| Records |
| Author |
Liebermann, D.G.; Goodman, D. |
| Title |
Pre-landing muscle timing and post-landing effects of falling with continuous vision and in blindfold conditions |
Type |
Journal Article |
| Year |
2007 |
Publication |
Journal of Electromyography and Kinesiology : Official Journal of the International Society of Electrophysiological Kinesiology |
Abbreviated Journal |
J Electromyogr Kinesiol |
| Volume |
17 |
Issue |
2 |
Pages |
212-227 |
| Keywords |
Adult; Analysis of Variance; Biomechanics; *Blindness; *Electromyography; Humans; Joints/physiology; Lower Extremity/physiology; Male; Movement/*physiology; Muscle, Skeletal/*physiology; Orientation; *Vision, Ocular |
Abstract  |
The present study examined the effect of continuous vision and its occlusion in timing of pre-landing actions during free falls. When vision is occluded, muscle activation is hypothesized to start relative to onset of the fall. However, when continuous vision is available onset of action is hypothesized to be relative to the moment of touchdown. Six subjects performed 6 randomized sets of 6 trials after becoming familiar with the task. The 36 trials were divided in 2 visual conditions (vision and blindfold) and 3 heights of fall (15, 45 and 75 cm). EMG activity was recorded from the gastrocnemius and rectus femoris muscles during the falls. The latency of onset (L(o)) and the lapse from EMG onset to touchdown (T(c)) were obtained from these muscles. Vertical forces were recorded to assess the effects of pre-landing activity on the impacts at collision with and without continuous vision. Peak amplitude (F(max)), time to peak (T(max)) and peak impulse normalized to momentum (I(norm)) were used as outcome measures. Within flight time ranges of approximately 50-400 ms, the results showed that L(o) and T(c) follow a similar linear trend whether continuous vision was available or occluded. However, the variability of T(c) for each of the muscles was larger in the vision occluded condition. Analyses of variance showed that the rectus femoris muscle started consistently earlier in no vision trials. Finally, impact forces were not different in vision or blindfold conditions, and thus, they were not affected by minor differences in the timing of muscles prior to landing. Thus, it appears that knowing the surroundings before falling may help to reduce the need for a continuous visual input. The relevance of such input cannot be ruled out for falls from high landing heights, but cognitive factors (e.g., attention to specific cues and anticipation of a fall) may play a dominant role in timing actions during short duration falls encountered daily. |
| Address |
Physical Therapy Department, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel. dlieberm@post.tau.ac.il <dlieberm@post.tau.ac.il> |
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English |
Summary Language |
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Edition |
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| ISSN |
1050-6411 |
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| Notes |
PMID:16600637 |
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no |
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37 |
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| Author |
Liebermann, D.G.; Krasovsky, T.; Berman, S. |
| Title |
Planning maximally smooth hand movements constrained to nonplanar workspaces |
Type |
Journal Article |
| Year |
2008 |
Publication |
Journal of Motor Behavior |
Abbreviated Journal |
J Mot Behav |
| Volume |
40 |
Issue |
6 |
Pages |
516-531 |
| Keywords |
Adaptation, Physiological; Adult; Algorithms; Female; Hand/*physiology; Humans; *Intention; Kinesthesis/*physiology; Male; Models, Statistical; Movement/*physiology; Psychomotor Performance/*physiology; Reference Values; Writing |
| Abstract |
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. |
| Address |
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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English |
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0022-2895 |
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| Notes |
PMID:18980905 |
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no |
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Serial |
33 |
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| Author |
Falk, B.; Eliakim, A.; Dotan, R.; Liebermann, D.G.; Regev, R.; Bar-Or, O. |
| Title |
Birth weight and physical ability in 5- to 8-yr-old healthy children born prematurely |
Type |
Journal Article |
| Year |
1997 |
Publication |
Medicine and Science in Sports and Exercise |
Abbreviated Journal |
Med Sci Sports Exerc |
| Volume |
29 |
Issue |
9 |
Pages |
1124-1130 |
| Keywords |
*Birth Weight; Child; Child Development/physiology; Child, Preschool; Female; Follow-Up Studies; Humans; Infant, Newborn; *Infant, Premature; Male; *Motor Skills; *Physical Fitness |
| Abstract |
Recent advances in perinatal care have resulted in increased survival rates of extremely small and immature newborns. This has resulted in some neurodevelopmental impairment. The purpose of this study was to quantitatively evaluate and compare neuromuscular performance in children born prematurely at various levels of subnormal birth weight (BW). Subjects were 5- to 8-yr-old children born prematurely at different levels of subnormal BW (535-1760 g, N = 22, PM), and age-matched controls born at full term (> 2500 g, N = 15, CON). None of the subjects had any clinically defined neuromuscular disabilities. Body mass (BM) of PM was lower than that of CON (18.3 +/- 2.7 vs 21.7 +/- 3.8 kg) with no difference in height or sum of 4 skinfolds. Peak mechanical power output determined with a 15-s modified Wingate Anaerobic Test and corrected for BM was lower (P = 0.07) in PM than in CON (5.11 +/- 1.07 vs 5.94 +/- 1.00 W.kg-1). This was especially noticeable in children born at extremely low BW (ELBW, < 1000 g, 4.49 +/- 1.04 W.kg-1, P < 0.01). Peak power, determined in a force-plate vertical jump, corrected for BM was lower in PM vs CON (25.5 +/- 5.4 vs 30.8 +/- 5.2 W.kg-1, respectively P = 0.01), especially in the ELBW group (20.0 +/- 5.5 W.kg-1). Similarly, the elapsed time between peak velocity and actual jump take-off was longer in PM than in CON (41.2 +/- 9.4 vs 35.8 +/- 5.8 ms, respectively, P = 0.04). No differences were observed in peak force. The results suggest that performance deficiencies of prematurely-born children may be a result of inferior inter-muscular coordination. The precise neuromotor factors responsible for this should be identified by future research. |
| Address |
Ribstein Center for Research and Sport Medicine Sciences, Wingate Institute, Netanya, Israel. bfalk@ccsg.tau.ac.il |
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English |
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0195-9131 |
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| Notes |
PMID:9309621 |
Approved |
no |
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Serial |
64 |
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| Author |
Tamir-Ostrover, H.; Hassin-Baer, S.; Fay-Karmon, T.; Friedman, J. |
| Title |
Quantifying Changes in Dexterity as a Result of Piano Training in People with Parkinson's Disease |
Type |
Journal Article |
| Year |
2024 |
Publication |
Sensors (Basel, Switzerland) |
Abbreviated Journal |
Sensors (Basel) |
| Volume |
24 |
Issue |
11 |
Pages |
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| Keywords |
Humans; *Parkinson Disease/physiopathology; Pilot Projects; Male; Aged; Female; Quality of Life; Middle Aged; Motor Skills/physiology; Music; Surveys and Questionnaires; Activities of Daily Living; Fingers/physiology/physiopathology; Parkinson's disease; dexterity; force sensors; music; piano; sonification; training; uncontrolled manifold |
| Abstract |
People with Parkinson's disease often show deficits in dexterity, which, in turn, can lead to limitations in performing activities of daily life. Previous studies have suggested that training in playing the piano may improve or prevent a decline in dexterity in this population. In this pilot study, we tested three participants on a six-week, custom, piano-based training protocol, and quantified dexterity before and after the intervention using a sensor-enabled version of the nine-hole peg test, the box and block test, a test of finger synergies using unidimensional force sensors, and the Quantitative Digitography test using a digital piano, as well as selected relevant items from the motor parts of the MDS-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) and the Parkinson's Disease Questionnaire (PDQ-39) quality of life questionnaire. The participants showed improved dexterity following the training program in several of the measures used. This pilot study proposes measures that can track changes in dexterity as a result of practice in people with Parkinson's disease and describes a potential protocol that needs to be tested in a larger cohort. |
| Address |
Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel |
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English |
Summary Language |
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1424-8220 |
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| Notes |
PMID:38894110; PMCID:PMC11174779 |
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no |
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124 |
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| Author |
Hoffman, J.R.; Liebermann, D.; Gusis, A. |
| Title |
Relationship of leg strength and power to ground reaction forces in both experienced and novice jump trained personnel |
Type |
Journal Article |
| Year |
1997 |
Publication |
Aviation, Space, and Environmental Medicine |
Abbreviated Journal |
Aviat Space Environ Med |
| Volume |
68 |
Issue |
8 |
Pages |
710-714 |
| Keywords |
*Aerospace Medicine; *Aviation; Biomechanics; Humans; Leg/*physiology; Male; Military Personnel/*education; *Physical Education and Training; Physical Fitness/*physiology; Range of Motion, Articular; Wounds and Injuries/etiology/*prevention & control |
| Abstract |
METHODS: There were 14 male soldiers who participated in this study examining the relationship of leg strength and power on landing performance. Subjects were separated into two groups. The first group (E, n = 7) were parachute training instructors and highly experienced in parachute jumping. The second group of subjects (N, n = 7) had no prior parachute training experience and were considered novice jumpers. All subjects were tested for one-repetition maximum (1 RM) squat strength and maximal jump power. Ground reaction forces (GRF) and the time to peak force (TPF) at landing were measured from jumps at four different heights (95 cm, 120 cm, 145 cm, and 170 cm). All jumps were performed from a customized jump platform onto a force plate. RESULTS: No differences were seen between E and N in either IRM squat strength or in MJP. In addition, no differences were seen between the groups for time to peak force at any jump height. However, significantly greater GRF were observed in E compared to N. Moderate to high correlations between maximal jump power and GRF (r values ranging from 0.62-0.93) were observed in E. Although maximal jump power and the TPF was significantly correlated (r = -0.89) at only 120 cm for E, it was interesting to note that the correlations between MJP and the time to peak force in E were all negative and that the correlations between these variables in N were all positive. CONCLUSIONS: These results suggest that experienced parachutists may use a different landing strategy than novice jumpers. This difference may be reflected by differences in GRF generated during impact and a more efficient utilization of muscle power during the impact phase of the landing. |
| Address |
Aeromedical Center, Physiological Training Unit, Israel Air Force, Israel |
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English |
Summary Language |
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Series Issue |
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Edition |
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| ISSN |
0095-6562 |
ISBN |
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| Notes |
PMID:9262813 |
Approved |
no |
| Call Number |
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Serial |
60 |
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