Control Of Movement Direction Research Articles

Effect of a structured aqua-plyometric exercise program on postural control and functional ability in children with hemiparetic cerebral palsy: A two-arm randomized controlled trial.

Individuals with hemiparetic cerebral palsy (h-CP) encounter postural control issues that largely interfere with activity and participation. So, there might be a need for improved, clearly effective rehabilitation protocols that target postural control dysfunction, which may, then, reduce activity limitations and participation restrictions. This trial was undertaken to examine the effect of a structured, 12-week aqua-plyometric (Aqua-PLYO) exercise program on postural control and functional ability in children with h-CP. Fifty-six children with h-CP took part in a two-arm, randomized single-blind controlled trial. They were randomly assigned to either receive the standard physical therapy (Control group; n = 28) or the Aqua-PLYO training program (Aqua-PLYO group; n = 28), three times/week over 12 consecutive weeks. The dynamic limit of stability [i.e., movement directional control (M-DC), reaction time (ReT), movement velocity (M-Vel), endpoint excursion (EP-Exc), and maximum excursion (M-Exc)] and functional ability [i.e., 30-second sit-to-stand test (30sec-STS), timed up and down stairs test (TUDS), and the dynamic gait index (DGI)] were assessed pre- and post-treatment. From the pre- to post-treatment occasion, the Aqua-PLYO group achieved greater improvement for the M-DC (P = 0.013), ReT (P = 0.004), M-Vel (P = 0.03), EP-Exc (P = 0.002), and M-Exc (P = 0.006), compared to controls. Besides, the Aqua-PLYO group showed more conducive changes in functional ability [as evidenced by the 30sec-STS (P = 0.005), TUDS (P = 0.002), and DGI (P = 0.004) scores]. Aqua-PLYO training is likely an effective training paradigm for enhancing postural control and functional ability in children with h-CP. Further studies are, however, recommended to substantiate the current evidence.

The utilization of visual feedback from peripheral and central vision in the control of direction

Past research has demonstrated that both peripheral and central vision play an important role in the control of movement direction. However, it has been unclear whether the benefits of these sources of information are due to adjustments in the limb trajectory during movement execution (i.e., online) or modification in motor commands prior to movement initiation (i.e., offline). In the present paper, we analyzed the variability in limb trajectories in a directional aiming task to examine the relative contributions of peripheral and central vision in both the planning and execution of movements. The point of gaze was manipulated to vary where in the limb trajectory information was gained from central and peripheral vision. Analysis of the variability in directional error at various stages of the movement revealed that participants utilized information from early in the trajectory during movement execution when it appeared in both peripheral and central visual fields. Information from late in the trajectory was used offline to improve the programming of subsequent movements regardless of where this information was available in the visual field.

The utilization of visual feedback in the control of movement direction: evidence from a video aiming task.

The purpose of the present study was to establish the contribution of visual feedback in the correction of errors during movement execution (i.e., online) and the utilization of visual feedback from a completed movement in the programming of upcoming trials (i.e., offline). Participants performed 2 dimensional sweeping movements on a digitizing tablet through 1 of 3 targets, which were represented on a video monitor. The movements were performed with and without visual feedback under 4 criterion movement times (150, 250, 350, 450 msec). We analyzed the variability in directional error at 25%, 50%, 75%, and 100% of the distance between the home position and the target. There were significant differences in variability between visual conditions at each movement time. However, in the 150-msec condition, the form of the variability profiles did not differ between visual conditions, suggesting that the contribution of visual feedback was due to offline processes. In the 250-, 350-, and 450-msec conditions, there was evidence for both online and offline control, as the form of the variability profiles differed between the vision and no vision conditions.

Evidence Supporting the Importance of Peripheral Visual Information for the Directional Control of Aiming Movement

The focus of the present study was on determining whether the high level of directional accuracy found in aiming studies in which the subjects can see their hand in the visual periphery supports the existence of a kinetic visual channel or, rather, the advantage of binocular over monocular vision for movement directional control. The limits of this kinetic visual channel were also explored. The results of the 1st experiment indicated that seeing one's hand in the visual periphery is sufficient to ensure optimal directional aiming accuracy. Further, no differences in aiming accuracy were noted between monocular and binocular vision. These results supported the existence of a visual kinetic channel. In the 2nd experiment, whether this kinetic visual channel would operate with movements slower (55°/s) than those usually used in studies that had proved its existence (over 110°/s) was determined. The results indicated that this visual kinetic channel was operative even at relatively slow movement velocities. Central vision of the hand seemed to be used for on-line directional control of relatively slow movements.

Effects of handedness and arm position on stroke-direction preferences in drawing

Summary. In the present experiment we study the degree to which movements in graphic workspace are dictated by the geometrical features of that workspace, and by the anatomical features of the effector system that performs the movements. We investigate the effects of handedness and arm position on stroke-direction preferences in a drawing task. The subjects, 10 righthanders, 7 lefthanded inverters, and 7 lefthanded non-inverters, repeatedly produced small back-and-forth drawing movements in many directions. The position of their writing arm was varied at two levels. An analysis of polar frequency distributions derived from the digitally recorded drawing movements revealed different group effects and arm-position effects. The results indicate that multiple reference systems are involved in the control of movement direction. Whereas anatomical features of the effector system induce preferences for diagonal movement directions in graphic work space, non-anatomical factors are shown to be responsible for preferences for horizontal and vertical movement directions. Moreover, the present results support the view that the inverted hand position adopted by many lefthanders in writing tasks is probably used for biomechanical rather than for neurological reasons. This posture allows lefthanders to increase the relative contribution of wrist abduction and adduction in producing rightward-slanted script.