1,721,128 research outputs found
Anticompensatory fast eye movements in the horizontal and vertical vestibulo-ocular reflexes
No full textThe otolithic influence on the anticompensatory fast phases causes gaze stability to be higher in the vertical than in the horizontal plane. The high density of ganglion cells in the horizontal visual streak should be taken into account to explain the enhancement of gaze stability in the vertical plane
Kerbside Waste Collection Round Risk Assessment by Means of Physiological Parameters: sEMG and Heart Rate
No full textThe occupational health risks in waste collection workers have been widely investigated. Many studies show that workers are exposed to several risk factors. Aim of the study is biomechanical risk assessment of kerbside waste collection workers. The paper focused on the task that literature showed as the most overloading, that is emptying the bin in the lorry. Simulations were made in a rubbish dump where upper limbs and trunk muscles activity were recorded through surface electromyography (sEMG) to verify the biomechanical load for the four emptying techniques usually adopted. It was also recorded heart rate of workers during the collection round to determine their Relative Cardiac Cost (RCC). sEMG results for the task of emptying the bin, showed a significant effort of the paravertebral muscles for each techniques. About upper limbs, sEMG showed that emptying the bin directly into the collection lorry from the back was the most overloading technique. This is due to the workers arms raise well over shoulder height. The lightest technique was the emptying of the bin inside a certified container but, due to its small volume, this led to an increase in collection round time. RCC results showed moderate activity, according to the Chamoux scale, in three of the four workers, only one of them showed a quite heavy activity. A redesign of the collection lorries with certified and larger containers would reduce the risk. It would be also desirable a turnover of employees to allow them to work alternatively in areas of high population density, with higher risk, and in low-density areas with lower risk
Biomechanical risk assessment of pathologists in the morgue
No full textThe purpose of this study is to research the risk of biomechanical overload in pathologists during autopsies performed in dissection room. During autopsies, operators are exposed both to the risks of manual handling, in transferring the cadaver from the trolley to the dissection table (and vice versa), and to awkward postures during the incision and opening of the cadaver to examine the organs. Following task analysis, we decided to use, according to the task, the methods that best describes it and include its peculiar characteristics. The methods used were: the REBA protocol, 3DSSPP software and surface electromyography. The results show that, in almost all the tasks investigated and with all the methods used, there was a medium-high risk of biomechanical overload. In the light of these results, we suggest possible intervention strategies for the prevention of musculoskeletal disorders (MSDs) during the performance of autopsies
Asymmetries in the vertical vestibulo-collic reflex
No full textThe results support the hypothesis that vestibulo-ocular reflez and vestibulo-collic reflex share a common circuitry having an intrinsic asymmetry aimed at counterbalancing the gravity load during upward head displacements. This asymmetry is present in the vestibulo-collic reflex while it is suppressed by the macular input in the vestibulo-ocular reflex
Back and Shoulder Biomechanical Load in Curbside Waste Workers
No full textData from various countries (USA, Great Britain, Brazil, Italy, India, etc.) shows a significant prevalence and incidence of musculoskeletal disorders in kerbside waste collection workers. We investigated some biomechanical parameters of the task of pouring bins in collection kerb through 3DSSPP software. (v 7.0.6). Bins manual handling was investigated in four different operating modes: through 1) a lorry side window; 2) at the back of the lorry; 3) in a certified container; 4) in a non-certified container. 3DSSPP risk assessment showed that bin pouring implies a high level of biomechanical load in each of the four modes. The most dangerous mode was that in which the worker empties the bin directly into the back of the van (mode 2). 3DSSPP showed significant values of percentage of maximum voluntary contraction (%MVC) for trunk flexion (67% MVC), left shoulder abduction (30% MVC) and left wrist ulnar deviation (50% MVC). These values imply a low level of the maximum recommended exertion duty cycle (1% for trunk flexion, 3.2% for left wrist ulnar deviation). Also the balance was unacceptable. Emptying technique that showed the lowest level of risk was mode 3 (certified container) that reported 29% of MVC for trunk flexion and a maximum recommended exertion duty cycle of 13.6%. 3DSSPP showed no relevant values of orthogonal and shear forces at L4/L5 and L5/S1 levels. Finally, this technique was the only one that showed an acceptable balance. It would be desirable to design the vehicles for collection with easier access, as the operator is continuously getting on and off
Upward/Downward asymmetries of vertical vestibulo-ocular reflex
No full textAsymmetries were present at the level of the vestibulo-collic reflex in the upright as well as in side-down position during stimulation about pitch axis. Indeed the lead of extensor neck muscle activation peak was greater than that of the inhibition peak; this relationship was inverted for the flexor muscles of the neck. Asymmetry was found in both upright and side-down position indicating that the origin of the vertical response asymmetry is from semicircular canals and the otolithic input does not suppress it. Interestingly, in the frontal plane the electromyographic response was much more symmetric. We suggest that the activation of both anterior and or inhibition of both posterior semicircular canals during downward head pitch causes greater phase lead in the electromyographic responses than that observed during upward head pitch. Conversely, the combined stimulation of both anterior and posterior canals (roll stimulation) gives rise to more symmetric responses
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