Postmovement Changes in the Frequency and Amplitude of Physiological Tremor Despite Unchanged Neural Output

2010 ◽  
Vol 104 (4) ◽  
pp. 2020-2023 ◽  
Author(s):  
Raymond Reynolds ◽  
Martin Lakie
Keyword(s):  
Passive Movement ◽  
Muscle Stiffness ◽  
Emg Activity ◽  
Hand Position ◽  
Vertical Acceleration ◽  
Physiological Tremor ◽  
Joint Mechanics ◽  
Wrist Flexion ◽  
Temporary Reduction ◽  
Flexion Extension

Active or passive movement causes a temporary reduction in muscle stiffness that gradually returns to baseline levels when the muscle remains still. This effect, termed muscle thixotropy, alters the mechanical properties of the joint around which the muscle acts, reducing its resonant frequency. Because physiological tremor is affected by joint mechanics, this suggests that prior movement may alter tremor independently of neural output. To address this possibility, vertical acceleration of the outstretched prone hand was recorded in eight healthy subjects, along with EMG activity of the extensor digitorum communis muscle. A series of voluntary wrist flexion/extension movements was performed every 20 s, interspersed by periods during which hand position was maintained. Time-dependent changes in the amplitude and frequency of acceleration and EMG were analyzed using a continuous wavelet transform. Immediately following movement, acceleration displayed a significant increase in wavelet power accompanied by a reduction in peak frequency. During the postmovement period, power declined by 63%, and frequency increased from 7.2 to 8.0 Hz. These changes occurred with an exponential time constant of 2–4 s, consistent with a thixotropic mechanism. In contrast to acceleration, EMG activity showed no significant changes despite being strongly related to acceleration during the movement itself. These results show that prior movement transiently increases the amplitude and reduces the frequency of physiological tremor, despite unchanging neural output. This effect is best explained by a reduction in joint stiffness caused by muscle thixotropy, highlighting the importance of mechanical factors in the genesis of physiological tremor.

Combined effect of repetitive work and cold on muscle function and fatigue

2002 ◽  
Vol 92 (1) ◽  
pp. 354-361 ◽  
Author(s):  
Juha Oksa ◽  
Michel B. Ducharme ◽  
Hannu Rintamäki
Keyword(s):  
Muscle Function ◽  
Voluntary Contraction ◽  
Overuse Injuries ◽  
Emg Activity ◽  
Wrist Flexion ◽  
Fatigue Index ◽  
Local Cooling ◽  
Repetitive Work ◽  
Flexion Extension ◽  
Forearm Muscle

This study compared the effect of repetitive work in thermoneutral and cold conditions on forearm muscle electromyogram (EMG) and fatigue. We hypothesize that cold and repetitive work together cause higher EMG activity and fatigue than repetitive work only, thus creating a higher risk for overuse injuries. Eight men performed six 20-min work bouts at 25°C (W-25) and at 5°C while exposed to systemic (C-5) and local cooling (LC-5). The work was wrist flexion-extension exercise at 10% maximal voluntary contraction. The EMG activity of the forearm flexors and extensors was higher during C-5 (31 and 30%, respectively) and LC-5 (25 and 28%, respectively) than during W-25 ( P < 0.05). On the basis of fatigue index (calculated from changes in maximal flexor force and flexor EMG activity), the fatigue in the forearm flexors at the end of W-25 was 15%. The corresponding values at the end of C-5 and LC-5 were 37% ( P < 0.05 in relation to W-25) and 20%, respectively. Thus repetitive work in the cold causes higher EMG activity and fatigue than repetitive work in thermoneutral conditions.

The complete frequency spectrum of physiological tremor can be recreated by broadband mechanical or electrical drive

2015 ◽  
Vol 113 (2) ◽  
pp. 647-656 ◽  
Author(s):  
Carlijn Andrea Vernooij ◽  
Martin Lakie ◽  
Raymond Francis Reynolds
Keyword(s):  
Middle Finger ◽  
Muscle Stiffness ◽  
Emg Activity ◽  
Physiological Tremor ◽  
Mechanical Resonance ◽  
Low Frequencies ◽  
High Frequency Peak ◽  
Input Intensity ◽  
Frequency Peak ◽  
Finger Tremor

Two frequency peaks of variable preponderance have been reported for human physiological finger tremor. The high-frequency peak (20–25 Hz, seen only in postural tremor) is generally attributed to mechanical resonance, whereas the lower frequency peak (8–12 Hz, seen in both postural and kinetic tremor) is usually attributed to synchronous central or reflexive neural drive. In this study, we determine whether mechanical resonance could generate both peaks. In relaxed subjects, an artificial finger tremor was evoked by random mechanical perturbations of the middle finger or random electrical muscular stimulation of the finger extensor muscle. The high and the low frequencies observed in physiological tremor could both be created by either type of artificial input at appropriate input intensity. Resonance, inferred from cross-spectral gain and phase, occurred at both frequencies. To determine any neural contribution, we compared truly passive subjects with those who exhibited some electromyographic (EMG) activity in the finger extensor; artificially created tremor spectra were almost identical between groups. We also applied electrical stimuli to two clinically deafferented subjects lacking stretch reflexes. They exhibited the same artificial tremor spectrum as control subjects. These results suggest that both typical physiological finger tremor frequencies can be reproduced by random artificial input; neither requires synchronized neural input. We therefore suggest that mechanical resonance could generate both dominant frequency peaks characteristic of physiological finger tremor. The inverse relationship between the input intensity and the resulting tremor frequency can be explained by a movement-dependent reduction in muscle stiffness, a conjecture we support using a simple computational model.

Upper Extremity Kinetics in Poultry Processing: A Comparison between Two Different Cutting Tasks

2003 ◽  
Vol 19 (2) ◽  
pp. 169-177 ◽  
Author(s):  
Dwight E. Waddell ◽  
Craig Wyvill ◽  
Robert J. Gregor
Keyword(s):  
Risk Factors ◽  
Upper Extremity ◽  
Assessment System ◽  
Emg Activity ◽  
Wrist Flexion ◽  
External Work ◽  
Factors Associated ◽  
Flexion Extension ◽  
Poultry Processing ◽  
Trauma Disorders

A field study was performed using a new data collection system looking at upper extremity kinetics during two different cutting tasks, wing vs. tender cuts, in three poultry plants. The Ergonomic Work Assessment System (EWAS) was designed to simultaneously record knife forces (Fx, Fy, and Fz), electromyographic (EMG) activity (forearm flexors/extensors), and goniometric data (wrist flexion/extension), all of which may represent risk factors associated with cumulative trauma disorders, specifically carpal tunnel syndrome (CTS). The objective of this study was to monitor workers in an unencumbered fashion as they performed two different poultry cutting tasks. It was assumed that the variables measured by EWAS would be able to discriminate between the two cuts and quantify possible differences between the two. The results confirmed that EWAS successfully showed significant differences in knife forces between the wing and tender cuts. Knife force differences were also observed between plants for the same cut. Differences in the two cuts were also identified in the EMG and wrist angles. EWAS successfully quantified variables that may represent risk factors associated with CTS in three poultry plants. Knowledge of a better quantitatively described external work environment may enable plants to better design rotation schedules for their deboners.

scholarly journals Design and Development of Continuous Passive Motion (CPM) for Fingers and Wrist Grounded-Exoskeleton Rehabilitation System

2021 ◽  
Vol 11 (2) ◽  
pp. 815
Author(s):  
Husam Almusawi ◽  
Géza Husi
Keyword(s):  
Experimental Testing ◽  
Hand Movement ◽  
Evaluation Process ◽  
Continuous Passive Motion ◽  
Wrist Flexion ◽  
Design And Development ◽  
Passive Motion ◽  
Assistive Robots ◽  
Flexion Extension ◽  
Design Characteristics

Impairments of fingers, wrist, and hand forearm result in significant hand movement deficiencies and daily task performance. Most of the existing rehabilitation assistive robots mainly focus on either the wrist training or fingers, and they are limiting the natural motion; many mechanical parts associated with the patient’s arms, heavy and expensive. This paper presented the design and development of a new, cost-efficient Finger and wrist rehabilitation mechatronics system (FWRMS) suitable for either hand right or left. The proposed machine aimed to present a solution to guide individuals with severe difficulties in their everyday routines for people suffering from a stroke or other motor diseases by actuating seven joints motions and providing them repeatable Continuous Passive Motion (CPM). FWRMS approach uses a combination of; grounded-exoskeleton structure to provide the desired displacement to the hand’s four fingers flexion/extension (F/E) driven by an indirect feed drive mechanism by adopting a leading screw and nut transmission; and an end-effector structure to provide angular velocity to the wrist flexion/ extension (F/E), wrist radial/ulnar deviation (R/U), and forearm supination/pronation (S/P) driven by a rotational motion mechanism. We employed a single dual-sided actuator to power both mechanisms. Additionally, this article presents the implementation of a portable embedded controller. Moreover, this paper addressed preliminary experimental testing and evaluation process. The conducted test results of the FWRMS robot achieved the required design characteristics and executed the motion needed for the continuous passive motion rehabilitation and provide stable trajectories guidance by following the natural range of motion (ROM) and a functional workspace of the targeted joints comfortably for all trainable movements by FWRMS.

Unraveling Interlimb Interactions Underlying Bimanual Coordination

2005 ◽  
Vol 94 (5) ◽  
pp. 3112-3125 ◽  
Author(s):  
Arne Ridderikhoff ◽  
C. (Lieke) E. Peper ◽  
Peter J. Beek
Keyword(s):  
Bimanual Coordination ◽  
Feedforward Control ◽  
Emg Activity ◽  
Minor Role ◽  
Error Corrections ◽  
Flexion Extension ◽  
Contralateral Hand ◽  
Phase Coordination ◽  
The Stability ◽  
Passive Movements

Three sources of interlimb interactions have been postulated to underlie the stability characteristics of bimanual coordination but have never been evaluated in conjunction: integrated timing of feedforward control signals, phase entrainment by contralateral afference, and timing corrections based on the perceived error of relative phase. In this study, the relative contributions of these interactions were discerned through systematic comparisons of five tasks involving rhythmic flexion–extension movements about the wrist, performed bimanually (in-phase and antiphase coordination) or unimanually with or without comparable passive movements of the contralateral hand. The main findings were the following. 1) Contralateral passive movements during unimanual active movements induced phase entrainment to interlimb phasing of either 0° (in-phase) or 180° (antiphase). 2) Entrainment strength increased with the passive movements' amplitude, but was similar for in-phase and antiphase movements. 3) Coordination of unimanual active movements with passive movements of the contralateral hand (kinesthetic tracking) was characterized by similar bilateral EMG activity as observed in active bimanual coordination. 4) During kinesthetic tracking the timing of the movements of the active hand was modulated by afference-based error corrections, which were more pronounced during in-phase coordination. 5) Indications of in-phase coordination being more stable than antiphase coordination were most prominent during active bimanual coordination and marginal during kinesthetic tracking. Together the results indicated that phase entrainment by contralateral afference contributed equally to the stability of in-phase and antiphase coordination, and that differential stability of these patterns depended predominantly on integrated timing of feedforward signals, with only a minor role for afference-based error corrections.

Quantification of Hand Grip Force under Dynamic Conditions

1993 ◽  
Vol 37 (10) ◽  
pp. 715-719 ◽  
Author(s):  
Katherine R. Lehman ◽  
W. Gary Allread ◽  
P. Lawrence Wright ◽  
William S. Marras
Keyword(s):  
Grip Force ◽  
Wrist Flexion ◽  
Range Of Movement ◽  
Ulnar Deviation ◽  
Dynamic Conditions ◽  
Radial Deviation ◽  
Hand Grip ◽  
Flexion Extension ◽  
Maximum Grip ◽  
Lower Grip

A laboratory experiment was conducted to determine whether grip force capabilities are lower when the wrist is moved than in a static position. The purpose was to determine the wrist velocity levels and wrist postures that had the most significant effect on grip force. Maximum grip forces of five male and five female subjects were determined under both static and dynamic conditions. The dominant wrist of each subject was secured to a CYBEX II dynamometer and grip force was collected during isokinetic wrist deviations for four directions of motion (flexion to extension, extension to flexion, radial to ulnar, and ulnar to radial). Six different velocity levels were analyzed and grip forces were recorded at specific wrist positions throughout each range of movement. For flexion-extension motions, wrist positions from 45 degrees flexion to 45 degrees extension were analyzed whereas positions from 20 degrees radial deviation to 20 degrees ulnar deviation were studied for radial-ulnar activity. Isometric exertions were also performed at each desired wrist position. Results showed that, for all directions of motion, grip forces for all isokinetic conditions were significantly lower than for the isometric exertions. Lower grip forces were exhibited at extreme wrist flexion and extreme radial and ulnar positions for both static and dynamic conditions. The direction of motion was also found to affect grip strength; extension to flexion exertions produced larger grip forces than flexion to extension exertions and radial to ulnar motion showed larger grip forces than ulnar to radial deviation. Although, males produced larger grip forces than females in all exertions, significant interactions between gender and velocity were noted.

The Spatial Dependency of Shoulder Muscle Demands for Seated Lateral Hand Force Exertions

2014 ◽  
Vol 30 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Alison C. McDonald ◽  
Elora C. Brenneman ◽  
Alan C. Cudlip ◽  
Clark R. Dickerson
Keyword(s):  
Repeated Measures ◽  
Muscle Activation ◽  
Three Dimensional ◽  
Emg Activity ◽  
Hand Position ◽  
Individual Muscle ◽  
Repeated Measures Analysis ◽  
Spatial Parameters ◽  
Shoulder Complex ◽  
The Right

As the modern workplace is dominated by submaximal repetitive tasks, knowledge of the effect of task location is important to ensure workers are unexposed to potentially injurious demands imposed by repetitive work in awkward or sustained postures. The purpose of this investigation was to develop a three-dimensional spatial map of the muscle activity for the right upper extremity during laterally directed submaximal force exertions. Electromyographic (EMG) activity was recorded from fourteen muscles surrounding the shoulder complex as the participants exerted 40N of force in two directions (leftward, rightward) at 70 defined locations. Hand position in both push directions strongly influenced total and certain individual muscle demands as identified by repeated measures analysis of variance (P< .001). During rightward exertions individual muscle activation varied from 1 to 21% MVE and during leftward exertions it varied from 1 to 27% MVE with hand location. Continuous prediction equations for muscular demands based on three-dimensional spatial parameters were created with explained variance ranging from 25 to 73%. The study provides novel information for evaluating existing and proactive workplace designs, and may help identify preferred geometric placements of lateral exertions in occupational settings to lower muscular demands, potentially mitigating fatigue and associated musculoskeletal risks.

Arthroscopic ligament-specific repair for triangular fibrocartilage complex foveal avulsions: a minimum 2-year follow-up study

2020 ◽  
pp. 175319342095790
Author(s):  
Bo Liu ◽  
Margareta Arianni ◽  
Feiran Wu
Keyword(s):  
Patient Reported Outcomes ◽  
Triangular Fibrocartilage Complex ◽  
Wrist Flexion ◽  
Level Of Evidence ◽  
Flexion Extension ◽  
Patient Reported ◽  
Triangular Fibrocartilage ◽  
The Mean ◽  
Viable Method

This study reports the arthroscopic ligament-specific repair of the triangular fibrocartilage complex (TFCC) that anatomically restores both the volar and dorsal radioulnar ligaments into their individual foveal footprints. Twenty-five patients underwent arthroscopic ligament-specific repair with clinical and radiological diagnoses of TFCC foveal avulsions. The mean age was 28 years (range 14–47) and the mean follow-up was 31 months (range 24–47). Following arthroscopic assessment, 20 patients underwent double limb radioulnar ligament repairs and five had single limb repairs. At final follow-up, there were significant improvements in wrist flexion–extension, forearm pronation–supination and grip strength. There were also significant improvements in pain and patient-reported outcomes as assessed by the patient-rated wrist evaluation, Disabilities of the Arm, Shoulder and Hand score and modified Mayo wrist scores. Arthroscopic ligament-specific repair of the TFCC does not require specialist dedicated equipment or consumables and offers a viable method of treating these injuries. Level of evidence: IV

Outcomes of Supplementary Spring Wire Fixation With Volar Plating for Volar Lunate Facet Fragments in Distal Radius Fractures

Hand ◽  
2020 ◽  
pp. 155894472097640
Author(s):  
Nathaniel Fogel ◽  
Lauren M. Shapiro ◽  
Allison Roe ◽  
Sahitya Denduluri ◽  
Marc J. Richard ◽  
...  
Keyword(s):  
Distal Radius ◽  
Distal Radius Fractures ◽  
Wrist Flexion ◽  
Volar Plating ◽  
Radius Fractures ◽  
Locked Plating ◽  
Spring Wire ◽  
Flexion Extension ◽  
Wire Fixation ◽  
The Mean

Background Intra-articular distal radius fractures with small volar lunate facet fragments can be challenging to address with volar plate fixation alone. Volar locked plating with supplementary spring wire fixation has been previously described in a small series but has not been further described in the literature. We hypothesized that this technique can provide adequate fixation for volar lunate facet fragments smaller than 15 mm in length, which are at risk of displacement. Methods We completed a retrospective chart review (2015-2019) of patients who underwent volar locked plating with the addition of supplementary spring wire fixation for intra-articular distal radius fractures with a volar lunate facet fragment (<15 mm). Postoperative radiographs were assessed to evaluate union, evidence of hardware failure, escape of the volar lunate facet fragment, and postoperative volar tilt. Clinical outcome was assessed with wrist flexion/extension, arc of pronosupination, and Quick Disabilities of the Arm, Shoulder, and Hand Score ( QuickDASH) scores. Results Fifteen patients were identified, of which all went on to fracture union. There were no hardware failures or escape of the volar lunate facet fragment at final follow-up. One patient underwent hardware removal for symptoms of flexor tendon irritation. The mean wrist flexion was 59°, wrist extension was 70°, pronation was 81°, and supination was 76°. The mean QuickDASH score was 18.5. The mean postoperative volar tilt was 3.6°. Conclusions Supplementary spring wire fixation with standard volar plating provides stable fixation for lunate facet fragments less than 15 mm. This technique is a safe and reliable alternative to commercially available fragment-specific implants.

Re-motion total wrist arthroplasty: 39 non-rheumatoid cases with a mean follow-up of 7 years

2019 ◽  
Vol 44 (9) ◽  
pp. 946-950 ◽  
Author(s):  
Stefan M. Froschauer ◽  
Maximilian Zaussinger ◽  
Dietmar Hager ◽  
Manfred Behawy ◽  
Oskar Kwasny ◽  
...  
Keyword(s):  
Radial Component ◽  
Visual Analogue Scale Pain ◽  
Wrist Flexion ◽  
Level Of Evidence ◽  
Pain Scores ◽  
Total Wrist Arthroplasty ◽  
Flexion Extension ◽  
Analogue Scale Pain ◽  
Wrist Arthroplasty

We evaluated the outcomes of the Re-motion total wrist arthroplasty in 39 non-rheumatoid patients. The mean follow-up was 7 years (range 3–12). Postoperative wrist flexion-extension and radial-ulnar deviation as well as the scores of the Disability of Arm Shoulder and Hand questionnaire and the visual analogue scale pain scores improved significantly. Complications occurred in 13 wrists, five of which required further surgery. The most frequent complication was impingement between the scaphoid and the radial implant (n = 5), which can be avoided by complete or almost complete scaphoid resection. Periprosthetic radiolucency developed around the radial component in three cases and three radial screws loosened. Despite the incidence of high implant survival in 38 of 39 wrists over 7 years (97%), the complication rate is not satisfying. Knowledge of the risk of complications and patient selection are essential when making the decision to choose wrist arthroplasty over arthrodesis. Level of evidence: IV

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