Eryk Przysucha

Intersegmental dynamics shape joint coordination during catching in typically developing children but not in children with developmental coordination disorder

Factors shaping joint coordination during multijoint movements were studied using a one-handed ball-catching task. Typically developing (TD) boys between 9 and 12 yr of age, at which catching becomes consistently successful, and boys with developmental coordination disorder (DCD) of the same age participated in the study. The arm was initially stretched down. Catching was performed by flexing the shoulder and elbow and extending the wrist in the parasagittal plane. Catching success rate was substantially lower in children with DCD. Amplitudes and directions of joint motions were similar in both groups. Group differences were found in shoulder and elbow coordination patterns. TD children performed the movement predominantly by actively accelerating into flexion, one joint at a time-first the elbow and then the shoulder-and allowing passive interaction torque (IT) to accelerate the other joint into extension. Children with DCD tended to accelerate both joints into flexion simultaneously, suppressing IT. The results suggest that the TD joint coordination was shaped by the tendency to minimize active control of IT despite the complexity of the emergent joint kinematics. The inefficient control of IT in children with DCD points to deficiency of the internal model of intersegmental dynamics. Together, the findings advocate that joint coordination throughout a multijoint movement is a by-product of the control strategy that benefits from movement dynamics by actively accelerating a single joint and using IT for rotation of the other joint. Reduction of control-dependent noise is discussed as a possible advantage of this control strategy.

Establishing the Test-Retest Reliability & Concurrent Validity for the Repeat Ice Skating Test (RIST) in Adolescent Male Ice Hockey Players.

In this study the authors examine the test–retest reliability and concurrent validity of the Repeat Ice Skating Test (RIST). This was an on-ice field anaerobic test that measured average peak power and was validated with 3 anaerobic lab tests: (a) vertical jump, (b) the Margaria–Kalamen stair test, and (c) the Wingate Anaerobic Test. The participants (n = 14) were 11- to 12-year-old males selected from a Peewee “A” level ice hockey team (Thunder Bay, Canada). The results of the test–retest reliability estimation showed that the RIST was a reliable test at measuring average peak power in watts (R = .99, C.I.95% = 0.97 to 0.99) and watts per kilogram (R = .98, C.I.95% = 0.94 to 0.99). The RIST was also a valid test when correlated with the 3 anaerobic lab tests for measuring peak power in watts: vertical jump (r = .86, C.I.95% = 0.72 to 0.94), Margaria–Kalamen stair test (r = .66, C.I.95% = 0.39 to 0.83) and Wingate Anaerobic Test (r = .86, C.I.95% = 0.72 to 0.93). The test is considered promising because it does not require any specific equipment, and is a sport-specific, on-ice test, that can be administered during a regular ice hockey practice session.

Intralimb Coordination in Children With and Without Developmental Coordination Disorder in One-Handed Catching

ABSTRACT There is a gap in the literature in regard to analysis of intralimb coordination exhibited by children with (n = 10) and without developmental coordination disorder (DCD; n = 9) in 1-handed catching. The functional data showed that children without DCD (M age = 10.6 years, SD = 1.08 years) were nearly perfect. Children with DCD (M age = 11.0 years, SD = 1.16 years) caught significantly fewer balls, and this was despite the fact that not all of them had difficulties organizing their actions at intralimb level of coordination. The analysis of the coinciding actions revealed differences at the distal (elbow-wrist relations), but not at the proximal joints where both groups exhibited decoupling between the shoulder and elbow joints. Large variability within the groups also suggested that the notion of universal coordinative tendencies at intralimb level of coordination has to be treated with caution. This is particularly true for children with DCD as different subgroups emerged in the present sample.

Low Levels of Attentional Interference have Similar Effects on Static Balance Control of Typically Developing Children and Those with Symptoms of Developmental Coordination Disorder (DCD)

Conceptually, attentional interference should affect balance of typically developing children and even more so those with Developmental Coordination Disorder (DCD). However, due to equivocal findings and limited methodologies this issue remains unclear. Thus, the purpose of this study was to examine the effects of cognitive task on static balance control in typically developing children and those with symptoms of DCD by using traditional and non-traditional measures of postural sway. Ten typically developing children and ten with symptoms of DCD, between 8 and 10 y of age, were recruited. A dual-task methodology was implemented involving quiet standing as a motor task and a numeric classification as an attentional task. Mean and intra-individual variability for three traditional (Ao, Ap sway, Lat) and nontraditional measures of sway (fdis, fmode, Pp) were derived from 10 trials performed with and without attentional interference. The results showed no interaction effects, and aside from area of sway, the differences between the groups or attentional conditions were marginal. In terms of non-traditional measures, the impact of interference was evident from two out of three measures (fdis, fmode), but the emerging values were still within what would be considered as adult-like performance. Collectively, the expected differences between the groups did not emerge, and like-wise the impact of attentional interference was measure-specific as majority of analyses failed to reveal any reliable effects. The emerging small effect sizes further confirmed that the differences between the group means were marginal. However, due to the characteristics of sample these inferences should be treated with caution as they may not generalize to all children with this diagnosis (e.g., ADHD and DCD).