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Background: Individuals with Developmental Coordination Disorder (DCD) experience difficulty with motor coordination and this affects their daily functioning. Research indicated inferior visuospatial processing and oculomotor control in DCD. As visual information is essential for locomotor control, more insight in the gaze behaviour of this population during walking is required and crucial for gaze training interventions as a possible means to improve daily functioning of children and adults with DCD., Aim: This study explored differences and similarities in gaze behaviour during walking between typically developing young adults and those with DCD., Methods and Procedures: Ten young adults with DCD (age: 22.13 ± 0.64) and ten typically developing individuals (age: 22.00 ± 1.05) completed a walking task in which they had to place their feet on irregularly placed targets wearing eye tracking glasses., Outcomes and Results: Individuals with DCD walked slower and demonstrated a different gaze strategy compared to their neurotypical peers as they fixated almost each and every target sequentially. Typically developing individuals, on the other hand, directed gaze further along the path and often fixated areas around the targets., Conclusions and Implications: Despite adequate walking performance in daily situations in young adults with DCD, fundamental control deficits persist into adulthood. WHAT THIS PAPER ADDS?: This paper is the first to demonstrate differences in gaze behaviour between young adults with DCD and typically developing individuals in a task that resembles a task of daily living, as previous research focused on laboratory tasks. This is a valuable finding as DCD has a clear impact on the daily life. Furthermore, this study demonstrated that the fundamental control deficits of DCD persist into adulthood despite frequent performance and practice of these daily tasks. Lastly, these findings might contribute to the therapeutic potential of gaze training interventions to improve the daily functioning of children and adults with DCD., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Infants with congenital heart disease are at risk of impaired neurodevelopment, which frequently manifests as motor delay during their first years of life. This delay is multifactorial in origin and environmental factors, such as a limited experience in prone, may play a role. In this study, we evaluated the motor development of a prospective cohort of 71 infants (37 males) with congenital heart disease at 4 months of age using the Alberta Infant Motor Scales (AIMS). We used regression analyses to determine whether the 4-month AIMS scores predict the ability to walk by 18 months. The influence of demographic and clinical variables was also assessed. Fifty-one infants (71.8%) were able to maintain the prone prop position (AIMS score of ≥3 in prone) at 4 months. Of those, 47 (92.2%) were able to walk by 18 months compared to only 12/20 (60%) of those who did not maintain the position. Higher AIMS scores were predictive of a greater likelihood of walking by 18 months ( P < .001), with the scores in prone having a higher predictive ability compared to those in other positions (Exp(B) 15.2 vs 4.0). Shorter hospital stays and female gender were also associated with an earlier onset of walking. In conclusion, our study demonstrates that early ventral performance in infants with congenital heart disease impacts the age of acquisition of walking and could be used to guide referral to rehabilitation.

Background: The aim was to examine inter-rater and alternate-form reliability of the Microscale Audit of Pedestrian Streetscapes (MAPS) Global tool to assess the physical environment along likely walking routes in Belgium., Methods: For 65 children participating in the BEPAS-children study, routes between their individual homes and the nearest pre-defined destination were defined. Using MAPS Global, physical environmental characteristics of the routes were audited by 4 trained auditors (2 on-site, 2 online using Google Street View). Inter-rater reliability was studied for on-site and online ratings separately. Alternate-form reliability was examined by comparing on-site with online ratings., Results: Inter-rater reliability for on-site ratings was acceptable for 68% of items (kappa range 0.03-1.00) and for online ratings for 60% of items (kappa range -0.03 to 1.00). Acceptable alternate-form reliability was reported for 60% of items (kappa range -0.01 to 1.00/r range 0.31-1.00)., Conclusions: MAPS Global can be used to assess the physical environment of potential walking routes. For areas where Google Street View imagery is widely covered and often updated, MAPS Global can be completed online.

Background: There is a greater prevalence of lower extremity malalignment in obese children during static posture; however, there has been less examination of dynamic joint function in this cohort. Therefore, the purpose of this study was to determine kinematic differences that exist between obese and non-obese children that would support previously reported static joint malalignment., Methods: Forty children were classified as obese (n=20) or non-obese (n=20). Lower extremity joint kinematics were collected during five walking trials at a self-selected pace. Peak joint displacement and amount of joint motion throughout the gait cycle (calculated as the integrated displacement curve) were analyzed for group differences., Findings: Non-obese children had greater peak knee and hip extension during gait; however, there were no group differences in the integrated sagittal displacement curve. Obese children had greater peak angular displacement and integrals of angular displacement for peak hip adduction, hip internal rotation, and foot abduction (toe-out) than non-obese children. Obese children also had greater peak knee external rotation than non-obese children., Interpretation: Non-obese children showed greater range of motion in the sagittal plane, particularly at the hip and knee. Frontal and transverse plane differences suggest that obese children function in a more genu valgum position than non-obese children. Static measures of genu valgum have been previously associated with pediatric obesity; the findings indicate that there are also dynamic implications of said malalignment in obese children. Genu valgum presents increased risk of osteoarthritis for obese children and should be considered when prescribing weight bearing exercise to this cohort., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

The present study investigated the visuomotor and balance limitations during obstacle crossing in typically developing (TD) children and those with Developmental Coordination Disorder (DCD) (7-9 years old; N=12 per group). Spatiotemporal gait parameters as well as range and velocity of the centre of mass (COM) were determined in three conditions: overground walking at a self-selected speed, crossing a low obstacle and crossing a high obstacle (5% or 30% of the leg length, respectively). Both groups walked more slowly during obstacle crossing than walking over level ground. In addition, both groups exhibited a significant decrease in the spatial variability of their foot placements as they approached the obstacle, which was then negotiated with a similar strategy. There were no differences in approach distance, length of lead and trail step, or lead and trail foot elevation. Compared to walking over level ground, obstacle crossing led to a longer swing phase of the lead and trail foot and increased maximal medio-lateral COM velocity. In children with DCD, however, medio-lateral COM velocity was higher and accompanied by significantly greater medio-lateral COM amplitude. In conclusion, the results indicate that while TD-children and those with DCD exhibit satisfactory anticipatory control and adequate visual guidance, the latter group have a reduced ability to control the momentum of the COM when crossing obstacles that impose increased balance demands., (Crown Copyright © 2010. Published by Elsevier B.V. All rights reserved.)

The goal of this study was to analyse the role of the plantarflexor muscles in the walk-to-run transition (WRT) by means of a powered ankle-foot-exoskeleton. 11 female subjects performed several WRT's on an accelerating treadmill while their plantarflexors were assisted or resisted during push off. The WRT speed was lower in the resist condition than in the control condition which reinforces hypotheses from previous simulations, descriptive and experimental studies. There was no increase in WRT speed in the assist condition which is in contrast to another study where the plantarflexor push off was assisted indirectly by a horizontal traction at waist level. The lack of effect from the assist condition in the present study is possibly due to the narrowly focused nature of the experimental manipulation.

Perturbations of optic flow can induce changes in walking speed since subjects modulate their speed with respect to the speed perceived from optic flow. The purpose of this study was to examine the effects of optic flow on steady-state as well as on non steady-state locomotion, i.e. on spontaneous overground walk-to-run transitions (WRT) during which subjects were able to accelerate in their preferred way. In this experiment, while subjects moved along a specially constructed hallway, a series of stripes projected on the side walls and ceiling were made to move backward (against the locomotion direction) at an absolute speed of -2 m s(-1) (condition B), or to move forward at an absolute speed of +2 m s(-1) (condition F), or to remain stationary (condition C). While condition B and condition F entailed a decrease and an increase in preferred walking speed, respectively, the spatiotemporal characteristics of the spontaneous walking acceleration prior to reaching WRT were not influenced by modified visual information. However, backward moving stripes induced a smaller speed increase when making the actual transition to running. As such, running speeds after making the WRT were lower in condition B. These results indicate that the walking acceleration prior to reaching the WRT is more robust against visual perturbations compared to walking at preferred walking speed. This could be due to a higher contribution from spinal control during the walking acceleration phase. However, the finding that subjects started to run at a lower running speed when experiencing an approaching optic flow faster than locomotion speed shows that the actual realization of the WRT is not totally independent of external cues.

The purpose of the current study was to examine spontaneous overground walk-to-run transitions (WRT). For the first time, subjects' WRT was examined during an overground protocol that allowed them to accelerate freely. The overground speed profile prior to reaching the WRT was analysed together with the spatiotemporal characteristics of the actual transition. Nine women (height: 166.4+/-3.5 cm) performed five spontaneous WRT. Speed, step frequency (SF) and step length (SL) of the accelerating walking steps and the transition step were determined. By means of fourth degree polynomials, subjects' spatiotemporal profiles prior to reaching WRT were determined. A step length index (SLI) was used to calculate the contribution of SF and SL to the increase in walking speed. Subjects took on average 5.9+/-0.9 walking steps prior to reaching transition. When speeding up towards the transition to running, subjects chose to accelerate predominantly in the first half of the walking acceleration period, followed by smaller speed increments in the second half. The SLI values indicated that subjects tended to increase walking speed by increasing SL, more than SF, except during the first 20% of the acceleration period. WRT-speed was 2.664+/-0.230 m s(-1), which was higher than in former treadmill studies using a constant acceleration protocol (+/-2.1 m s(-1)). Subjects made a speed jump of 0.417 m s(-1) from the last walking step to the WRT-step. We can conclude that further transition studies studying the interaction between the acceleration and gait transition behaviour are necessary in order to complete the understanding of the transition phenomenon.

The purpose of this study was to examine the kinetics of the walk-to-run transition (WRT) and run-to-walk transition (RWT), when accelerating or decelerating across transition speed (a = 0.17 m.s-2). Nine women performed gait transitions on a 50-m-long walkway. Vertical ground reaction forces (GRFs) and the center of pressure (COP) were examined in the range from 3 steps before to 3 steps after transition in order to identify the possible occurrence of a transition process, in order to facilitate the actual realization of transition. The actual transition is realized in one step, during WRT and RWT. This transition step was characterized by an outlying vertical GRF and COP trajectory (deviating from walking and running). Despite this clear discontinuity, a transitional adaptation period (process) appeared in both transitions. In the WRT, transition was prepared and kinetic adaptations were found in the last step before transition. The RWT was pre- and "post"-pared and only completed during the first walking step after transition. Thus, the WRT and RWT are two distinct phenomena, with different kinetics.

The purpose of this study was to examine kinematics of the walk-to-run transition (WRT) and run-to-walk transition (RWT) when speed is altered with a constant acceleration of 0.1 m s(-2), respectively -0.1 m s(-2). Thirteen women (height: 168.9+/-3.36 cm) performed gait transitions on a motor-driven treadmill. WRT-speed was 2.16+/-0.12 m s(-1), RWT-speed 2.19+/-0.12 m s(-1). Kinematics were examined in the range from eight steps before to eight steps after transition in order to identify the possible occurrence of a transition process to facilitate the actual realization of transition. A transition step in which the main changes from one gait to another are realized is present in WRT and RWT. Despite this clear discontinuity, a transition process also appeared in both transitions. In the WRT, transition was prepared and kinematic adaptations were found in the last swing before transition leading to altered landing conditions. During RWT posttransition changes were observed and RWT was only completed after reorientation of the trunk in the first walking stride after transition. A noteworthy finding was that spatiotemporal (presence of a flight phase), kinematic (knee flexion) and energetic (kinetic and gravitational potential energy fluctuating in-phase versus out-of-phase) criteria to define transition stride correspond to each other. Furthermore, a functional interlimb asymmetry was recognized as a unique characteristic of the transition stride, offering a fourth way of identifying the transition stride.

The purpose of this study was to examine the influence of muscular fatigue of tibialis anterior (TA) on the walk-to-run transition (WRT) and run-to-walk transition (RWT) when speed is altered at different constant accelerations (a=0.01, 0.07 and 0.05 ms(-2)). Twenty women (height: 168.9+/-3.36 cm) performed WRTs and RWTs on a motor-driven treadmill, before and after a protocol inducing muscular fatigue of the TA. WRT-speed decreased after TA fatigue whereas RWT-speed did not change except during the intermediate deceleration. Integrated EMG (iEMG) of the activity burst of TA around heel contact was examined in the last steps before transition, the transition step and the first steps after transition. iEMG increased before WRT, then decreased after transition to running. In the RWT the opposite was observed: iEMG increased after RWT, then decreased with decreasing walking speed. After inducing fatigue in the TA, there was a decrease in iEMG in the WRT whereas no influence of fatigue was found on iEMG in the RWT. As a result of TA fatigue, WRT occurred at a lower speed, probably to avoid over-exertion of the TA. This indicates that the TA is a likely determinant of WRT as previously reported. The RWT, on the other hand, was not altered following TA fatigue, which would indicate that WRT and RWT are determined by different factors.

Judged by whole body dynamics, walking and running in humans clearly differ. When walking, potential and kinetic energy fluctuate out-of-phase and energy is partially recovered in a pendulum-like fashion. In contrast, running involves in-phase fluctuations of the mechanical energy components of the body centre of mass, allowing elastic energy recovery. We show that, when constantly accelerating across the transition speed, humans make the switch from walking to running abruptly in one single step. In this step, active mechanical energy input triples the normal step-by-step energy increment needed to power the imposed constant acceleration. This extra energy is needed to launch the body into the flight phase of the first running step and to bring the trunk into its more inclined orientation during running. Locomotor cycles immediately proceed with the typical in-phase fluctuations of kinetic and potential energy. As a result, the pendular energy transfer drops in one step from 43% to 5%. Kinematically, the transition step is achieved by landing with the knee and hip significantly more flexed compared to the previous walking steps. Flexion in these joints continues during the first half of stance, thus bringing the centre of mass to its deepest position halfway through stance phase to allow for the necessary extension to initiate the running gait. From this point of view, the altered landing conditions seem to constitute the actual transition.

Background: The motor co-ordination problems of children with Developmental Coordination Disorder (DCD) have been frequently associated with poor visuospatial processing. In order to extend these findings mainly based on fine motor experiments, the present study investigates the contribution of vision to the control of walking in children with DCD., Methods: Children with DCD (n = 12) walked at their preferred speed on a straight, firm and uncluttered walkway in a condition with normal lighting and in a dark condition. Spatiotemporal gait variables were assessed by means of a three-dimensional ProReflex camera system and compared with the gait pattern of matched, typically developing (TD) children (n = 12)., Results: In normal lighting, the gait pattern of both groups was similar, with the exception of subtle differences in the temporal phasing, showing a slightly longer support phase in the children with DCD. In the dark, step frequency and step length were decreased in the children with DCD, resulting in a significantly slower walking velocity. In addition, the medio-lateral excursion of the centre of mass tended to increase in this group. In the TD children, adaptations to the spatiotemporal pattern remained absent., Conclusions: These results suggest that children with DCD are more dependent on global visual flow information than TD children for the maintenance of balance and the control of velocity during walking. This increased dependency on visual control might be associated with a poorly developed internal sensorimotor model.

The purpose of this study was to examine spatiotemporal parameters of the walk-to-run transition (WRT) and run-to-walk transition (RWT) when speed is altered with different constant accelerations. Twenty women (height: 168.9+/-3.36cm) performed three accelerations (0.05, 0.07 and 0.1ms(-2)) and three decelerations (-0.05, -0.07 and -0.1ms(-2)) on a motor-driven treadmill. The transition step in the WRT (first step with a flight phase) and RWT (first step with a double stance phase) occurred at the same speed for all accelerations but these did not occur in the same way. The most striking difference was the presence of a transition step with specific spatiotemporal characteristics in the WRT, whereas this was not observed in the RWT. The transition is not a sudden one-step-event. WRT occurred before transition and consisted of a "pre-transition period" and the transition step whereas RWT occurred after transition and consisted of the transition step and a "post-transition period". Both transition periods were characterized by an exponential evolution of step frequency and step length. Step frequency and step length showed a linear evolution before and after transition. The flight phase of the transition step in the WRT reached a minimum with comparable duration of the last flight phase in the RWT. The flight phase could be considered as an intrinsic dynamical factor of transition. Further research in kinematics, the trajectory of the body centre of mass and energy fluctuations will give more insight in these transitions.