When an object appears unexpectedly: anticipatory movement and object circumvention in individuals with and without Developmental Coordination Disorder

Abstract

Obstacles often appear unexpectedly in our pathway and these require us to make adjustments to avoid collision. Previous research has demonstrated that healthy adults will make anticipatory adjustments to gait where they have been told there is the possibility of an obstacle appearing. One population that may find this type of anticipatory movement difficult is individuals with Developmental Coordination Disorder (DCD). The current study considered how individuals with and without DCD adjust to the possibility of an obstacle appearing which would require circumvention. Fortyfour individuals with DCD and 44 age-matched controls (aged from 7 to 34 years of age) walked down an 11 m walkway under three conditions. Initially they were told this was a clear pathway and nothing in the environment would change (1, no possibility of an obstacle, no obstacle). They then performed a series of trials in which a gate may (2, possibility of an obstacle, obstacle) or may not (3, possibility of an obstacle, no obstacle) partially obstruct their pathway. We found that all participants increased medio-lateral trunk acceleration when there was the possibility of an obstacle but before the obstacle appeared, in addition the typical adults and older children also increased step width. When describing circumvention we found that the younger children showed an increase in trunk velocity and acceleration in all three directions compared to older children and adults. We also found that the individuals with DCD adjusted their path sooner and deviated more than their peers. The degree of adjustment to step width in anticipation of an obstacle was related to later medio-lateral velocity and timing of the deviation. Therefore, the lack of 'readying' the system where there is the possibility of an obstacle appearing seen in the individuals with DCD and the younger typical children may explain the increased medio-lateral velocity seen during circumvention.

When an object appears unexpectedly: foot placement during obstacle circumvention in children and adults with Developmental Coordination Disorder

“…When comparing the use of these preferred strategies, participants showed a preference for shortening of the step when three steps away, but then focusing on changing step width to move the participant away from the obstacle on subsequent steps. These results are in line with previous findings which used the same task in typically developing adults (Wilmut et al, 2017). As with this previous study we saw very few instances of step lengthening, despite this being the preferred adjustment while stepping over an obstacle in healthy adults (Moraes, Allard, & Patla, 2007), older females (Weerdesteyn et al, 2005) and individuals recovering from stroke (Den Otter et al, 2005).…”

“…Essentially this shows us that the youngest typically developing children tended to start their adjustments while further from the obstacle while the youngest children with DCD waited until they were closer. Given previous findings that children and adults with DCD start a movement adjustment earlier in the movement (Wilmut & Barnett, 2017;Wilmut et al, 2016) it is surprising that this has not also been shown in the current study. However, the previous studies have considered adjustments to movement in terms of the path of the trunk or the speed of locomotion.…”

“…In a recent study we measured the approach towards and circumvention around an obstacle (Wilmut & Barnett, 2017). The primary aim of this previous study was not to consider the exact nature of obstacle circumvention per se but rather to look at how individuals prepared for such a movement, in other words when faced with an environment where an obstacle could or could not appear do individuals change their movement in anticipation of that possibility.…”

“…The aim of the current study was, therefore, to further analyse these data in order to describe the nature of foot placement during obstacle circumvention in children and adults with and without DCD. Previous studies have shown that children and adults with DCD tend to start an adjustment to locomotion earlier than their peers during both an aperture crossing task where we see them start to turn when further from the aperture (Wilmut et al, 2016) and a circumvention task where we see them starting to adjust their path further from the obstacle (Wilmut and Barnett, 2017). Therefore, we considered adjustments to foot placement during four steps prior to and during obstacle circumvention.…”

Neuroimaging Findings for Developmental Coordination Disorder (DCD) in Adults: Critical Evaluation and Future Directions

“…13 Maximal voluntary contraction. 14 Inter-trial intervals. 15 Bruininks-Oseretsky test of motor proficiency.…”