quantified using 10 Motion Analysis Corporation cameras and a Kistler(™) force platform. The Yo-Yo intermittent recovery Level 1 fatigue protocol was employed. Stance foot initial contact and peak forces, and peak joint knee moments of the lower limb were submitted to a 3-way mixed-model repeated measure ANOVA. The results suggested that males tend to elicit significantly higher knee joint loadings when fatigued. In addition, males elicited significantly higher peak proximal tibia anterior/posterior shear force, vertical ground reaction force at initial contact and peak internal rotational moments than females. These findings suggested that males were at greater overall injury risk than females, especially in the sagittal plane. Neuromuscular control-based training programmes/interventions that are designed to reduce the risk of the non-contact ACL injury need to be customised for the different genders.

Lifting motion simulation using a hybrid approach.

In this study, a hybrid dynamic model for lifting motion simulation is presented. The human body is represented by a two-dimensional (2D) five-segment model. The lifting motions are predicted by solving a nonlinear optimisation problem, the objective function of which is defined based on a minimal-effort performance criterion. In the optimisation procedure, the joint angular velocities are bounded by time-functional constraints that are determined by actual motions. Symmetric lifting motions performed by younger and older adults under varied task conditions were simulated. Comparisons between the simulation results and actual motion data were made for model evaluation. The results showed that the mean and median joint angle errors were less than 10°, which suggests the proposed model is able to accurately simulate 2D lifting motions. The proposed model is also comparable with the existing motion simulation models in terms of the prediction accuracy. Strengths and limitations of this hybrid model are discussed. Practitioner Summary: Human motion simulation is a useful tool in assessing the risks of occupational injuries. Lifting motions are associated with low-back pain. A hybrid model for lifting motion simulation was constructed. The model was able to accurately simulate 2D lifting motions in varied task scenarios for younger and older subjects.

Human factors assessment of conflict resolution aid reliability and time pressure in future air traffic control.

Though it has been reported that air traffic controllers' (ATCos') performance improves with the aid of a conflict resolution aid (CRA), the effects of imperfect automation on CRA are so far unknown. The main objective of this study was to examine the effects of imperfect automation on conflict resolution. Twelve students with ATC knowledge were instructed to complete ATC tasks in four CRA conditions including reliable, unreliable and high time pressure, unreliable and low time pressure, and manual conditions. Participants were able to resolve the designated conflicts more accurately and faster in the reliable versus unreliable CRA conditions. When comparing the unreliable CRA and manual conditions, unreliable CRA led to better conflict resolution performance and higher situation awareness. Surprisingly, high time pressure triggered better conflict resolution performance as compared to the low time pressure condition. The findings from the present study highlight the importance of CRA in future ATC operations. Practitioner Summary: Conflict resolution aid (CRA) is a proposed automation decision aid in air traffic control (ATC). It was found in the present study that CRA was able to promote air traffic controllers' performance even when it was not perfectly reliable. These findings highlight the importance of CRA in future ATC operations.

Age-related cognitive task effects on gait characteristics: do different working memory components make a difference?

BACKGROUND: Though it is well recognized that gait characteristics are affected by concurrent cognitive tasks, how different working memory components contribute to dual task effects on gait is still unknown. The objective of the present study was to investigate dual-task effects on gait characteristics, specifically the application of cognitive tasks involving different working memory components. In addition, we also examined age-related differences in such dual-task effects. METHODS: Three cognitive tasks (i.e. 'Random Digit Generation', 'Brooks' Spatial Memory', and 'Counting Backward') involving different working memory components were examined. Twelve young (6 males and 6 females, 20 ~ 25 years old) and 12 older participants (6 males and 6 females, 60 ~ 72 years old) took part in two phases of experiments. In the first phase, each cognitive task was defined at three difficulty levels, and perceived difficulty was compared across tasks. The cognitive tasks perceived to be equally difficult were selected for the second phase. In the second phase, four testing conditions were defined, corresponding to a baseline and the three equally difficult cognitive tasks. Participants walked on a treadmill at their self-selected comfortable speed in each testing condition. Body kinematics were collected during treadmill walking, and gait characteristics were assessed using spatial-temporal gait parameters. RESULTS: Application of the concurrent Brooks' Spatial Memory task led to longer step times compared to the baseline condition. Larger step width variability was observed in both the Brooks' Spatial Memory and Counting Backward dual-task conditions than in the baseline condition. In addition, cognitive task effects on step width variability differed between two age groups. In particular, the Brooks' Spatial Memory task led to significantly larger step width variability only among older adults. CONCLUSION: These findings revealed that cognitive tasks involving the visuo-spatial sketchpad interfered with gait more severely in older versus young adults. Thus, dual-task training, in which a cognitive task involving the visuo-spatial sketchpad (e.g. the Brooks' Spatial Memory task) is concurrently performed with walking, could be beneficial to mitigate impairments in gait among older adults.

Effects of age and its interaction with task parameters on lifting biomechanics.

This study investigated the age-related differences in lifting biomechanics. Eleven younger and 12 older participants were instructed to perform symmetric lifting tasks defined by different combinations of destination heights and load magnitudes. Lifting biomechanics was assessed. It was found that the trunk flexion in the starting posture was 32% lower and the peak trunk extension velocity was 46% lower in older participants compared with those in younger ones, indicating that older adults tended to use safer lifting strategies than did younger adults. Based on these findings, we recommend that physical exercise programmes may be a more effective ergonomic intervention for reducing the risks of low back pain (LBP) in lifting among older workers, compared with instructions of safe lifting strategies. As for younger workers, instructions of safe lifting strategies would be effective in LBP risk reduction.

Effects of mental fatigue on biomechanics of slips.

The objective of this study was to investigate the effects of mental fatigue on biomechanics of slips. A total of 44 healthy young participants were evenly categorised into two groups: no fatigue and mental fatigue. Mental fatigue was induced by performing an AX-continuous performance test. The participants in both groups were instructed to walk on a linear walkway, and slips were induced unexpectedly during walking. We found that mental fatigue has adverse effects in all the three phases of slips. In particular, it leads to increased likelihood of slip initiation, poorer slip detection and a more insufficient reactive recovery response to slips. Based on the findings from the present study, we can conclude that mental fatigue is a risk factor for slips and falls. In order to prevent slip-induced falls, interventions, such as providing frequent rest breaks, could be applied in the workplace to avoid prolonged exposures to cognitively demanding activities.