Search Results

You are looking at 1 - 10 of 40 items for :

  • "limb control" x
  • Refine by Access: All Content x
Clear All
Restricted access

Miya K. Rand and George E. Stelmach

This study examined how aging compromises coordinative eye-hand movements with multiple segments. Older adults and young controls performed two-segment movements with the eyes only or with the eyes and hand together. The results showed minimal age-related changes on the initiation and execution of primary saccade during the first segment. However, the older adults showed a scaling problem of saccade velocity when hand movements were included. They were also slow in stabilizing gaze fixation to the first target. Regarding hand movements, the older adults pronouncedly increased the deceleration phase compared with the controls while fixating their gazes to the target. They also increased the intersegment interval for both eye and hand movements. Taken together, aging differentially affects various components of movements, which contributes to the slowness of overall performance.

Restricted access

Jacqueline C. Ladwig, Tamires C. do Prado, Stephanie J. Tomy, Jonathan J. Marotta, and Cheryl M. Glazebrook

researchers observed positive effects on spatiotemporal movement organization, with smoother and faster movement trajectories ( Johansson et al., 2014 ). In posttest interviews (6 months), participants reported a sense of improved limb control and decreased spasticity ( Johansson et al., 2012 ). As

Restricted access

Jungyun Hwang, I-Min Lee, Austin M. Fernandez, Charles H. Hillman, and Amy Shirong Lu

), moderate (3–5.9 METs), and vigorous (≥6 METs) intensities. Exergaming Sessions In terms of movement patterns and intensities, we chose 3 exergames using a Kinect camera monitor sensor on an Xbox One console (Microsoft Inc, Redmond, WA) that included predominantly an upper limb–controlled game (slicing

Restricted access

Steve Hansen, Digby Elliott, and Michael A. Khan

The utility of ellipsoids for quantifying central tendency and variability throughout the trajectory of goal-directed movements is described. Aiming movements were measured over 2 days of practice and under full-vision and no-vision conditions. A three-dimensional optoelectronic system measured the movements. Individual ellipsoid locations, dimensions, and volumes were derived from the average location and the spatial variability of the effector’s trajectory at proportional temporal periods throughout the movement. Changes in ellipsoid volume over time illustrate the evolution in motor control that occurred with practice and the processes associated with visual control. This technique has the potential to extend our understanding of limb control and can be applied to practical problems such as equipment design and evaluation of movement rehabilitation.

Restricted access

Ann Lavrysen, Werner F. Helsen, Digby Elliott, and Jos J. Adam

The one-target advantage refers to a shorter movement time for one-target aiming movements, in comparison to aiming attempts followed by a second movement. Theoretical explanations of the one-target advantage vary in the extent to which they attribute this phenomenon to prior planning or to online control mechanisms. In this research, we attempted to gain insight into the control of sequential aiming movements by manipulating the availability of online feedback during this first or second movement component. When the participants' vision was occluded during the first movement (Experiment 1) or during the second movement (Experiment 2), their performance was affected, showing that vision was important for online control of the movement sequence. A one-target advantage was found when the second movement was in the same direction as me first, but not when it was reversed with respect to the home button. Both prior planning and online control processes contribute to the one-target advantage. The degree to which these processes are important for limb control depends on the specific task demands.

Restricted access

Simon J. Bennett, Digby Elliott, Daniel J. Weeks, and Damian Keil

The aim of the present study was to examine the effects of intermittent binocular and monocular vision on the preparation and execution of the transport and grasp phases of prehension, and hence the temporal limit of binocular and monocular integration. Participants in two groups (speed or accuracy) performed prehensile movements of two amplitudes (20 and 40 cm) to either a large or small object (6 × 6 × 2 and 6 × 4 × 2 cm) under conditions of binocular and monocular viewing. The interval between visual samples was manipulated with liquid crystal goggles (continuous vision, 20on/60off, and 20on/120off ms). A kinematic analysis indicated that participants modified variables associated with the preparation and execution of prehension in the intermittent vision conditions when instructed to emphasize accuracy. Participants instructed to emphasize speed, modified variables associated with the preparation phase only. The impact of intermittent vision was similar under binocular and monocular viewing. Thus, for prehension, it appears that consecutive binocular or monocular samples need to occur less than 60 ms apart in order to be fully integrated for limb control.

Restricted access

Matthew Heath, David A. Westwood, and Gordon Binsted

The goal of the present investigation was to explore the putative contributions of feedforward- and feedback-based processes in the control of memory-guided reaching movements. Participants (N = 4) completed an extensive number of reaching movements (2700) to 3 midline targets (20, 30, 40 cm) in 6 visual conditions: full-vision, open-loop, and four memory-guided conditions (0, 200, 400, and 600 ms of delay). To infer limb control, we used a regression technique to examine the within-trial correspondence between the spatial position of the limb at peak acceleration, peak velocity, peak deceleration, and the ultimate movement endpoint. A high degree of within-trial correspondence would suggest that the final position of the limb was largely specified prior to movement onset and not adjusted during the action (i.e., feedforward control); conversely, a low degree of within-trial correspondence would suggest that movements were modified during the reaching trajectory (i.e., feedback control). Full-vision reaches were found to be more accurate and less variable than open-loop and memory-guided reaches. Moreover, full-vision reaches demonstrated only modest within-trial correspondence between the spatial position of the limb at each kinematic marker and the ultimate movement endpoint, suggesting that reaching accuracy was achieved by adjusting the limb trajectory throughout the course of the action. Open-loop and memory-guided movements exhibited strong within-trial correspondence between final limb position and the position of the limb at peak velocity and peak deceleration. This strong correspondence indicates that the final position of the limb was largely determined by processes that occurred before the reach was initiated; errors in the planning process were not corrected during the course of the action. Thus, and contrary to our previous findings in a video-based aiming task, it appears that stored target information is not extensively (if at all) used to modify the trajectory of reaching movements to remembered targets in peripersonal space.

Restricted access

Damien Murphy, Quinette A. Louw, Colum Moloney, Dominique Leibbrandt, and Amanda M. Clifford

expressed as mean (SD). Absolute Hop Scores Involved Limb (ACLR group) Versus Matched Control Limb (Control Group) No significant differences were found in absolute hop scores between involved and matched control limbs, except for in the SHT where the mean distance hopped by control dominant limbs was

Restricted access

Theofanis Tzatzakis, Konstantinos Papanikolaou, Dimitrios Draganidis, Panagiotis Tsimeas, Savvas Kritikos, Athanasios Poulios, Vasiliki C. Laschou, Chariklia K. Deli, Athanasios Chatzinikolaou, Alexios Batrakoulis, Georgios Basdekis, Magni Mohr, Peter Krustrup, Athanasios Z. Jamurtas, and Ioannis G. Fatouros

C throughout recovery ( P  < .05). No differences were observed between SEPT trials. Table 4 Changes in DOMS and Creatine Kinase Activity During Recovery Baseline Post 24 h 48 h 72 h DOMS, knee extensors/dominant limbControl 1.0 (0.0) 1.0 (0.0) 0.0% 1.0 (0.0) 0.0% 1.0 (0.0) 0.0% 1.0 (0.0) 0

Restricted access

Rob van der Straaten, Oren Tirosh, William A. (Tony) Sparrow, and Rezaul Begg

hazardous when lower limb control is compromised. 1 , 2 One consequence of impaired foot-ground clearance is tripping-related balance loss, 1 , 2 the primary cause of falls. 3 , 4 Falls are a particular concern in patients with neurological impairments; for example, 37% to 73% of stroke patients fall at