Trunk-Assisted Prehension: Specification of Body Segments With Imposed Temporal Constraints

The authors used a trunk-assisted prehension task to examine intersegment coordination. Participants (N = 7) reached to grasp an object placed beyond full arm extension, thus requiring trunk flexion to achieve the target object, under 4 varying temporal constraints. Kinematic analyses were performed in which the motions of the arm, the trunk, and the endpoint were characterized. The spatial trajectories and the segments' peak velocity data revealed that under high temporal constraints the arm was more responsible for endpoint motion than the trunk, whereas in the unconstrained condition the trunk was more involved. In addition, the arm exhibited a decline in spatial variability toward the end of the movement in all conditions, whereas the trunk did not. The present study is the first to show that when temporal demand is increased for a trunk-assisted prehensile task, the arm plays a larger role than the trunk in the transport of the hand to the object The data also suggest that the arm participates in the fine accuracy control of the reach, whereas the trunk does not.     

A social-psychological perspective on tacit coordination: How it works,when it works, (and when it does not)

We present a programmatic line of experimental studies which focus on the how and when of tacit coordination (i.e., the phenomenon that people can successfully coordinate their decisions without communication). We investigated this phenomenon using different types of economic games (i.e., social dilemmas as well as coordination games). Our studies broadly cover three themes: (a) fairness as a coordination rule, (b) uncertainty and common understanding, (c) social information as a cue. By focusing on these themes we have obtained several new insights on the prerequisites and boundary conditions of tacit coordination. We conclude that tacit coordination is often facilitated by mutual adherence to social norms (e.g., fairness rules, rules of deference, etcetera), but that in order to employ such norms people need sufficient environmental and/or social information.     

Integrating different notions of employability in a dynamic chain: The relationship between job transitions,movement capital and perceived employability

This study connects different notions of employability with the ultimate aim to arrive at integration of a research field that has been criticized for being fragmented and fuzzy. We define employability as “an individual's chance of a job in the internal and/or external labor market”. Employability research assesses employability differently, looking at the realization of this chance (i.e., job transitions), personal strengths that increase this chance (i.e., movement capital) and appraisals of this chance (i.e., perceived employability). We hypothesize and establish in a two-wave sample of 643 Belgian (Dutch-speaking) employees that these different notions of employability form a dynamic chain, so that job transitions promote movement capital, which then affects perceived employability and ultimately feeds back to job transitions. Furthermore, we found that the internal labor market versus the external labor market are important foci in employability research since internal and external job transitions were found to relate differently to the other notions of employability.     

Emotional influences on sit-to-walk in healthy young adults

The purpose of this study was to investigate influences of emotional feelings on sit-to-walk (STW). Eighteen healthy young adults performed STW while feeling sadness, anger, joy and neutral emotion. Emotions were elicited using an autobiographical memories task. We used an optoelectronic motion capture system to collect motion data and assessed kinematics of STW. Emotion-related differences in STW kinematics were consistent with differences in movement speed. Compared to neutral emotion, sadness was associated with increased STW duration and phase durations, decreased peak forward and vertical center-of-mass (COM) velocity, increased drop in forward COM velocity, and increased forward and vertical normalized jerk score (NJS). Anger and joy were associated with decreased STW duration and phase durations, increased peak forward and vertical COM velocity, decreased drop in forward COM velocity, and decreased forward and vertical NJS compared to neutral emotion. Findings suggest that emotional feelings affect movement speed, hesitation, and movement smoothness during STW.     

Do motor ability and handwriting kinematic measures predict organizational ability among children with Developmental Coordination Disorders?

Background and aimChildren with Developmental Coordination Disorders (DCD) exhibit deficient daily performance concealed in their perception–action mechanism. The aim of this study was to analyze behavior organization of children with DCD, in varied tasks that require generating and monitoring mental representations related to space and time inputs/requirements, for achieving better insight about their perception–action mechanism.MethodParticipants included 42 children aged 7–10, half of whom were defined with DCD and half were typically developing (TD). The children were matched for age, gender and school. They were evaluated using the Movement–ABC and performed three handwriting tasks on an electronic tablet that is part of a computerized system (ComPET – Computerized Penmanship Evaluation Tool). In addition, their teachers completed the Questionnaire for Assessing Students’ Organizational Abilities-Teachers (QASOA-T) to assess the children’s daily organizational ability.ResultsSignificant group differences (DCD versus controls) were found for all handwriting kinematic measures across the three handwriting tasks and for the children’s organizational abilities. Motor ability predicted a considerable percentage of the variance of the kinematic handwriting measures (30–37%), as well as a high percentage of the variance of their organizational abilities (67%). The coefficient of variance of the pen tilt added an additional 3% to the prediction of their organizational abilities.ConclusionsThe results of this study exhibited deficient ability among children with DCD in organizing their behavior in varied real-world tasks requiring generation and monitoring representation related to space and time. The significance of the results to understanding the performance mechanism and implication to the clinical field are discussed.     

Early static standing is associated with prolonged standing induced low back pain

Previous research points to the lack of movement during prolonged standing as a pre-disposing factor to low back pain (LBP). Such movements could be at the level of the lumbar spine or at the foot–ground interface. The primary purpose of this in vivo study was to determine if there were differences in magnitude, region, and frequency of movement patterns between non-pain developers (non-PDs) and standing induced pain developers (PDs). Thirty-two participants reported their LBP development using a visual analog scale over 2-h of prolonged standing. Time-varying lumbar spine kinematics were used to assess the magnitude and frequency of lumbar spine fidgets and shifts. Ground reaction forces were used to assess the magnitude and frequency of whole body weight transfers and anterior–posterior center of pressure movements. Fourteen of 32 participants (43.75%) were categorized as PDs. The first 15 min of standing distinguished the two pain groups, as non-PD performed a higher frequency of lumbar spine flexion/extension fidgets and large body weight transfers. Both of these differences may be pre-disposing factors for transient LBP development, as they both occurred prior to PDs reaching the 10 mm visual analog scale threshold for LBP classification.     

Moved to messiness: Physical activity,feelings, and transdisciplinarity

This paper is based on conversations that took place during a scholarly reading group on the sociology of emotions. The members of the group shared an interest in the body, movement, and culture, but our academic and ‘athletic’ backgrounds were quite varied. Our diverse socio-cultural understandings of emotions were complicated by our own (emotional) experiences of physical (in)activity, thus conversations cut a wide and varied path. One idea, however, continued to resonate throughout our discussions; we found the experiential, theoretical, and methodological notion of messiness to hold great possibility as it allowed us to avoid the urge to reduce diverse experiences to a singular voice (Christians, 2011, Cornforth et al., 2012, Ellingson, 2009, Noble, 2009). Consequently, our project here is twofold. First, we experiment with communal writing as a method for undertaking a study of physical activity. Second, rather than any one perspective taking precedence we use this practice as a way to demonstrate the potential of embracing messiness as a collaborative ethical and theoretical method for understanding the complexities of emotions in relation to (in)active bodies. Specifically, using a variety of disciplinary and theoretical lenses we explore physical (in)activity in relation to pain/pleasure, and the gaze and performance. The result is a conversation made up of traditional and non-traditional approaches to academic writing that work to reconfigure and to challenge traditional dichotomies and hierarchical understandings of the active body, understandings that potentially over-simplify and close-down our emotional experiences of physical (in)activity.     

Coping with asymmetry: How infants and adults walk with one elongated leg

The stability of a system affects how it will handle a perturbation: The system may compensate for the perturbation or not. This study examined how 14-month-old infants—notoriously unstable walkers—and adults cope with a perturbation to walking. We attached a platform to one of participants’ shoes, forcing them to walk with one elongated leg. At first, the platform shoe caused both age groups to slow down and limp, and caused infants to misstep and fall. But after a few trials, infants altered their gait to compensate for the platform shoe whereas adults did not; infants recovered symmetrical gait whereas adults continued to limp. Apparently, adult walking was stable enough to cope with the perturbation, but infants risked falling if they did not compensate. Compensation depends on the interplay of multiple factors: The availability of a compensatory response, the cost of compensation, and the stability of the system being perturbed.     

How perceiving additional targets modifies teams’ tactical behavior during football small-sided games

This study aimed to measure how the change on targets information modifies teams’ tactical behavior during football small-sided games. 20 male senior professional players divided in 4 teams of 5 players participated in the study. Each team played two small-sided games, one with 2 official targets with goalkeeper and one with 6 small targets. Positional data of each player were recorded using a 15 Hz portable GPS. The distance between the centers of gravity (CG) of both team, the stretch index and the relative stretch index were measured and differences accessed via standardized differences, coefficient intervals and meta-analysis procedures. A moderate increase on the distance between the CG of each team and a small decrease on the stretch index and on the relative stretch index from 2 targets to the 6 targets games was observed. It was also identified that pitch location affected the interaction between teams. When the game was played in lateral corridors or defensive sectors, the differences between game conditions increased. Emphasizing the information for attacking team to shoot at goal, by manipulating the number of targets constrained tactical behavior of teams. The amplification of specific information on small-sided games can help coaches to promote players and teams’ emergent adapted behaviors.     

Human hip–ankle coordination emerging from multisensory feedback control

Human sensorimotor control involves inter-segmental coordination to cope with the complexity of a multi-segment system. The combined activation of hip and ankle muscles during upright stance represents the hip–ankle coordination. This study postulates that the coordination emerges from interactions on the sensory levels in the feedback control. The hypothesis was tested in a model-based approach that compared human experimental data with model simulations. Seven subjects were standing with eyes closed on an anterior–posterior tilting motion platform. Postural responses in terms of angular excursions of trunk and legs with respect to vertical were measured and characterized using spectral analysis. The presented control model consists of separate feedback modules for the hip and ankle joints, which exchange sensory information with each other. The feedback modules utilize sensor-derived disturbance estimates rather than ‘raw’ sensory signals. The comparison of the human data with the simulation data revealed close correspondence, suggesting that the model captures important aspects of the human sensory feedback control. For verification, the model was re-embodied in a humanoid robot that was tested in the human laboratory. The findings show that the hip–ankle coordination can be explained by interactions between the feedback control modules of the hip and ankle joints.