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J.D. DeFreese, Travis E. Dorsch and Travis A. Flitton

). Laursen and Collins ( 2009 ) argue that researchers may gain a more distilled picture of the parent–child relationship by measuring perceptions of the relational markers of warmth and conflict. Warmth is the tendency for the parent–child relationship to be characterized by supportive, affectionate, and

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Brent Hardin and Marie Hardin

This study explores the media-related attitudes and values of 10 male wheelchair athletes by soliciting their opinions and suggestions concerning disability sport print media. Using the “auto drive” technique for qualitative data collection, the analysis reveals four themes: (a) athletes are avid consumers of mainstream sport media; b) they use both mainstream and niche publications; (c) they do not want “courtesy coverage,” but instead, coverage focusing on elite elements of their sports; (d) they are unsure of media obligation in the coverage of sports involving athletes with disabilities. While the scope of this investigation is limited to male wheelchair athletes, the themes can provide a basis for further analysis and study in the emerging area of sport media research as it relates to disability.

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Ran Zheng, Ilana D. Naiman, Jessica Skultety, Steven R. Passmore, Jim Lyons and Cheryl M. Glazebrook

Foundation for Innovation for funding this work. The authors would also like to thank Kelsey Brown for her assistance with data collection as well as all of the participants and their families for their willingness to participate and their helpful comments. The authors declare that they have no conflict of

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Jeroen B.J. Smeets, Leonie Oostwoud Wijdenes and Eli Brenner

We begin our response by clarifying the concept of detection, and explaining why this is needed for initiating, but not for adjusting a movement. We present a simulation to illustrate this difference. Several commentators referred to studies with results that might seem in conflict with our proposal that movement adjustments have short latencies because there is no need to detect anything. In the last part of our response, we discuss how we interpret these studies as being in line with our proposal.

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Rebekah L. Scott and J. Gregory Anson

Conversion Disorder affects voluntary motor and sensory function and involves unexplained neurological symptoms without an organic cause. Many researchers have attempted to explain how these symptoms arise but the neural correlates associated with Conversion Disorder remain largely unknown to clinicians and neuroscientists alike. This review focuses on investigations of Conversion Disorder (with motor symptoms) when deficits in voluntary movement occur. No single consistent hypothesis has emerged regarding the underlying cortical mechanisms associated with motor Conversion Disorder. However, findings from electrophysiology, neuroimaging, and behavioral research implicate the involvement of prefrontal networks. With further research using measurement techniques precise in spatial as well as temporal resolution, the conflict associated with two views of the neural correlates of motor Conversion Disorder may be resolved. This will provide a better understanding of the impairment associated with the preparation, generation, and execution of intentional movement in Conversion Disorder.

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Yun Wang and Kazuhiko Watanabe

The notion of limb dominance has been commonly used in the upper extremity, yet the two lower extremities are often treated as equal for analytical purposes. Attempts to determine the effects of limb laterality on gait have produced conflicting results. The purpose of this study was to determine if limb dominance affects the vertical ground reaction force and center of pressure (COP) during able-bodied gait. The Parotec system (Paromed GmbH, Germany) was used to collect plantar foot pressure data. Fifteen subjects volunteered to participate in this study. The coefficient of variation of the COP displacement in the mediolateral direction and the variability of peak force beneath the lateral forefoot in the nondominant foot were significant greater than in the dominant foot. Moreover, COP velocity in the anterior-posterior direction during the terminal stance phase showed greater value in the dominant foot. Our study provides support for limb laterality by showing limb dominance affected the vertical ground reaction force and center of pressure during walking gait. This finding suggests it is an important issue in movement science for clinicians and would assist in improving sports performance and rehabilitation program.

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Erin Hanlon and Cynthia Bir

Soccer heading has been studied previously with conflicting results. One major issue is the lack of knowledge regarding what actually occurs biomechanically during soccer heading impacts. The purpose of the current study is to validate a wireless head acceleration measurement system, head impact telemetry system (HITS) that can be used to collect head accelerations during soccer play. The HIT system was fitted to a Hybrid III (HIII) head form that was instrumented with a 3-2-2-2 accelerometer setup. Fifteen impact conditions were tested to simulate impacts commonly experienced during soccer play. Linear and angular acceleration were calculated for both systems and compared. Root mean square (RMS) error and cross correlations were also calculated and compared for both systems. Cross correlation values were very strong with r = .95 ± 0.02 for ball to head forehead impacts and r = .96 ± 0.02 for head to head forehead impacts. The systems showed a strong relationship when comparing RMS error, linear head acceleration, angular head acceleration, and the cross correlation values.

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James J. Hannigan, Louis R. Osternig and Li-Shan Chou

Weak hip muscle strength and excessive hip motion during running have been suggested as potential risk factors for developing patellofemoral pain syndrome (PFPS) in females, but not males. There is conflicting evidence on the relationship between hip strength and hip kinematics, which may be partly due to sex differences in the relationship between these parameters. Hip, pelvis, and trunk kinematics were collected while 60 healthy, habitual runners (23 females, 37 males) ran overground, and isometric hip abduction and external rotation strengths were measured bilaterally. Pearson correlation coefficients quantified sex-specific correlations between hip strength and kinematics, and unpaired t tests assessed sex differences in hip strength and kinematics. Hip abduction strength was moderately and inversely correlated to hip adduction excursion in females, and pelvic internal rotation excursion in males. Hip external rotation strength was moderately and inversely correlated to trunk flexion excursion in females. Finally, females displayed less hip external rotation strength and greater excursion at the hip and trunk during running compared to males. Despite the significant correlations, the relatively low r 2 values suggest that additional factors outside of strength contribute to a substantial portion of the variance in trunk, pelvis, and hip kinematics.

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Olivier Oullier, Benoît G. Bardy, Thomas A. Stoffregen and Reinoud J. Bootsma

Surfaces shorter in extent than the feet elicit multi-joint coordination that differs from what is elicited by stance on extensive surfaces. This well-known effect arises from the mechanics of the actor-environment interaction. Multi-joint control of stance is also known to be influenced by non-mechanical aspects of a situation, including participants' task or intention. Intentional constraints do not originate in mechanics, and for this reason one might suppose that constraints imposed by mechanics would dominate constraints imposed by intentions, when the two were in conflict. We evaluated this hypothesis by varying participants' supra-postural task during stance on a short surface. While standing on a 10-cm wide beam, participants were exposed to optic flow generated by fore-aft oscillations of a moving room. Participants faced a target attached to the front wall of the moving room and were asked either to look at the target (with no instruction to move) or intentionally to track it with their head (i.e., to keep the target-head distance constant). Within trials, we varied the frequency of room (and target) motion, from 0.15 to 0.75 Hz, in steps of 0.05 Hz. In both conditions, ankle and hip rotations exhibited antiphase coordination, but behavior was not identical across conditions. Coupling between motion of the room and the head was stronger for the tracking task than for the looking task, and the stability of ankle-hip coordination was greater during tracking than during looking. These results indicate that the influence of support surface mechanics did not eliminate the influence of the supra-postural task. Environment-based and task-based constraints interacted in determining the coordination of hips and ankles during stance.

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Jeffrey J. Chu and Graham E. Caldwell

Studies on shock attenuation during running have induced alterations in impact loading by imposing kinematic constraints, e.g., stride length changes. The role of shock attenuation mechanisms has been shown using mass-spring-damper (MSD) models, with spring stiffness related to impact shock dissipation. The present study altered the magnitude of impact loading by changing downhill surface grade, thus allowing runners to choose their own preferred kinematic patterns. We hypothesized that increasing downhill grade would cause concomitant increases in both impact shock and shock attenuation, and that MSD model stiffness values would reflect these increases. Ten experienced runners ran at 4.17 m/s on a treadmill at surface grades of 0% (level) to 12% downhill. Accelerometers were placed on the tibia and head, and reflective markers were used to register segmental kinematics. An MSD model was used in conjunction with head and tibial accelerations to determine head/arm/trunk center of mass (HATCOM) stiffness (K1), and lower extremity (LEGCOM) stiffness (K2) and damping (C). Participants responded to increases in downhill grade in one of two ways. Group LowSA had lower peak tibial accelerations but greater peak head accelerations than Group HighSA, and thus had lower shock attenuation. LowSA also showed greater joint extension at heelstrike, higher HATCOM heelstrike velocity, reduced K1 stiffness, and decreased damping than HighSA. The differences between groups were exaggerated at the steeper downhill grades. The separate responses may be due to conflicts between the requirements of controlling HATCOM kinematics and shock attenuation. LowSA needed greater joint extension to resist their higher HATCOM heelstrike velocities, but a consequence of this strategy was the reduced ability to attenuate shock with the lower extremity joints during early stance. With lower HATCOM impact velocities, the HighSA runners were able to adopt a strategy that gave more control of shock attenuation, especially at the steepest grades.