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  1. Article ; Online: Neuromuscular control: from a biomechanist's perspective.

    Mulla, Daanish M / Keir, Peter J

    Frontiers in sports and active living

    2023  Volume 5, Page(s) 1217009

    Abstract: Understanding neural control of movement necessitates a collaborative approach between many disciplines, including biomechanics, neuroscience, and motor control. Biomechanics grounds us to the laws of physics that our musculoskeletal system must obey. ... ...

    Abstract Understanding neural control of movement necessitates a collaborative approach between many disciplines, including biomechanics, neuroscience, and motor control. Biomechanics grounds us to the laws of physics that our musculoskeletal system must obey. Neuroscience reveals the inner workings of our nervous system that functions to control our body. Motor control investigates the coordinated motor behaviours we display when interacting with our environment. The combined efforts across the many disciplines aimed at understanding human movement has resulted in a rich and rapidly growing body of literature overflowing with theories, models, and experimental paradigms. As a result, gathering knowledge and drawing connections between the overlapping but seemingly disparate fields can be an overwhelming endeavour. This review paper evolved as a need for us to learn of the diverse perspectives underlying current understanding of neuromuscular control. The purpose of our review paper is to integrate ideas from biomechanics, neuroscience, and motor control to better understand how we voluntarily control our muscles. As biomechanists, we approach this paper starting from a biomechanical modelling framework. We first define the theoretical solutions (i.e., muscle activity patterns) that an individual could feasibly use to complete a motor task. The theoretical solutions will be compared to experimental findings and reveal that individuals display structured muscle activity patterns that do not span the entire theoretical solution space. Prevalent neuromuscular control theories will be discussed in length, highlighting optimality, probabilistic principles, and neuromechanical constraints, that may guide individuals to families of muscle activity solutions within what is theoretically possible. Our intention is for this paper to serve as a primer for the neuromuscular control scientific community by introducing and integrating many of the ideas common across disciplines today, as well as inspire future work to improve the representation of neural control in biomechanical models.
    Language English
    Publishing date 2023-07-05
    Publishing country Switzerland
    Document type Journal Article ; Review
    ISSN 2624-9367
    ISSN (online) 2624-9367
    DOI 10.3389/fspor.2023.1217009
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Relative motion between the flexor digitorum superficialis tendon and subsynovial connective tissue is time dependent.

    Kociolek, Aaron M / Keir, Peter J

    Journal of orthopaedic research : official publication of the Orthopaedic Research Society

    2023  Volume 41, Issue 8, Page(s) 1661–1669

    Abstract: The subsynovial connective tissue is an integral component of flexor tendon gliding in the carpal tunnel, which is strained during longitudinal tendon displacement. We tested the effects of repetition frequency and finger load on flexor tendon function ... ...

    Abstract The subsynovial connective tissue is an integral component of flexor tendon gliding in the carpal tunnel, which is strained during longitudinal tendon displacement. We tested the effects of repetition frequency and finger load on flexor tendon function throughout active finger movement. Eleven participants performed metacarpophalangeal joint flexion/extension of the long finger cyclically at three repetition frequencies (0.75, 1.00, 1.25 Hz) and two finger loads (3.5, 7 N). Relative displacement between the flexor digitorum superficialis tendon and subsynovial connective tissue was assessed as the shear-strain index with color ultrasound throughout the entire time history of finger flexion and extension. In addition, long finger joint angles were measured with electrogoniometry while flexor digitorum superficialis and extensor digitorum muscle activities were measured with fine-wire electromyography to characterize the finger movements. The shear-strain index increased with greater finger flexion (p = 0.001), representing higher relative displacement between tendon and subsynovial connective tissue; however, no changes were observed throughout finger extension. The shear-strain index also increased with higher repetition frequencies (p = 0.013) and finger loads (p = 0.029), further modulating time-dependent effects during finger flexion versus extension. Using ultrasound, we characterized the time-dependent response of the shear-strain index, in vivo, providing valuable data on flexor tendon function during active finger movement. Our results infer greater subsynovial connective tissue strain and shear during repetitive and forceful finger movements. Future research characterizing time-dependent effects in carpal tunnel syndrome patients may further elucidate the relations between subsynovial connective tissue function, damage, and carpal tunnel syndrome.
    MeSH term(s) Humans ; Carpal Tunnel Syndrome/diagnostic imaging ; Connective Tissue/diagnostic imaging ; Connective Tissue/physiology ; Tendons/physiology ; Fingers ; Hand
    Language English
    Publishing date 2023-02-07
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 605542-4
    ISSN 1554-527X ; 0736-0266
    ISSN (online) 1554-527X
    ISSN 0736-0266
    DOI 10.1002/jor.25524
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  3. Article ; Online: Effects of sex and age on work-related upper extremity musculoskeletal disorders in Ontario, Canada.

    Tilley, Paul M / Mulla, Daanish M / Keir, Peter J

    Work (Reading, Mass.)

    2023  Volume 75, Issue 3, Page(s) 1009–1020

    Abstract: Background: Effective targeting of workplace upper extremity musculoskeletal disorder (MSD) prevention strategies requires the identification of demographic groups most at risk. Workers' compensation data provides an effective means of surveillance of ... ...

    Abstract Background: Effective targeting of workplace upper extremity musculoskeletal disorder (MSD) prevention strategies requires the identification of demographic groups most at risk. Workers' compensation data provides an effective means of surveillance of MSDs at the population level.
    Objective: The primary purpose of this study was to identify the effects of age and sex on rates of tendon injuries of the wrist and hand, carpal tunnel syndrome (CTS), epicondylitis, and soft tissue shoulder injuries in Ontario, Canada between 2000-2019 using workers' compensation data from the Association of Workers Compensation Boards of Canada (AWCBC).
    Methods: Age and sex specific rates of lost-time injury claims from the four identified injury categories as well as "non-specific" upper extremity MSDs which did not fit into the four categories were calculated by standardizing injury claim totals with "at-risk" population estimates from the Canada Labour Force Survey. A multiple regression analysis was used to analyze the effects of age and sex on rates of specific injury claims.
    Results: Statistically significant age and sex effects were identified for rates of claims from tendon injuries of the wrist and hand, CTS, and shoulder injuries, while only age effects were significant for epicondylitis. Between 2000-2019, rates of claims from the four injury categories studied and the magnitude of the age and sex effects declined substantially over time.
    Conclusion: Detailed surveillance of workplace ergonomic hazards in Ontario workplaces is needed to determine what is causing rates of upper extremity claims to decline.
    MeSH term(s) Male ; Female ; Humans ; Ontario/epidemiology ; Occupational Diseases/epidemiology ; Occupational Diseases/etiology ; Occupational Diseases/prevention & control ; Carpal Tunnel Syndrome/epidemiology ; Carpal Tunnel Syndrome/etiology ; Upper Extremity ; Musculoskeletal Diseases/etiology ; Musculoskeletal Diseases/complications ; Shoulder Injuries/complications ; Workers' Compensation ; Tendon Injuries/complications
    Language English
    Publishing date 2023-01-10
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 1394194-x
    ISSN 1875-9270 ; 1051-9815
    ISSN (online) 1875-9270
    ISSN 1051-9815
    DOI 10.3233/WOR-220175
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Carpal tunnel tendon and sub-synovial connective tissue mechanics are affected by reduced venous return.

    Wong, Andrew Y W / Farias Zuniga, Amanda / Keir, Peter J

    Clinical biomechanics (Bristol, Avon)

    2023  Volume 107, Page(s) 106039

    Abstract: Background: The effects of blood flow occlusion and sex-specific differences in tendon-subsynovial connective tissue relative strain are not well understood. Thus, the purpose of this study was to investigate the influence of blood flow, biological sex, ...

    Abstract Background: The effects of blood flow occlusion and sex-specific differences in tendon-subsynovial connective tissue relative strain are not well understood. Thus, the purpose of this study was to investigate the influence of blood flow, biological sex, and finger movement speed on carpal tunnel tendon mechanics to further develop our understanding of carpal tunnel syndrome.
    Methods: Colour Doppler ultrasound imaging quantified relative motion between flexor digitorum superficialis tendon and subsynovial connective tissue in 20 healthy male and female participants during repetitive finger flexion-extension under brachial occlusion of blood flow and two movement speeds (0.75 & 1.25 Hz).
    Findings: Flexor digitorum superficialis and subsynovial connective tissue displacement decreased with occlusion (small effect) and fast speed (large effect). Speed × Condition interactions were found for mean FDS displacement and peak FDS velocity, where slow speed with occlusion reduced both outcomes. Movement speed had a small but significant effect on tendon-subsynovial connective tissue shear outcomes, where MVR decreased with fast finger motion.
    Interpretation: These results suggest the influence of localized edema through venous occlusion on tendon-subsynovial connective tissue gliding within the carpal tunnel. This insight further develops our understanding of carpal tunnel syndrome pathophysiology and suggests ramifications on carpal tunnel tissue motion when the local fluid environment of the carpal tunnel is disturbed.
    MeSH term(s) Male ; Female ; Humans ; Carpal Tunnel Syndrome ; Connective Tissue ; Tendons ; Wrist ; Movement ; Tendon Injuries ; Vascular Diseases
    Language English
    Publishing date 2023-07-05
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 632747-3
    ISSN 1879-1271 ; 0268-0033
    ISSN (online) 1879-1271
    ISSN 0268-0033
    DOI 10.1016/j.clinbiomech.2023.106039
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  5. Article ; Online: Thirty Minutes of Sub-diastolic Blood Flow Occlusion Alters Carpal Tunnel Tissue Function and Mechanics.

    Farias Zuniga, Amanda / Keir, Peter J

    Ultrasound in medicine & biology

    2022  Volume 48, Issue 6, Page(s) 1110–1121

    Abstract: There is evidence that carpal tunnel syndrome (CTS) development is driven by vascular factors, specifically those resulting from ischemia and edema. The purpose of this study was to investigate the vascular hypothesis of CTS development by quantifying ... ...

    Abstract There is evidence that carpal tunnel syndrome (CTS) development is driven by vascular factors, specifically those resulting from ischemia and edema. The purpose of this study was to investigate the vascular hypothesis of CTS development by quantifying the temporal effects of 30 min of sub-diastolic brachial blood flow occlusion on median nerve edema, intraneural blood flow velocity, nerve function as measured through nerve conduction study (NCS), tendon-connective tissue mechanics and carpal tunnel tissue stiffness. Forty healthy volunteers underwent 30 min of sub-diastolic brachial occlusion while an NCS and ultrasound examination were performed consecutively every 5 min. Motor latency (p < 0.001), sensory conduction velocity (p < 0.001), sensory amplitude (p = 0.04), nerve blood flow (p < 0.001), peak relative flexor digitorum superficialis tendon-sub-synovial connective tissue displacement (p = 0.02) and shear strain (p = 0.04) were significantly affected by partial ischemia. Our results highlight the dependency of carpal tunnel tissue function on adequate blood flow.
    MeSH term(s) Carpal Tunnel Syndrome/diagnostic imaging ; Connective Tissue ; Humans ; Ischemia ; Median Nerve/diagnostic imaging ; Tendons/physiology
    Language English
    Publishing date 2022-03-14
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 186150-5
    ISSN 1879-291X ; 0301-5629
    ISSN (online) 1879-291X
    ISSN 0301-5629
    DOI 10.1016/j.ultrasmedbio.2022.02.008
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  6. Article ; Online: Diagnostic and Research Techniques in Carpal Tunnel Syndrome.

    Zuniga, Amanda Farias / Keir, Peter J

    Critical reviews in biomedical engineering

    2020  Volume 47, Issue 6, Page(s) 457–471

    Abstract: Carpal tunnel syndrome is the most common neuropathy, costing upward of $2B USD annually in North America. Carpal tunnel syndrome is a result of chronic trauma to the median nerve, resulting in nerve damage, decreased conductivity of nerve impulses, and ... ...

    Abstract Carpal tunnel syndrome is the most common neuropathy, costing upward of $2B USD annually in North America. Carpal tunnel syndrome is a result of chronic trauma to the median nerve, resulting in nerve damage, decreased conductivity of nerve impulses, and ultimately presents with clinical symptoms such as pain, tingling, numbness, and thumb muscle atrophy in severe cases. Although patient history, symptoms, and a nerve conduction study are the primary diagnosis tools, there are several techniques and tools that may be used to assess carpal tunnel syndrome and characterize the condition. The purpose of this critical review is to discuss the multitude of techniques that can be applied to study carpal tunnel syndrome, including Phalen's and Tinel's tests, nerve conduction study, Semmes-Weinstein monofilaments, laser Doppler flowmetry, pressure catheters, and ultrasound and magnetic resonance imaging. Additionally, this review discusses the reliability, sensitivity, and accuracy of these methods. A combination of these techniques may ultimately improve the accuracy in diagnosing carpal tunnel syndrome, especially in cases where nerve conduction study results are borderline or inconclusive by analyzing other aspects that may differently contribute to the development of carpal tunnel syndrome.
    MeSH term(s) Biomedical Research/methods ; Biomedical Research/standards ; Carpal Tunnel Syndrome/diagnosis ; Carpal Tunnel Syndrome/physiopathology ; Humans ; Laser-Doppler Flowmetry ; Magnetic Resonance Imaging ; Ultrasonography
    Language English
    Publishing date 2020-04-30
    Publishing country United States
    Document type Journal Article ; Review
    ZDB-ID 1411103-2
    ISSN 1943-619X ; 0278-940X
    ISSN (online) 1943-619X
    ISSN 0278-940X
    DOI 10.1615/CritRevBiomedEng.2020030827
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  7. Article ; Online: Investigating acute changes in osteoarthritic cartilage by integrating biomechanics and statistical shape models of bone: data from the osteoarthritis initiative.

    Gatti, Anthony A / Keir, Peter J / Noseworthy, Michael D / Maly, Monica R

    Magma (New York, N.Y.)

    2022  Volume 35, Issue 5, Page(s) 861–873

    Abstract: Objective: This proof-of-principle study integrates joint reaction forces (JRFs) and bone shape to assess acute cartilage changes from walking and cycling.: Methods: Sixteen women with symptomatic knee osteoarthritis were recruited. Biomechanical ... ...

    Abstract Objective: This proof-of-principle study integrates joint reaction forces (JRFs) and bone shape to assess acute cartilage changes from walking and cycling.
    Methods: Sixteen women with symptomatic knee osteoarthritis were recruited. Biomechanical assessment estimated JRFs during walking and cycling. Subsamples had magnetic resonance imaging (MRI) performed before and after a 25-min walking (n = 7) and/or cycling (n = 9) activity. MRI scans were obtained to assess cartilage shape and composition (T
    Results: Cartilage thickness (interior lateral, Δ - 0.10 mm) and T
    Discussion: Walking and cycling caused distinct patterns of cartilage deformation, which depended on knee JRFs and bone morphology. For the first time, these results show that cartilage deformation is dependent on bone shapes and JRFs in vivo.
    MeSH term(s) Biomechanical Phenomena ; Cartilage, Articular/diagnostic imaging ; Cartilage, Articular/pathology ; Female ; Femur/diagnostic imaging ; Femur/pathology ; Humans ; Knee Joint/diagnostic imaging ; Knee Joint/pathology ; Magnetic Resonance Imaging/methods ; Osteoarthritis, Knee/diagnostic imaging ; Tibia
    Language English
    Publishing date 2022-03-14
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 1160826-2
    ISSN 1352-8661 ; 0968-5243
    ISSN (online) 1352-8661
    ISSN 0968-5243
    DOI 10.1007/s10334-022-01004-8
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  8. Article ; Online: Effect of wrist posture, rate of force development/relaxation, and isotonic contractions on finger force independence.

    May, Stephen E / Keir, Peter J

    Journal of electromyography and kinesiology : official journal of the International Society of Electrophysiological Kinesiology

    2018  Volume 38, Page(s) 215–223

    Abstract: The multi-articular anatomy and inter-connections of the extrinsic finger muscles suggests that wrist posture may affect enslaved finger forces. The purpose of this study was to determine the effects of (i) wrist posture on enslaved finger forces during ... ...

    Abstract The multi-articular anatomy and inter-connections of the extrinsic finger muscles suggests that wrist posture may affect enslaved finger forces. The purpose of this study was to determine the effects of (i) wrist posture on enslaved finger forces during ramp and isotonic exertions, and (ii) the rate of force development on enslaved forces and error. Twelve men performed 3 repetitions of isometric finger flexion and extension force with index and ring fingers with the wrist in 30° flexion, neutral, and 30° extension. Trials consisted of an isotonic contraction at 25% of maximum, and two ramp contractions performed at 25% MVC/s and 10% MVC/s up to 50% MVC, returning to zero at the same rate. Electromyography was recorded from compartments of extensor digitorum (ED) and flexor digitorum superficialis and analyzed at 25% MVC. Wrist posture significantly affected enslaving effect (EE) during extension exertions (F
    MeSH term(s) Adult ; Fingers/physiology ; Humans ; Isotonic Contraction ; Male ; Muscle, Skeletal/physiology ; Pinch Strength ; Posture ; Range of Motion, Articular ; Wrist/physiology
    Language English
    Publishing date 2018-02
    Publishing country England
    Document type Journal Article
    ZDB-ID 1073161-1
    ISSN 1873-5711 ; 1050-6411
    ISSN (online) 1873-5711
    ISSN 1050-6411
    DOI 10.1016/j.jelekin.2017.11.014
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  9. Article ; Online: Effect of Force, Posture, and Repetitive Wrist Motion on Intraneural Blood Flow in the Median Nerve.

    Ehmke, Samantha / Farias Zuniga, Amanda / Keir, Peter J

    Journal of ultrasound in medicine : official journal of the American Institute of Ultrasound in Medicine

    2020  Volume 40, Issue 5, Page(s) 939–950

    Abstract: Objectives: Pinching, deviated wrist postures, and repetitive motion are risk factors for carpal tunnel syndrome. Hypervascularization of the median nerve and increased intraneural blood flow proximal to the carpal tunnel result in finger force and ... ...

    Abstract Objectives: Pinching, deviated wrist postures, and repetitive motion are risk factors for carpal tunnel syndrome. Hypervascularization of the median nerve and increased intraneural blood flow proximal to the carpal tunnel result in finger force and deviated wrist postures. The purpose of this study was to determine the effects of pinching with and without force, wrist posture, and repetitive wrist motion on intraneural blood flow in the median nerve.
    Methods: Eleven healthy and 11 carpal tunnel syndrome-symptomatic individuals completed 3 sections of this study: 15 pinch posture force trials, 3 repetitive wrist motion trials, and 3 static wrist posture trials. Intraneural blood flow (centimeters per second) was measured with pulsed wave Doppler ultrasound during each trial. Transverse B-mode images obtained from static trials were used to calculate the median nerve cross-sectional area and circumference.
    Results: An analysis of variance statistical analysis revealed significant main effects of pinch posture force (F
    Conclusions: Flexed wrists as well as applied finger and thumb forces increase median nerve blood flow at the entry to the carpal tunnel, which may negatively affect the median nerve.
    MeSH term(s) Carpal Tunnel Syndrome/diagnostic imaging ; Humans ; Median Nerve/diagnostic imaging ; Posture ; Wrist/diagnostic imaging ; Wrist Joint/diagnostic imaging
    Language English
    Publishing date 2020-09-08
    Publishing country England
    Document type Journal Article
    ZDB-ID 604829-8
    ISSN 1550-9613 ; 0278-4297
    ISSN (online) 1550-9613
    ISSN 0278-4297
    DOI 10.1002/jum.15467
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  10. Article: Muscle Architecture and Subcutaneous Fat Measurements of Rectus Femoris and Vastus Lateralis at Optimal Length Aided by a Novel Ultrasound Transducer Attachment.

    Bulbrook, Brittany D / Chopp-Hurley, Jaclyn N / Wiebenga, Emily G / Pritchard, Janet M / Gatti, Anthony A / Keir, Peter J / Maly, Monica R

    Physiotherapy Canada. Physiotherapie Canada

    2023  Volume 75, Issue 1, Page(s) 74–82

    Abstract: Purpose: ...

    Abstract Purpose:
    Language English
    Publishing date 2023-02-08
    Publishing country Canada
    Document type Journal Article
    ZDB-ID 639189-8
    ISSN 1708-8313 ; 0300-0508
    ISSN (online) 1708-8313
    ISSN 0300-0508
    DOI 10.3138/ptc-2021-0016
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