Joseph Weir

University of Kansas | KU · Department of Health, Sport, and Exercise Sciences

Due to decentralized autonomic nervous system function, individuals with spinal cord injury (SCI) are reported to have an increased prevalence of orthostatic hypotension (OH). Diagnosis of OH is made with active standing or tilt table testing, with limited the use in individuals with SCI. An alternative approach to assess OH is the sit-up test whic...

BACKGROUND To compare pharmacological treatment of hypotension and orthostatic hypotension (OH) initiated based upon a blood pressure (BP) threshold, regardless of symptoms (TXT), to usual care pharmacological treatment of symptomatic hypotension (UC), during acute inpatient rehabilitation (AIR) following spinal cord injury (SCI). METHODS Block ra...

Purpose The present study examined the effects of sustained, isometric low- versus high-intensity tasks on time to task failure (TTF), performance fatigability (PF), ratings of perceived exertion (RPE), and the perceived causes of task termination from a post-test questionnaire (PTQ). Methods Ten men (mean ± SD: age = 21.1 ± 2.3 years; height = 18...

Transcutaneous spinal cord stimulation (tSCS) is an emerging therapeutic strategy to target spinal autonomic circuitry to normalize and stabilize blood pressure (BP) in hypotensive persons living with chronic spinal cord injury (SCI). Our aim is to describe our current methodological approach to identify individual tSCS parameters that result in th...

To examine associations between parameters of psychological well-being, injury characteristics, cardiovascular autonomic nervous system (ANS) control, and cognitive performance in persons with spinal cord injury (SCI) compared with age-matched uninjured controls. This is an observational, cross-sectional study including a total of 94 participants (...

Background: Individuals with spinal cord injury (SCI) above thoracic level-6 (T6) experience impaired descending cortical control of the autonomic nervous system which predisposes them to blood pressure (BP) instability, including includes hypotension, orthostatic hypotension (OH), and autonomic dysreflexia (AD). However, many individuals do not r...

Introduction Post-traumatic headache (PTH) is commonly reported after concussion. Calcitonin gene-related peptide (CGRP) is implicated in the pathogenesis of migraine. We explored how single nucleotide polymorphisms (SNPs) from CGRP-alpha (CALCA) and the receptor activity modifying protein-1 (RAMP1) related to headache burden during the first week...

Assessment of the degree of impaired autonomic nervous system (ANS) function is not part of routine clinical practice during inpatient rehabilitation following traumatic spinal cord injury (SCI). The goal of this investigation was to determine the utility of the International Standards for Neurologic Classification of SCI (ISNCSCI) and the recently...

Background Low blood pressure (BP) may lead to reduced cerebral blood flow velocity (CBFv) during an orthostatic challenge in newly injured patients with traumatic spinal cord injury (SCI), which, may relate to the neurological level of injury (NLI) as documented on the International Standards for the Neurologic Classification of SCI (ISNCSCI), or...

This study examined the effects of continuous endurance training on motor unit (MU) mean firing rates (MFR), percent myosin heavy chain (%MHC) isoforms, and muscle cross-sectional area (mCSA) of the vastus lateralis (VL). Twelve females completed 5-weeks of continuous cycling-training (CYC), while 8 females were controls (CON). Participants perform...

The Marine Corps Martial Arts Program (MCMAP) was developed to prepare Marines for complex battlefield situations that include hand-to-hand combat and ethical decision making. The objective of this study was to quantify changes in ethical decision-making following MCMAP training. Fifty-five, active duty, newly enlisted U.S. Marines (Males: n = 37;...

Transcutaneous spinal cord stimulation (TSCS) has demonstrated potential to beneficially modulate spinal cord motor and autonomic circuitry. We are interested in pairing cervical TSCS with other forms of nervous system stimulation to enhance synaptic plasticity in circuits serving hand function. We use a novel configuration for cervical TSCS in whi...

Dysregulation of cardiovascular autonomic control is gaining recognition as a prevailing consequence of concussion injury. Characterizing the presence of autonomic dysfunction in concussed persons is inconsistent and conventional metrics of autonomic function cannot differentiate the presence/absence of injury. Mayer wave (MW) activity originates t...

Profound dysfunction of the cardiovascular system occurs after spinal cord injury (SCI), which is a leading cause of mortality in this population. Most individuals with chronic SCI experience transient episodes of hypotensive and hypertensive blood pressure in response to daily life activities. There are currently limited tools available to evaluat...

Ciccone, AB, Fry, AC, Emerson, DM, Gallagher, PM, Herda, TJ, and Weir, JP. Effects of transspinal direct current stimulation on cycling perception of effort and time to exhaustion. J Strength Cond Res XX(X): 000-000, 2020-In the past decade, researchers have investigated the efficacy of transspinal direct current stimulation (tsDCS) on the central...

Increased pulse wave velocity (PWV), a marker of cardiovascular disease (CVD), has been reported in otherwise healthy individuals with spinal cord injury (SCI) compared to age-matched uninjured controls. Due to decentralized descending sympathetic vascular control, individuals with injuries above T6 are prone to orthostatic hypotension and, as a re...

Clinical trial. Individuals with spinal cord injury (SCI) above T6 experience impaired descending cortical control of the autonomic nervous system, which predisposes them to hypotension. However, treatment of hypotension is uncommon in the SCI population because there are few safe and effective pharmacological options available. The primary aim of...

We report a novel posteroanterior approach to cervical spinal stimulation. This approach easily activates arm and hand muscles on both sides simultaneously. A mix of afferent and efferent nerve roots is activated across stimulus intensities. a b s t r a c t Objective: We aim to non-invasively facilitate activation of spared neural circuits after ce...

Background: To determine the degree of blood pressure instability over a 30-day home observation in participants with spinal cord injury grouped by level of injury pertaining to cardiovascular autonomic regulation. Methods: This is an observational study completed at the Kessler Foundation and James J. Peters Veterans Medical Center. Seventy-two...

Objective To determine the contribution of cholinergic withdrawal and adrenergic activation on the heart rate (HR) and systolic blood pressure (SBP) responses to head‐up tilt (HUT) in persons with spinal cord injury (SCI), categorized by the level of sympathetic cardiac innervation. Participants/methods Fifteen individuals with chronic SCI (13±12y...

Objective Arterial stiffness (AS) has been identified as an independent risk factor for cardiovascular disease (CVD) progression. Increases in AS are associated with advancing age and resting blood pressure (BP) in the general population; however, these associations have not been described in the spinal cord injury (SCI) population. The objective o...

Background Vagal modulation of heart rate periodicity occurs in response to presynaptic release of acetylcholine (Acyl) and post‐synaptic binding to muscarinic receptors at the sino‐atrial node (SAN). Acetylcholinesterase inhibition (ACI) prolongs Acyl action leading to enhanced depression of SAN discharge rate and variability. In persons with spin...

Cognitive deficits are prevalent in the spinal cord injury (SCI) population, and consensus suggests that concomitant traumatic brain injury or co-morbid conditions are primarily responsible for these deficits. However, mounting evidence supports the possibility that systemic and cerebral hemodynamic dysfunction may contribute to the cognitive defic...

Background and purpose Spared fibers after spinal cord injury (SCI) tend to consist predominantly of subcortical circuits that are not under volitional (cortical) control. We aim to improve function after SCI by using targeted physical exercises designed to simultaneously stimulate cortical and spared subcortical neural circuits. Methods Participa...

List of skilled upper extremity tasks. (XLSX)

IRB approval letter. (PDF)

Subject-level outcome data. (XLSX)

Aim To investigate the relationships between motor unit action potential amplitudes (MUAPAMP), muscle cross‐sectional area (mCSA) and composition (mEI), percent myosin heavy chain (%MHC) areas, and sex in the vastus lateralis (VL). Methods Ten males and 10 females performed a submaximal isometric trapezoid muscle action that included a linearly in...

Stimulation of the left insular cortex may affect heart rate variability (HRV) and exercise effort perception. These studies investigated the effects transcranial direct current stimulation (tDCS) and electrode orientation on HRV and repeated maximal knee extensions. In study 1, following sham stimulation, anodal left temporal lobe stimulation, or...

Venous occlusion plethysmography (VOP) has been used as a non-invasive measure to compare lower extremity venous vascular function in individuals with spinal cord injury (SCI) to healthy controls. However, the inter-day reliability of VOP has not been sufficiently reported in the SCI population. The purpose of this investigation was to determine th...

Impaired autonomic regulation of the cardiovascular system individuals with spinal cord injury (SCI) is generally accepted, which may be dependent on the level and severity of injury. However, the extent of alteration in this regulatory process cannot be accurately measured due to the lack of validated and reliable clinical assessment tools. A shor...

Background: The heart rate (HR) response to deep breathing (Db) can provide insight into the integrity of the cardio-vagal reflex; however, the reliability of this test has not been reported in persons with spinal cord injury (SCI). The purpose of this investigation was to determine the inter-day reliability of the Db test in individuals with SCI c...

Individuals with chronic spinal cord injury (SCI) are at a heightened risk of cardiovascular disease (CVD) due to autonomic nervous system dysfunction, physical inactivity and increased inflammatory processes. Arterial stiffness (AS) is recognized as an independent risk factor for CVD and, specifically, pulse wave analysis (PWA) has proven to be a...

Background Isokinetic fatigue protocols are commonly used in both research as well as in kinesiology education. However, fatigue quantification methods vary between studies. Objective Therefore, the purpose of this study was to determine how fatigue quantification methods affect data interpretation and which methods may be most appropriate. Metho...

Assessment of heart rate variability (HRV) is a common approach to examine cardiac autonomic nervous system modulation that has been employed in a variety of settings. Frequently, both the root mean square of successive differences (RMSSD) and SD1, which is a Poincaré plot component, have been used to quantify short term heart rate variability. It...

The purpose of the present study was to examine the effects of electrode placements centered over and offset from the innervation zone (IZ) with different interelectrode distances (IED) on the time and frequency domain parameters of the electromyographic (EMG) signal during a fatiguing submaximal, isometric workout. 11 adults performed an isometric...

Introduction: This study examined relationships among mechanomyographic (MMG), electromyographic (EMG), and peak twitch torque (PTT) responses as well as test-retest reliability when recorded during recruitment curves in the soleus muscle. Methods: PTT, EMG (M-wave, H-reflex), and MMG responses were recorded during recruitment curves in 16 subje...

Numerous conditions and types of physical activity (e.g., exercise, aging, muscle-related diseases) can influence muscle fiber types and the proteins expressed. To date, muscle fibers can only be characterized by actually obtaining a tissue sample using the invasive muscle biopsy procedure. Mechanomyography (MMG) is the assessment of the vibration...

Smith, CM, Housh, TJ, Herda, TJ, Zuniga, JM, Camic, CL, Bergstrom, HC, Smith, DB, Weir, JP, Hill, EC, Cochrane, KC, Jenkins, NDM, Schmidt, RJ, and Johnson, GO. Time course of changes in neuromuscular parameters during sustained isometric muscle actions. J Strength Cond Res 30(10): 2697-2702, 2016-The objective of the present study was to identify t...

This study examined the electromyographic (EMG) responses from the vastus medialis (VM) for electrodes placed over and away from the innervation zone (IZ) during a maximal voluntary isometric contraction (MVIC) and sustained, submaximal isometric muscle action. A linear electrode array was placed on the VM to identify the IZ and muscle fiber pennat...

Repeated maximal effort isokinetic knee extension tests are commonly used to examine fatigue. Electromyographic (EMG) median power frequency (MPF) is thought to be related to peripheral fatigue. Multiple synergist muscles contribute to knee extension torque, and multiple range-of-motion (ROM) windows have been used to collect surface EMG data. MPF...

Repeated maximal effort isokinetic knee extension tests are common in fatigue research. The theory of common drive dictates that surface electromyographic (EMG) amplitude should be highly correlated between synergist muscles. However, researchers collect EMG data from different ROM (range-of-motion) windows. Different data collection windows will i...

Objective: Lymphocyte proliferative responses are commonly used to assess immune function in clinical settings, yet it is unclear how proliferative capacity is altered by exercise. This analysis aims to quantitatively assess the proliferative response of lymphocytes following an acute bout of exercise. Methods: Electronic databases were searched...

We previously showed that increases in mean arterial pressure (MAP) following administration of midodrine hydrochloride (MH) and nitro-L-arginine methyl ester (L-NAME) resulted in increased mean cerebral blood flow velocity (MFV) during head-up tilt in hypotensive individuals with spinal cord injury (SCI) and question if this same association was e...

Background: Due to interruption of cardiovascular autonomic control unstable blood pressure (BP) is common in individuals with spinal cord injury (SCI) above the sixth thoracic vertebral level. The impact of unstable BP on cerebral blood flow (CBF) is not well appreciated, but symptoms associated with altered cerebral perfusion are reported, which...

Purpose: Abnormal blood pressure (BP) response to orthostatic maneuvers may predict adverse health outcomes. Orthostatic hypotension (OH) is defined as a fall in BP of ≥20/10 mmHg, and orthostatic hypertension (OHTN) is defined as an increase in systolic BP (SBP) of ≥20 mmHg, with standing. Herein, we document the prevalence of OH and OHTN in Amer...

Repeated maximal effort isokinetic knee extension tests are common in fatigue research. The theory of common drive dictates that surface electromyographic (EMG) amplitude should be highly correlated between synergist muscles. However, researchers collect EMG data from different ROM (range-of-motion) windows. Different data collection windows will i...

The purposes of the present study were to examine the effects of electrode placements over, proximal, and distal to the innervation zone (IZ) on electromyographic (EMG) amplitude (RMS) and frequency (MPF) responses during: (1) a maximal voluntary isometric contraction (MVIC), and; (2) a sustained, submaximal isometric muscle action. A linear array...

This study quantified systematic and intraindividual variability among three repetitions of concentric isokinetic knee extension and flexion tests to determine velocity-related differences in peak torque (PT) and mean power (MP) in healthy elderly (HE) versus sarcopenic and malnourished elderly (SME). In total, 107 HE (n = 54 men, n = 53 women) and...

This study examined the effects of electromyographic (EMG) recording methods and innervation zone (IZ) on the mean power frequency (MPF)-torque relationships. Nine subjects performed isometric ramp muscle actions of the leg extensors from 5% to 100% of maximal voluntary contraction with an eight channel linear electrode array over the IZ of the vas...

Introduction: We examined motor unit (MU) control properties of resistance- (RT) and endurance-trained (ET) individuals. Methods: Five RT (age=25±4 yrs) and 5 ET (age=19±1 yrs) participated. Surface electromyographic (EMG) was recorded from the vastus lateralis during isometric trapezoid muscle actions at 40% and 70% of maximal voluntary contractio...

Objective: Increased prevalence of heart rate and blood pressure abnormalities are evident in persons with spinal cord injury (SCI), but age, comorbid medical conditions, and prescription medication use may contribute. To determine differences in the prevalence of cardiac acceleration (heart rate ≥80 beats per minute), hypotension (blood pressure...

The purpose of this study was to determine the agreement of physiological parameters measured during exercise testing on 2 devices at established power outputs (POs). Ten trained male cyclists were recruited. The devices used for comparison were the Lode stationary bicycle ergometer (SBE) (Lode Excalibur) and the PowerTap Pro+ (BPT) (Saris Cycling...

This study examined the effects of 6 weeks of conjugated linoleic acid (CLA) supplementation and moderate aerobic exercise on peak oxygen uptake ([Formula: see text] peak), the gas exchange threshold (GET), the respiratory compensation point (RCP), and serum concentrations of cholesterol, triacylglycerol, and glucose in humans. Thirty-four untraine...

Vitamin D deficiency has been associated with both increased risk and severity of Multiple Sclerosis (MS) as it has a modulating effect on the immune process that causes inflammation/demyelination and axonal damage. Optical Coherence Tomography (OCT) offers a quick, reliable and non-invasive way to assess the Retinal Nerve Fiber Layer (RNFL) and id...

The purpose of this study was to examine the effects of CLA supplementation in conjunction with 6 weeks of aerobic exercise training on the physical working capacity at the fatigue threshold (PWCFT), timed sit-ups, and the standing long jump. Thirty-three untrained to moderately trained men (mean ± SD; age = 21.6 ± 2.8 years) participated in this d...

The purpose of this study was to determine the agreement of physiological parameters measured during exercise testing on two devices at established power outputs (PO). Ten trained male cyclists were recruited. The devices used for comparison were the Lode stationary bicycle ergometer (SBE) (Lode Excalibur, Netherlands) and the PowerTap Pro+ (BPT) (...

Decentralized autonomic cardiovascular regulation may lead to increased prevalence of heart rate (HR) and blood pressure (BP) abnormalities in veterans with SCI. In addition, comorbid medical conditions and prescription medication use may increase HR and BP abnormalities. These abnormalities include bradycardia, and tachycardia, hypotension, hypert...

Numerous natural products are marketed and sold claiming to decrease body weight and fat, but few undergo finished product-specific research demonstrating their safety and efficacy. To determine the safety and efficacy of a multi-ingredient supplement containing primarily raspberry ketone, caffeine, capsaicin, garlic, ginger and Citrus aurantium (P...

Objectives: To determine the effect of an escalating dose of droxidopa (100, 200, and 400 mg) compared with placebo on seated blood pressure (BP) in hypotensive individuals with spinal cord injury (SCI). Secondarily, we aimed to determine the effect of droxidopa on (1) supine BP and heart rate, (2) the change in BP and heart rate when these indivi...