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Author |
Issurin, V.B.; Liebermann, D.G.; Tenenbaum, G. |
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Title |
Effect of vibratory stimulation training on maximal force and flexibility |
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Year |
1994 |
Publication |
Journal of Sports Sciences |
Abbreviated Journal |
J Sports Sci |
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Volume |
12 |
Issue |
6 |
Pages |
561-566 |
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Keywords |
Adult; Humans; Male; Muscle Contraction/physiology; Muscle, Skeletal/*physiology; *Physical Education and Training; Vibration/*therapeutic use |
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Abstract |
In this study, we investigated a new method of training for maximal strength and flexibility, which included exertion with superimposed vibration (vibratory stimulation, VS) on target muscles. Twenty-eight male athletes were divided into three groups, and trained three times a week for 3 weeks in one of the following conditions: (A) conventional exercises for strength of the arms and VS stretching exercises for the legs; (B) VS strength exercises for the arms and conventional stretching exercises for the legs; (C) irrelevant training (control group). The vibration was applied at 44 Hz while its amplitude was 3 mm. The effect of training was evaluated by means of isotonic maximal force, heel-to-heel length in the two-leg split across, and flex-and-reach test for body flexion. The VS strength training yielded an average increase in isotonic maximal strength of 49.8%, compared with an average gain of 16% with conventional training, while no gain was observed for the control group. The VS flexibility training resulted in an average gain in the legs split of 14.5 cm compared with 4.1 cm for the conventional training and 2 cm for the control groups, respectively. The ANOVA revealed significant pre-post training effects and an interaction between pre-post training and 'treatment' effects (P < 0.001) for the isotonic maximal force and both flexibility tests. It was concluded that superimposed vibrations applied for short periods allow for increased gains in maximal strength and flexibility. |
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Ribstein Centre for Research and Sport Medicine Sciences, Wingate Institute, Wingate Post, Israel |
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0264-0414 |
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PMID:7853452 |
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56 |
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Author |
Falk, B.; Eliakim, A.; Dotan, R.; Liebermann, D.G.; Regev, R.; Bar-Or, O. |
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Title |
Birth weight and physical ability in 5- to 8-yr-old healthy children born prematurely |
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Journal Article |
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Year |
1997 |
Publication |
Medicine and Science in Sports and Exercise |
Abbreviated Journal |
Med Sci Sports Exerc |
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Volume |
29 |
Issue |
9 |
Pages |
1124-1130 |
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Keywords |
*Birth Weight; Child; Child Development/physiology; Child, Preschool; Female; Follow-Up Studies; Humans; Infant, Newborn; *Infant, Premature; Male; *Motor Skills; *Physical Fitness |
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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. |
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Ribstein Center for Research and Sport Medicine Sciences, Wingate Institute, Netanya, Israel. bfalk@ccsg.tau.ac.il |
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0195-9131 |
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PMID:9309621 |
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64 |
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Berman, S.; Liebermann, D.G.; McIntyre, J. |
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Title |
Constrained Motion Control on a Hemispherical Surface – Path Planning |
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Journal Article |
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Year |
2014 |
Publication |
Journal of Neurophysiology |
Abbreviated Journal |
J Neurophysiol |
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111 |
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5 |
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954-968 |
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Keywords |
Constrained motion; geodesics; path planning |
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Surface-constrained motion, i.e., motion constraint by a rigid surface, is commonly found in daily activities. The current work investigates the choice of hand paths constrained to a concave hemispherical surface. To gain insight regarding the paths and their relationship with task dynamics, we simulated various control policies. The simulations demonstrated that following a geodesic path is advantageous not only in terms of path length, but also in terms of motor planning and sensitivity to motor command errors. These stem from the fact that the applied forces lie in a single plane (that of the geodesic path itself). To test whether human subjects indeed follow the geodesic, and to see how such motion compares to other paths, we recorded movements in a virtual haptic-visual environment from eleven healthy subjects. The task was comprised of point-to-point motion between targets at two elevations (30 degrees and 60 degrees ). Three typical choices of paths were observed from a frontal plane projection of the paths: circular arcs, straight lines, and arcs close to the geodesic path for each elevation. Based on the measured hand paths, we applied k-means blind separation to divide the subjects into three groups and compared performance indicators. The analysis confirmed that subjects who followed paths closest to the geodesic produced faster and smoother movements, compared to the others. The 'better' performance reflects the dynamical advantages of following the geodesic path, as shown by the simulations, and may also reflect invariant features of the control policies used to produce such a surface-constrained motion. |
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Ben-Gurion University of the Negev |
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0022-3077 |
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PMID:24259548 |
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72 |
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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.; Biess, A.; Friedman, J.; Gielen, C.C.A.M.; Flash, T. |
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Title |
Intrinsic joint kinematic planning. I: reassessing the Listing's law constraint in the control of three-dimensional arm movements |
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Journal Article |
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2006 |
Publication |
Experimental Brain Research |
Abbreviated Journal |
Exp Brain Res |
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171 |
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2 |
Pages |
139-154 |
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Adolescent; Adult; Analysis of Variance; *Arm; Biomechanics; Eye Movements/*physiology; Humans; Joints/*physiology; Male; Movement/*physiology; *Musculoskeletal System; Orientation/*physiology; Posture |
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This study tested the validity of the assumption that intrinsic kinematic constraints, such as Listing's law, can account for the geometric features of three-dimensional arm movements. In principle, if the arm joints follow a Listing's constraint, the hand paths may be predicted. Four individuals performed 'extended arm', 'radial', 'frontal plane', and 'random mixed' movements to visual targets to test Listing's law assumption. Three-dimensional rotation vectors of the upper arm and forearm were calculated from three-dimensional marker data. Data fitting techniques were used to test Donders' and Listing's laws. The coefficient values obtained from fitting rotation vectors to the surfaces described by a second-order equation were analyzed. The results showed that the coefficients that represent curvature and twist of the surfaces were often not significantly different from zero, particularly not during randomly mixed and extended arm movements. These coefficients for forearm rotations were larger compared to those for the upper arm segment rotations. The mean thickness of the rotation surfaces ranged between approximately 1.7 degrees and 4.7 degrees for the rotation vectors of the upper arm segment and approximately 2.6 degrees and 7.5 degrees for those of the forearm. During frontal plane movements, forearm rotations showed large twist scores while upper arm segment rotations showed large curvatures, although the thickness of the surfaces remained low. The curvatures, but not the thicknesses of the surfaces, were larger for large versus small amplitude radial movements. In conclusion, when examining the surfaces obtained for the different movement types, the rotation vectors may lie within manifolds that are anywhere between curved or twisted manifolds. However, a two-dimensional thick surface may roughly represent a global arm constraint. Our findings suggest that Listing's law is implemented for some types of arm movement, such as pointing to targets with the extended arm and during radial reaching movements. |
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Department of Physical Therapy, Sackler Faculty of Medicine, Tel-Aviv University, 69978, Ramat Aviv, Israel. dlieberm@post.tau.ac.il |
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0014-4819 |
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PMID:16341526 |
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Penn State @ write.to.jason @ |
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18 |
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