This study investigated temporal changes in movement strategy and performance during fatiguing short-cycle work. Eighteen participants performed six 7-min work blocks with repetitive reaching movements at 0.5 Hz, each followed by a 5.5-min rest break for a total duration of 1 h. Electromyography (EMG) was collected continuously from the upper trapezius muscle, the temporal movement strategy and timing errors were obtained on a cycle-to-cycle basis, and perceived fatigue was rated before and after each work block. Clear signs of fatigue according to subjective ratings and EMG manifestations developed within each work block, as well as during the entire hour. For most participants, timing errors gradually increased, as did the waiting time at the near target. Changes in temporal movement strategy were negatively correlated with changes in the level and variability of EMG, suggesting that an adaptive temporal strategy offset the development of unstable motor solutions in this fatiguing, short-cycle work.Practitioner Summary: Sustained performance of operators is essential to maintain competitiveness. In this study of repetitive work, participants gradually changed their temporal movement strategy, for possibly alleviating the effects of fatigue. This suggests that in order to effectively counteract fatigue and sustain performance, industrial production should allow extensive spatial and temporal flexibility.
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Background: Development of more effective interventions for nonspecific chronic low back pain (LBP), requires a robust theoretical framework regarding mechanisms underlying the persistence of LBP. Altered movement patterns, possibly driven by pain-related cognitions, are assumed to drive pain persistence, but cogent evidence is missing. Aim: To assess variability and stability of lumbar movement patterns, during repetitive seated reaching, in people with and without LBP, and to investigate whether these movement characteristics are associated with painrelated cognitions. Methods: 60 participants were recruited, matched by age and sex (30 back-healthy and 30 with LBP). Mean age was 32.1 years (SD13.4). Mean Oswestry Disability Index-score in LBP-group was 15.7 (SD12.7). Pain-related cognitions were assessed by the ‘Pain Catastrophizing Scale’ (PCS), ‘Pain Anxiety Symptoms Scale’ (PASS) and the task-specific ‘Expected Back Strain’ scale(EBS). Participants performed a seated repetitive reaching movement (45 times), at self-selected speed. Lumbar movement patterns were assessed by an optical motion capture system recording positions of cluster markers, located on the spinous processes of S1 and T8. Movement patterns were characterized by the spatial variability (meanSD) of the lumbar Euler angles: flexion-extension, lateralbending, axial-rotation, temporal variability (CyclSD) and local dynamic stability (LDE). Differences in movement patterns, between people with and without LBP and with high and low levels of pain-related cognitions, were assessed with factorial MANOVA. Results: We found no main effect of LBP on variability and stability, but there was a significant interaction effect of group and EBS. In the LBP-group, participants with high levels of EBS, showed increased MeanSDlateral-bending (p = 0.004, η2 = 0.14), indicating a large effect. MeanSDaxial-rotation approached significance (p = 0.06). Significance: In people with LBP, spatial variability was predicted by the task-specific EBS, but not by the general measures of pain-related cognitions. These results suggest that a high level of EBS is a driver of increased spatial variability, in participants with LBP.
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Introduction Negative pain-related cognitions are associated with persistence of low-back pain (LBP), but the mechanism underlying this association is not well understood. We propose that negative pain-related cognitions determine how threatening a motor task will be perceived, which in turn will affect how lumbar movements are performed, possibly with negative long-term effects on pain. Objective To assess the effect of postural threat on lumbar movement patterns in people with and without LBP, and to investigate whether this effect is associated with task-specific pain-related cognitions. Methods 30 back-healthy participants and 30 participants with LBP performed consecutive two trials of a seated repetitive reaching movement (45 times). During the first trial participants were threatened with mechanical perturbations, during the second trial participants were informed that the trial would be unperturbed. Movement patterns were characterized by temporal variability (CyclSD), local dynamic stability (LDE) and spatial variability (meanSD) of the relative lumbar Euler angles. Pain-related cognition was assessed with the task-specific ‘Expected Back Strain’-scale (EBS). A three-way mixed Manova was used to assess the effect of Threat, Group (LBP vs control) and EBS (above vs below median) on lumbar movement patterns. Results We found a main effect of threat on lumbar movement patterns. In the threat-condition, participants showed increased variability (MeanSDflexion-extension, p<0.000, η2 = 0.26; CyclSD, p = 0.003, η2 = 0.14) and decreased stability (LDE, p = 0.004, η2 = 0.14), indicating large effects of postural threat. Conclusion Postural threat increased variability and decreased stability of lumbar movements, regardless of group or EBS. These results suggest that perceived postural threat may underlie changes in motor behavior in patients with LBP. Since LBP is likely to impose such a threat, this could be a driver of changes in motor behavior in patients with LBP, as also supported by the higher spatial variability in the group with LBP and higher EBS in the reference condition.
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This dissertation describes the dynamics of motor competence (MC) development from early childhood (EC) to middle childhood (MCD). Being motor competent in early childhood creates a window of opportunity for taking part in physical activities later in childhood and adulthood. However, there is a worrying trend in MC development during childhood. This trend shows that, last decades, children struggle more with executing fundamental movement skills (e.g., hopping, dribbling, balancing, throwing and catching) and that general motor fitness levels of children are decreasing. A delay in MC development during childhood has a negative impact on the general health status later in life. Therefore, it is important to support young children to develop their MC. The main research question of this dissertation was: How can motor competence be promoted as efficient and effective as possible in early childhood by sport professionals? Chapter 2 showed that MC development from early to middle childhood proceeds with variation. The majority of the children had a stable ‘normal’ or increasing ‘high’ development of MC over time. However, a concerning level of 18.2% of the young children showed an undesirable pattern (i.e., a negative course of motor development over time and a ‘low’ MQ score during the final measurement) of MC development as they grow older. Chapters 3 and 4 showed that characteristics of the social and physical home environment and direct living environment were associated with MC disparities during early childhood. Both parenting practices and parental PA-involved behaviours were relevant modifiable factors. For example, stronger parental active transportation routines and PA parental practices decreased the odds of a lower MC. Also, the presence of a home garden decreased the likelihood of children being classified as low motor competent. With regard to gender differences, girls showed lower levels of MC compared to boys. Special attention should also be paid to obese children as they experience less enjoyment of PA compared with normal weighted peers (chapter 3). Excessive body weight is also a risk factor associated with an undesirable MC development, just like lack of sports participation (chapter 5). Intervention strategies (chapter 6) incorporating all fundamental movement skills with a great variety of activities for at least 3 to 4 times a week seem to be most effective to stimulate MC development. Methodological and didactical aspects like deliberate practice and play should be implemented together with training and coaching sessions for sport professionals to increase the effectiveness of the interventions. With respect to the efficiency of promoting MC development, policy makers and sport professionals should pay more attention on early childhood and especially focus on those children at risk for a delay in MC development. So, overweighted children and children not participating in organized sports should be given more attention by sport professionals. Additionally, the effectiveness of MC interventions can be increased by making use of the home environment, childcare context and school context of young children. Sport professionals can act as connectors between parents, school, and sports clubs.
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Introduction: Falling causes long term disability and can even lead to death. Most falls occur during gait. Therefore improving gait stability might be beneficial for people at risk of falling. Recently arm swing has been shown to influence gait stability. However at present it remains unknown which mode of arm swing creates the most stable gait. Aim: To examine how different modes of arm swing affect gait stability. Method: Ten healthy young male subjects volunteered for this study. All subjects walked with four different arm swing instructions at seven different gait speeds. The Xsens motion capture suit was used to capture gait kinematics. Basic gait parameters, variability and stability measures were calculated. Results: We found an increased stability in the medio-lateral direction with excessive arm swing in comparison to normal arm swing at all gait speeds. Moreover, excessive arm swing increased stability in the anterior–posterior and vertical direction at low gait speeds. Ipsilateral and inphase arm swing did not differ compared to a normal arm swing. Discussion: Excessive arm swing is a promising gait manipulation to improve local dynamic stability. For excessive arm swing in the ML direction there appears to be converging evidence. The effect of excessive arm swing on more clinically relevant groups like the more fall prone elderly or stroke survivors is worth further investigating. Conclusion: Excessive arm swing significantly increases local dynamic stability of human gait.
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Many students persistently misinterpret histograms. This calls for closer inspection of students’ strategies when interpreting histograms and case-value plots (which look similar but are diferent). Using students’ gaze data, we ask: How and how well do upper secondary pre-university school students estimate and compare arithmetic means of histograms and case-value plots? We designed four item types: two requiring mean estimation and two requiring means comparison. Analysis of gaze data of 50 students (15–19 years old) solving these items was triangulated with data from cued recall. We found five strategies. Two hypothesized most common strategies for estimating means were confirmed: a strategy associated with horizontal gazes and a strategy associated with vertical gazes. A third, new, count-and-compute strategy was found. Two more strategies emerged for comparing means that take specific features of the distribution into account. In about half of the histogram tasks, students used correct strategies. Surprisingly, when comparing two case-value plots, some students used distribution features that are only relevant for histograms, such as symmetry. As several incorrect strategies related to how and where the data and the distribution of these data are depicted in histograms, future interventions should aim at supporting students in understanding these concepts in histograms. A methodological advantage of eye-tracking data collection is that it reveals more details about students’ problem-solving processes than thinking-aloud protocols. We speculate that spatial gaze data can be re-used to substantiate ideas about the sensorimotor origin of learning mathematics.
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The recent shift towards the interdisciplinary study of the human-environment relationship is largely driven by environmental justice debates. This article will distinguish four types of environmental justice and link them to questions of neoliberalism and altruism. First, environmental justice seeks to redress inequitable distribution of environmental burdens to vulnerable groups and economically disadvantaged populations. Second, environmental justice highlights the developed and developing countries’ unequal exposure to environmental risks and benefits. Third, temporal environmental justice refers to the issues associated with intergenerational justice or concern for future generations of humans. In all three cases, environmental justice entails equitable distribution of burdens and benefits to different nations or social groups. By contrast, ecological justice involves biospheric egalitarianism or justice between species. This article will focus on ecological justice since the rights of non-human species lags behind social justice debates and discuss the implications of including biospheric egalitarianism in environmental justice debates. https://doi.org/10.1186/2194-6434-1-8 https://www.linkedin.com/in/helenkopnina/
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From the introduction: "There are two variants of fronto-temporal dementia: a behavioral variant (behavioral FTD, bvFTD, Neary et al. (1998)), which causes changes in behavior and personality but leaves syntax, phonology and semantics relatively intact, and a variant that causes impairments in the language processing system (Primary Progessive Aphasia, PPA (Gorno-Tempini et al., 2004). PPA can be subdivided into subtypes fluent (fluent but empty speech, comprehension of word meaning is affected / `semantic dementia') and non-fluent (agrammatism, hesitant or labored speech, word finding problems). Some identify logopenic aphasia as a FTD-variant: fluent aphasia with anomia but intact object recognition and underlying word meaning."
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Motor learning is particularly challenging in neurological rehabilitation: patients who suffer from neurological diseases experience both physical limitations and difficulties of cognition and communication that affect and/or complicate the motor learning process. Therapists (e.g.,, physiotherapists and occupational therapists) who work in neurorehabilitation are therefore continuously searching for the best way to facilitate patients during these intensive learning processes. To support therapists in the application of motor learning, a framework was developed, integrating knowledge from the literature and the opinions and experiences of international experts. This article presents the framework, illustrated by cases from daily practice. The framework may assist therapists working in neurorehabilitation in making choices, implementing motor learning in routine practice, and supporting communication of knowledge and experiences about motor learning with colleagues and students. The article discusses the framework and offers suggestions and conditions given for its use in daily practice.
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This article provides a description of the emergence of the Spanish ‘Occupy’ movement, Democracia real ya. The aim is to analyse the innovative discursive features of this movement and to connect this analysis to what we consider the innovative potential of the critical sciences. The movement is the result of a spontaneous uprising that appeared on the main squares of Madrid and Barcelona on 15 May 2011 and then spread to other Spanish cities. This date gave it its name: 15M. While the struggle for democracy in Spain is certainly not new, the 15M group shows a series of innovative features. These include the emphasis on peaceful struggle and the imaginary of a new democracy or worldview, transmitted through innovative placards and slogans designed by Spanish citizens. We consider these innovative not only due to their creativity, but also because of their use as a form of civil action. Our argument is that these placards both functioned as a sign of protest and, in combination with the demonstrations and the general dynamics of 15M, helped to reframe the population’s understanding of the crisis and rearticulate the identity of the citizens from victims to agents. In order to analyse the multimodal character of this struggle, we developed an interdisciplinary methodology, which combines socio-cognitive approaches that consider ideological proposals as socio-cognitive constructs (i.e. the notion of narrative or cognitive frame), and Critical Discourse Analysis (CDA) in the analysis of discourses related to processes of social imagination and transformation. The socio-constructivist perspective is used to consider these discourses in relation to their actors, particular contexts and actions. The use of CDA, which included a careful rhetoric analysis, helped to analyse the process of deconstruction, transformation and reconstruction that 15M uses to maintain its struggle. The narrative analysis and the discursive theoretical concept of articulation helped to methodologically show aspects of the process of change alluded to above. This change was both in terms of cognition and in the modification of identity that turned a large part of the Spanish population from victims to indignados and to the neologism indignadanos, which is a composition of indignado and ciudadano (citizen).
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