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Liebermann, D.G.; Levin, M.F.; McIntyre, J.; Weiss, P.L.; Berman, S. |
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Title |
Arm path fragmentation and spatiotemporal features of hand reaching in healthy subjects and stroke patients |
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Journal Article |
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Year |
2010 |
Publication |
Conference Proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference |
Abbreviated Journal |
Conf Proc IEEE Eng Med Biol Soc |
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2010 |
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5242-5245 |
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Keywords |
Aged; Aged, 80 and over; Analysis of Variance; Arm/*physiology; Biomechanics/physiology; Female; Hand/*physiology; *Health; Humans; Male; Middle Aged; Movement/*physiology; Posture/physiology; Principal Component Analysis; Stroke/*physiopathology; Time Factors |
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Abstract |
Arm motion in healthy humans is characterized by smooth and relatively short paths. The current study focused on 3D reaching in stroke patients. Sixteen right-hemiparetic stroke patients and 8 healthy adults performed 42 reaching movements towards 3 visual targets located at an extended arm distance. Performance was assessed in terms of spatial and temporal features of the movement; i.e., hand path, arm posture and smoothness. Differences between groups and within subjects were hypothesized for spatial and temporal aspects of reaching under the assumption that both are independent. As expected, upper limb motion of patients was characterized by longer and jerkier hand paths and slower speeds. Assessment of the number of sub-movements within each movement did not clearly discriminate between groups. Principal component analyses revealed specific clusters of either spatial or temporal measures, which accounted for a large proportion of the variance in patients but not in healthy controls. These findings support the notion of a separation between spatial and temporal features of movement. Stroke patients may fail to integrate the two aspects when executing reaching movements towards visual targets. |
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Physical Therapy Dept., Sackler Faculty of Medicine, Tel Aviv University, 69978 Israel. dlieberm@post.tau.ac.il |
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1557-170X |
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PMID:21096047 |
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30 |
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Author |
Liebermann, D.G.; Krasovsky, T.; Berman, S. |
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Title |
Planning maximally smooth hand movements constrained to nonplanar workspaces |
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Journal Article |
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Year |
2008 |
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Journal of Motor Behavior |
Abbreviated Journal |
J Mot Behav |
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40 |
Issue |
6 |
Pages |
516-531 |
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Keywords |
Adaptation, Physiological; Adult; Algorithms; Female; Hand/*physiology; Humans; *Intention; Kinesthesis/*physiology; Male; Models, Statistical; Movement/*physiology; Psychomotor Performance/*physiology; Reference Values; Writing |
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The article characterizes hand paths and speed profiles for movements performed in a nonplanar, 2-dimensional workspace (a hemisphere of constant curvature). The authors assessed endpoint kinematics (i.e., paths and speeds) under the minimum-jerk model assumptions and calculated minimal amplitude paths (geodesics) and the corresponding speed profiles. The authors also calculated hand speeds using the 2/3 power law. They then compared modeled results with the empirical observations. In all, 10 participants moved their hands forward and backward from a common starting position toward 3 targets located within a hemispheric workspace of small or large curvature. Comparisons of modeled observed differences using 2-way RM-ANOVAs showed that movement direction had no clear influence on hand kinetics (p < .05). Workspace curvature affected the hand paths, which seldom followed geodesic lines. Constraining the paths to different curvatures did not affect the hand speed profiles. Minimum-jerk speed profiles closely matched the observations and were superior to those predicted by 2/3 power law (p < .001). The authors conclude that speed and path cannot be unambiguously linked under the minimum-jerk assumption when individuals move the hand in a nonplanar 2-dimensional workspace. In such a case, the hands do not follow geodesic paths, but they preserve the speed profile, regardless of the geometric features of the workspace. |
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Department of Physical Therapy, The Stanley Steyer School of Health Professions, Sackler Faculty of Medicine, Tel Aviv University, Israel. dlieberm@post.tau.ac.il |
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0022-2895 |
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PMID:18980905 |
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33 |
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Liebermann, D.G.; Katz, L.; Hughes, M.D.; Bartlett, R.M.; McClements, J.; Franks, I.M. |
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Title |
Advances in the application of information technology to sport performance |
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Journal Article |
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2002 |
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Journal of Sports Sciences |
Abbreviated Journal |
J Sports Sci |
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20 |
Issue |
10 |
Pages |
755-769 |
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*Biofeedback, Psychology; *Computer Simulation; Humans; Models, Biological; Physical Education and Training/*methods; Psychomotor Performance/physiology; Sports Medicine/methods; *Task Performance and Analysis; Videotape Recording |
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This paper overviews the diverse information technologies that are used to provide athletes with relevant feedback. Examples taken from various sports are used to illustrate selected applications of technology-based feedback. Several feedback systems are discussed, including vision, audition and proprioception. Each technology described here is based on the assumption that feedback would eventually enhance skill acquisition and sport performance and, as such, its usefulness to athletes and coaches in training is critically evaluated. |
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Department of Physical Therapy, Sackler Faculty of Medicine, University of Tel Aviv, Israel |
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0264-0414 |
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PMID:12363293 |
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40 |
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Author |
Liebermann, D.G.; Issurin V. |
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Title |
Effects of vibratory stimulation on the perception of effort during isotonic contractions |
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Year |
1997 |
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Journal of Human Movement Studies |
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32 |
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171-186 |
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61 |
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Author |
Liebermann, D.G.; Hoffman, J.R. |
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Title |
Timing of preparatory landing responses as a function of availability of optic flow information |
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Journal Article |
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Year |
2005 |
Publication |
Journal of Electromyography and Kinesiology : Official Journal of the International Society of Electrophysiological Kinesiology |
Abbreviated Journal |
J Electromyogr Kinesiol |
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15 |
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1 |
Pages |
120-130 |
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Keywords |
Adult; Cues; Electromyography; Humans; Male; Movement/physiology; Muscle, Skeletal/*physiology; Posture/physiology; Psychomotor Performance/*physiology; Vision, Ocular/*physiology |
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Abstract |
This study investigated temporal patterns of EMG activity during self-initiated falls with different optic flow information ('gaze directions'). Onsets of EMG during the flight phase were monitored from five experienced volunteers that completed 72 landings in three gaze directions (downward, mid-range and horizontal) and six heights of fall (10-130 cm). EMG recordings were obtained from the right gastrocnemius, tibialis anterior, biceps femoris and rectus femoris muscles, and used to determine the latency of onset (L(o)) and the perceived time to contact (T(c)). Impacts at touchdown were also monitored using as estimates the major peak of the vertical ground reaction forces (F(max)) normalized to body mass, time to peak (T(max)), peak impulse (I(norm)) normalized to momentum, and rate of change of force (dF(max)/dt). Results showed that L(o) was longer as heights of fall increased, but remained within a narrow time-window at >50 cm landings. No significant differences in L(o) were observed when gaze direction was changed. The relationship between T(c) and flight time followed a linear trend regardless of gaze direction. Gaze direction did not significantly affect the landing impacts. In conclusion, availability of optic flow during landing does not play a major role in triggering the preparatory muscle actions in self-initiated falls. Once a structured landing plan has been acquired, the relevant muscles respond relative to the start of the fall. |
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Department of Physical Therapy, Sackler Faculty of Medicine, Stanley Steyer School of Health Professions, University of Tel Aviv, Ramat Aviv, 69978 Tel Aviv, Israel |
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1050-6411 |
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PMID:15642660 |
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39 |
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