TY - JOUR AU - Tibold, Róbert AU - Fazekas, Gábor AU - Laczkó, József TI - Three-Dimensional Model to Predict Muscle Forces and Their Relation to Motor Variances in Reaching Arm Movements JF - JOURNAL OF APPLIED BIOMECHANICS J2 - J APPL BIOMECH VL - 27 PY - 2011 IS - 4 SP - 362 EP - 374 PG - 13 SN - 1065-8483 DO - 10.1123/jab.27.4.362 UR - https://m2.mtmt.hu/api/publication/1854515 ID - 1854515 AB - A three-dimensional (3-D) arm movement model is presented to simulate kinematic properties and muscle forces in reaching arm movements. Healthy subjects performed reaching movements repetitively either with or without a load in the hand. Joint coordinates were measured. Muscle moment arms, 3-D angular acceleration, and moment of inertias of arm segments were calculated to determine 3-D joint torques. Variances of hand position, arm configuration, and muscle activities were calculated. Ratios of movement variances observed in the two conditions (load versus without load) showed no differences for hand position and arm configuration variances. Virtual muscle force variances for all muscles except deltoid posterior and EMG variances for four muscles increased significantly by moving with the load. The greatly increased variances in muscle activity did not imply equally high increments in kinematic variances. We conclude that enhanced muscle cooperation through synergies helps to stabilize movement at the kinematic level when a load is added. LA - English DB - MTMT ER - TY - JOUR AU - Keresztenyi, Z AU - Cesari, P AU - Fazekas, Gábor AU - Laczkó, József TI - The relation of hand and arm configuration variances while tracking geometric figures in Parkinson's disease: aspects for rehabilitation JF - INTERNATIONAL JOURNAL OF REHABILITATION RESEARCH J2 - INT J REHABIL RES VL - 32 PY - 2009 IS - 1 SP - 53 EP - 63 PG - 11 SN - 0342-5282 DO - 10.1097/MRR.0b013e32830d369c UR - https://m2.mtmt.hu/api/publication/1854524 ID - 1854524 AB - Variances of drawing arm movements between patients with Parkinson's disease and healthy controls were compared. The aim was to determine whether differences in joint synergies or individual joint rotations affect the endpoint (hand position) variance. Joint and endpoint coordinates were measured while participants performed drawing tasks. Variances of arm configurations and endpoints were computed and statistically analyzed for 12 patients and 12 controls. The variance of arm movements for patients (both for arm configuration and endpoint) was overall higher than that for the control group. Variation was smaller for drawing a circle versus a square and for drawing with the dominant versus the nondominant hand within both groups. The ratio of arm configuration variances between groups was similar to the ratio of endpoint variances. There were significant differences in the velocity, but not in the path lengths of movements comparing the two groups. Patients presented less movement stability while drawing different figures in different trials. Moreover, the similarity of the ratios suggests that the ill-coordinated hand movement was caused by the error in the movements of individual body parts rather than by the lack of intersegmental coordination. Thus, rehabilitation may focus on the improvement of the precision of individual joint rotations. LA - English DB - MTMT ER - TY - JOUR AU - Laczkó, József AU - Keresztényi, Z TI - Variances of Hand Positions and Arm Configurations During Arm Movements Under External Load and Without External Load JF - MOTOR CONTROL J2 - MOTOR CONTROL VL - 11 PY - 2007 IS - Supplement SP - S127 SN - 1087-1640 UR - https://m2.mtmt.hu/api/publication/1861130 ID - 1861130 N1 - Progress in Motor Control VI LA - English DB - MTMT ER - TY - JOUR AU - Domkin, D AU - Laczkó, József AU - Djupsjöbacka, M AU - Jaric, S AU - Latash, ML TI - Joint angle variability in 3D bimanual pointing: uncontrolled manifold analysis JF - EXPERIMENTAL BRAIN RESEARCH J2 - EXP BRAIN RES VL - 163 PY - 2005 IS - 1 SP - 44 EP - 57 PG - 14 SN - 0014-4819 DO - 10.1007/s00221-004-2137-1 UR - https://m2.mtmt.hu/api/publication/140416 ID - 140416 LA - English DB - MTMT ER - TY - JOUR AU - Domkin, D AU - Laczkó, József AU - Jaric, S AU - Johansson, H AU - Latash, ML TI - Structure of joint variability in bimanual pointing tasks JF - EXPERIMENTAL BRAIN RESEARCH J2 - EXP BRAIN RES VL - 143 PY - 2002 IS - 1 SP - 11 EP - 23 PG - 13 SN - 0014-4819 DO - 10.1007/s00221-001-0944-1 UR - https://m2.mtmt.hu/api/publication/139813 ID - 139813 LA - English DB - MTMT ER - TY - CHAP AU - Laczkó, József AU - Pellionisz, A AU - Jongen, H AU - Gielen, CCAM ED - Society, for Neuroscience TI - Computer Modeling of Human Forelimb Muscle Activation in Multidimensional Intrinsic Coordinate Frames T2 - Society for Neuroscience Abstracts: Volume 14, 18th Annual Meeting, Toronto, Ontario, November 13-18,1988, 2. rész PB - Society for Neuroscience CY - Toronto SN - 0916110303 PY - 1988 SP - 955 PG - 1 UR - https://m2.mtmt.hu/api/publication/2538957 ID - 2538957 LA - English DB - MTMT ER -