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Forman GN, Melchiorre LP, Holmes MWR. Impact of repetitive mouse clicking on forearm muscle fatigue and mouse aiming performance. APPLIED ERGONOMICS 2024; 118:104284. [PMID: 38583318 DOI: 10.1016/j.apergo.2024.104284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 02/09/2024] [Accepted: 04/02/2024] [Indexed: 04/09/2024]
Abstract
Exercise induced performance fatigue has been shown to impair many aspects of fine motor function in the distal upper limb. However, most fatiguing protocols do not reflect the conditions experienced with computer use. The purpose of this study was to determine how a prolonged, low-force mouse clicking fatigue protocol impacts performance fatigue of the distal upper limb for gamers and non-gamers. Participants completed a total of 1 h of mouse clicking at 5 clicks per second. Muscle fatigue and performance were intermittently assessed. RMS amplitude increased for the forearm flexors throughout the fatigue protocol. Accuracy decreased following the first bout of clicking and returned to baseline values after 40-min. EDC and ECU displayed the greatest muscle activity while aiming, producing 11.4% and 12.9% of MVC, respectively. These findings indicate that mouse clicking may not result in performance fatigue, however, high levels of extensor activity may explain common injuries among gamers.
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Affiliation(s)
- Garrick N Forman
- Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, Canada
| | - Lucas P Melchiorre
- Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, Canada
| | - Michael W R Holmes
- Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, Canada.
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2
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Pillai RS, Kothari SF, Svensson P, Castrillon E. Comparison of force profiles from two musculoskeletal palpation methods: A methodological study. J Oral Rehabil 2024; 51:879-885. [PMID: 38240374 DOI: 10.1111/joor.13651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 12/05/2023] [Accepted: 12/13/2023] [Indexed: 04/09/2024]
Abstract
BACKGROUND The Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) protocol recommends a 5 s and 1 kg force dynamic palpation around the lateral condylar pole of the temporomandibular joint. However, the accuracy and precision of the generated force are not known. OBJECTIVE To assess and compare the force profiles generated from dynamic palpation manually and using a palpometer, based on the forces and time recommendations suggested by the DC/TMD protocol. METHODS Nineteen healthy adults applied forces of 0.5 kg, 1.0 kg and 2.0 kg on a calibrated force sensor in a circular motion within target times of 2 s and 5 s. Participants used their right index finger for manual palpation and a calibrated palpometer for device-assisted palpation. Ten repetitions of each target force at both target times were applied. Time taken to complete each application was recorded. Repeated measures analysis of variance was used for analysis of accuracy measured as the relative difference between targeted force and actual force values and precision measured as the coefficient of variation (CV) within the 10 repeated measurements. RESULTS Accuracy was significantly lower (better) and precision higher (lower CV) with the palpometer than with manual palpation (p < .001). There were significant differences in accuracy and precision between the different forces but not palpation times. Most participants could not achieve the target times and tended to be faster, irrespective of the palpation method (p > .063). CONCLUSION A palpometer is a more accurate and precise palpation method for dynamic force assessment compared to manual palpation; however, it remains difficult to standardize the palpation duration.
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Affiliation(s)
- Rajath Sasidharan Pillai
- Section for Orofacial Pain and Jaw Function, Department of Dentistry and Oral Health, Aarhus University, Aarhus, Denmark
- Scandinavian Center for Orofacial Neurosciences (SCON), Aarhus, Denmark/Malmö, Sweden
| | - Simple Futarmal Kothari
- Section for Orofacial Pain and Jaw Function, Department of Dentistry and Oral Health, Aarhus University, Aarhus, Denmark
- Scandinavian Center for Orofacial Neurosciences (SCON), Aarhus, Denmark/Malmö, Sweden
- Hammel Neurorehabilitation and University Research Clinic, Hammel, Denmark
| | - Peter Svensson
- Section for Orofacial Pain and Jaw Function, Department of Dentistry and Oral Health, Aarhus University, Aarhus, Denmark
- Scandinavian Center for Orofacial Neurosciences (SCON), Aarhus, Denmark/Malmö, Sweden
- Faculty of Odontology, Malmö University, Malmö, Sweden
| | - Eduardo Castrillon
- Section for Orofacial Pain and Jaw Function, Department of Dentistry and Oral Health, Aarhus University, Aarhus, Denmark
- Scandinavian Center for Orofacial Neurosciences (SCON), Aarhus, Denmark/Malmö, Sweden
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3
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Ricotta JM, De SD, Nardon M, Benamati A, Latash ML. Effects of fatigue on intramuscle force-stabilizing synergies. J Appl Physiol (1985) 2023; 135:1023-1035. [PMID: 37732378 DOI: 10.1152/japplphysiol.00419.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 08/22/2023] [Accepted: 09/14/2023] [Indexed: 09/22/2023] Open
Abstract
We applied the recently introduced concept of intramuscle synergies in spaces of motor units (MUs) to quantify indexes of such synergies in the tibialis anterior during ankle dorsiflexion force production tasks and their changes with fatigue. We hypothesized that MUs would be organized into robust groups (MU modes), which would covary across trials to stabilize force magnitude, and the indexes of such synergies would drop under fatigue. Healthy, young subjects (n = 15; 8 females) produced cyclical, isometric dorsiflexion forces while surface electromyography was used to identify action potentials of individual MUs. Principal component analysis was used to define MU modes. The framework of the uncontrolled manifold (UCM) was used to analyze intercycle variance and compute the synergy index, ΔVZ. Cyclical force production tasks were repeated after a nonfatiguing exercise (control) and a fatiguing exercise. Across subjects, fatigue led, on average, to a 43% drop in maximal force and fewer identified MUs per subject (29.6 ± 2.1 vs. 32.4 ± 2.1). The first two MU modes accounted for 81.2 ± 0.08% of variance across conditions. Force-stabilizing synergies were present across all conditions and were diminished after fatiguing exercise (1.49 ± 0.40) but not control exercise (1.76 ± 0.75). Decreased stability after fatigue was caused by an increase in the amount of variance orthogonal to the UCM. These findings contrast with earlier studies of multieffector synergies demonstrating increased synergy index under fatigue. We interpret the results as reflections of a drop in the gain of spinal reflex loops under fatigue. The findings corroborate an earlier hypothesis on the spinal nature of intramuscle synergies.NEW & NOTEWORTHY Across multielement force production tasks, fatigue of an element leads to increased indexes of force stability (synergy indexes). Here, however, we show that groups of motor units in the tibialis anterior show decreased indexes of force-stabilizing synergies after fatiguing exercise. These findings align intramuscle synergies with spinal mechanisms, in contrast to the supraspinal control of multimuscle synergies.
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Affiliation(s)
- Joseph M Ricotta
- Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania, United States
- Clinical and Translational Science Institute, Penn State College of Medicine, Hershey, Pennsylvania, United States
| | - Sayan D De
- Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania, United States
| | - Mauro Nardon
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Anna Benamati
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Mark L Latash
- Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania, United States
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4
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Goubault E, Turner C, Mailly R, Begon M, Dal Maso F, Verdugo F. Neuromotor variability partially explains different endurance capacities of expert pianists. Sci Rep 2023; 13:15163. [PMID: 37704661 PMCID: PMC10499816 DOI: 10.1038/s41598-023-42408-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 09/10/2023] [Indexed: 09/15/2023] Open
Abstract
During fatiguing piano tasks, muscle fatigue develops differently between expert pianists. Differences in neuromotor strategies employed could explain a slower rate of fatigue development. The objective was to compare muscle activation and kinematic variabilities between ShortDuration (i.e., pianists with less endurance) and LongDuration groups. Results from 49 pianists showed that EMG activation variability of most shoulder and upper limbs muscles was greater for the ShortDuration group with time during two piano fatiguing tasks, namely Digital and Chord tasks. Segment acceleration variability, assessed using inertial measurement units, was also greater with time for the ShortDuration group at the right arm during the Digital task, and at the thorax and head during the Chord task. Finally, thorax lateroflexion variability increased with time for the LongDuration group (but not the ShortDuration group) during the Digital task. During the Chord task, wrist flexion variability was higher for the LongDuration group compared to the ShortDuration group. These results showed a direct effect of time on the pianists' acceleration variability and EMG activation variability. In contrast, a protective effect of fatigue development could be attributed to kinematic variability. Results also suggest a higher risk of injury among pianists in the ShortDuration group.
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Affiliation(s)
- Etienne Goubault
- Laboratoire de Simulation et Modélisation du Mouvement, École de Kinésiologie et des sciences de l'activité physique, Université de Montréal, Montréal, QC, Canada.
| | - Craig Turner
- Laboratoire de Simulation et Modélisation du Mouvement, École de Kinésiologie et des sciences de l'activité physique, Université de Montréal, Montréal, QC, Canada
| | - Robin Mailly
- Laboratoire de Simulation et Modélisation du Mouvement, École de Kinésiologie et des sciences de l'activité physique, Université de Montréal, Montréal, QC, Canada
| | - Mickaël Begon
- Laboratoire de Simulation et Modélisation du Mouvement, École de Kinésiologie et des sciences de l'activité physique, Université de Montréal, Montréal, QC, Canada
- Sainte-Justine Hospital Research Center, Montréal, QC, Canada
| | - Fabien Dal Maso
- Laboratoire de Simulation et Modélisation du Mouvement, École de Kinésiologie et des sciences de l'activité physique, Université de Montréal, Montréal, QC, Canada
- Centre Interdisciplinaire de recherche sur le cerveau et l'apprentissage, Montréal, QC, Canada
| | - Felipe Verdugo
- Laboratoire de Simulation et Modélisation du Mouvement, École de Kinésiologie et des sciences de l'activité physique, Université de Montréal, Montréal, QC, Canada
- Faculté de Musique, Université de Montréal, Montréal, QC, Canada
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Koh K, Oppizzi G, Kehs G, Zhang LQ. Abnormal coordination of upper extremity during target reaching in persons post stroke. Sci Rep 2023; 13:12838. [PMID: 37553412 PMCID: PMC10409717 DOI: 10.1038/s41598-023-39684-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 07/28/2023] [Indexed: 08/10/2023] Open
Abstract
Understanding abnormal synergy of the upper extremity (UE) in stroke survivors is critical for better identification of motor impairment. Here, we investigated to what extent stroke survivors retain the ability to coordinate multiple joints of the arm during a reaching task. Using an exoskeleton robot, 37 stroke survivors' arm joint angles (θ) and torques (τ) during hand reaching in the horizontal plane was compared to that of 13 healthy controls. Kinematic and kinetic coordination patterns were quantified as variances of the multiple-joint angles and multiple-joint torques across trials, respectively, that were partitioned into task-irrelevant variance (TIVθ and TIVτ) and task-relevant variance (TRVθ and TRVτ). TIVθ and TRVθ (or TIVτ and TRVτ) led to consistent and inconsistent hand position (or force), respectively. The index of synergy (ISθ and ISτ) was determined as [Formula: see text] and [Formula: see text] for kinematic and kinetic coordination patterns, respectively. Both kinematic ISθ and kinetic ISτ in the stroke group were significantly lower than that of the control group, indicating stroke survivors had impaired reaching abilities in utilizing the multiple joints of the UE for successful completion of a reaching task. The reduction of kinematic ISθ in the stroke group was mainly attributed to the lower TIVθ as compared to the control group, while the reduction of kinetic ISτ was mainly due to the higher [Formula: see text] as well as lower TIVτ. Our results also indicated that stroke may lead to motor deficits in formation of abnormal kinetic synergistic movement of UE, especially during outward movement. The findings in abnormal synergy patterns provides a better understanding of motor impairment, suggesting that impairment-specific treatment could be identified to help improve UE synergies, focusing on outward movements.
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Affiliation(s)
- Kyung Koh
- Fischell Department of Bioengineering, University of Maryland, College Park, MD, 20742, USA
| | - Giovanni Oppizzi
- Fischell Department of Bioengineering, University of Maryland, College Park, MD, 20742, USA
- Department of Physical Therapy and Rehabilitation Science, University of Maryland, 100 Penn St, Baltimore, MD, 21201, USA
| | - Glenn Kehs
- University of Maryland Rehabilitation and Orthopaedic Institute, Baltimore, MD, 21207, USA
- Department of Neurology, University of Maryland, Baltimore, MD, 21201, USA
| | - Li-Qun Zhang
- Fischell Department of Bioengineering, University of Maryland, College Park, MD, 20742, USA.
- Department of Physical Therapy and Rehabilitation Science, University of Maryland, 100 Penn St, Baltimore, MD, 21201, USA.
- Department of Orthopaedics, University of Maryland, Baltimore, MD, 21201, USA.
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6
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Geelen JE, van der Helm FCT, Schouten AC, Mugge W. Sensory weighting of position and force feedback during pinching. Exp Brain Res 2023:10.1007/s00221-023-06654-1. [PMID: 37382669 PMCID: PMC10386968 DOI: 10.1007/s00221-023-06654-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 06/15/2023] [Indexed: 06/30/2023]
Abstract
Human hands are complex biomechanical systems that allow for dexterous tasks with many degrees of freedom. Coordination of the fingers is essential for many activities of daily living and involves integrating sensory signals. During this sensory integration, the central nervous system deals with the uncertainty of sensory signals. When handling compliant objects, force and position are related. Interactions with stiff objects result in reduced position changes and increased force changes compared to compliant objects. Literature has shown sensory integration of force and position at the shoulder. Nevertheless, differences in sensory requirements between proximal and distal joints may lead to different proprioceptive representations, hence findings at proximal joints cannot be directly transferred to distal joints, such as the digits. Here, we investigate the sensory integration of force and position during pinching. A haptic manipulator rendered a virtual spring with adjustable stiffness between the index finger and the thumb. Participants had to blindly reproduce a force against the spring. In both visual reference trials and blind reproduction trials, the relation between pinch force and spring compression was constant. However, by covertly changing the spring characteristics in catch trials into an adjusted force-position relation, the participants' weighting of force and position could be revealed. In agreement with previous studies on the shoulder, participants relied more on force sense in trials with higher stiffness. This study demonstrated stiffness-dependent sensory integration of force and position feedback during pinching.
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Affiliation(s)
- Jinne E Geelen
- BioMechanical Engineering, Delft University of Technology, Mekelweg 2, Delft, 2628 CD, The Netherlands.
| | - Frans C T van der Helm
- BioMechanical Engineering, Delft University of Technology, Mekelweg 2, Delft, 2628 CD, The Netherlands
| | - Alfred C Schouten
- BioMechanical Engineering, Delft University of Technology, Mekelweg 2, Delft, 2628 CD, The Netherlands
| | - Winfred Mugge
- BioMechanical Engineering, Delft University of Technology, Mekelweg 2, Delft, 2628 CD, The Netherlands
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7
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Bailey CA, Hasanbarani F, Slopecki M, Yang C, Côté JN. Size and structure of motor variability in young and old adults performing a rhythmic, repetitive tapping task. J Biomech 2023; 152:111595. [PMID: 37119701 DOI: 10.1016/j.jbiomech.2023.111595] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 02/15/2023] [Accepted: 04/18/2023] [Indexed: 05/01/2023]
Abstract
The size of motor variability increases with fatigue in repetitive upper limb tasks, and the structure of variability differs with old age. However, the combined influences of old age and fatigue on the size and structure of movement-to-movement variability are unclear. Eighteen young and sixteen old adults performed a fatiguing repetitive tapping task while seated using their dominant arm. Optoelectronic motion capture served to measure upper body angles via forward kinematics. Movement-to-movement variability was measured by the size at joints (standard deviation: SD) and by the structure of the uncontrolled manifold (variance: VUCM, VORT; synergy index: ΔVz) in the first and final minutes of the task for the early, middle, and late forward movement phases. Outcomes were analyzed by Age*Condition*Phase general estimating equations. Old adults had lower humerothoracic abduction/adduction and flexion/extension SD, wrist flexion/extension SD, VUCM, and VORT, mainly in the early movement phase (p < 0.014). With fatigue, humerothoracic flexion/extension SD increased in young adults only and humerothoracic abduction/adduction SD, wrist pronation/supination SD, wrist flexion/extension SD, and VUCM increased in both groups. ΔVz was positive and did not differ with age or fatigue (p > 0.014). Results indicate that fatigue adjustments were mainly in the frontal plane, old age did not affect the ratio of good vs. bad variability, and motor synergy was preserved during fatigue despite less motor flexibility in old age.
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Affiliation(s)
- Christopher A Bailey
- Department of Kinesiology and Physical Education, McGill University, Montreal, QC, Canada; Center for Interdisciplinary Research in Rehabilitation of Greater Montreal, Jewish Rehabilitation Hospital, Laval, QC, Canada.
| | - Fariba Hasanbarani
- Department of Kinesiology and Physical Education, McGill University, Montreal, QC, Canada; Center for Interdisciplinary Research in Rehabilitation of Greater Montreal, Jewish Rehabilitation Hospital, Laval, QC, Canada
| | - Matthew Slopecki
- Department of Kinesiology and Physical Education, McGill University, Montreal, QC, Canada; Center for Interdisciplinary Research in Rehabilitation of Greater Montreal, Jewish Rehabilitation Hospital, Laval, QC, Canada
| | - Chen Yang
- Department of Kinesiology and Physical Education, McGill University, Montreal, QC, Canada; Center for Interdisciplinary Research in Rehabilitation of Greater Montreal, Jewish Rehabilitation Hospital, Laval, QC, Canada
| | - Julie N Côté
- Department of Kinesiology and Physical Education, McGill University, Montreal, QC, Canada; Center for Interdisciplinary Research in Rehabilitation of Greater Montreal, Jewish Rehabilitation Hospital, Laval, QC, Canada
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8
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Temporal and spatial goal-directed reaching in upper limb prosthesis users. Exp Brain Res 2022; 240:3011-3021. [PMID: 36222884 DOI: 10.1007/s00221-022-06476-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Accepted: 09/30/2022] [Indexed: 11/04/2022]
Abstract
Understanding the fundamental characteristics of prosthetic movement control is imperative in improving prosthesis design and training. This study quantified how using an upper limb prosthesis affected performance during goal-directed reaching tasks. Nine prosthesis users with unilateral transradial limb absence and nine healthy controls completed a series of goal-directed reaching movements with different goals: one spatial and three temporal with different goal frequencies. We quantified end-point accuracy, smoothness, and peak speed for the spatial task and temporal accuracy, horizontal distance, and speed for the temporal task. For the temporal task, we also used a goal-equivalent manifold (GEM) approach to decompose variability in movement distance and speed into those perpendicular and tangential to the GEM. Detrended fluctuation analysis (DFA) quantified the temporal persistence of each time series. For the spatial task, movements made with prostheses were less smooth, had larger end-point errors, and had slower peak speed compared to those with control limbs (p < 0.041). For the temporal task, movements made with prostheses and intact limbs of prosthesis users and control limbs were similar in distance and speed and had similar timing errors (p > 0.138). Timing errors, distance, speed, and GEM deviations were corrected similarly between prosthetic limbs and control limbs (p > 0.091). The mean and variability of distance, speed, and perpendicular deviations decreased with increased goal frequency (p < 0.001). Our results suggest that prosthesis users have a sufficient internal model to successfully complete ballistic movements but are unable to accurately complete movements requiring substantial feedback.
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Uncontrolled Manifold Analysis of the Effects of Different Fatigue Locations on Kinematic Coordination During a Repetitive Upper-Limb Task. Motor Control 2022; 26:713-728. [PMID: 36087930 DOI: 10.1123/mc.2021-0114] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 07/04/2022] [Accepted: 07/20/2022] [Indexed: 11/18/2022]
Abstract
Fatigue at individual joints is known to affect interjoint coordination during repetitive multijoint tasks. However, how these coordination adjustments affect overall task stability is unknown. Twelve participants completed a repetitive pointing task at rest and after fatigue of the shoulder, elbow, and trunk. Upper-limb and trunk kinematics were collected. Uncontrolled manifold framework was applied to a kinematic model to link elemental variables to endpoint fingertip position. Mixed and one-way analysis of variances determined effects (phase and fatigue location) on variance components and synergy index, respectively. The shoulder fatigue condition had the greatest impact in causing increases in variance components and a decreased synergy index in the late phase of movement, suggesting more destabilization of the interjoint task caused by shoulder fatigue.
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Möhler F, Fadillioglu C, Scheffler L, Müller H, Stein T. Running-Induced Fatigue Changes the Structure of Motor Variability in Novice Runners. BIOLOGY 2022; 11:biology11060942. [PMID: 35741462 PMCID: PMC9220051 DOI: 10.3390/biology11060942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 06/15/2022] [Accepted: 06/18/2022] [Indexed: 11/16/2022]
Abstract
Understanding the effects of fatigue is a central issue in the context of endurance sports. Given the popularity of running, there are numerous novices among runners. Therefore, understanding the effects of fatigue in novice runners is an important issue. Various studies have drawn conclusions about the control of certain variables by analyzing motor variability. One variable that plays a crucial role during running is the center of mass (CoM), as it reflects the movement of the whole body in a simplified way. Therefore, the aim of this study was to analyze the effects of fatigue on the motor variability structure that stabilizes the CoM trajectory in novice runners. To do so, the uncontrolled manifold approach was applied to a 3D whole-body model using the CoM as the result variable. It was found that motor variability increased with fatigue (UCMꓕ). However, the UCMRatio did not change. This indicates that the control of the CoM decreased, whereas the stability was not affected. The decreases in control were correlated with the degree of exhaustion, as indicated by the Borg scale (during breaking and flight phase). It can be summarized that running-induced fatigue increases the step-to-step variability in novice runners and affects the control of their CoM.
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Affiliation(s)
- Felix Möhler
- BioMotion Center, Institute of Sports and Sports Science (IfSS), Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany; (C.F.); (L.S.); (T.S.)
- Correspondence:
| | - Cagla Fadillioglu
- BioMotion Center, Institute of Sports and Sports Science (IfSS), Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany; (C.F.); (L.S.); (T.S.)
| | - Lucia Scheffler
- BioMotion Center, Institute of Sports and Sports Science (IfSS), Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany; (C.F.); (L.S.); (T.S.)
| | - Hermann Müller
- Training Science, Department of Sports Science, Justus-Liebig-Universität Giessen, 35394 Giessen, Germany;
| | - Thorsten Stein
- BioMotion Center, Institute of Sports and Sports Science (IfSS), Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany; (C.F.); (L.S.); (T.S.)
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11
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Forman GN, Sonne MW, Kociolek AM, Gabriel DA, Holmes MWR. Influence of muscle fatigue on motor task performance of the hand and wrist: A systematic review. Hum Mov Sci 2021; 81:102912. [PMID: 34929434 DOI: 10.1016/j.humov.2021.102912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 08/06/2021] [Accepted: 12/03/2021] [Indexed: 11/16/2022]
Abstract
Muscle fatigue is represented as a reduction in force production capability; however, fatigue does not necessarily result in performance impairments. As the distal upper limb serves as the end effector when interacting or manipulating objects, it is important to understand how muscle fatigue may impact motor functionality. The aim of this study was to systematically review the literature to identify how various aspects of motor performance of the distal upper limb are impaired following muscle fatigue. Four databases were searched using 23 search terms describing the distal upper limb, muscle fatigue, and various performance metrics. A total of 4561 articles were screened with a total of 28 articles extracted and critically appraised. Evidence extracted indicates that muscle fatigue results in unique impairments based on the type of motor performance being evaluated. Furthermore, much data suggests that muscle fatigue does not result in consistent, predictable performance impairments, particularly while performing submaximal tasks. Additionally, magnitude of fatigue does not directly correlate with reductions in performance outcomes at the hand and wrist. Fatiguing protocols used highlighted the importance of fatigue specificity. When fatiguing and performance tasks are similar, performance impairment is likely to be observed. The numerous muscles found in the hand and wrist, often considered redundant, play a critical role in maintaining task performance in the presence of muscle fatigue. The presence of motor abundance (e.g. multiple muscles with similar function) is shown to reduce the impairment in multiple performance metrics by compensating for reduced function of fatigued muscles. Continued exploration into various fatiguing protocols (i.e. maximal or submaximal) will provide greater insights into performance impairments in the distal upper limb.
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Affiliation(s)
- Garrick N Forman
- Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, Canada
| | | | - Aaron M Kociolek
- Department of Physical and Health Education, Nipissing University, North Bay, ON, Canada
| | - David A Gabriel
- Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, Canada
| | - Michael W R Holmes
- Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, Canada.
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12
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Latash ML, Yamagata M. Recent Advances in the Neural Control of Movements: Lessons for Functional Recovery. Phys Ther Res 2021; 25:1-11. [PMID: 35582118 PMCID: PMC9095426 DOI: 10.1298/ptr.r0018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 07/12/2021] [Indexed: 09/05/2023]
Abstract
We review the current views on the control and coordination of movements following the traditions set by Nikolai Bernstein. In particular, we focus on the theory of neural control of effectors - from motor units to individual muscles, to joints, limbs, and to the whole body - with spatial referent coordinates organized into a hierarchy with multiple few-to-many mappings. Further, we discuss synergies ensuring stability of natural human movements within the uncontrolled manifold hypothesis. Synergies are organized within the neural control hierarchy based on the principle of motor abundance. Movement disorders are discussed as consequences of an inability to use the whole range of changes in referent coordinates (as in spasticity) and an inability to ensure controlled stability of salient variables as reflected in indices of multi-element synergies and their adjustments in preparation to actions (as in brain disorders, including Parkinson's disease, multiple-system atrophy, and stroke). At the end of the review, we discuss possible implications of this theoretical approach to peripheral disorders and their rehabilitations using, as an example, osteoarthritis. In particular, "joint stiffening" is viewed as a maladaptive strategy, which can compromise stability of salient variables during walking.
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Affiliation(s)
- Mark L Latash
- Department of Kinesiology, The Pennsylvania State University, USA
| | - Momoko Yamagata
- Department of Human Development, Graduate School of Human Development and Environment, Kobe University, Japan
- Department of Physical Therapy, Human Health Science, Graduate School of Medicine, Kyoto University, Japan
- Research Fellow of the Japan Society for the Promotion of Science, Japan
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Hasanbarani F, Yang C, Bailey CA, Slopecki M, Côté JN. Sex-specific effects of a repetitive fatiguing task on stability: Analysis with motor equivalence model. J Biomech 2021; 129:110769. [PMID: 34607280 DOI: 10.1016/j.jbiomech.2021.110769] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 08/18/2021] [Accepted: 09/19/2021] [Indexed: 10/20/2022]
Abstract
Although studies showed that several internal factors affect task-specific stability, the sex-specific effects of fatigue on whole-limb stability during a semi-cycle repetitive pointing task remain unidentified. Synergy and Motor Equivalence concepts in the UCM framework have been developed to explain task-specific stability. The motor equivalence model quantifies the amount of deviation in the space of elemental variables that occurs in two directions; one that preserves the performance variable (good variance), and the other that affects it (bad variance). Synergy index (the difference between good and bad variance divided by the total variance > 0) represent stability in performing a task. Healthy adults (n = 26, 13F; age: 35.3 ± 10.6 yrs.) performed an RPT by moving their dominant arm between a proximal target and a distal target in a standing position until near fatigue (Borg CR10 rating 8/10). Tridimensional kinematics of trunk, upper arm, forearm, and hand segments were captured by high-resolution cameras every minute, and joint angles were extracted according to the ZX'Y″ Euler sequence. Results showed the synergy > 0 for both women and men, reflecting synergies stabilizing the endpoint coordinate in both Non-Fatigue and Fatigue conditions. Statistics (ANOVA) showed a significant Condition * Sex effect (p = 0.01), with higher good (by 0.19 ± 0.1 rad) and bad variances (by 0.15 ± 0.09 rad) in women compared to men after fatigue. Higher good and bad variability, with no change in women's performance could represent a less stable strategy, leading to the development of risk factors for neck-shoulder disorders.
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Affiliation(s)
- Fariba Hasanbarani
- Department of Kinesiology and Physical Education, McGill University, Montreal, QC H2W 1S4, Canada; Occupational Biomechanics and Ergonomics Laboratory, Michael Feil and Ted Oberfeld/CRIR Research Centre, Jewish Rehabilitation Hospital, Laval, QC H7V 1R2, Canada.
| | - Chen Yang
- Department of Kinesiology and Physical Education, McGill University, Montreal, QC H2W 1S4, Canada; Occupational Biomechanics and Ergonomics Laboratory, Michael Feil and Ted Oberfeld/CRIR Research Centre, Jewish Rehabilitation Hospital, Laval, QC H7V 1R2, Canada
| | - Christopher A Bailey
- Department of Kinesiology and Physical Education, McGill University, Montreal, QC H2W 1S4, Canada; Occupational Biomechanics and Ergonomics Laboratory, Michael Feil and Ted Oberfeld/CRIR Research Centre, Jewish Rehabilitation Hospital, Laval, QC H7V 1R2, Canada
| | - Matthew Slopecki
- Department of Kinesiology and Physical Education, McGill University, Montreal, QC H2W 1S4, Canada; Occupational Biomechanics and Ergonomics Laboratory, Michael Feil and Ted Oberfeld/CRIR Research Centre, Jewish Rehabilitation Hospital, Laval, QC H7V 1R2, Canada
| | - Julie N Côté
- Department of Kinesiology and Physical Education, McGill University, Montreal, QC H2W 1S4, Canada; Occupational Biomechanics and Ergonomics Laboratory, Michael Feil and Ted Oberfeld/CRIR Research Centre, Jewish Rehabilitation Hospital, Laval, QC H7V 1R2, Canada
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14
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The Nature of Finger Enslaving: New Results and Their Implications. Motor Control 2021; 25:680-703. [PMID: 34530403 DOI: 10.1123/mc.2021-0044] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 07/01/2021] [Accepted: 07/25/2021] [Indexed: 11/18/2022]
Abstract
We present a review on the phenomenon of unintentional finger action seen when other fingers of the hand act intentionally. This phenomenon (enslaving) has been viewed as a consequence of both peripheral (e.g., connective tissue links and multifinger muscles) and neural (e.g., projections of corticospinal pathways) factors. Recent studies have shown relatively large and fast drifts in enslaving toward higher magnitudes, which are not perceived by subjects. These and other results emphasize the defining role of neural factors in enslaving. We analyze enslaving within the framework of the theory of motor control with spatial referent coordinates. This analysis suggests that unintentional finger force changes result from drifts of referent coordinates, possibly reflecting the spread of cortical excitation.
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Inhibitory Control of Adjacent Finger Movements while Performing a Modified Version of the Halstead Finger Tapping Test: Effects of Age, Education and Sex. J Int Neuropsychol Soc 2021; 27:813-824. [PMID: 33190661 DOI: 10.1017/s1355617720001101] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
OBJECTIVE Selective motor inhibition is known to decline with age. The purpose of this study was to determine the frequency of failures at inhibitory control of adjacent finger movements while performing a repetitive finger tapping task in young, middle-aged and older adults. Potential education and sex effects were also evaluated. METHODS Kinematic recordings of adjacent finger movements were obtained on 107 healthy adults (ages 20-80) while they performed a modified version of the Halstead Finger Tapping Test (HTFF). Study participants were instructed to inhibit all finger movements while tapping with the index finger. RESULTS Inability to inhibit adjacent finger movements while performing the task was infrequent in young adults (2.9% of individuals between 20 and 39 years of age) but increased with age (23.3% between the ages of 40 and 59; 31.0% between ages 60 and 80). Females and males did not differ in their inability to inhibit adjacent finger movements, but individuals with a college education showed a lower frequency of failure to inhibit adjacent finger movements (10.3%) compared to those with a high school education (28.6%). These findings were statistically significant only for the dominant hand. CONCLUSION Selective motor inhibition failures are most common in the dominant hand and occur primarily in older healthy adults while performing the modified version of the HFTT. Monitoring selective motor inhibition failures may have diagnostic significance.
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16
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Latash ML. One more time about motor (and non-motor) synergies. Exp Brain Res 2021; 239:2951-2967. [PMID: 34383080 DOI: 10.1007/s00221-021-06188-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 08/03/2021] [Indexed: 11/28/2022]
Abstract
We revisit the concept of synergy based on the recently translated classical book by Nikolai Bernstein (On the construction of movements, Medgiz, Moscow 1947; Latash, Bernstein's Construction of Movements, Routledge, Abingdon 2020b) and progress in understanding the physics and neurophysiology of biological action. Two aspects of synergies are described: organizing elements into stable groups (modes) and ensuring dynamical stability of salient performance variables. The ability of the central nervous system to attenuate synergies in preparation for a quick action-anticipatory synergy adjustments-is emphasized. Recent studies have demonstrated synergies at the level of hypothetical control variables associated with spatial referent coordinates for effectors. Overall, the concept of synergies fits naturally the hierarchical scheme of control with referent coordinates with an important role played by back-coupling loops within the central nervous system and from peripheral sensory endings. Further, we review studies showing non-trivial changes in synergies with development, aging, fatigue, practice, and a variety of neurological disorders. Two aspects of impaired synergic control-impaired stability and impaired agility-are introduced. The recent generalization of the concept of synergies for non-motor domains, including perception, is discussed. We end the review with a list of unresolved and troubling issues.
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Affiliation(s)
- Mark L Latash
- Department of Kinesiology, Rec.Hall-268N, The Pennsylvania State University, University Park, PA, 16802, USA.
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17
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Gugelmin-Almeida D, Clark C, Rolfe U, Jones M, Williams J. Dominant versus non-dominant hand during simulated infant CPR using the two-finger technique: a randomised study. Resusc Plus 2021; 7:100141. [PMID: 34223397 PMCID: PMC8244244 DOI: 10.1016/j.resplu.2021.100141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 05/10/2021] [Accepted: 05/16/2021] [Indexed: 11/28/2022] Open
Abstract
Aims The aim of this randomised study was to compare the two-finger technique (TFT) performance using dominant hand (DH) and non-dominant hand (NH) during simulated infant CPR (iCPR). Methods 24 participants performed 3-min iCPR using TFT with DH or NH followed by 3-min iCPR with their other hand. Perceived fatigue was rated using visual analogue scale. Primary outcomes - (i) difference between DH and NH for compression depth (CCD), compression rate (CCR), residual leaning (RL) and duty cycle (DC); (ii) difference between first and last 30 s of iCPR performance with DH and NH. Secondary outcomes - (i) perception of fatigue between DH and NH; (ii) relationship between perception of fatigue and iCPR performance. Results No significant difference between DH and NH for any iCPR metric. CCR (DH: P = 0.02; NH: P = 0.004) and DC (DH: P = 0.04; NH: P < 0.001) were significantly different for the last 30 s for DH and NH. Perception of fatigue for NH (76.8 ± 13.4 mm) was significantly higher (t = -3.7, P < 0.001) compared to DH (62.8 ± 12.5 mm). No significant correlation between iCPR metrics and perception of fatigue for DH. However, a significant correlation was found for CCR (r = 0.43; P = 0.04) and RL (r = -0.48; P = 0.02) for NH. Conclusion No difference in performance of iCPR with DH versus NH was determined. However, perception of fatigue is higher in NH and was related to CCR and RL, with no effect on quality of performance. Based on our results, individuals performing iCPR can offer similar quality of infant chest compressions regardless of the hand used or the perception of fatigue, under the conditions explored in this study.
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Affiliation(s)
- Debora Gugelmin-Almeida
- Faculty of Health and Social Sciences, Bournemouth University, Bournemouth Gateway Building, St. Pauls Lane, Bournemouth, BH8 8GP, England.,Department of Anaesthesiology, Main Theatres, Royal Bournemouth and Christchurch Hospitals, Castle Lane East, Bournemouth, BH7 7DW, England
| | - Carol Clark
- Faculty of Health and Social Sciences, Bournemouth University, Bournemouth Gateway Building, St. Pauls Lane, Bournemouth, BH8 8GP, England
| | - Ursula Rolfe
- Faculty of Health and Social Sciences, Bournemouth University, Bournemouth Gateway Building, St. Pauls Lane, Bournemouth, BH8 8GP, England
| | - Michael Jones
- Cardiff School of Engineering, Cardiff University, Cardiff, CF23 3AA, Wales
| | - Jonathan Williams
- Faculty of Health and Social Sciences, Bournemouth University, Bournemouth Gateway Building, St. Pauls Lane, Bournemouth, BH8 8GP, England
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18
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Goubault E, Verdugo F, Pelletier J, Traube C, Begon M, Dal Maso F. Exhausting repetitive piano tasks lead to local forearm manifestation of muscle fatigue and negatively affect musical parameters. Sci Rep 2021; 11:8117. [PMID: 33854088 PMCID: PMC8047012 DOI: 10.1038/s41598-021-87403-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 03/23/2021] [Indexed: 02/02/2023] Open
Abstract
Muscle fatigue is considered as a risk factor for developing playing-related muscular disorders among professional pianists and could affect musical performance. This study investigated in 50 pianists the effect of fatiguing repetitive piano sequences on the development of forearm muscle fatigue and on piano performance parameters. Results showed signs of myoelectric manifestation of fatigue in the 42-electromyographic bipolar electrodes positioned on the forearm to record finger and wrist flexor and extensor muscles, through a significant non-constant decrease of instantaneous median frequency during two repetitive Digital (right-hand 16-tones sequence) and Chord (right-hand chords sequence) excerpts, with extensor muscles showing greater signs of fatigue than flexor muscles. In addition, muscle fatigue negatively affected key velocity, a central feature of piano sound intensity, in both Digital and Chord excerpts, and note-events, a fundamental aspect of musicians' performance parameter, in the Chord excerpt only. This result highlights that muscle fatigue may alter differently pianists' musical performance according to the characteristics of the piece played.
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Affiliation(s)
- Etienne Goubault
- grid.14848.310000 0001 2292 3357Laboratoire de Simulation et Modélisation du Mouvement, École de Kinésiologie et des Sciences de l’activité Physique, Université de Montréal, 1700 Rue Jacques-Tétreault, Laval, QC Canada
| | - Felipe Verdugo
- grid.14709.3b0000 0004 1936 8649Input Devices and Music Interaction Laboratory, Centre for Interdisciplinary Research in Music Media and Technology, Schulich School of Music, McGill University, Montreal, QC Canada ,grid.267180.a0000 0001 2168 0285EXPRESSION Team, Université Bretagne-Sud, Vannes, France
| | - Justine Pelletier
- grid.38678.320000 0001 2181 0211Laboratoire Arts vivants et interdisciplinarité, Département de danse, Université du Québec à Montréal, Montreal, QC Canada
| | - Caroline Traube
- grid.14848.310000 0001 2292 3357Laboratoire de recherche sur le geste musicien, Faculté de musique, Université de Montréal, Montreal, QC Canada
| | - Mickaël Begon
- grid.14848.310000 0001 2292 3357Laboratoire de Simulation et Modélisation du Mouvement, École de Kinésiologie et des Sciences de l’activité Physique, Université de Montréal, 1700 Rue Jacques-Tétreault, Laval, QC Canada ,grid.411418.90000 0001 2173 6322Sainte-Justine Hospital Research Center, Montreal, QC Canada
| | - Fabien Dal Maso
- grid.14848.310000 0001 2292 3357Laboratoire de Simulation et Modélisation du Mouvement, École de Kinésiologie et des Sciences de l’activité Physique, Université de Montréal, 1700 Rue Jacques-Tétreault, Laval, QC Canada ,Centre interdisciplinaire de recherche sur le cerveau et l’apprentissage, Montréal, QC Canada
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19
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Koh K, Park YS, Park DW, Shim JK. Dance training improves the CNS's ability to utilize the redundant degrees of freedom of the whole body. Sci Rep 2020; 10:22197. [PMID: 33335153 PMCID: PMC7747644 DOI: 10.1038/s41598-020-79081-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 11/30/2020] [Indexed: 11/09/2022] Open
Abstract
Professional dancers demonstrate an amazing ability to control their balance. However, little is known about how they coordinate their body segments for such superior control. In this study, we investigated how dancers coordinate body segments when a physical perturbation is given to their body. A custom-made machine was used to provide a short pulling impulse at the waist in the anterior direction to ten dancers and ten non-dancers. We used Uncontrolled Manifold analysis to quantify the variability in the task-relevant space and task-irrelevant space within the multi-dimensional space made up of individual segments’ centers of mass with a velocity adjustment. The dancers demonstrated greater utilization of redundant degrees of freedom (DoFs) supported by the greater task-irrelevant variability as compared to non-dancers. These findings suggest that long-term specialized dance training can improve the central nervous system’s ability to utilize the redundant DoFs in the whole-body system.
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Affiliation(s)
- Kyung Koh
- Department of Kinesiology, University of Maryland, College Park, MD, USA.,Department of Physical Therapy and Rehabilitation Science, University of Maryland, Baltimore, MD, USA
| | - Yang Sun Park
- Department of Sports Welfare, Korea National University of Transportation, Chungcheongbuk-do, South Korea.
| | - Da Won Park
- Department of Kinesiology, Seoul National University, Seoul, South Korea
| | - Jae Kun Shim
- Department of Kinesiology, University of Maryland, College Park, MD, USA. .,Department of Mechanical Engineering, Kyung Hee University, Yongin-Si, Gyeonggi-do, South Korea. .,Neuroscience and Cognitive Science Program, University of Maryland, College Park, MD, USA. .,Fischell Department of Bioengineering, University of Maryland, College Park, MD, USA.
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20
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Hibino H, Gorniak SL. Effects of aging on rapid grip force responses during bimanual manipulation of an active object. Exp Brain Res 2020; 238:2161-2178. [PMID: 32661648 PMCID: PMC10103105 DOI: 10.1007/s00221-020-05865-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 07/01/2020] [Indexed: 12/17/2022]
Abstract
Rapid grip force responses to unexpected pulling loads on the fingertips are deteriorated in older adults due to, in part, age-related declines in somatosensory function. Such reports are limited to one-hand conditions despite the higher frequency of using two hands together in daily living activities of older adults. Unexpected perturbations during bimanual movements elicit goal-oriented and cortically-meditated bilateral rapid motor responses. Since aging is associated with declined somatosensory and cognitive functions, we hypothesized that bilateral rapid motor responses differ between young and older adults, such that older adults exert stronger grip forces following perturbation and the unperturbed hand is more involved in stabilizing the object in older adults. We tested our hypothesis by comparing the rapid grip force responses of both hands in young and older adults. A total of 13 right-handed young individuals (24.2 ± 4.0 years old, 5 men) and 13 right-handed older individuals (68.7 ± 7.1 years old, 5 men) were recruited. Tactile detection threshold, fingertip friction, and the rapid grip force responses of both hands triggered by unpredicted pulling loads during grip-lift movements were assessed. Older adults had higher tactile detection thresholds and lower fingertip friction compared to young adults. Regardless of age, rapid motor responses were found in both the perturbed (right) hand and the indirectly perturbed (left) hand at 73 ms and 135 ms after the perturbation, respectively, while magnitudes of the responses depended on perturbation magnitudes. Higher values in maximum grip force and maximum grip force rate were found in older adults as compared to young adults. In older adults, the indirectly perturbed (left) hand was more involved in stabilizing the object as compared to young healthy adults. The current study suggests that age-related changes in the peripheral and central nervous systems contribute to the greater involvement of the indirectly perturbed hand in older adults.
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Affiliation(s)
- Hidetaka Hibino
- Department of Health and Human Performance, University of Houston, 3855 Holman St., Garrison 104, Houston, TX, 77204-6015, USA
| | - Stacey L Gorniak
- Department of Health and Human Performance, University of Houston, 3855 Holman St., Garrison 104, Houston, TX, 77204-6015, USA.
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21
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Satas A, Jurgelaitiene G, Brazaitis M, Eimantas N, Skurvydas A. Effect of knee extensors muscles fatigue on bilateral force accuracy, variability, and coordination. Hum Mov Sci 2020; 72:102659. [DOI: 10.1016/j.humov.2020.102659] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 06/01/2020] [Accepted: 07/02/2020] [Indexed: 01/08/2023]
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22
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Möhler F, Ringhof S, Debertin D, Stein T. Influence of fatigue on running coordination: A UCM analysis with a geometric 2D model and a subject-specific anthropometric 3D model. Hum Mov Sci 2019; 66:133-141. [PMID: 30981149 DOI: 10.1016/j.humov.2019.03.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 03/19/2019] [Accepted: 03/25/2019] [Indexed: 10/27/2022]
Abstract
Although fatigue is a central issue in endurance sports little is known about the effects of fatigue on coordination. The uncontrolled manifold (UCM) approach has been widely used in recent studies to examine coordination in human movement; however, it has not been used to study the effects of fatigue on running. Therefore, the aim of this study was to analyze the effects of fatigue on the synergy structure stabilizing the center of mass (CoM) trajectory in experienced runners during high-intensity running using the UCM approach. A total of 13 healthy young experienced runners participated in the study. Based on a lactate threshold testing undertaken one week prior to the measurements, participants were asked to run on a treadmill at their individual "fatigue-speed" until exhaustion. The kinematics of 20 consecutive gait cycles were recorded at the beginning (rested) and at the end (fatigue) of the protocol. The effects of fatigue on the synergy structure were investigated using a geometric 2D model and a subject-specific anthropometric 3D model. Specifically, the variance affecting the CoM trajectory (UCM⊥), the variance not affecting the CoM trajectory (UCM‖), and their ratio (UCMRatio) were analyzed for different gait cycle phases (absorption, propulsion and flight phase). Three-way repeated-measures ANOVA tests revealed differences between the two models. Fatigue-induced changes in the UCM structure could only be detected using the 3D model. UCMRatio did not change, but UCM⊥ increased during flight phase. In the 2D model, UCMRatio and both components were higher during the propulsion phase than during the absorption phase in both the rested and the fatigued state. Using a current concept for analyzing motor coordination, the UCM approach, only minor changes with fatigue were detected using the 3D subject-specific model. This indicates that the runners were able to control the trajectory of their CoM when fatigued. As the 2D model was not able to detect these changes, our study emphasizes that future studies on the effects of fatigue should focus on 3D analyses.
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Affiliation(s)
- Felix Möhler
- BioMotion Center, Institute of Sports and Sports Science (IfSS), Karlsruhe Institute of Technology, Karlsruhe, Germany.
| | - Steffen Ringhof
- BioMotion Center, Institute of Sports and Sports Science (IfSS), Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Daniel Debertin
- BioMotion Center, Institute of Sports and Sports Science (IfSS), Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Thorsten Stein
- BioMotion Center, Institute of Sports and Sports Science (IfSS), Karlsruhe Institute of Technology, Karlsruhe, Germany
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23
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Coordination in adults with neurological impairment - A systematic review of uncontrolled manifold studies. Gait Posture 2019; 69:66-78. [PMID: 30677709 DOI: 10.1016/j.gaitpost.2019.01.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 12/21/2018] [Accepted: 01/01/2019] [Indexed: 02/02/2023]
Abstract
BACKGROUND Analysis of sensorimotor synergies has been greatly advanced by the Uncontrolled Manifold (UCM) approach. The UCM method is based on partitioning inter-trial variance displayed by elemental variables into 'good' (VUCM) and 'bad' (VORT) variability that, respectively, indicate maintenance or loss of task stability. In clinical populations, these indices can be used to investigate the strength, flexibility, stereotypy and agility of synergistic control. RESEARCH QUESTION How are synergies affected by neurological impairment in adults? Specifically, this study aimed to determine i) the impact of pathology on VUCM, VORT, and their ratio (synergy index); ii) the relationship between synergy indices and functional performance; iii) changes in anticipatory synergy adjustments (ASAs); and iv) the effects of interventions on synergies. METHODS Systematic review of UCM studies on adults with neurological impairment. RESULTS Most of the 17 studies had moderate to high quality scores in the adapted Critical Review Form and the UCM reporting quality checklist developed for this review. i) Most of the studies found reduced synergy indices for patients with Parkinson's disease (PD), olivo-ponto-cerebellar atrophy, multiple sclerosis and spinocerebellar degeneration, with variable levels of change in VUCM and VORT. Reduction in synergy indices was not as consistent for stroke, in three out of six studies it was unchanged. ii) Five of seven studies found no significant correlations between scores on motor function scales and UCM indices. iii) Seven studies consistently reported ASAs that are smaller in magnitude, delayed, or both, for patients compared to healthy controls. iv) Two studies reported increased synergy indices, either via increase in VUCM or decrease in VORT, after dopaminergic drugs for patients with PD. There were similar synergy indices but improved ASAs after deep brain stimulation for patients with PD. SIGNIFICANCE UCM can provide reliable and sensitive indicators of altered synergistic control in adults with neurological impairment.
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24
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Effect of Kinetic Degrees of Freedom on Multi-Finger Synergies and Task Performance during Force Production and Release Tasks. Sci Rep 2018; 8:12758. [PMID: 30143688 PMCID: PMC6109105 DOI: 10.1038/s41598-018-31136-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Accepted: 08/13/2018] [Indexed: 11/08/2022] Open
Abstract
Complex structures present in a human body has relatively large degrees-of-freedom (DOFs) as compared to the requirement of a particular task. This phenomenon called motor redundancy initially deemed as a computational problem rather can be understood as having the flexibility to perform the certain task successfully. Hence, the purpose of our study was to examine the positive impact of extra DOFs (redundant DOFs) during force production tasks. For this purpose, an experimental setup was designed to simulate archery-like shooting, and purposeful organization of a redundant set of finger forces determined the stability of important performance variables as well as accurate and precise performance. DOFs were adjusted by changing the number of fingers explicitly involved in the task. The concept of motor synergy and computational framework of uncontrolled manifold (UCM) approach was used to quantify stability indices during finger force production. As a result, accuracy and precision of the task improved with an increase in DOFs. Also, the stability indices of net finger forces and moment increased with active DOFs of fingers. We concluded that the controller actively utilizes extra DOFs to increase the stability of the performance, which is associated with the improved accuracy and precision of the task.
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25
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Yang C, Bouffard J, Srinivasan D, Ghayourmanesh S, Cantú H, Begon M, Côté JN. Changes in movement variability and task performance during a fatiguing repetitive pointing task. J Biomech 2018; 76:212-219. [PMID: 29908654 DOI: 10.1016/j.jbiomech.2018.05.025] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2018] [Revised: 05/12/2018] [Accepted: 05/30/2018] [Indexed: 11/26/2022]
Abstract
Changes in neuromuscular strategies employed with fatigue during multi-joint movements are still poorly understood. Studies have shown that motor variability of individual joints increases when performing upper limb tasks to fatigue, while movement parameters related to the task goal remain constant. However, how the inter-limb coordination and its variability change during specific movement phases with fatigue is still unclear. The aim of this study was to assess the effects of neck-shoulder fatigue on shoulder and elbow kinematic variabilities, shoulder-elbow coordination and its variability, and endpoint characteristics during different phases of a forward pointing movement. Nineteen healthy young adults continuously performed a repetitive pointing task until fatigue (Borg rating of 8/10). Changes in elbow-shoulder coordination through the movement were assessed using the continuous relative phase and statistical nonparametric mapping methods. At the end of the task, muscle fatigue was evidenced by significant increases in anterior deltoid (+13%) and biceps brachii (+30%) activity. Shoulder horizontal abduction, elbow flexion variability and shoulder-elbow coordination variability were increased with fatigue at different moments of the movement cycle (shoulder: during the first 17% and most of the second half movement, elbow: from 73% to 91%, coordination: almost the whole movement). However, movement timing errors and endpoint spatial variability were mostly preserved, even with fatigue. We showed that increased variability with fatigue is not only observed in the fatigued joint (shoulder), but also in the elbow and shoulder-elbow coordination, and may have a goal of preserving global task performance.
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Affiliation(s)
- Chen Yang
- Department of Kinesiology and Physical Education, McGill University, Montreal, QC H2W 1S4, Canada; Occupational Biomechanics and Ergonomics Laboratory, Michael Feil and Ted Oberfeld/CRIR Research Centre, Jewish Rehabilitation Hospital, Laval, QC H7V 1R2, Canada.
| | - Jason Bouffard
- Department of Kinesiology and Physical Education, McGill University, Montreal, QC H2W 1S4, Canada; Occupational Biomechanics and Ergonomics Laboratory, Michael Feil and Ted Oberfeld/CRIR Research Centre, Jewish Rehabilitation Hospital, Laval, QC H7V 1R2, Canada; Laboratoire de simulation et modélisation du mouvement, Département de kinésiologie, Université de Montréal, Laval, QC H7N 0A5, Canada
| | - Divya Srinivasan
- Grado Department of Industrial and Systems Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | - Shaheen Ghayourmanesh
- Department of Kinesiology and Physical Education, McGill University, Montreal, QC H2W 1S4, Canada; Occupational Biomechanics and Ergonomics Laboratory, Michael Feil and Ted Oberfeld/CRIR Research Centre, Jewish Rehabilitation Hospital, Laval, QC H7V 1R2, Canada
| | - Hiram Cantú
- Department of Kinesiology and Physical Education, McGill University, Montreal, QC H2W 1S4, Canada; Occupational Biomechanics and Ergonomics Laboratory, Michael Feil and Ted Oberfeld/CRIR Research Centre, Jewish Rehabilitation Hospital, Laval, QC H7V 1R2, Canada
| | - Mickaël Begon
- Laboratoire de simulation et modélisation du mouvement, Département de kinésiologie, Université de Montréal, Laval, QC H7N 0A5, Canada
| | - Julie N Côté
- Department of Kinesiology and Physical Education, McGill University, Montreal, QC H2W 1S4, Canada; Occupational Biomechanics and Ergonomics Laboratory, Michael Feil and Ted Oberfeld/CRIR Research Centre, Jewish Rehabilitation Hospital, Laval, QC H7V 1R2, Canada
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de Freitas PB, Freitas SMSF, Lewis MM, Huang X, Latash ML. Stability of steady hand force production explored across spaces and methods of analysis. Exp Brain Res 2018; 236:1545-1562. [PMID: 29564506 PMCID: PMC5984153 DOI: 10.1007/s00221-018-5238-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Accepted: 03/16/2018] [Indexed: 10/17/2022]
Abstract
We used the framework of the uncontrolled manifold (UCM) hypothesis and explored the reliability of several outcome variables across different spaces of analysis during a very simple four-finger accurate force production task. Fourteen healthy, young adults performed the accurate force production task with each hand on 3 days. Small spatial finger perturbations were generated by the "inverse piano" device three times per trial (lifting the fingers 1 cm/0.5 s and lowering them). The data were analyzed using the following main methods: (1) computation of indices of the structure of inter-trial variance and motor equivalence in the space of finger forces and finger modes, and (2) analysis of referent coordinates and apparent stiffness values for the hand. Maximal voluntary force and the index of enslaving (unintentional finger force production) showed good to excellent reliability. Strong synergies stabilizing total force were reflected in both structure of variance and motor equivalence indices. Variance within the UCM and the index of motor equivalent motion dropped over the trial duration and showed good to excellent reliability. Variance orthogonal to the UCM and the index of non-motor equivalent motion dropped over the 3 days and showed poor to moderate reliability. Referent coordinate and apparent stiffness indices co-varied strongly and both showed good reliability. In contrast, the computed index of force stabilization showed poor reliability. The findings are interpreted within the scheme of neural control with referent coordinates involving the hierarchy of two basic commands, the r-command and c-command. The data suggest natural drifts in the finger force space, particularly within the UCM. We interpret these drifts as reflections of a trade-off between stability and optimization of action. The implications of these findings for the UCM framework and future clinical applications are explored in the discussion. Indices of the structure of variance and motor equivalence show good reliability and can be recommended for applied studies.
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Affiliation(s)
- Paulo B de Freitas
- Interdisciplinary Graduate Program in Healthy Sciences, Cruzeiro do Sul University, São Paulo, SP, Brazil
- Department of Kinesiology, Rec.Hall-267, The Pennsylvania State University, University Park, 16802, PA, USA
- Department of Neurology, Milton S. Hershey Medical Center, The Pennsylvania State University, Hershey, PA, USA
| | - Sandra M S F Freitas
- Department of Kinesiology, Rec.Hall-267, The Pennsylvania State University, University Park, 16802, PA, USA
- Department of Neurology, Milton S. Hershey Medical Center, The Pennsylvania State University, Hershey, PA, USA
- Graduate Program in Physical Therapy, City University of São Paulo, São Paulo, SP, Brazil
| | - Mechelle M Lewis
- Department of Neurology, Milton S. Hershey Medical Center, The Pennsylvania State University, Hershey, PA, USA
- Department of Pharmacology, Milton S. Hershey Medical Center, The Pennsylvania State University, Hershey, PA, USA
| | - Xuemei Huang
- Department of Neurology, Milton S. Hershey Medical Center, The Pennsylvania State University, Hershey, PA, USA
- Department of Pharmacology, Milton S. Hershey Medical Center, The Pennsylvania State University, Hershey, PA, USA
- Department of Radiology, Milton S. Hershey Medical Center, The Pennsylvania State University, Hershey, PA, USA
- Department of Neurosurgery, Milton S. Hershey Medical Center, The Pennsylvania State University, Hershey, PA, USA
| | - Mark L Latash
- Department of Kinesiology, Rec.Hall-267, The Pennsylvania State University, University Park, 16802, PA, USA.
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Park J, Xu D. Multi-Finger Interaction and Synergies in Finger Flexion and Extension Force Production. Front Hum Neurosci 2017; 11:318. [PMID: 28674489 PMCID: PMC5474495 DOI: 10.3389/fnhum.2017.00318] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 06/02/2017] [Indexed: 11/13/2022] Open
Abstract
The aim of this study was to discover finger interaction indices during single-finger ramp tasks and multi-finger coordination during a steady state force production in two directions, flexion, and extension. Furthermore, the indices of anticipatory adjustment of elemental variables (i.e., finger forces) prior to a quick pulse force production were quantified. It is currently unknown whether the organization and anticipatory modulation of stability properties are affected by force directions and strengths of in multi-finger actions. We expected to observe a smaller finger independency and larger indices of multi-finger coordination during extension than during flexion due to both neural and peripheral differences between the finger flexion and extension actions. We also examined the indices of the anticipatory adjustment between different force direction conditions. The anticipatory adjustment could be a neural process, which may be affected by the properties of the muscles and by the direction of the motions. The maximal voluntary contraction (MVC) force was larger for flexion than for extension, which confirmed the fact that the strength of finger flexor muscles (e.g., flexor digitorum profundus) was larger than that of finger extensor (e.g., extensor digitorum). The analysis within the uncontrolled manifold (UCM) hypothesis was used to quantify the motor synergy of elemental variables by decomposing two sources of variances across repetitive trials, which identifies the variances in the uncontrolled manifold (VUCM) and that are orthogonal to the UCM (VORT). The presence of motor synergy and its strength were quantified by the relative amount of VUCM and VORT. The strength of motor synergies at the steady state was larger in the extension condition, which suggests that the stability property (i.e., multi-finger synergies) may be a direction specific quantity. However, the results for the existence of anticipatory adjustment; however, no difference between the directional conditions suggests that feed-forward synergy adjustment (changes in the stability property) may be at least independent of the magnitude of the task-specific apparent performance variables and its direction (e.g., flexion and extension forces).
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Affiliation(s)
- Jaebum Park
- Department of Physical Education, Seoul National UniversitySeoul, South Korea.,Institute of Sport Science, Seoul National UniversitySeoul, South Korea
| | - Dayuan Xu
- Department of Physical Education, Seoul National UniversitySeoul, South Korea
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Vaz DV. Motor synergies research in physical therapy: advantages of the uncontrolled manifold approach. FISIOTERAPIA E PESQUISA 2017. [DOI: 10.1590/1809-2950/12646024012017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
ABSTRACT Movement is central to physical therapy identity and practice. Advances in the science of movement control, motor learning and development are thus inextricably tied to professional development and clinical activity. This paper aims to describe a prominent approach to motor control with potential to greatly advance the understanding of movement dysfunction: the uncontrolled manifold (UCM). An argument is formulated for incorporating this method of data analysis in rehabilitation research. It is a narrative review of the relevant literature. Research in physical therapy could greatly benefit from investigating synergies with the theory and methods of UCM. Research should seek connections between functioning in daily life tasks and the assembling of synergies to stabilize different performance variables, the UCM variability measures, the synergy strength indexes, and the anticipatory synergy adjustments. Changes in these synergy variables should also be quantified after rehabilitation interventions. UCM can offer one solid science-based approach to inform clinical decisions on whether synergies have to be broken, rebalanced, created, or reinforced in patients with movement dysfunction.
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29
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Babikian S, Kanso E, Kutch JJ. Cortical activity predicts good variation in human motor output. Exp Brain Res 2017; 235:1139-1147. [PMID: 28161821 DOI: 10.1007/s00221-017-4876-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 01/04/2017] [Indexed: 10/20/2022]
Abstract
Human movement patterns have been shown to be particularly variable if many combinations of activity in different muscles all achieve the same task goal (i.e., are goal-equivalent). The nervous system appears to automatically vary its output among goal-equivalent combinations of muscle activity to minimize muscle fatigue or distribute tissue loading, but the neural mechanism of this "good" variation is unknown. Here we use a bimanual finger task, electroencephalography (EEG), and machine learning to determine if cortical signals can predict goal-equivalent variation in finger force output. 18 healthy participants applied left and right index finger forces to repeatedly perform a task that involved matching a total (sum of right and left) finger force. As in previous studies, we observed significantly more variability in goal-equivalent muscle activity across task repetitions compared to variability in muscle activity that would not achieve the goal: participants achieved the task in some repetitions with more right finger force and less left finger force (right > left) and in other repetitions with less right finger force and more left finger force (left > right). We found that EEG signals from the 500 milliseconds (ms) prior to each task repetition could make a significant prediction of which repetitions would have right > left and which would have left > right. We also found that cortical maps of sites contributing to the prediction contain both motor and pre-motor representation in the appropriate hemisphere. Thus, goal-equivalent variation in motor output may be implemented at a cortical level.
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Affiliation(s)
- Sarine Babikian
- Aerospace and Mechanical Engineering, University of Southern California, Los Angeles, CA, 90089, USA
| | - Eva Kanso
- Aerospace and Mechanical Engineering, University of Southern California, Los Angeles, CA, 90089, USA
| | - Jason J Kutch
- Division of Biokinesiology and Physical Therapy, University of Southern California, 1540 E. Alcazar Street, CHP 155, Los Angeles, CA, 90033, USA.
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Jo HJ, Mattos D, Lucassen EB, Huang X, Latash ML. Changes in Multidigit Synergies and Their Feed-Forward Adjustments in Multiple Sclerosis. J Mot Behav 2016; 49:218-228. [PMID: 27715488 DOI: 10.1080/00222895.2016.1169986] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The authors explored the changes in multidigit synergies in patients with multiple sclerosis (MS) within the framework of the uncontrolled manifold hypothesis. The specific hypotheses were that both synergy indices and anticipatory synergy adjustments prior to the initiation of a self-paced quick action would be diminished in the patients compared to age-matched controls. The MS patients and age-matched controls (n = 13 in both groups) performed one-finger and multifinger force production tasks involving both accurate steady-state force production and quick force pulses. The patients showed significantly lower maximal finger forces and a tendency toward slower force pulses. Enslaving was increased in MS, but only in the lateral fingers (index and little). Indices of multifinger synergies during steady-state force production were lower in MS, mainly due to the lower amount of intertrial variance that did not affect total force. Anticipatory synergy adjustments were significantly delayed in MS. The results show that MS leads to significant changes in multidigit synergies and feed-forward adjustments of the synergies prior to a quick action. The authors discuss possible contributions of subcortical structures to the impaired synergic control.
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Affiliation(s)
- Hang Jin Jo
- a Department of Kinesiology , The Pennsylvania State University, University Park
| | - Daniela Mattos
- a Department of Kinesiology , The Pennsylvania State University, University Park
| | - Elisabeth B Lucassen
- b Department of Neurology , Pennsylvania State University-Milton S. Hershey Medical Center , Hershey
| | - Xuemei Huang
- b Department of Neurology , Pennsylvania State University-Milton S. Hershey Medical Center , Hershey.,c Department of Pharmacology , Pennsylvania State University-Milton S. Hershey Medical Center , Hershey.,d Department of Radiology , Pennsylvania State University-Milton S. Hershey Medical Center , Hershey.,e Department of Neurosurgery , Pennsylvania State University-Milton S. Hershey Medical Center , Hershey
| | - Mark L Latash
- a Department of Kinesiology , The Pennsylvania State University, University Park
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31
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Mudie KL, Gupta A, Green S, Clothier PJ. Adaptation of lower limb movement patterns when maintaining performance in the presence of muscle fatigue. Hum Mov Sci 2016; 48:28-36. [DOI: 10.1016/j.humov.2016.04.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 04/03/2016] [Accepted: 04/12/2016] [Indexed: 10/21/2022]
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Hansen EA. On voluntary rhythmic leg movement behaviour and control during pedalling. Acta Physiol (Oxf) 2015; 214 Suppl 702:1-18. [PMID: 26094819 DOI: 10.1111/apha.12529] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The overall purpose of the present dissertation was to contribute to the understanding of voluntary human rhythmic leg movement behaviour and control. This was achieved by applying pedalling as a movement model and exposing healthy and recreationally active individuals as well as trained cyclists to for example cardiopulmonary and mechanical loading, fatiguing exercise, and heavy strength training. As a part of the background, the effect of pedalling frequency on diverse relevant biomechanical, physiological, and psychophysiological variables as well as on performance was initially explored. Freely chosen pedalling frequency is considerably higher than the energetically optimal pedalling frequency. This has been shown by others and was confirmed in the present work. As a result, pedal force is relatively low while rates of VO2 and energy turnover are relatively high during freely chosen pedalling as compared to a condition where a lower and more efficient pedalling frequency is imposed. The freely chosen pedalling frequency was in the present work, and by others, found to most likely be less advantageous than the lower energetically optimal pedalling frequency with respect to performance during intensive cycling following prolonged submaximal cycling. This stimulates the motivation to understand the behaviour and control of the freely chosen pedalling frequency during cycling. Freely chosen pedalling frequency was in the present work shown to be highly individual. In addition, the pedalling frequency was shown to be steady in a longitudinal perspective across 12 weeks. Further, it was shown to be unaffected by both fatiguing hip extension exercise and hip flexion exercise as well as by increased loading on the cardiopulmonary system at constant mechanical loading, and vice versa. Based on this, the freely chosen pedalling frequency is considered to be characterised as a highly individual, steady, and robust innate voluntary motor rhythm under primary influence of central pattern generators. The last part of the characterisation is largely based on, and supported by, work of other researchers in the field. Despite the robustness of the freely chosen pedalling frequency, it may be affected by some particular factors. As an example from the present work, freely chosen pedalling frequency during treadmill cycling increased by on average 15 to 17 rpm when power output was increased from a value corresponding to 86% and up to 165% of Wmax . This phenomenon is supported by other studies. As another example from the present work, freely chosen pedalling frequency decreased by on average 9 to 14 rpm following heavy strength training that involved both hip extension and hip flexion. Further, the present work suggested that the latter phenomenon occurred within the first week of training and was caused by in particular the hip extension strength training rather than the hip flexion strength training. The fast response to the strength training indicated that neural adaptations presumably caused the observed changes in movement behaviour. The internal organisation of the central pattern generator is by some other researchers in the field considered to be functionally separated into two components, in which, one is responsible for movement frequency and another is responsible for movement pattern. For the present dissertation, the freely chosen pedalling frequency was considered to reflect the rhythmic movement frequency of the voluntary rhythmic leg movement of pedalling. The tangential pedal force profile was considered to reflect the rhythmic movement pattern. The present work showed that fatiguing hip flexion exercise in healthy and recreationally active individuals modified the tangential pedal force profile during cycling at a pre-set target pedalling frequency in a way that the minimum tangential pedal force became more negative, the maximum tangential pedal force increased, and the phase with negative tangential pedal force increased. In other words, the legs were "actively lifted" to a lesser extent in the upstroke phase. Fatiguing hip extension exercise did not have that effect. And none of the fatiguing exercises affected the freely chosen pedalling frequency. The present work furthermore showed that the primary effect of hip extension strength training was that it decreased the freely chosen pedalling frequency. An interpretation of this could be that the hip extension strength training, in particular, influenced the output from the component of the central pattern generator that may be responsible for rhythmic movement frequency.
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Affiliation(s)
- E. A. Hansen
- Motor Behaviour and Performance Laboratory; Research Interest Group of Physical Activity and Human Performance, SMI; Department of Health Science and Technology; Aalborg University; Aalborg Denmark
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33
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Gopalakrishnan A, Modenese L, Phillips ATM. A novel computational framework for deducing muscle synergies from experimental joint moments. Front Comput Neurosci 2014; 8:153. [PMID: 25520645 PMCID: PMC4253955 DOI: 10.3389/fncom.2014.00153] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Accepted: 11/04/2014] [Indexed: 01/08/2023] Open
Abstract
Prior experimental studies have hypothesized the existence of a "muscle synergy" based control scheme for producing limb movements and locomotion in vertebrates. Such synergies have been suggested to consist of fixed muscle grouping schemes with the co-activation of all muscles in a synergy resulting in limb movement. Quantitative representations of these groupings (termed muscle weightings) and their control signals (termed synergy controls) have traditionally been derived by the factorization of experimentally measured EMG. This study presents a novel approach for deducing these weightings and controls from inverse dynamic joint moments that are computed from an alternative set of experimental measurements-movement kinematics and kinetics. This technique was applied to joint moments for healthy human walking at 0.7 and 1.7 m/s, and two sets of "simulated" synergies were computed based on two different criteria (1) synergies were required to minimize errors between experimental and simulated joint moments in a musculoskeletal model (pure-synergy solution) (2) along with minimizing joint moment errors, synergies also minimized muscle activation levels (optimal-synergy solution). On comparing the two solutions, it was observed that the introduction of optimality requirements (optimal-synergy) to a control strategy solely aimed at reproducing the joint moments (pure-synergy) did not necessitate major changes in the muscle grouping within synergies or the temporal profiles of synergy control signals. Synergies from both the simulated solutions exhibited many similarities to EMG derived synergies from a previously published study, thus implying that the analysis of the two different types of experimental data reveals similar, underlying synergy structures.
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Affiliation(s)
- Anantharaman Gopalakrishnan
- The Royal British Legion Centre for Blast Injury Studies at Imperial College London London, UK ; Structural Biomechanics, Department of Civil and Environmental Engineering, Imperial College London London, UK
| | - Luca Modenese
- Griffith Health Institute, Centre for Musculoskeletal Research, Griffith University Gold Coast, QLD, Australia
| | - Andrew T M Phillips
- The Royal British Legion Centre for Blast Injury Studies at Imperial College London London, UK ; Structural Biomechanics, Department of Civil and Environmental Engineering, Imperial College London London, UK
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34
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Wu YH, Truglio TS, Zatsiorsky VM, Latash ML. Learning to Combine High Variability With High Precision: Lack of Transfer to a Different Task. J Mot Behav 2014; 47:153-65. [DOI: 10.1080/00222895.2014.961892] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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35
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Reschechtko S, Zatsiorsky VM, Latash ML. Stability of multifinger action in different state spaces. J Neurophysiol 2014; 112:3209-18. [PMID: 25253478 DOI: 10.1152/jn.00395.2014] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
We investigated stability of action by a multifinger system with three methods: analysis of intertrial variance, application of transient perturbations, and analysis of the system's motion in different state spaces. The "inverse piano" device was used to apply transient (lifting-and-lowering) perturbations to individual fingers during single- and two-finger accurate force production tasks. In each trial, the perturbation was applied either to a finger explicitly involved in the task or one that was not. We hypothesized that, in one-finger tasks, task-specific stability would be observed in the redundant space of finger forces but not in the nonredundant space of finger modes (commands to explicitly involved fingers). In two-finger tasks, we expected that perturbations applied to a nontask finger would not contribute to task-specific stability in mode space. In contrast to our expectations, analyses in both force and mode spaces showed lower stability in directions that did not change total force output compared with directions that did cause changes in total force. In addition, the transient perturbations led to a significant increase in the enslaving index. We consider these results within a theoretical scheme of control with referent body configurations organized hierarchically, using multiple few-to-many mappings organized in a synergic way. The observed volatility of enslaving, greater equifinality of total force compared with elemental variables, and large magnitude of motor equivalent motion in both force and mode spaces provide support for the concept of task-specific stability of performance and the existence of multiple neural loops, which ensure this stability.
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Affiliation(s)
- Sasha Reschechtko
- Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania
| | - Vladimir M Zatsiorsky
- Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania
| | - Mark L Latash
- Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania
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36
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Singh T, Zatsiorsky VM, Latash ML. Prehension synergies during fatigue of a single digit: adaptations in control with referent configurations. Motor Control 2014; 18:278-96. [PMID: 24457335 PMCID: PMC6003241 DOI: 10.1123/mc.2013-0069] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The effects of muscle fatigue on the stability of precision grasps are not well known. The purpose of the current study was to investigate the effects of exercise-induced fatigue of a digit on prehension synergies in a static precision grasp. One group of participants performed the fatiguing exercise using the thumb (group-thumb) and the second group performed the exercise using the index finger (group-index). Grasp force and load-resisting force-stabilizing synergies were weaker during fatigue for group-thumb and showed no significant change for group-index. These results indicate that fatiguing the thumb compromises the stability of the precision grasp more than when the index finger is fatigued. Our results support the idea of hierarchical organization of prehension control. We proffer an explanation of our results based on two control constructs: a) Principle of superposition. This principle states that prehension can be viewed as a superposition of two independent processes controlling the slip and the tilt of the object respectively; and b) The referent configuration hypothesis. According to this hypothesis, the neural control of actions is associated with defining a set of referent values for task-related coordinates (given an external force field) defined as the referent configuration.
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Affiliation(s)
- Tarkeshwar Singh
- Department of Biomedical Engineering, Cleveland Clinic, Cleveland,
OH-44195
- Department of Kinesiology, The Pennsylvania State University,
University Park, PA- 16802
| | - Vladimir M. Zatsiorsky
- Department of Kinesiology, The Pennsylvania State University,
University Park, PA- 16802
| | - Mark L. Latash
- Department of Kinesiology, The Pennsylvania State University,
University Park, PA- 16802
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37
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Paclet F, Ambike S, Zatsiorsky VM, Latash ML. Enslaving in a serial chain: interactions between grip force and hand force in isometric tasks. Exp Brain Res 2013; 232:775-87. [PMID: 24309747 DOI: 10.1007/s00221-013-3787-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Accepted: 11/18/2013] [Indexed: 01/16/2023]
Abstract
This study was motivated by the double action of extrinsic hand muscles that produce grip force and also contribute to wrist torque. We explored interactions between grip force and wrist torque in isometric force production tasks. In particular, we tested a hypothesis that an intentional change in one of the two kinetic variables would produce an unintentional change in the other (enslaving). When young healthy subjects produced accurate changes in the grip force, only minor effects on the force produced by the hand (by wrist flexion/extension action) were observed. In contrast, a change in the hand force produced consistent changes in grip force in the same direction. The magnitude of such unintentional grip force change was stronger for intentional hand force decrease as compared to hand force increase. These effects increased with the magnitude of the initial grip force. When the subjects were asked to produce accurate total force computed as the sum of the hand and grip forces, strong negative covariation between the two forces was seen across trials interpreted as a synergy stabilizing the total force. An index of this synergy was higher in the space of "modes," hypothetical signals to the two effectors that could be changed by the controller one at a time. We interpret the complex enslaving effects (positive force covariation) as conditioned by typical everyday tasks. The presence of synergic effects (negative, task-specific force covariation) can be naturally interpreted within the referent configuration hypothesis.
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Affiliation(s)
- Florent Paclet
- Department of Kinesiology, Rec.Hall-268N, The Pennsylvania State University, University Park, PA, 16802, USA
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38
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Greve C, Zijlstra W, Hortobágyi T, Bongers RM. Not all is lost: old adults retain flexibility in motor behaviour during sit-to-stand. PLoS One 2013; 8:e77760. [PMID: 24204952 PMCID: PMC3808394 DOI: 10.1371/journal.pone.0077760] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Accepted: 09/04/2013] [Indexed: 12/27/2022] Open
Abstract
Sit-to-stand is a fundamental activity of daily living, which becomes increasingly difficult with advancing age. Due to severe loss of leg strength old adults are required to change the way they rise from a chair and maintain stability. Here we examine whether old compared to young adults differently prioritize task-important performance variables and whether there are age-related differences in the use of available motor flexibility. We applied the uncontrolled manifold analysis to decompose trial-to-trial variability in joint kinematics into variability that stabilizes and destabilizes task-important performance variables. Comparing the amount of variability stabilizing and destabilizing task-important variables enabled us to identify the variable of primary importance for the task. We measured maximal isometric voluntary force of three muscle groups in the right leg. Independent of age and muscle strength, old and young adults similarly prioritized stability of the ground reaction force vector during sit-to-stand. Old compared to young adults employed greater motor flexibility, stabilizing ground reaction forces during sit-to-sand. We concluded that freeing those degrees of freedom that stabilize task-important variables is a strategy used by the aging neuromuscular system to compensate for strength deficits.
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Affiliation(s)
- Christian Greve
- University of Groningen, University Medical Center Groningen, Center for Human Movement Science, Groningen, The Netherlands
| | - Wiebren Zijlstra
- Institute of Movement and Sports Gerontology, German Sport University, Cologne, Germany
| | - Tibor Hortobágyi
- University of Groningen, University Medical Center Groningen, Center for Human Movement Science, Groningen, The Netherlands
| | - Raoul M. Bongers
- University of Groningen, University Medical Center Groningen, Center for Human Movement Science, Groningen, The Netherlands
- * E-mail:
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39
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Singh T, Zatsiorsky VM, Latash ML. Contrasting effects of fatigue on multifinger coordination in young and older adults. J Appl Physiol (1985) 2013; 115:456-67. [PMID: 23743395 PMCID: PMC3742945 DOI: 10.1152/japplphysiol.00375.2013] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Accepted: 05/30/2013] [Indexed: 11/22/2022] Open
Abstract
We investigated the effects of fatigue produced by timed maximal voluntary contraction (MVC) of the index finger of the right hand on performance in MVC and accurate cyclic force production tasks in right-handed young (Young group) and strength-matched elderly (Elderly group) participants. We hypothesized that, before fatigue, the Elderly group would show weaker force-stabilizing synergies and smaller adaptive changes in the synergy index during fatigue. Synergies were defined as covaried adjustments of neural commands to fingers (finger modes) across trials that stabilize total force. Fatigue caused a significant reduction in the MVC, which was larger in the Young group compared with the Elderly group for both fatigued finger (index finger) and four fingers (index, middle, ring, and little fingers pressing together). Indexes of finger enslaving (lack of individuation) increased with fatigue in both groups. The index of force-stabilizing synergies was similar for the two groups before fatigue, while its increase with fatigue was significantly larger in the Elderly group compared with the Young group. We infer that changes in the indexes of finger interaction (enslaving) and coordination (synergy) with age seem to be correlated with changes in muscle strength. This correlation may be causally related to the progressive death of neurons at different levels of the neuromotor hierarchy. The surprisingly large changes in the synergy index with fatigue in older adults suggest that, by itself, aging does not necessarily lead to impairment in synergic control. Strength training may be a method to avoid age-related decrement in finger interaction and coordination.
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Affiliation(s)
- Tarkeshwar Singh
- Department of Biomedical Engineering, Cleveland Clinic, Cleveland, Ohio 44195, USA.
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Martin JR, Terekhov AV, Latash ML, Zatsiorsky VM. Optimization and variability of motor behavior in multifinger tasks: what variables does the brain use? J Mot Behav 2013; 45:289-305. [PMID: 23742067 PMCID: PMC4064684 DOI: 10.1080/00222895.2013.792234] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The neural control of movement has been described using different sets of elemental variables. Two possible sets of elemental variables have been suggested for finger pressing tasks: the forces of individual fingers and the finger commands (also called finger modes or central commands). The authors analyzed which of the 2 sets of the elemental variables is more likely used in the optimization of the finger force sharing and which set is used for the stabilization of performance. They used two recently developed techniques-the analytical inverse optimization (ANIO) and the uncontrolled manifold (UCM) analysis-to evaluate each set of elemental variables with respect to both aspects of performance. The results of the UCM analysis favored the finger commands as the elemental variables used for performance stabilization, while ANIO worked equally well on both sets of elemental variables. A simple scheme is suggested as to how the CNS could optimize a cost function dependent on the finger forces, but for the sake of facilitation of the feed forward control it substitutes the original cost function by a cost function, which is convenient to optimize in the space of finger commands.
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Affiliation(s)
- Joel R. Martin
- Department of Kinesiology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Alexander V. Terekhov
- Institut des Systèmes Intelligents et de Robotique, Université Pierre et Marie Curie, Paris 75005, France
| | - Mark L. Latash
- Department of Kinesiology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Vladimir M. Zatsiorsky
- Department of Kinesiology, The Pennsylvania State University, University Park, PA 16802, USA
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Singh T, Zatsiorsky VM, Latash ML. Adaptations to fatigue of a single digit violate the principle of superposition in a multi-finger static prehension task. Exp Brain Res 2013; 225:589-602. [PMID: 23322417 DOI: 10.1007/s00221-013-3403-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Accepted: 12/27/2012] [Indexed: 10/27/2022]
Abstract
We investigated the effects of exercise-induced fatigue of a digit on the biomechanics of a static prehension task. The participants were divided into two groups. One group performed the fatiguing exercise using the thumb (group-thumb) and the second group performed the exercise using the index finger (group-index). We analyzed the prehensile action as being based on a two-level hierarchy. Our first hypothesis was that fatigue of the thumb would have stronger effects at the upper level (action shared between the thumb and all four fingers combined-virtual finger) and fatigue of the index finger would have stronger effects at the lower level of the hierarchy (action of the virtual finger shared among actual fingers). We also hypothesized that fatigue would cause a decrease in the normal force applied by the exercised digit and correspondingly lead to a decrease in the normal force applied by the opposing digit(s). Our third hypothesis was that fatigue would leave the tangential forces unaffected. Fatigue led to a significant drop in the normal force of both exercised and non-exercised (opposing) digits. The tangential forces of the exercised digits increased after fatigue. This led to a drop in the safety margin in the group-thumb, but not group-index. As such, the results supported the first two hypotheses but not the third hypothesis. Overall, the results suggested that fatigue triggered a chain reaction that involved both forces and moments of force produced by individual digits leading to a violation of the principle of superposition. The findings are interpreted within the framework of the referent configuration hypothesis.
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Affiliation(s)
- Tarkeshwar Singh
- Department of Biomedical Engineering, Cleveland Clinic, Cleveland, OH, 44195, USA.
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42
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Abstract
A hypothesis was proposed that the central nervous system controls force production by the fingers through hypothetical neural commands. The neural commands are scaled between values of 0 to 1, indicating no intentional force production or maximal voluntary contraction (MVC) force production, respectively. A matrix of interfinger connections transforms neural commands into finger forces. Two methods have been proposed to compute the interfinger connection matrix. The first method uses only single finger MVC trials and multiplies the interfinger connection matrix by a gain factor. The second method uses a neural network model based on experimental data. The performance of the two methods was compared on the MVC data and on a data set of submaximal forces, collected over a range of total forces and moments of force. The methods were compared in terms of (1) ability to predict finger forces, (2) accuracy of neural command reconstruction, and (3) preserved planarity of force data for submaximal force production task. Both methods did a reasonable job of predicting the total force in multifinger MVC trials; however, the neural network model performed better in regards to all other criteria. Overall, the results indicate that for modeling multifinger interaction the neural network method is preferable.
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Park J, Lewis MM, Huang X, Latash ML. Effects of olivo-ponto-cerebellar atrophy (OPCA) on finger interaction and coordination. Clin Neurophysiol 2012. [PMID: 23182835 DOI: 10.1016/j.clinph.2012.10.021] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVES We investigated changes in finger interaction and coordination in patients with olivo-ponto-cerebellar atrophy (OPCA) using the recently developed approach to motor synergies based on the principle of motor abundance. METHODS OPCA patients and control subjects performed sets of maximal and submaximal force production tasks by the fingers of each of the hands. Indices of multi-finger synergies were quantified within the framework of the uncontrolled manifold hypothesis. RESULTS The patients showed lower maximal forces, higher indices of finger interdependence (enslaving), and lower indices of multi-finger synergies stabilizing total force in four-finger tasks. In addition, the patients showed an impaired ability to adjust synergies in preparation to a quick action (small and delayed anticipatory synergy adjustments). The synergy indices showed significant correlations with the clinical scores (both UPDRS total motor scores and ataxia related sub-scores). The observed changes in the indices of finger interaction and coordination were qualitatively similar to those reported earlier for patients with Parkinson's disease; however, the magnitude of the changes was much higher in the OPCA group. CONCLUSIONS These findings fit the hypotheses on the role of the cerebellum in assembling motor synergies and in the feed-forward control of action. They suggest that the synergy index measured in artificial, constrained laboratory tasks may be predictive of more general changes in motor behavior. SIGNIFICANCE The results suggest that studies of multi-digit synergies may be particularly sensitive to subcortical disorders and may provide a much-needed tool for quantitative assessment of impaired coordination in such patients.
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Affiliation(s)
- Jaebum Park
- Department of Kinesiology, The Pennsylvania State University, University Park, PA 16802, USA
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Abstract
We investigated the effect of fatigue produced by timed maximal voluntary contraction (MVC) of the index finger of one of the hands on performance in MVC and accurate cyclic force production tasks in right-handed subjects. Based on earlier studies, we hypothesized that fatigue would produce an increase in the indices of force-stabilizing synergies in both hands as well as between the hands in two-hand tasks. Synergies were defined as co-varied adjustments of commands to fingers (modes) across cycles that stabilized total force. Fatigue caused a significant reduction in the MVC of the exercised as well as the non-exercised hand. Indices of finger enslaving (lack of individuation) increased with fatigue in both hands, although the increase was significant in the exercised hand only. In contrast to the significant effects of fatigue on MVC forces performed by the non-exercised hand, there were no comparable transfer effects on the root mean square errors during accurate force production. During one-hand tasks, both hands showed high indices of force-stabilizing synergies. These indices were larger in the left hand. Fatigue led to a general increase in synergy indices. Exercise by the left hand had stronger effects on synergy indices seen in both hands. Exercise by the right hand showed ipsilateral effects only. Smaller effects of fatigue were observed on accuracy of performance of the force-down segments of the force cycles compared to the force-up segments. For the bimanual tasks, synergies were analyzed at two hierarchical levels, two-hand (four-finger) and within-a-hand (two-finger). An increase in the synergy index with fatigue was observed at the lower (two-finger) level of the hierarchy only. We interpret the lack of effects of fatigue at the upper (two-hand) level as a consequence of a trade-off between synergies at different levels of the hierarchy. The differences between the hands are discussed within the dynamic dominance hypothesis.
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Park J, Wu YH, Lewis MM, Huang X, Latash ML. Changes in multifinger interaction and coordination in Parkinson's disease. J Neurophysiol 2012; 108:915-24. [PMID: 22552184 DOI: 10.1152/jn.00043.2012] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
In this study, we tested several hypotheses related to changes in finger interaction and multifinger synergies during multifinger force production tasks in Parkinson's disease. Ten patients with Parkinson's disease, mostly early stage, and 11 healthy control subjects participated in the study. Synergies were defined as covaried adjustment of commands to fingers that stabilized the total force produced by the hand. Both Parkinson's disease patients and control subjects performed accurate isometric force production tasks with the fingers of both the dominant and nondominant hands. The Parkinson's disease patients showed significantly lower maximal finger forces and higher unintended force production (enslaving). These observations suggest that changes in supraspinal control have a major effect on finger individuation. The synergy indexes in the patients were weaker in both steady-state and cyclic force production tasks compared with the controls. These indexes also were stronger in the left (nondominant) hand in support of the dynamic-dominance hypothesis. Half of the patients could not perform the cyclic task at the highest frequency (2 Hz). Anticipatory adjustments of synergies prior to a quick force pulse production were delayed and reduced in the patients compared with the controls. Similar differences were observed between the asymptomatic hands of the patients with symptoms limited to one side of the body and matched hands of control subjects. Our study demonstrates that the elusive changes in motor coordination in Parkinson's disease can be quantified objectively, even in patients at a relatively early stage of the disease. The results suggest an important role of the basal ganglia in synergy formation and demonstrate a previously unknown component of impaired feedforward control in Parkinson's disease reflected in the reduced and delayed anticipatory synergy adjustments.
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Affiliation(s)
- Jaebum Park
- Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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Latash ML. The bliss (not the problem) of motor abundance (not redundancy). Exp Brain Res 2012; 217:1-5. [PMID: 22246105 DOI: 10.1007/s00221-012-3000-4] [Citation(s) in RCA: 359] [Impact Index Per Article: 29.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Accepted: 01/02/2012] [Indexed: 11/26/2022]
Abstract
Motor control is an area of natural science exploring how the nervous system interacts with other body parts and the environment to produce purposeful, coordinated actions. A central problem of motor control-the problem of motor redundancy-was formulated by Nikolai Bernstein as the problem of elimination of redundant degrees-of-freedom. Traditionally, this problem has been addressed using optimization methods based on a variety of cost functions. This review draws attention to a body of recent findings suggesting that the problem has been formulated incorrectly. An alternative view has been suggested as the principle of abundance, which considers the apparently redundant degrees-of-freedom as useful and even vital for many aspects of motor behavior. Over the past 10 years, dozens of publications have provided support for this view based on the ideas of synergic control, computational apparatus of the uncontrolled manifold hypothesis, and the equilibrium-point (referent configuration) hypothesis. In particular, large amounts of "good variance"-variance in the space of elements that has no effect on the overall performance-have been documented across a variety of natural actions. "Good variance" helps an abundant system to deal with secondary tasks and unexpected perturbations; its amount shows adaptive modulation across a variety of conditions. These data support the view that there is no problem of motor redundancy; there is bliss of motor abundance.
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Affiliation(s)
- Mark L Latash
- Department of Kinesiology, The Pennsylvania State University, Rec.Hall-267, University Park, PA 16802, USA.
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Park J, Singh T, Zatsiorsky VM, Latash ML. Optimality versus variability: effect of fatigue in multi-finger redundant tasks. Exp Brain Res 2011; 216:591-607. [PMID: 22130781 DOI: 10.1007/s00221-011-2963-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Accepted: 11/18/2011] [Indexed: 11/29/2022]
Abstract
We used two methods to address two aspects of multi-finger synergies and their changes after fatigue of the index finger. Analytical inverse optimization (ANIO) was used to identify cost functions and corresponding spaces of optimal solutions over a broad range of task parameters. Analysis within the uncontrolled manifold (UCM) hypothesis was used to quantify co-variation of finger forces across repetitive trials that helped reduce variability of (stabilized) performance variables produced by all the fingers together. Subjects produced steady-state levels of total force and moment of force simultaneously as accurately as possible by pressing with the four fingers of the right hand. Both before and during fatigue, the subjects performed single trials for many force-moment combinations covering a broad range; the data were used for the ANIO analysis. Multiple trials were performed at two force-moment combinations; these data were used for analysis within the UCM hypothesis. Fatigue was induced by 1-min maximal voluntary contraction exercise by the index finger. Principal component (PC) analysis showed that the first two PCs explained over 90% of the total variance both before and during fatigue. Hence, experimental observations formed a plane in the four-dimensional finger force space both before and during fatigue conditions. Based on this finding, quadratic cost functions with linear terms were estimated from the experimental data. The dihedral angle between the plane of optimal solutions and the plane of experimental observations (D (ANGLE)) was very small (a few degrees); it increased during fatigue. There was an increase in fatigue of the coefficient at the quadratic term for the index finger force balanced by a drop in the coefficients for the ring and middle fingers. Within each finger pair (index-middle and ring-little), the contribution of the "central" fingers to moment production increased during fatigue. An index of antagonist moment production dropped with fatigue. Fatigue led to higher co-variation indices during pronation tasks (index finger is an agonist) but opposite effects during supination tasks. The results suggest that adaptive changes in co-variation indices that help stabilize performance may depend on the role of the fatigued element, agonist or antagonist.
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Affiliation(s)
- Jaebum Park
- Department of Kinesiology, Rec.Hall-39, The Pennsylvania State University, University Park, PA 16802, USA,
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Park J, Zatsiorsky VM, Latash ML. Finger coordination under artificial changes in finger strength feedback: a study using analytical inverse optimization. J Mot Behav 2011; 43:229-35. [PMID: 21512936 DOI: 10.1080/00222895.2011.568990] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A recently developed method of analytical inverse optimization (ANIO) was used to compute cost functions based on sets of experimental observations in 4-finger pressing tasks with accurate total force and moment production. In different series, feedback on total force and moment was provided using the index finger force at its value, doubled, or halved. Finger force data across different force-moment combinations formed a plane. This allowed reconstructing cost functions as 2nd-order polynomials with linear terms. Changes in the coefficients of the cost function across the 3 series allowed the authors to offer a biomechanical interpretation related to constraints on finger forces with different lever arms. ANIO allows the authors to describe preferred regions within the space of solutions for redundant tasks in terms of cost functions.
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Affiliation(s)
- Jaebum Park
- Department of Kinesiology, the Pennsylvania State University, University Park, PA 16802, USA
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Effects of muscle fatigue on multi-muscle synergies. Exp Brain Res 2011; 214:335-50. [PMID: 21842189 DOI: 10.1007/s00221-011-2831-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Accepted: 08/02/2011] [Indexed: 10/17/2022]
Abstract
We studied the effects of fatigue of ankle dorsiflexors on multi-muscle synergies defined as co-varied adjustments of elemental variables (M-modes) that stabilize a task-related performance variable (trajectory of the center of pressure, COP). M-modes were defined as muscle groups with parallel changes in activation levels. Healthy participants performed voluntary body sway in the anterior-posterior direction while trying to minimize sway in the medio-lateral direction at 0.25, 0.5, and 0.75 Hz. The trials were repeated before and during fatigue induced with a timed voluntary contraction against a constant load. Factor extraction using the principal component method was used to identify four M-modes within the space of integrated indices of muscle activity. Variance in the M-mode space at different phases across sway cycles was partitioned into two components, one that did not affect the average value of COP shift and the other that did. There were no significant effects of fatigue on variability of performance of the explicit task and on the amplitude of the COP shift. Variance of muscle activation indices and M-mode magnitudes increased during fatigue for muscles (and M-modes) both involved and not involved in the fatiguing exercise. Most of the M-mode variance increase was within the sub-space compatible with the unchanged COP trajectory resulting in an increase of the index of the multi-M-mode synergy. We conclude that one of the adaptive mechanisms to fatigue within a redundant multi-muscle system involves an increase in the variance of activation of non-fatigued muscles with a simultaneous increase in co-variation among muscle activations. The findings can be interpreted within the referent configuration hypothesis on the control of whole-body actions.
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Fuller JR, Fung J, Côté JN. Time-dependent adaptations to posture and movement characteristics during the development of repetitive reaching induced fatigue. Exp Brain Res 2011; 211:133-43. [DOI: 10.1007/s00221-011-2661-8] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Accepted: 03/24/2011] [Indexed: 10/18/2022]
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