The Slippery Slope Between Falling And Recovering: An Examination Of Sensory And Somatic Factors Influencing Recovery After A Slip

Background: Slips and falls account for large rates of injury and mortality in multiple populations. During an unexpected slip, sensory mechanisms are responsible for signaling the slip to the central nervous system, and a series of corrective responses is generated to arrest the slip and prevent a fall. While previous research has examined the corrective responses elicited, the answer of how these systems break down during a fall remains elusive. Purpose: To examine differences in postural control (slip detection), lower extremity corrective responses (slip recovery), and cortical control of the slip recovery response between individuals who fall and those who recover. Methods: One hundred participants were recruited for this study (50 males & 50 females). Participant’s gait kinematics and kinetics were collected during normal gait (NG) and an unexpected slip (US). The slip was classified as a fall or recovery, and by slip severity. Once classified, postural control, reaction times, corrective moments, and cortical contribution were examined between groups using ANOVAs and independent t-tests. Additionally, prediction equations for slip outcome, and slip severity were created using a binary logistic regression model. Slip Detection Results: Postural sway when the proprioceptive (OR = 0.02, CI: 0.01-1.34) and vestibular (OR = 0.60, CI: 0.26-1.39) systems are stressed were negatively associated with odds of falling. While postural sway when the visual system was stressed (OR = 3.18, CI: 0.887-11.445) was positively associated with odds of falling. Slip Recovery Results: Increased time to peak hip extension (OR = 1.006, CI: 1.00-1.01) and ankle dorsiflexion (OR = 1.005, CI: 1.00-1.01) moments increased the odds of falling. While the average ankle moment was negatively associated with falling (OR = 0.001, CI: 0.001-0.005). Cortical Contribution Results: Spectral power in the Piper frequency band was increased in US trials compared to NG. Further, fallers exhibited an increase in cortical activity compared to those who recovered. Conclusions: Rapid lower extremity corrective responses appear critical in arresting the slip and preventing a fall, and the temporal nature of this response may depend on slip detection and subsequent response selection. Moreover, our results suggest that more severe slips may require increased activation of higher centers of the motor cortex

Preliminary human safety assessment (PHSA) for the improvement of the behavioral aspects of safety climate in the construction industry

Occupational safety in the construction industry still represents a relevant problem at a global level. In fact, the complexity of working activities in this sector requires a comprehensive approach that goes beyond normative compliance to guarantee safer working conditions. In particular, empirical research on the factors influencing the unsafe behavior of workers needs to be augmented. Thus, the relationship between human factors and safety management issues following a bottom-up approach was investigated. In particular, an easy-to-use procedure that can be used to better address workers' safety needs augmenting the company's safety climate and supporting safety management issues was developed. Such an approach, based on the assessment of human reliability factors, was verified in a real case study concerning the users of concrete mixer trucks. The results showed that the majority of human failures were action and retrieval errors, underlining the importance of theoretical and practical training programs as a means to improve safety behavior. In such a context, information and communication activities also resulted beneficially to augment the company's safety climate. The proposed approach, despite its qualitative nature, allows a clearer understanding of workers' perceptions of hazards and their risk-taking behavior, providing practical cues to monitor and improve the behavioral aspects of safety climate. Hence, these first results can contribute to augmenting safety knowledge in the construction industry, providing a basis for further investigations on the causalities related to human performances, which are considered a key element in the prevention of accidents

Slip and Fall Risks: Pre-Slip Gait Contributions and Post-Slip Response Effects

This thesis describes analysis methods and results from slip-perturbed gait experiments. The risk for falls was related both to the conditions present at heel strike and to the nature of the response. Gait analysis was performed using the Human Movement and Balance Laboratory (HMBL) model, a fifteen segment, fourteen joint model of the human body that was developed as part of this thesis effort. Resulting kinematics and kinetics included three-dimensional angles describing relative segment rotations, segmental and whole-body centers-of-mass, and joint actuation torques for the entire body.The relationship between pre-slip gait characteristics and the magnitude of slips was explored for both younger and older adults. Slip severity, either hazardous or non-hazardous, was determined using a 1.0 m/s peak slip velocity threshold. Hazardous slips were associated with greater step lengths normalized by leg length, larger and more rapidly changing foot-floor angles at heel strike, and increased cadence across the two subject groups. These results suggest that gait characteristics play an important role in the severity of slips. Older adults were found to walk with shorter step lengths and with smaller and more slowly changing foot-floor angles at heel strike compared to younger subjects, suggesting that age effects also impact slip severity.The effects of slipping and trailing leg response on slip outcome (falls or recoveries) were explored. Slip severity was found to be the most significant parameter related to outcome. Response strategies were classified, based on trailing leg dynamics, as either minimal, foot-flat, mid-flight, or toe-down. Slipping and trailing leg hip and knee torques were determined using the HMBL model and timing and magnitude parameters from these torques were then identified. Relationships between these parameters, age group (younger/older), response strategy, and outcome were then explored. Age was not found to be significantly related to response strategy or outcome, nor was response strategy found to be related to outcome. Slipping leg knee torque timing and magnitude parameters were related to slip severity and to outcome for hazardous slips. These results suggest that slip responses, coupled with slip severity, determine fall or recovery outcomes

Lower extremity preventive measures for slips: joint moments and myoelectric analysis

This study investigated the lower extremity preventive measures for slips on simulated slippery surfaces in construction worksites. A total of 15 harnessed Chinese males walked without slips on a 5-m walkway in 16 simulated conditions 10 times at their natural cadence. Joint moments were calculated from kinetics, kinematics and anthropometric data recorded from a force plate, a Novel Pedar system and a motion analysis system. Data were evaluated from footstrike to mid-stance at 10%-stance intervals. Electromyography signals from tibialis anterior, gastrocnemius, rectus femoris and biceps femoris in one stride were evaluated in four phases, including early/late stance and swing. Results showed that lower extremity preventive measures for slips included prolonged ankle plantar flexion moments from 25% to 92% stance, increased ankle plantar flexion moments from 30% stance to mid-stance, and diminished knee extension moments from 10% to 30% stance. Higher activity of rectus femoris and gastrocnemius were found in the late stance and the swing phase respectively

The Global Economic Crisis: Towards Syndrome-Free Recovery for Africa

This paper outlines the impact of the global economic crisis on Africa. Recovery requires coordinated and consistent efforts to assist individual countries in mitigating (reducing) the risk, coping with the impact, and reducing risk over the longer term. Care should be exercised to maintain and improve good governance, which is essential for African countries to avoid introducing various .anti-growth policy syndromes. into their economies. These could arise if responses to the crisis result in (i) further boom-bust cycles and flaming the historically high volatility of African growth, including inflation, (ii) another debt crisis, (iii) household engaging in adverse coping strategies with lasting impacts; (iv) reversal of gains made in opening up African economies and re-introducing crippling state controls; and (v) entrenchment of inequities and inefficiencies in the global financial and aid architecture.Africa, least developed countries, global economic crisis, financial crisis, governance

Fall prevention strategy for an active orthotic system

Dissertação de mestrado integrado em Engenharia Biomédica (especialização em Eletrónica Médica)Todos os anos, são reportadas cerca de 684,000 quedas fatais e 37.3 milhões de quedas não fatais que requerem atenção médica, afetando principalmente a população idosa. Assim, é necessário identificar eficientemente indivíduos com alto risco de queda, a partir da população alvo idosa, e prepará los para superar perturbações da marcha inesperadas. Uma estratégia de prevenção de queda capaz de eficientemente e atempadamente detetar e contrariar os eventos de perdas de equilíbrio (PDE) mais frequentes pode reduzir o risco de queda. Como slips foram identificados como a causa mais prevalente de quedas, estes eventos devem ser abordados como foco principal da estratégia. No entanto, há falta de estratégias de prevenção de quedas por slip. Esta dissertação tem como objetivo o design de uma estratégia de prevenção de quedas de slips baseada na conceção das etapas de atuação e deteção. A estratégia de atuação foi delineada com base na resposta biomecânica humana a slips, onde o joelho da perna perturbada (leading) apresenta um papel proeminente para contrariar LOBs induzidas por slips. Quando uma slip é detetada, a estratégia destaca uma ortótese de joelho que providencia um torque assisstivo para prevenir a queda. A estratégia de deteção considerou as propriedades atrativas dos controladores Central Pattern Generator (CPG) para prever parâmetros da marcha. Algoritmos baseados em threshold monitorizam o erro de previsão do CPG, que aumenta após uma perturbação inesperada na marcha, para a deteção de slips. O ângulo do joelho e a velocidade angular da canela foram selecionados como os parâmetros de monitorização da marcha. Um protocolo experimental concebido para provocar perturbações de slip a sujeitos humanos permitiu a recolha de dados destas variáveis para posteriormente validar o algoritmo de deteção de perturbações. Algoritmos CPG foram capazes de produzir aproximações aceitáveis dos sinais de marcha em estado estacionário do ângulo do joelho e da velocidade angular da canela com sucesso. Além disso, o algoritmo de threshold adaptativo detetou LOBs induzidas por slips eficientemente. A melhor performance global foi obtida usando este algoritmo para monitorizar o ângulo do joelho, que detetou quase 80% (78.261%) do total de perturbações com um tempo médio de deteção (TMD) de 250 ms. Além disso, uma média de 0.652 falsas perturbações foram detetadas por cada perturbação corretamente identificada. Estes resultados sugerem uma performance aceitável de deteção de perturbações do algoritmo, de acordo com os requisitos especificados para a deteção.Every year, an estimated 684,000 fatal falls and 37.3 million non-fatal falls requiring medical attention are reported, mostly affecting the older population. Thus, it is necessary to effectively screen high fall risk individuals from targeted elderly populations and prepare them to successfully overcome unexpected gait perturbations. A fall prevention strategy capable of effectively and timely detect and counteract the most frequent loss of balance (LOB) events may reduce the fall risk. Since slips were identified as the main contributors to falls, these events should be addressed as a main focus of the strategy. Nonetheless, there is a lack of slip-induced fall prevention strategies. This dissertation aims the design of a slip-related fall prevention strategy based on the conception of an actuation and a detection stage. The actuation strategy was delineated based on the human biomechanical reactions to slips, where the perturbed (leading) leg’s knee joint presents a prominent role to counteract slip-induced LOBs. Thereby, upon the detection of a slip, this strategy highlighted a knee orthotic device that provides an assistive torque to prevent the falls. The detection strategy considered the attractive properties of biological-inspired Central Pattern Generator (CPG) controllers to predict gait parameters. Threshold-based algorithms monitored the CPG’s prediction error produced, which increases upon an unexpected gait perturbation, to perform slip detection. The knee angle and shank angular velocity were selected as the monitoring gait parameters. An experimental protocol designed to provoke slip perturbations to human subjects allowed to collect data from these variables to further validate the perturbation detection algorithm. CPG algorithms were able to successfully produce acceptable estimations of the knee angle and shank angular velocity signals during steady-state walking. Furthermore, an adaptive threshold algorithm effectively detected slip-induced LOBs. The best overall performance was obtained using this algorithm to monitor the knee angle from the perturbed leg, which detected almost 80% (78.261%) of the total perturbations with a mean detection time (MDT) of 250 ms. In addition, a mean of 0.652 false perturbations were detected for each correct perturbation identified. These results suggest an acceptable perturbation detection performance of the algorithm implemented in light of the detection requirements specified

SLIP-RELATED MUSCLE ACTIVATION PATTERNS OF THE STANCE LEG DURING GAIT

Falls precipitated by slipping are a major cause of injury, death and disability in the elderly. This research focused on muscle activation patterns generated in response to slipping and anticipation of slippery surfaces. The goal was to identify the muscle activation patterns of the stance leg in response to an unexpected slip (reactive strategies) and investigate muscle activity when anticipating slippery floors during gait on dry surfaces (proactive strategies). Additionally, age-related differences were examined. Electromyographic recordings were made from the Vastus Lateralis, Medial Hamstring, Tibialis Anterior and Medial Gastrocnemius of eleven young and nine older adults. Participants walked during the following conditions: (1) baseline dry (subjects knew the floor was dry); (2) unexpected slip (contaminant was applied to floor without subjects' knowledge); (3) alert dry (subjects were uncertain of the floor's condition). Reactive strategies, which were similar among young and older adults, consisted of activation of the Medial Hamstring at around 21% stance (~ 175 ms) followed by the Vastus Lateralis at around 29% stance (~ 240 ms). Corrective responses were scaled to slip severity with more severe slip reactions consisting of longer, higher magnitude responses. Delayed Vastus Lateralis latency and Medial Hamstring cessation were associated with an increased slip severity as quantified by peak slip velocity. Additionally, when experiencing a severe slip, young adults demonstrated a longer, more powerful response compared to older adults. Anticipation of a slippery surface resulted in increased magnitude of activation (48% increase) and ankle/knee co-contraction (30% increase), as well as earlier onsets and longer durations of posterior muscles. Young adults demonstrated earlier onsets (3% stance, 24 ms) and longer durations (10% stance, 83 ms) than older adults reducing their slip potential. Finally, adults with baseline gait on dry floors characterized by greater ankle co-contraction at heel contact and delayed Tibialis Anterior onset were predisposed to experience less severe slips when encountering an unexpected slippery floor. Older adults' natural gait predisposes them to experience a less hazardous slip. However, once a slip occurs, older adults cannot react with the long, powerful response needed to prevent balance loss whereas young adults are capable of this response