Stephen H M Brown

Stephen H M Brown
University of Guelph | UOGuelph · Department of Human Health and Nutritional Sciences (HHNS)

PhD

About

132
Publications
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Publications

Publications (132)
Article
Study design: Basic science study of the relationship between spine pathology and the contractile ability of the surrounding muscles. Objective: To investigate single muscle fibre contractile function in a model of progressive spine mineralization (ENT1-/- mice). Summary of background data: Altered muscle structure and function have been assoc...
Article
Cognitive motor interference (CMI) is a psychomotor phenomenon characterized by alterations in kinematic spatial-temporal parameters during concurrent cognitive and motor tasks (i.e. dual-tasking). Previous literature has demonstrated that cognitive-motor dual-tasking induces alterations gait parameters; however, the influence of CMI on spine refle...
Article
Full-text available
PurposeTo examine whether unilateral multifidus damage could promote degeneration at the L5-6 facet joint (FJ) and compensatory changes in lumbo-pelvic muscles in rats.Methods12 facet clamp, 12 facet sham and 7 control rats were studied. Facet clamp and sham animals had the left L5-6 FJ exposed, and the clamp group had a mild compressive clamp appl...
Article
Full-text available
Low back pain disorders affect more than 80% of adults in their lifetime and are the leading cause of global disability. The muscles attaching to the spine (ie, paraspinal muscles) are critical for proper spine health and play a crucial role in the functioning of the spine and whole body; however, reports of muscle dysfunction and insufficiency in...
Article
Previous work has identified that individuals adopt different dynamic lumbar spine stability responses when experiencing back muscle fatigue, and that the neuromuscular system adjusts multi-joint coordination in response to fatigue. Therefore, this study was designed to determine whether distinct differences in coordination and coordination variabi...
Article
Full-text available
Paraspinal muscles are vital to the functioning of the spine. Changes in muscle physiological cross-sectional area significantly affect spinal loading, but the importance of other muscle biomechanical properties remains unclear. This study explored the changes in spinal loading due to variation in five muscle biomechanical properties: passive stiff...
Article
Full-text available
Purpose Various aspects of paraspinal muscle anatomy, biology, and histology have been studied; however, information on paraspinal muscle contractile function is almost nonexistent, thus hindering functional interpretation of these muscles in healthy individuals and those with low back disorders. The aim of this study was to measure and compare the...
Preprint
Increased serial sarcomere number (SSN) has been observed in rats via downhill running training due to the emphasis on active lengthening contractions; however, little is known about the influence on dynamic contractile function. Therefore, we employed 4 weeks of weighted downhill running training in rats, then assessed soleus SSN and work loop per...
Article
Full-text available
Understanding the processing of tactile information is crucial for the development of biofeedback interventions that target cutaneous mechanoreceptors. Mechanics of the skin have been shown to influence cutaneous tactile sensitivity. It has been established that foot skin mechanics are altered due to foot posture, but whether these changes affect c...
Article
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Background: Few studies have quantified dynamic balance in fencers despite previous suggestions that balance training may be beneficial for these athletes. Generally, asymmetry in dynamic balance performance between the left and right legs can be an indicator of lower extremity injury risk and used to monitor rehabilitation progress. Fencing is re...
Article
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This study investigated feasibility of imaging lumbopelvic musculature and geometry in tandem using upright magnetic resonance imaging (MRI) in asymptomatic adults, and explored the effect of pelvic retroversion on lumbopelvic musculature and geometry. Six asymptomatic volunteers were imaged (0.5 T upright MRI) in 4 postures: standing, standing pel...
Article
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The passive elastic modulus of muscle fiber appears to be size-dependent. The objectives of this study were to determine whether this size effect was evident in the mechanical testing of muscle fiber bundles and to examine whether the muscle fiber bundle cross-section is circular. Muscle fibers and fiber bundles were extracted from lumbar spine mul...
Article
Spine models are typically developed from supine clinical imaging data, and hence clearly do not fully reflect postures that replicate subjects’ clinical symptoms. Our objectives were to develop a method to: (i) estimate the subject-specific sagittal curvature of the whole spine in different postures from limited imaging data, (ii) obtain muscle li...
Article
Natural adult aging is associated with declines in skeletal muscle performance, including impaired Ca2+ sensitivity and a slowing of rapid force production (rate of force redevelopment; ktr). The purpose of this study was to investigate the relationship between impaired Ca2+ sensitivity and ktr of single muscle fibres from young and older adults. P...
Article
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The number and organization of sarcomeres within a muscle (referred to as muscle architecture) can be used to predict functional capability. The six deep external rotator muscles of the hip (piriformis (PI), quadratus femoris (QF), obturator internus (OI), obturator externus (OE), superior gemellus (SG), and inferior gemellus (IG)) play a role in b...
Article
Study design: Pre-clinical study in rodents. Objective: To investigate changes in biomechanical properties of paraspinal muscles following a posterior spinal surgery in an animal model SUMMARY OF BACKGROUND DATA.: Posterior spine surgery damages paraspinal musculature per histological and imaging studies. The biomechanical effects of these chang...
Article
Naturally occurring spine osteoarthritis is clinically associated with the manifestation of chronic inflammatory muscle (myofascial) disease. The purpose of this study was to investigate the causal association between experimentally induced spine osteoarthritis and neurogenic inflammatory responses within neurosegmentally linked myotomes. Wistar Ky...
Article
Introduction Passive mechanical properties of the paraspinal muscles are important to the biomechanical functioning of the spine. In most computational models, the same biomechanical properties are assumed for each paraspinal muscle group, while cross sectional area or fatty infiltration in these muscles have been reported to differ between the ver...
Article
Full-text available
Objective Spinal‐muscle morphological differences between weight‐bearing and supine postures have potential diagnostic, prognostic, and therapeutic applications. While the focus to date has been on cervical and lumbar regions, recent findings have associated spinal deformity with smaller paraspinal musculature in the thoracic region. We aim to quan...
Article
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Following active muscle shortening, steady-state isometric force is less than a purely isometric contraction at the same muscle length and level of activation; this is known as residual force depression (rFD). It is unknown whether rFD at the single muscle fiber level can be modified via training. Here we investigated whether rFD in single muscle f...
Article
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PurposeTo assess the effect of upright, seated, and supine postures on lumbar muscle morphometry at multiple spinal levels and for multiple muscles.Methods Six asymptomatic volunteers were imaged (0.5 T upright open MRI) in 7 postures (standing, standing holding 8 kg, standing 45° flexion, seated 45° flexion, seated upright, seated 45° extension, a...
Article
Inter-segmental coordination patterns and mechanical energy transfer were compared between vertical jumping tasks which possess different countermovement characteristics. Thirteen participants completed squat (SJ), countermovement (CMJ) and drop (DVJ) vertical jumps. Inter-segmental coordination patterns became more out-of-phase with increases in c...
Article
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Introduction: The passive mechanical behavior of skeletal muscle represents both important and generally underappreciated biomechanical properties with little attention paid to their trainability. These experiments were designed to gain insight into the trainability of muscle passive mechanical properties in both single fibers and fiber bundles. Me...
Article
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Objective MRI derived spinal‐muscle morphology measurements have potential diagnostic, prognostic, and therapeutic applications in spinal health. Muscle morphology in the thoracic spine is an important determinant of kyphosis severity in older adults. However, the literature on quantification of spinal muscles to date has been limited to cervical a...
Article
Abdominal bracing is a voluntary method of increasing spine stiffness to restrict spine displacement. Previous investigations of abdominal bracing have measured effects on whole lumbar motion; however, how this effect is distributed across the lumbar spine is unknown. Therefore, this study was designed to test the influence of abdominal bracing on...
Article
The increase or decrease in isometric force following active muscle lengthening or shortening, relative to a reference isometric contraction at the same muscle length and level of activation, are referred to as residual force enhancement (rFE) and residual force depression (rFD), respectively. The purpose of these experiments was to investigate the...
Article
Studies on single muscle fibre passive material properties often report relatively large variation in elastic modulus, and it is not clear where this variation arises. This study was designed to determine if the elastic modulus is inherently different between type 1 and type 2 muscle fibres. Vastus lateralis fibres (n=93), from ten young men, were...
Article
Prolonged or repetitive spine flexion induces creep deformation of posterior spine tissues allowing for increased intervertebral motion beyond ‘normal’ limits, which may influence sub-regional (intersegmental) spine motion during subsequent manual lifting tasks. Using spine skin-surface kinematics, intersegmental lumbar spine motion was recorded ov...
Article
Full-text available
Proper coordination and function of muscles is required to move and stabilize the spine. However, due to difficulty in sampling, few empirical data exist regarding the specific structural and architectural characteristics of spine muscles in humans. The use of animal models is an alternative; but comparisons between animal and human spine muscles a...
Article
Purpose Studies have revealed an age-related decrease in the ability to produce force as well as an increase in the contractile stiffness and passive stress of single muscle fibres. However, further insight into age-related changes to the passive properties of human skeletal muscles is needed. The aim of this study was to characterize single muscle...
Preprint
Full-text available
The increase or decrease in isometric force following active muscle lengthening or shortening, relative to a reference isometric contraction at the same muscle length and level of activation, are referred to as residual force enhancement (rFE) and residual force depression (rFD), respectively. The purpose of these experiments was to gain further me...
Article
Full-text available
Using a technique of tracking intersegmental spine kinematics via skin surface markers, this study aimed to estimate local dynamic spine stability across smaller sub-regions (or segments) of the lumbar spine while also considering the impact of an external pelvic constraint during repetitive movements. Sixteen participants (10 males) performed two...
Article
When an individual enters a maximally flexed spine position, their largest extensor muscles become electrically inactive despite a substantial extensor moment demand being placed on the low back; this is termed flexion relaxation. Stresses within intervertebral discs, ligaments, and passive muscles are thought to support this moment thereby allowin...
Article
The Static Optimization (SO) solver in OpenSim estimates muscle activations and forces that only equilibrate applied moments. In this study, SO was enhanced through an open-access MATLAB interface, where calculated muscle activations can additionally satisfy crucial mechanical stability requirements. This Stability-Constrained SO (SCSO) is applicab...
Article
Residual force depression (rFD) and residual force enhancement (rFE) are intrinsic contractile properties of muscle. rFD is characterized as a decrease in steady-state isometric force following active shortening compared with a purely isometric contraction at the same muscle length and level of activation. By contrast, isometric force is increased...
Article
Passive mechanical properties differ between muscle groups within a species. Altered functional demands can also shift the passive force-length relationship. The extent that passive mechanical properties differ within a muscle group (e.g. spine extensors) or between homologous muscles of different species is unknown. It was hypothesized that multif...
Article
As the largest and most superficial organ, the skin is well positioned for receiving sensory information from the environment. It is conceivable that changes in posture could result in deformations of the skin and subsequent changes in skin material properties. Specifically, the ankle and metatarsophalangeal joints have the capability to undergo la...
Article
Maintenance of spine stability is considered to be a critical component of spine health. Ross et al. (2015) used a topical capsaicin/heat pain sensitization model to experimentally induce lower back pain, and demonstrated that the experimental pain experience caused a decrease in the muscular contribution to lumbar spine rotational stiffness (relat...
Article
Despite ‘abnormal’ motion being considered a risk factor for low back injury, the current understanding of ‘normal’ spine motion is limited. Identifying normal motion within an individual is complicated by the considerable variation in movement patterns amongst healthy individuals. Therefore, the purpose of this study was to characterize sources of...
Article
Background context: The spine is an anatomically complex system with numerous degrees of freedom. Due to this anatomical complexity, it is likely that multiple motor control options exist to complete a given task. Purpose: To identify if distinct spine spatiotemporal movement strategies are utilized in a homogenous sample of young healthy partic...
Article
Due to the increased popularity of standing-based occupational work stations there is a growing need to understand the impact of ergonomic aids such as standing mats. In particular, while standing mats have been studied in relation to musculoskeletal discomfort and pain, there have been no studies exploring the effects of their use on metabolism an...
Conference Paper
Full-text available
Chronic myofascial pain (MPS) is the most common form of chronic musculoskeletal pain, however, the pathophysiology is poorly understood 1. The Neurogenic Hypothesis proposes that MPS may be the clinical expression of intramuscular neurogenic inflammation arising from central sensitization induced by a primary pathology residing within the common n...
Article
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Augmented expression of substance P (SP) in the cartilaginous tissue has been shown to promote degenerative changes in the cartilaginous matrix of distal contralateral articular joints via neurogenic inflammation post-monoarthritis-induction contributing to the symmetrical spread of osteoarthritis (OA). However, no studies have explored whether sim...
Article
This study was designed to assess the utility of using a measure of dynamic spine stability in an unfatigued, rested state as a predictor of dynamic spine stability in a challenged, fatigued state. Participants completed three trials (Day 1: Rested, Fatigued; Day 2: Recovery) during which the dynamic stability of the spine was assessed over 30 repe...
Article
Full-text available
Purpose: To determine if the mechanical properties of the annulus fibrosus (AF) are altered following end-plate fracture. Vertebral fractures, particularly those in the growth plate, are relatively common among adolescents. What is unclear is whether or not these fractures are also associated with concomitant damage to the intervertebral disc (IVD...
Article
Given the appropriate cues, kinematic factors associated with low back injury risk and pain, such as spine flexion, can be avoided. Recent research has demonstrated the potential for tactile sensory information to change movement. In this study an athletic strapping tape was applied bilaterally along the lumbar extensor muscles to provide continuou...
Article
Background: Walking is often considered a beneficial management strategy for certain populations of low back pain patients. However, little is known about how simple challenges that people often encounter, such as carrying loads in the hands, affect the low back during walking. Research Question: How do variations in hand loading affect arm swing,...
Poster
Full-text available
Patients with lumbar facet joint injury have been shown to develop maladaptive responses within the central nervous system, including neuropathic and central sensitization. Central sensitization is characterized as an amplification of neural signaling within the central nervous system that elicits sensory changes such as mechanical allodynia as we...
Article
This experiment investigates the efficacy of tactile feedback in affecting changes to dynamic spine movements. A sample of (n = 24) young, healthy males were assessed while completing targeted spine flexion movements with instruction to minimize stretching of the skin beneath an applied tactile stimulus (liquid bandage). Localized tactile stimuli w...
Article
The purpose of this study was to determine if vibration, a potential method of pain management, applied to the low back could alleviate pain developed during prolonged standing. Eighteen healthy individuals participated in a 2.5-h standing task during which vibration (3-min duration) was applied at the 2-h and 2.25-h marks. During the full 2.5 h, p...
Article
The purpose of this study was to induce both trunk extensor and abdominal muscle fatigue, on separate occasions, and compare their effects on standing postural control and trunk proprioception, as well as look at the effects of a recovery period on these outcome measures. A total of 20 individuals participated, with 10 (5 males and 5 females) compl...
Article
Despite claims of functional benefits of kinesio tape application, little mechanistic evidence exists to support physiological pathways to achieve these benefits. As kinesio tape is adhered directly to the skin, it can be supposed that any pathway needs to first achieve effects at this level. To address this, two layers of the skin, the epidermis a...
Article
A novel method of recording intersegmental spine kinematics was developed. The method was required to: (1) have similar accuracy and precision as current methods that record gross spine kinematics; (2) be reasonably insensitive to errors associated with marker detection or misplacement; and (3) be reasonably insensitive to skin movement artefacts....
Article
Background: Context: Muscle tissue is known to remodel in response to changes to its mechanical environment. Alterations in passive mechanical properties of muscles can influence spine stiffness and stability. Purpose: To determine whether passive muscle elastic moduli and passive muscle stresses increased 28 days following mechanical disruption...
Article
Study design: Basic science study of the relationship between the structural properties of the spine and its surrounding musculature. Objective: To determine if an increase in spine stiffness causes an inverse compensatory change in the passive stiffness of the adjacent paraspinal muscles. Summary of background data: Intervertebral disc degene...
Article
Core stabilisation exercises are often promoted for purposes ranging from general fitness to high-performance athletics, and the prevention and rehabilitation of back troubles. These exercises, when performed properly, may have the potential to enhance torso postural awareness and control, yet the potential for achieving immediate gains has not bee...
Article
The purpose of the current work was to quantify the influence of posture-mediated skin deformation on trunk dorsum tactile perceptual sensitivity. 12 young and healthy individuals were assessed while adopting three different spine postures (extension, neutral and flexion). Tactile sensitivity threshold tests (T10 and L4 vertebral levels) included m...
Article
Cutaneous mechanoreceptors in the anterior lower leg and foot dorsum provide important information about contact with objects and movement at the knee and ankle. This cutaneous feedback contributes to static and dynamic balance control. We conducted experiment 1 to determine the effects of ageing on anterior lower leg cutaneous feedback. We measure...
Article
Objective: To compare upper extremity muscle activity and workload between simulated open surgery, multiple port laparoscopic surgery (MLS), and single incision laparoscopic surgery (SLS) techniques in veterinary students. Study design: Pilot study. Population: Veterinary students (n = 10) from years 1 to 4. Methods: Bipolar skin surface ele...
Article
Trunk motor control is essential for athletic performance, and inadequate trunk motor control has been linked to an increased risk of developing low back and lower limb injury in athletes. Research is limited in comparing relationships between trunk neuromuscular control, postural control, and trunk proprioception in athletes from different sportin...
Conference Paper
Full-text available
Objective: To investigate the expression of the major player in neurogenic inflammation, Substance P, in neurosegmentally linked knee joints in rats exposed to experimentally induced spinal facet joint compression injury at L5-L6.
Article
Full-text available
Background The purpose of this study was to measure the muscular activation in four forelimb muscles while dogs performed agility tasks (i.e., jumping and A-frame) and to provide insight into potential relationships between level of muscular activation and risk of injury. Muscle activation in eight healthy, client-owned agility dogs was measured us...
Article
As the most superficial organ, the skin is the most accessible sensory system interfacing one's body and environment. With changes in posture, it is possible that the skin may undergo large deformations resulting in changes in its structural properties. The purpose of the current work was to determine the influence of spine posture on measures of t...
Article
Full-text available
The purpose of the current work was to (1) determine whether low back cutaneous sensitivity could be reduced through the use of a topical lidocaine-prilocaine anesthetic (EMLA(®)) to mirror reductions reported in chronic lower back pain (CLBP) patients, as well as to (2) identify whether reductions in cutaneous sensitivity resulted in decreased lum...
Article
Full-text available
Several different state-space reconstruction methods have been employed to assess the local dynamic stability (LDS) of a 3D kinematic system. One common method is to use a Euclidean norm (N) transformation of three orthogonal x, y, and z time-series' followed by the calculation of the maximum finite-time Lyapunov exponent (λmax) from the resultant...
Article
Changes to intersegmental locomotor control patterns may affect body stability. Our study aimed to (a) characterize upper body dynamic stability in response to the unilateral addition of mass to the lower extremity and (b) evaluate the efficacy of 2 different stability measures commonly used in the literature to detect resulting symmetrical step pa...
Article
Flexion relaxation (FR) is characterized by the lumbar erector spinae (LES) becoming myoelectrically silent near full trunk flexion. This study was designed to: 1) determine if decreasing the lumbar moment during flexion would induce FR to occur earlier; 2) characterize thoracic and abdominal muscle activity during FR. Ten male participants perform...
Article
Background: Two of the most common Quantitative Sensory Techniques (QST) employed to detect allodynia include mechanical brush allodynia and Semmes-Weinstein monofilaments. However, their relative sensitivity at detecting allodynia is poorly understood. The purpose of this study was to compare the sensitivity of brush allodynia against Semmes-Wein...
Article
Background: Patients with chronic low back pain and associated radiculopathy present with neuromuscular symptoms both in their lower back and down their leg; however, investigations of muscle activation have so far been isolated to the lower back. During balance perturbations, it is necessary that lower limb muscles activate with proper timing and...
Article
Flexion relaxation (FR), a myoelectric silence of extensor muscles near end range of lumbar flexion, is commonly reported as the lumbar flexion angle at the instant the extensor muscles become silent. However, lumbar flexion angle alone is insufficient to characterize mechanisms that modulate FR. As FR requires the moment generated by passive lumba...
Article
Background Context: Human studies have revealed a link between muscle degeneration and low back pain, although the cause and effect of this relationship is not clear. Dogs provide a naturally developing model of intervertebral disc (IVD) related low back pain that may provide insight into relationships between IVD and muscle degeneration. Purpose:...
Article
This study was designed to investigate the potential effects of kinesio tape on the flexion-relaxation phenomenon, trunk postural control and trunk position sense when applied for a short period (30 min) to the low back of healthy female participants. Twenty-four participants were assigned to one of two groups: kinesio tape applied in either the re...