Search Results

You are looking at 1 - 10 of 152 items for :

  • "decomposition" x
  • Refine by Access: All Content x
Clear All
Restricted access

Kara L. Gavin, Julian Wolfson, Mark Pereira, Nancy Sherwood, and Jennifer A. Linde

would be influenced by individuals’ physical activity levels during the maintenance phase. Using this decomposition method, we further expected a portion of the effect of reported life events on weight following a behavioral weight loss intervention would be moderated by physical activity level during

Restricted access

Otmar Bock, Charles Worringham, and Sandi Dawson

Previous work has shown that amplitude and direction are two independently controlled parameters of aimed arm movements, and performance, therefore, suffers when they must be decomposed into Cartesian coordinates. We now compare decomposition into different coordinate systems. Subjects pointed at visual targets in 2-D with a cursor, using a two-axis joystick or two single-axis joysticks. In the latter case, joystick axes were aligned with the subjects’ body axes, were rotated by −45°, or were oblique (i.e., one axis was in an egocentric frame and the other was rotated by −45°). Cursor direction always corresponded to joystick direction. We found that compared with the two-axis joystick, responses with single-axis joysticks were slower and less accurate when the axes were oriented egocentrically; the deficit was even more pronounced when the axes were rotated and was most pronounced when they were oblique. This confirms that decomposition of motor commands is computationally demanding and documents that this demand is lowest for egocentric, higher for rotated, and highest for oblique coordinates. We conclude that most current vehicles use computationally demanding man–machine interfaces.

Restricted access

Kreg G. Gruben, Citlali López-Ortiz, and Robert S. Giachetti

The forces acting within and upon a limb are derived from three sources: postural (gravitational), inertial, and muscular. A method for decomposition has been established for free limb movements (Hoy & Zernicke, 1986); however, that method does not apply to kinematically constrained tasks whereby the limb exerts force on the environment. Presented here is a method for calculating the muscular and postural components for a quasi-static limb during a kinematically constrained task. It is a modified form of the inverse dynamic method reported by Kautz and Hull (1993) combined with the technique of Gruben and López-Ortiz (2000). This method stabilizes the limb against gravity with moments at each joint of the limb. Data from quasi-static lower limb extension efforts in one individual were analyzed to compare predictions of our method with those of the Kautz and Hull (1993) method. Differences in the postural component of foot force between the two methods increased with knee extension. The novelty of the method presented here was the use of an experimentally derived direction for the muscle component of foot force and the inclusion of a physiologically-based criterion for determining the support of the limb against gravity.

Restricted access

Xiangyu Liu, Meiyu Zhou, Chenyun Dai, Wei Chen, and Xinming Ye

inconvenience in practical applications. To further simplify the training procedures of the subject-nonspecific model, Matsubara and Morimoto ( 2013 ) proposed a bilinear model of sEMG signals to decompose sEMG signals into two factors, namely a motion-dependent factor (i.e., the content variable depending on

Restricted access

Peter S. Myers, Kerri S. Rawson, Elinor C. Harrison, Adam P. Horin, Ellen N. Sutter, Marie E. McNeely, and Gammon M. Earhart

cerebellar dysfunction often decompose complex, multijoint movements into several single-joint movements. 12 Given the likely involvement of the cerebellum in freezing of gait, this study aimed to investigate intralimb coordination in freezers and nonfreezers during various gait conditions, probing for

Restricted access

Dafne Pires Pinto, Pedro Vieira Sarmet Moreira, and Luciano Luporini Menegaldo

musculoskeletal system, in a mixed feedback and feed-forward control ( Teixeira et al., 2020 ). Rambling (RM) and trembling (TR) decomposition of the center of pressure (COP) trajectory in quiet bipedal standing allow for the assessment of two mechanisms contributing to maintain upright posture ( Zatsiorsky

Restricted access

Carlo Massaroni, Eugenio Cassetta, and Sergio Silvestri

novel method based on chest wall decomposition in prisms and compares this new method to the conventional method by using spirometry as the reference standard, during spontaneous quiet breathing on healthy volunteers. The proposed method does not require extra virtual markers to close the chest wall

Restricted access

Prasanna Sritharan, Luke G. Perraton, Mario A. Munoz, Peter Pivonka, and Adam L. Bryant

mass in many tasks, from Newton’s Second Law of Motion ( resultant force = mass × acceleration ), the GRF can be used to directly characterize the resultant center-of-mass accelerations. Thus, by decomposing the GRF into contributions by individual muscles, gravity, and inertia, 16 , 17 it is possible

Restricted access

Breanne S. Baker, Kelsey J. Weitzel, Lisa A. Royse, Kristin Miller, Trent M. Guess, Stephen D. Ball, and Dana L. Duren

mineral density, bone-free lean body mass, and body fat percentage). Two-way RM-ANOVA was used to decompose the model with Bonferroni post hoc by determining group (SSSH, WALK, and CON) and time (pre and post) main effects and Group × Time interactions. Reported auxiliary PA (in minutes per week) was used

Restricted access

Vladimir M. Zatsiorsky and Marcos Duarte

The goal of this study was to explore the rambling-trembling decomposition in quiet standing. The center of pressure (COP) and the horizontal ground reaction force (Fhor) were registered in healthy subjects standing in an upright bipedal posture on a force platform. The COP positions at the instants when Fhor = 0 were identified (instant equilibrium points, IEP) for the anterior-posterior direction, then the COP time series, were partitioned into its components using 2 different techniques, rambling-trembling decomposition and gravity line decomposition. The two decomposition techniques provided very similar results. An unexpectedly large correlation between the trembling trajectory and the difference between COP and gravity line was found, r = 0.91 (range, 0.83 < r < 0.98). The correlation implies that the GL moves from an IEP to the subsequent IEP along a smooth trajectory that can be predicted by the spline approximation. A substantial negative cross-correlation at a zero time lag was observed between the trembling and the Fhor, -0.90 < r < -0.75. For the rambling trajectory, the coefficients of correlation with Fhor were low, -0.33 < r < -0.05. The data support the hypothesis that during quiet standing the body sways for two reasons: the migration of the reference point (rambling) and the deviation away from that point (trembling).