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Wei Liu, Jill Whitall, and Thomas M. Kepple

Functional arm reaching involves multilinked joints: shoulder, elbow, and wrist. We propose that induced position analysis is a useful analytical tool for multijoint coordination of arm reaching. This method was used to compute the contributions of the net joint moment to the hand position when reaching forward. We describe the method and give examples of validating this model with motion capture data. The shoulder and elbow were prime movers of the arm: both acted together with an “overshoot” and “undershoot” pattern respectively to move the hand forward into the final position.

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Anne Beuter

This paper proposes a computer graphics approach to represent the kinematics of the lower limb during a multijoint coordinated motor task. The methodology is based on automatic digitization by a microprocessor of reflective markers placed on anatomical landmarks and videotaped using a videomotion analyzer and camera. Thus, the investigator can represent complete movement patterns graphically. With joint angles, or the first or second derivative of the angles serving as the coordinates for the three mutually perpendicular axes in R3, the technique gives a point in space corresponding to each time increment as the movement sequence progresses. Using this method, a graphical representation of the position, velocity, or acceleration can be generated in movement space, velocity space, or acceleration space, respectively. A sample of the results of this technique is presented using the movement space of elderly, nonhandicapped, and cerebral palsied individuals as each steps over a low obstacle. The cluster of data points created for each subject are connected to form a three-dimensional graphical representation of the covariation between joint angles. The use of the approach is discussed in relation to future research in neuromuscular coordination using concepts from catastrophe theory. Possible applications for handicapped individuals are mentioned.

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Hiroshi Arakawa, Akinori Nagano, Dean C. Hay, and Hiroaki Kanehisa

The current study aimed to investigate the effect of ankle restriction on the coordination of vertical jumping and discuss the influence of energy transfer through m. gastrocnemius on the multijoint movement. Eight participants performed two types of vertical jumps: a normal squat jump, and a squat jump with restricted ankle joint movement. Mechanical outputs were calculated using an inverse dynamics analysis. Custom-made shoes were used to restrict plantar flexion, resulting in significantly (P < .001) reduced maximum power and work at the ankle joint to below 2% and 3%, while maintaining natural range of motion at the hip and knee. Based on the comparison between the two types of jumps, we determined that the ankle restriction increased (P < .001) the power (827 ± 346 W vs. 1276 ± 326 W) and work (92 ± 34 J vs. 144 ± 36 J) at the knee joint. A large part of the enhanced output at the knee is assumed to be due to ankle restriction, which results in the nullification of energy transport via m. gastrocnemius; that is, reduced contribution of the energy transfer with ankle restriction appeared as augmentation at the knee joint.

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Loren Z.F. Chiu and George J. Salem

Potentiation has been reported in power tasks immediately following a strength stimulus; however, only whole-body performance has been assessed. To determine the acute effects of weightlifting on vertical jump joint kinetics, performance was assessed before, during, and after snatch pull exercise in male athletes. Jumping was assessed using 3D motion analysis and inverse dynamics. Jump height was enhanced at the midpoint (5.77%; p = .001) and end (5.90%; p < .001) of the exercise session, indicating a greater powergenerating ability. At the midpoint, knee extensor net joint work was increased (p = .05) and associated with increased jump height (r = .57; p = .02). Following exercise, ankle plantar flexor net joint work was increased (p = .02) and associated with increased jump height (r = .67; p = .006). Snatch pull exercise elicited acute enhancements in vertical jump performance. At the midpoint of the exercise session, greater work at the knee joint contributed to enhanced performance. At the end of the exercise session, greater work at the ankle contributed to enhanced performance. Consequently, potentiation is not elicited uniformly across joints during multijoint exercise.

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David A. Rosenbaum, Ruud J.G. Meulenbroek, Jonathan Vaughan, and Catherine Elsinger

The hypothesis introduced by Smeets and Brenner concerning the perpendicular approach of the thumb and index finger during grasping has heuristic value, but it also has limitations. Among the limitations are the following: (a) the approach parameter is not directly testable and it is unclear how the values of deceleration at contact and movement time are set theoretically; (b) it is questionable that motion of the thumb and index finger are independent; (c) reliance on the minimum-jerk account ignores critiques of that account; and (d) the model begs the question of how the effectors proximal to the index finger and thumb are controlled. We briefly review an alternative model that can handle these challenges.

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Marzie Balali, Shahab Parvinpour, and Mohsen Shafizadeh

coordination among muscles ( Krishnamoorthy, Latash, Scholz, & Zatsiorsky, 2003 ). One way to quantify multijoint coordination, kinematic synergy, is the principal component analysis (PCA) method ( Jarque-Bou et al., 2019 ; Latash, Scholz, & Schöner, 2007 ). The PCA is a statistical procedure that uses an

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Derya Ozer Kaya, Irem Duzgun, Gul Baltaci, Selma Karacan, and Filiz Colakoglu

Objective:

To assess and compare the effects of 6 mo of Pilates and calisthenics on multijoint coordination and proprioception of the lower limbs at the 3rd and 6th mo of training.

Design:

Randomized, controlled, assessor-blinded, repeated-measures.

Setting:

University research laboratory.

Participants and Intervention:

Healthy, sedentary, female participants age 25–50 y were recruited and randomly divided into 3 groups: a calisthenic exercise group (n = 34, mean age ± SD 40 ± 8 y, body-mass index [BMI] 31.04 ± 4.83 kg/m2), a Pilates exercise group (n = 32, mean age ± SD 37 ± 8 y, BMI 31.04 ± 4.83 kg/m2), and a control group (n = 41, mean age ± SD 41 ± 7 y, BMI 27.09 ± 4.77 kg/m2). The calisthenics and Pilates groups underwent related training programs for 6 mo, while the controls had no specific training.

Main Outcome Measures:

Coordination and proprioception of the lower extremities with concentric and eccentric performances in the closed kinetic chain assessed with the monitored rehab functional squat system at baseline and at the 3rd and 6th mo of training.

Results:

For the within-group comparison, coordinative concentric and eccentric deviation values were significantly decreased for both dominant and nondominant lower limbs at pretraining and at the 3rd and 6th mo posttraining in the calisthenics group (P < .05). In contrast, there was no improvement in the Pilates group throughout the training. However, for comparisons between groups, the baseline values of coordinative concentric and eccentric deviations were different in the calisthenics group than in Pilates and the controls (P < .05). There were no differences in the proprioception values of either visible or nonvisible movement in any group throughout the training (P > .05).

Conclusions:

It seems that calisthenic exercises are more likely to improve coordination of the lower extremity after 3 and 6 mo of training than Pilates exercises. Calisthenic exercises may be useful for individuals who require improved coordination.

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Inge Tuitert, Tim A. Valk, Egbert Otten, Laura Golenia, and Raoul M. Bongers

subspaces of the two Jacobians were different, and, therefore, that the regression-based and analytical Jacobians were indeed different, and the differences between the two methods on the other measures were valid. Discussion When multijoint coordination is studied with the UCM method, the linear model is

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Matthew Slopecki, Fariba Hasanbarani, Chen Yang, Christopher A. Bailey, and Julie N. Côté

of Electromyography and Kinesiology, 14 ( 1 ), 13 – 23 . https://doi.org/10.1016/j.jelekin.2003.09.015 10.1016/j.jelekin.2003.09.015 Scholz , J.P. , Schöner , G. , & Latash , M.L. ( 2000 ). Identifying the control structure of multijoint coordination during pistol shooting . Experimental

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Christopher J. Palmer and Richard E.A. van Emmerik

.1113/jphysiol.2001.012648 10.1113/jphysiol.2001.012648 Hsu , W.L. , Scholz , J.P. , Schoner , G. , Jeka , J.J. , & Kiemel , T. ( 2007 ). Control and estimation of posture during quiet stance depends on multijoint coordination . Journal of Neurophysiology, 97 ( 4 ), 3024 – 3035 . PubMed ID