Single-unit activity in area M1 was recorded in awake, behaving monkeys during a three-dimensional (3D) reaching task performed in a virtual reality environment. This study compares motor cortical discharge rate to both the hand's velocity and the arm's joint angular velocities. Hand velocity is considered a parameter of extrinsic space ...

BACKGROUND: To determine range of motion and capsular characteristics of dominant and nondominant shoulders in baseball players. Our hypothesis was that there is a significant difference between dominant and nondominant range of motion in collegiate baseball players with unoperated and without shoulder pain. METHODS: Design: prospective, range of motion measurements ...

OBJECTIVE: To determine the effect of different joint positions on position sense of asymptomatic shoulders. DESIGN: Repeated-measures design. SETTING: Laboratory in an educational institution. PARTICIPANTS: Thirty-four asymptomatic, right-handed men. INTERVENTIONS: The ability of subjects to replicate 3 criterion positions was examined on subjects' right shoulders by using an isokinetic dynamometer. ...

Movements of different body segments may be combined in different ways to achieve the same motor goal. How this is accomplished by the nervous system was investigated by having subjects make fast pointing movements with the arm in combination with a forward bending of the trunk that was unexpectedly blocked ...

The biased movement of Brownian particles on a fluctuating two-state periodic potential made of identical distorted ratchets is studied. The purpose is to investigate how the direction of the particle movement is related to the asymmetry of the potential. In general, distorting one of the two linear arms of a ...

The purpose of this study was to describe 3-dimensional scapular motion patterns during dynamic shoulder movements with the use of a direct technique. Direct measurement of active scapular motion was accomplished by insertion of 2 1.6-mm bone pins into the spine of the scapula in 8 healthy volunteers (5 men, ...

The extreme forces and torques and the high speeds and excessive ranges of motion of baseball pitching place tremendous stress on the soft tissues of the throwing shoulder. Little is known about the relationship between pitching mechanics and shoulder joint stress, especially in professional athletes. The purpose of this study ...

New configurations of interferometric frequency discriminators (FD) for frequency stabilization of microwave oscillators are examined. The new FDs are arranged in single directional (SD) (patented), bi-directional (BD) (patent pending), and dual reflection (DR) (patent pending) configurations. In the SD configuration, the signals reflected off and transmitted through the resonator separately ...

When the coincidence of a limb's spatial axes and inertial eigenvectors is broken, haptic proprioception of the limb's position conforms to the eigenvectors. Additionally, when prisms break the coincidence between an arm's visual and actual positions, haptic proprioception is shifted toward the visual-spatial direction. In 3 experiments, variation of the ...

A three-dimensional, six-segment model was applied to the pitching motion of three professional pitchers to analyze the kinematics and kinetics of the hips, upper trunk, humerus and forearm plus hand of both the upper limbs. Subjects were filmed at 250 frames per second. An inverse dynamics approach and angular momentum ...

Fast and accurate throwing was undoubtedly important to ancestral hominids, and was subject to sexual-selection pressures that generated a male advantage in throwing accuracy that persists in modern humans. The balance of evidence, including that from a recent comparative study of throwing in humans and capuchin monkeys, suggests that high-performance ...

Six subjects performed a planar reaching arm movement to a target while unpredictable perturbations were applied to the endpoint; the perturbations consisted of pulling springs having different stiffness. Two conditions were applied; in the first, subjects had to reach for the target despite the perturbation, in the second condition, the ...

STUDY DESIGN: A cross-sectional, descriptive study of shoulder movements conducted on nonimpaired subjects. OBJECTIVE: To investigate whether a single functional rotation axis about the shoulder complex can be determined during elevation in the coronal or sagittal planes, and to identify their location. BACKGROUND: Accurate measurement of isokinetic torques about a ...

An important theoretical concept in motor control is the idea that the CNS uses an internal model of the motor system and environment to predict the sensory consequences of motor commands. In arm movement control, a critical factor affecting the transformation from motor commands to sensory consequences is limb dynamics, ...

The aim of the present study was to investigate the relationship between the focal and postural components of a functional movement during the preparatory phase of a task. The contribution of the arms, trunk, and legs were varied by having subjects reach for two targets within and two beyond arm's ...

STUDY DESIGN: Test-retest repeated measures and correlational design. OBJECTIVES: To examine the reliability and validity of a "modified" digital inclinometer to assess scapular upward rotation during humeral elevation in the scapular plane BACKGROUND: Evidence exists that scapular motion is related to shoulder pathology; however, evaluation and treatment planning for shoulder ...

In response to the need for a sophisticated powered upper-limb orthosis for use by people with disabilities and/or limb weakness or injury, the MULOS (motorized upper-limb orthotic system) has been developed. This is a five-degree-of-freedom electrically powered device having three degrees of freedom at the shoulder, one at the elbow ...

The present study utilized a trunk-assisted prehension task to examine the hypothesis that there is spatial regularity between the grasp and transport components. To test this hypothesis, we varied movement amplitude, reach speed, and object size. When examining the opening and closure phases of aperture formation, it was found that ...

We have evaluated the ability of a time-delayed artificial neural network (TDANN) to predict shoulder and elbow motions using only electromyographic (EMG) signals recorded from six shoulder and elbow muscles as inputs, both in able-bodied subjects and in subjects with tetraplegia arising from C5 spinal cord injury. For able-bodied subjects, ...

The authors used a trunk-assisted prehension task to examine intersegment coordination. Participants (N = 7) reached to grasp an object placed beyond full arm extension, thus requiring trunk flexion to achieve the target object, under 4 varying temporal constraints. Kinematic analyses were performed in which the motions of the arm, ...

To validate the assumption that the center of rotation in the glenohumeral (GH) joint can be described based on the geometry of the joint, two methods for calculation of the GH rotation center were compared. These are a kinematic estimation based on the calculation of instantaneous helical axes, and a ...

The effects of varying gaze direction on perceptions of the upper limb kinesthetic coordinate system axes and of the median plane location were studied in nine subjects with no history of neuromuscular disorders. In two experiments, six subjects aligned the unseen forearm to the trunk-fixed anterior-posterior (a/p) axis and earth-fixed ...

During goal-directed reaching in primates, a sensorimotor transformation generates a dynamical pattern of muscle activation. Within the context of this sensorimotor transformation, a fundamental question concerns the coordinate systems in which individual cells in the primary motor cortex (MI) encode movement direction. This article develops a mathematical framework that computes, ...

When subjects practice reaching movements in a force field, they learn a new sensorimotor map that associates desired trajectories to motor commands. The map is formed in the brain with elements that allow for generalization beyond the region of training. We quantified spatial generalization properties of these elements by training ...

The aim of this study was to quantify how elite high jumpers used their free limbs in a competitive high jump and to estimate the contribution that these made to vertical take-off velocity. This was achieved by analysing the competitive performances of six elite male high jumpers using 3D motion ...

Previous research revealed the existence of coupling mechanisms (e.g. iso-directionality) at the level of perception and action. The present experiment investigated how the strength of the perception-action coupling affected synchronization performance. Arm movements were to be synchronized with a moving light that traveled back and forth from the left to ...

The question of whether the final arm posture to be reached is determined in advance during prehension movements remains widely debated. To address this issue, we designed a psychophysical experiment in which human subjects were instructed to reach and grasp, with their right arm, a small sphere presented at various ...

Ergonomists need easy-to-use, quantitative job evaluation methods to assess risk factors for upper extremity work-related musculoskeletal disorders in field-based epidemiology studies. One device that may provide an objective measure of exposure to arm acceleration is a wrist-worn accelerometer or activity monitor. A field trial was conducted to evaluate the performance ...

Spatial characteristics and lateral differences between two upper extremities were investigated in unilateral graphical tasks involving fast oscillating movements in the vertical plane based on the model of restricted (less than 10 degrees) horizontal abduction adduction in the shoulder joint. The spatial locations of reversal points were used to identify ...

The kinematics of the human arm in terms of angles of rotations in the joints is reconstructed from the spatial tracking system (Fastrack() Polhemus) recordings. The human arm is modeled by three rigid bodies (the upper arm, the forearm and the hand) with seven degrees of freedom (three in the ...

The present study is aimed at investigating changes in the coordination of arm and leg movements in young healthy subjects. It was hypothesized that with changes in walking velocity there is a change in frequency and phase coupling between the arms and the legs. In addition, it was hypothesized that ...

OBJECTIVES: To study the effect of a recently described method of measuring shoulder rotational range of motion in which the scapula is manually stabilized, and to determine the reliability of that technique compared with measurements taken with the scapula unstabilized. DESIGN: Fifty high school athletes underwent measurement of shoulder rotational ...

The aim of this study was to identify those kinematic characteristics that are most closely related to an athlete's medical classification and measured distance of a put. Two S-VHS camcorders (60 fields per second) were used to record the performance of 17 males of different classes. Each participant performed six ...

This study compares the coordination patterns employed for the left and right arms during rapid targeted reaching movements. Six right-handed subjects reached to each of three targets, designed to elicit progressively greater amplitude interaction torques at the elbow joint. All targets required the same elbow excursion (20 degrees ), but ...

Previous studies addressing the problem of the control of multiple degrees of freedom have examined the influence of trunk movement on pointing movements within the arm's reach. Such movements may be controlled by two functionally independent units of coordination (synergies): one involving only arm joints and producing the hand trajectory ...

The shoulder can be primarily or secondarily stiff. Cadaveric cutting studies have shown increases in passive range of glenohumeral motion when certain portions of the capsule are released. This study has recorded the intraoperative gains made in passive range of motion for external rotation, flexion, abduction, and internal rotation with ...

The motion pattern and laxity of 8 cadaveric elbows were recorded with a 3-dimensional electromagnetic tracking device before and after the Souter-Strathclyde total elbow prosthesis was implanted. The Souter-Strathclyde prosthesis replicates the valgus-varus motion pattern of the intact elbow but causes a significant internal rotation of the ulnar shaft of ...

OBJECTIVE: To identify activation patterns of several muscles acting on the shoulder joint during isokinetic internal and external rotation. DESIGN: Combined EMG and isokinetic strength analysis in healthy subjects. BACKGROUND: EMG studies of the shoulder region revealed intricate muscular activation patterns during elevation of the arm but no parallel studies ...

Cerebellar patients throw inaccurately in the left-right direction but the cause of this multijoint ataxia is unclear. We tested whether it was due, as originally proposed, to variable left-right directions of the hand path, or, alternatively, to variable timing of ball release occurring on a right to left curved hand ...

Changes were studied in neuromotor control that were evoked by constraining the motion of the elbow joint during planar, supported movements of the dominant arm in eight normal human subjects. Electromyograph (EMG) recordings from shoulder and arm muscles were used to determine whether the normal multijoint muscle activity patterns associated ...

BACKGROUND: Very little research has been carried out on the ergonomics of surgeon-instrument interface. The aim of this study is to investigate the effect of experience on the motion pattern of the dominant upper limb during endoscopic intracorporeal knot tying. METHODS: Two groups of 5 surgeons (expert consultants and higher ...

OBJECTIVE: To develop a method to obtain accurate three-dimensional scapular attitudes and to assess their concurrent validity and reliability. STUDY DESIGN: In this methodological study, the three-dimensional scapular attitudes were calculated in degrees, using a rotation matrix (cyclic Cardanic sequence), from spatial coordinates obtained with the probing of three non ...

The purpose of this study was to examine the role of background texture on an interception task during self-motion. Twenty-six participants modulated tricycle speed along one arm of a V-shaped track so as to intercept a ball approaching horizontally on the other arm of the V. Either a plain or ...

We report the use of a mechatronic device for assessing arm movement impairment after chronic brain injury. The device, called the "Assisted Rehabilitation and Measurement Guide," is designed to guide reaching movements across the workspace, to measure movement and force generation, and to apply controlled forces to the arm along ...

During multijoint limb movements such as reaching, rotational forces arise at one joint due to the motions of limb segments about other joints. We report the results of three experiments in which we assessed the extent to which control signals to muscles are adjusted to counteract these "interaction torques." Human ...

An experiment was carried out to investigate the effects of handle design on the biomechanical stresses imposed in the use of a cylinder trolley. Nine combinations of handle orientations (35 degrees, 50 degrees, 70 degrees)and handle length (1.0, 1.1, 1.2 m) were tested for the initial starting off phase and ...

Adults are able to reach for an object for the first time with appropriate direction, speed, and accuracy. The rules by which the nervous system is able to set muscle activities to accomplish these outcomes are still debated and, indeed, the sensitivity of kinematics to variations in muscle torques is ...

This study stemmed from the observation that the brain of human as well as nonhuman primates is capable of forming and memorizing remarkably accurate internal representations of the dynamics of the arm. These dynamics establish a functional relation between applied force and ensuing arm motion, a relation that generally is ...

This chapter reviews progress made in our understanding of the neural control of dexterity. It stresses the increasing benefit derived by uniting the different disciplines concerned with the study of the hand. It highlights the study of natural movements and of the importance of tackling the function of the interface ...

PURPOSE: Our purpose was to determine the association between sonographically detected subacromial/subdeltoid (SA/SD) bursal and biceps tendon sheath effusions and arthrographically proven rotator cuff tears. METHODS: Shoulder sonography reports and sonograms of 105 shoulders in 102 patients who also underwent arthrography were retrospectively reviewed for the presence of fluid within ...