Participant engagement with a UK community-based preschool childhood obesity prevention programme: : a focused ethnography study

Background Children’s centres in the UK provide a setting for public health programmes; offering support to families living in the most disadvantaged areas where obesity prevalence is at its highest. Health, Exercise and Nutrition in the Really Young (HENRY) is an eight-week obesity prevention programme currently delivered in children’s centres across the UK. However, low participant engagement in some local authorities threatens its potential reach and impact. This study aimed to explore the factors influencing participant engagement with HENRY to describe where local intervention may support engagement efforts. Method A focused ethnography study was undertaken in five children’s centres delivering HENRY across the UK. One hundred and ninety hours of field observations, 22 interviews with staff (commissioners, HENRY co-ordinators, managers and facilitators) and six focus groups (36 parents), took place over five consecutive days in each centre. The Consolidated Framework for Implementation Research (CFIR) was used to guide the observations and analysis of the data. Results Three overarching themes described the factors influencing participant engagement with HENRY: local authority decision making around children’s centre programmes; children’s centre implementation of HENRY; and the participant experience of HENRY. The results indicate that factors influencing participant engagement with public health programmes begin at the commissioning body level, influencing children’s centre implementation and subsequently the experience of participants. Local authority funding priorities and constraints influence availability of places and who these places are offered to, with funding often targeted towards those deemed most at need. This was perceived to have a detrimental effect on participant experience of the programme. Conclusion In summary, participant engagement is affected by multiple factors, working at different levels of the children’s centre and local authority hierarchy, most of which are at play even before participants decide whether or not they choose to enrol and maintain attendance. For programmes to achieve their optimal reach and impact, factors at the commissioning and local implementation level need to be addressed prior to addressing participant facing issues

Grasping Kinematics from the Perspective of the Individual Digits: A Modelling Study

Grasping is a prototype of human motor coordination. Nevertheless, it is not known what determines the typical movement patterns of grasping. One way to approach this issue is by building models. We developed a model based on the movements of the individual digits. In our model the following objectives were taken into account for each digit: move smoothly to the preselected goal position on the object without hitting other surfaces, arrive at about the same time as the other digit and never move too far from the other digit. These objectives were implemented by regarding the tips of the digits as point masses with a spring between them, each attracted to its goal position and repelled from objects' surfaces. Their movements were damped. Using a single set of parameters, our model can reproduce a wider variety of experimental findings than any previous model of grasping. Apart from reproducing known effects (even the angles under which digits approach trapezoidal objects' surfaces, which no other model can explain), our model predicted that the increase in maximum grip aperture with object size should be greater for blocks than for cylinders. A survey of the literature shows that this is indeed how humans behave. The model can also adequately predict how single digit pointing movements are made. This supports the idea that grasping kinematics follow from the movements of the individual digits

Reorganization of prehension components following perturbation of object size

This study provides a kinematic comparison of the response of 12 older persons (ages 60-70) and 12 young persons (ages 20-26) to a perturbation of object size during a reach-to-grasp movement. For 80 out of 100 trials, each participant reached to grasp an illuminated cylinder of either small or large diameter (0.7 and 8.0 cm, respectively). For 20 out of 100 trials, a visual perturbation occurred at movement onset. This perturbation consisted of a switch of illumination from 1 to the other cylinder. For the switch from large to small cylinder, participants changed the distal grasp from whole-hand prehension to precision grip. For the opposite switch, participants changed from precision grip to whole-hand prehension. The older participants successfully adapted to these perturbations but showed a more conservative approach. Generally the approach time as the hand neared the object was prolonged, and the coordination between transport and manipulation components was maintained when comparing perturbed with nonperturbed trials. Young participants showed a more flexible pattern with a decrease or loss of temporal coupling between the components. It is hypothesized that the more rigid movement pattern of older participants to unanticipated motor requirements could be a contributory factor to the higher incidence of accidents for this group

The bilateral reach-to-grasp movement of Parkinson's disease subjects

The performance of simultaneous movements is said to be disrupted in Parkinson's disease, yet there are some indications that this dysfunction is less evident for bilateral inter-limb actions, as opposed to unilateral simultaneous actions. Focussing specifically upon natural actions, this study uses a three-dimensional kinematic system (ELITE) to assess the movement kinematics of a bilateral non-homologous reach-to-grasp action. The target device consisted of a large cylinder (diameter 8 cm) to which a handle (diameter 0.8 cm) was attached. The task was to reach and grasp the cylinder with one hand (gross grasp) while reaching to grasp the handle with the contralateral hand (precision grasp). Overall the results indicated that Parkinson's disease subjects, like controls showed independent and appropriate kinematic parameterization each limb. For example, and as a reflection of task precision requirements, the time taken to decelerate upon the item to be grasped was longer for the limb grasping the handle than for the limb grasping the cylinder Subtle indications of compensatory mechanisms, in response to left upper limb inadequacies of Parkinson's disease subjects, were suggested by findings of an earlier timing of maximum hand grip aperture for the left than for the right hand, and adjustments to the final transport phase of the left arm under bilateral conditions. It is proposed that left-right hand differences are more evident with basal ganglia dysfunction, bur that these differences are compensated for by CNS mechanisms so that natural non-homologous reach-to-grasp actions are performed in a functional, coordinated and appropriate manner

Reach to grasp: changes with age

This study provides the first known kinematic assessment of the reach-to-grasp movement in elderly subjects. Twelve subjects (aged 60-71) were compared to gender-matched younger subjects (aged 18-25). Subjects reached 35 cm to grasp either a small (0.7 cm) or a large (8 cm) diameter cylinder. Precision grip was naturally adopted for the small cylinder, and whole hand prehension for the large cylinder. The displacements of active infrared markers (wrist and hand) were recorded with an Optotrak system. Movement initiation time, movement duration, and kinematic parameters of the reach-and-grasp components were computed. Older subjects showed slower, longer movements with a prolonged approach phase. However, the patterning and coordination of this movement, with respect to the utilization of a precision grip or whole hand prehension, were similar for both groups. Subtle changes with age thus appear to reflect a strategy that develops to compensate for deterioration in other systems such as visual or proprioceptive

Three-dimensional covert attentional functions in Parkinson's disease subjects

This study assessed the ability of mildly affected Parkinson's disease (PD) subjects (n=16) to perform attentional cognitive tasks within a three-dimensional object. A hollow cube was displayed on a computer screen and the subject was required to respond as quickly as possible to the highlighting of one of the cube angles by pressing the spacebar of the keyboard. Prior to the appearance of this imperative stimulus, the same (''valid'' trials) or an alternative (''invalid'' trials) angle was highlighted. For the invalid trials this meant that the subject oriented attention to the cued angle but, on imperative stimulus appearance, was unexpectedly required to redirect attention to another angle, which could be on a different cube face to that which had been cued. For one experimental session the cube was stationary, that is, object-centred and viewer-centred coordinates of a cube angle corresponded. For another session, the cube rotated such that the viewer-centred coordinates of an angle changed between appearance of the cue and appearance of the stimulus, but the angle's object-centred coordinates remained constant. The finding of lower reaction times for the valid than for the invalid trials, even when the cube was rotating, indicated that PD subjects could operate attention using an object-centred coordinate system. However, PD subjects showed exaggerated reaction times when the stimulus appeared in a cube face that was opposite to, rather than the same as, that of the invalidly cued angle. It is suggested that this reflects a dysfunction in the grouping of the structural components of the whole object at an attentional level

Parkinson's disease: reorganization of the reach to grasp movement in response to perturbation of the distal motor patterning

This study assessed the kinematic changes to the reach to grasp movement in,response to a perturbation of object size in 15 Parkinson's disease (PD) and 15 control subjects. For non-perturbed trials subjects reached 35 cm to grasp and lift either an illuminated small (0.7 cm) or large (8 cm) diameter cylinder. For perturbed trials (20%), illumination shifted unexpectedly from the small to the large or from the large to the small cylinder at the onset of the reach. For Condition One trials subjects were given no instructions as to which grasp to use. With perturbation, they thus naturally changed grasp from precision grip to whole hand prehension or vice versa. The results for the PD subjects indicated a slowness at the transition from one to another grasp. This contrasted to the smooth transitions when perturbation required only a change of grasp aperture (precision grip-Condition Two. whole hand prehension-Condition Three). PD subjects thus showed dysfunction in the suppression/activation of different grasp programs rather than deficits in the on-line modification of an operating program

How perceived object dimension influences prehension

A kinematic study assessed the effects of the perceived dimensions of an object upon the patterning of a prehension movement involving that object. If an apple was perceived as two-dimensional, subjects utilized a large precision grip between the index finger and thumb. If the apple was perceived as three-dimensional, whole hand prehension involving all the digits was utilized. A visual perturbation from perceived two-dimensional to three-dimensional at movement onset resulted in a transition from the 2D precision grip pattern to the 3D whole hand prehension. These results suggest that visual mechanisms for interpreting the dimensions of an object directly influence motor selection pathways, and do not necessarily access a three-dimensional central nervous system representation of the object

The bilateral reach to grasp movement

This study investigated the kinematic organization of bilateral reach to grasp movements. In Experiment 1 non-homologous bilateral movements were performed. One limb reached to grasp an object using whole hand prehension; the contralateral limb simultaneously reached to grasp an object using precision grip. Corresponding unilateral movements were assessed. Movement duration for each limb in the bilateral condition was similar. However, with earlier temporal settings for peak wrist acceleration and velocity, the limb performing precision grip showed a longer approach (deceleration) phase to the object. Unilateral precision grip movements showed a longer movement duration and deceleration phase than unilateral whole hand prehension movements. In Experiment 2 homologous bilateral movements were assessed. Both limbs performed either a reach and whole hand prehension or a reach and precision grip. Again the precision grip movements showed longer movement and deceleration times. Experiment 3 consisted of bilateral non-homologous pointing movements and a pointing movement with one limb while reaching to grasp with the contralateral limb. It was found that the earlier temporal settings of peak acceleration and velocity with the precision grip limb of the non-homologous bilateral task (Expt. 1) were largely due to the performance of distal grasping actions. It is concluded that a kinematic parameterization which is independent to each limb is evident for bilateral tasks which require functionally independent actions

Does the type of prehension influence the kinematics of reaching?

Kinematic studies have indicated that when a subject reaches to grasp an object, the movement consists of two primary components: (a) a transport phase whereby the hand is brought towards the object and (b) a grip phase whereby the hand changes shape in anticipation of the grasp. Using a visual perturbation paradigm, we investigated the effect of different grip component strategies upon the transport phase. The distal strategy was determined by the size of the object to be grasped: for the small object (1.5 cm o.d.) subjects naturally adopted a precision grip between the index finger and thumb; for the large object (6 cm o.d.) subjects used a whole hand prehensile grip. During 20% of the reaching trials the perturbation was introduced by unexpectedly changing the object size. The results showed that corrections to the distal program in response to the perturbation were preceded by changes in the deceleration phase of the proximal component. The data supported previous findings of two visuo-motor channels for this prehensile movement but indicated that when unanticipated shifts of only the distal program are required, both channels show modifications