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Umeda M, Kim Y, Jaén CR, Okifuji A, Corbin LW, Maluf KS. Mediating role of physical activity in the relationship between exercise-induced muscle pain and symptom severity in women with fibromyalgia. Physiother Theory Pract 2024; 40:338-346. [PMID: 35968757 DOI: 10.1080/09593985.2022.2111674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 08/05/2022] [Indexed: 10/15/2022]
Abstract
BACKGROUND Individuals with fibromyalgia (FM) exhibit generalized hyperalgesia to pain stimuli, and physical activity (PA) is critical to manage FM symptoms. PURPOSE This study examined the relationship between exercise-induced muscle pain, symptom severity, and PA in 28 women with FM. METHODS Muscle pain rating (MPR) was assessed during 3 minutes of submaximal isometric handgrip exercise, whereas PA and symptom severity were evaluated via self-report questionnaires. The analysis examined the relationship between the variables, with the specific interest in the mediating role of PA in the relationship between exercise-induced muscle pain and symptom severity. RESULTS MPR was positively associated with symptom severity (b = 1.89; 95% CI = 0.01, 3.76; P = .048) and inversely associated with PA levels (b = -0.16; 95% CI = -0.30, -0.03; P = .021). PA levels were inversely associated with symptom severity (b = -7.94; 95% CI = -12.46, -3.42; P = .001). After statistically controlling for PA levels, the relationship between MPR and symptom severity was no longer significant (b = 0.60; Wald 95% CI = -1.05, 2.25; P = .474). CONCLUSION Results show the link between the variables, and specifically demonstrate that PA mediates the relationship between exercise-induced muscle pain and symptom severity.
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Affiliation(s)
- Masataka Umeda
- Department of Kinesiology, University of Texas at San Antonio, San Antonio, TX, USA
| | - Youngdeok Kim
- Department of Kinesiology and Health Sciences, Virginia Commonwealth University, Richmond, VA, USA
| | - Carlos R Jaén
- Department of Family and Community Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Akiko Okifuji
- Division of Pain Medicine, Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA
| | - Lisa W Corbin
- Department of Medicine, University of Colorado Hospital, Aurora, CO, USA
| | - Katrina S Maluf
- School of Exercise and Nutritional Sciences, Doctor of Physical Therapy Program, San Diego State University, San Diego, CA, USA
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Umeda M, Kim Y, Jaén CR, Okifuji A, Corbin LW, Maluf KS. Role Of Physical Activity In Relationship Between Exercise-induced Muscle Pain And Fibromyalgia Symptom Severity. Med Sci Sports Exerc 2022. [DOI: 10.1249/01.mss.0000878008.06520.25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Maluf KS, Giron T, Hatch M, Sao N, Rosenthal M. Blood Flow Restriction Augments Exercise-Induced Hypoalgesia In Accessory Muscles Distal And Proximal To Cuff Occlusion. Med Sci Sports Exerc 2022. [DOI: 10.1249/01.mss.0000879316.91436.54] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Chapman CR, Woo NT, Maluf KS. Preferred Communication Strategies Used by Physical Therapists in Chronic Pain Rehabilitation: A Qualitative Systematic Review and Meta-Synthesis. Phys Ther 2022; 102:6623303. [PMID: 35778939 PMCID: PMC9455645 DOI: 10.1093/ptj/pzac081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 03/12/2022] [Accepted: 06/06/2022] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Lack of clarity regarding effective communication behaviors in chronic pain management is a barrier for implementing psychologically informed physical therapy approaches that rely on competent communication by physical therapist providers. This study aimed to conduct a systematic review and meta-synthesis to inform the development of a conceptual framework for preferred communication behaviors in pain rehabilitation. METHODS Ten databases in the health and communication sciences were systematically searched for qualitative and mixed-method studies of interpersonal communication between physical therapists and adults with chronic pain. Two independent investigators extracted quotations with implicit and explicit references to communication and study characteristics following Standards for Reporting Qualitative Research and Strengthening the Reporting of Observational Studies in Epidemiology guidelines. Methodological quality for individual studies was assessed with Critical Appraisal Skills Programme, and quality of evidence was evaluated with GRADE-CERQual. An inductive thematic synthesis was conducted by coding each quotation, developing descriptive themes, and then generating behaviorally distinct analytical themes. RESULTS Eleven studies involving 346 participants were included. The specificity of operationalizing communication terms varied widely. Meta-synthesis identified 8 communication themes: (1) disclosure-facilitating, (2) rapport-building, (3) empathic, (4) collaborative, (5) professional accountability, (6) informative, (7) agenda-setting, and (8) meta-communication. Based on the quality of available evidence, confidence was moderate for 4 themes and low for 4 themes. CONCLUSION This study revealed limited operationalization of communication behaviors preferred by physical therapists in chronic pain rehabilitation. A conceptual framework based on 8 communication themes identified from the literature is proposed as a preliminary paradigm to guide future research. IMPACT This proposed evidence-based conceptual framework for preferred communication behaviors in pain rehabilitation provides a framework for clinicians to reflect on their own communication practices and will allow researchers to identify if and how specific communication behaviors impact clinical outcomes.
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Affiliation(s)
- Chelsea R Chapman
- Joint Doctoral Program in Public Health, San Diego State University and University of California San Diego, San Diego, California, USA
| | - Nathan T Woo
- Department of Communication, University of Arizona, Tucson, Arizona, USA
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Lang AJ, Malaktaris A, Maluf KS, Kangas J, Sindel S, Herbert M, Bomyea J, Simmons AN, Weaver J, Velez D, Liu L. A randomized controlled trial of yoga vs nonaerobic exercise for veterans with PTSD: Understanding efficacy, mechanisms of change, and mode of delivery. Contemp Clin Trials Commun 2021; 21:100719. [PMID: 33604485 PMCID: PMC7875811 DOI: 10.1016/j.conctc.2021.100719] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 10/07/2020] [Accepted: 01/15/2021] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND AND OBJECTIVES Posttraumatic stress disorder (PTSD) is a chronic, disabling, and prevalent mental health disorder among Veterans. Despite the availability of empirically supported psychotherapies, many Veterans remain symptomatic after treatment and/or prefer to seek complementary and integrative health approaches, including yoga, to manage PTSD. The randomized controlled trial (RCT) described herein will evaluate the efficacy of a manualized yoga program as compared to nonaerobic exercise in reducing PTSD severity among Veterans. A secondary aim of this study is to better understand the mechanisms of change. METHODS Veterans (N = 192) with PTSD will be randomized to hatha yoga or nonaerobic physical activity control; both groups consist of 12 weekly, 60-min group or online training sessions with 15-20 min of daily at-home practice. Outcome measures will be administered at baseline, mid-treatment, posttreatment, and 12-week follow-up. PROJECTED OUTCOMES This study will evaluate changes in PTSD severity (primary outcome) as well as depression, anxiety, anger, sleep problems, and psychosocial disability (secondary outcomes). We will also use multiple mediation to examine two potential models of the mechanisms of clinical effect: the Attention Model (i.e., yoga increases attentional control, which reduces PTSD symptoms), the Coping Model (i.e., yoga increases distress tolerance, which improves coping, which reduces PTSD symptoms), and the combination of these models. This aspect of the study is innovative and important given the absence of an existing, comprehensive model for understanding yoga's impact on PTSD. Ultimately, we hope to develop guidelines for application of yoga to PTSD recovery.
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Affiliation(s)
- Ariel J. Lang
- VA San Diego Center of Excellence for Stress and Mental Health, UCSD Departments of Psychiatry and Family Medicine and Public Health, 3350 La Jolla Village Dr. (MC 111N1), San Diego, CA, 92161, USA
| | - Anne Malaktaris
- VA San Diego Healthcare System/Center of Excellence for Stress and Mental Health, UCSD Department of Psychiatry, 3350 La Jolla Village Dr., San Diego, CA, 92161, USA
| | - Katrina S. Maluf
- San Diego State University, School of Exercise and Nutritional Sciences, Doctor of Physical Therapy Program, 5500 Campanile Dr., San Diego, CA, 92182, USA
| | - Julie Kangas
- VA San Diego Healthcare System, UCSD Department of Psychiatry, 8810 Rio San Diego Dr., San Diego, CA, 92108, USA
| | - Selin Sindel
- University of California San Diego, Department of Cognitive Science, 9500 Gilman Dr, La Jolla, CA, 92093, USA
| | - Matthew Herbert
- VA San Diego Center of Excellence for Stress and Mental Health, UCSD Department of Psychiatry, 9500 Gilman Dr. MC 0855, La Jolla, CA, 92037, USA
| | - Jessica Bomyea
- VA San Diego Center of Excellence for Stress and Mental Health, UCSD Department of Psychiatry, 9500 Gilman Dr. MC 0855, La Jolla, CA, 92037, USA
| | - Alan N. Simmons
- VA San Diego Center of Excellence for Stress and Mental Health, UCSD Department of Psychiatry, 9500 Gilman Dr. MC 0855, La Jolla, CA, 92037, USA
| | - Judy Weaver
- Connected Warriors, 4950 Communication Ave, Ste 115, Boca Raton, FL, 33431, USA
| | - Deborah Velez
- Veteran's Medical Research Foundation, 3350 La Jolla Village Dr, San Diego, CA, 92037, USA
| | - Lin Liu
- VA San Diego Healthcare System, UCSD Department of Preventive Medicine and Public Health, 9500 Gilman Dr., MC0725, La Jolla, CA, 92093-0725, USA
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Shahidi B, Bursch RW, Carmel JS, Carranza AC, Cooper KM, Lee JV, O'Connor CN, Sorg SF, Maluf KS, Schiehser DM. Greater Severity and Functional Impact of Post-traumatic Headache in Veterans With Comorbid Neck Pain Following Traumatic Brain Injury. Mil Med 2020; 186:1207-1214. [PMID: 33306100 DOI: 10.1093/milmed/usaa532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 11/17/2020] [Accepted: 11/20/2020] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Post-traumatic headache (PTH) is a commonly experienced symptom after mild traumatic brain injury (mTBI). Blast injury- or blunt injury-related mechanisms for mTBI in veterans can also affect musculoskeletal structures in the neck, resulting in comorbid neck pain (NP). However, it is unknown whether the presence of comorbid NP may be associated with a different pattern of headache symptoms, physical functioning, or emotional functioning compared to those without comorbid NP. The purpose of this study is to examine the role of comorbid NP in veterans with mTBI and PTH. DESIGN AND METHODS This was a cross-sectional investigation of an existing dataset that included 33 veterans who met inclusion criteria for PTH after mTBI. Standardized measures of headache severity and frequency, insomnia, fatigue, mood disorders, and physical and emotional role function were compared between groups with and without comorbid NP. RESULTS The majority of participants with PTH reported comorbid NP (n = 22/33, 67%). Those with comorbid NP experienced more headache symptoms that were severe or incapacitating, as compared to mild or moderate for those without NP (φ = 0.343, P = .049); however, no differences in headache frequency (φ = 0.231, P = .231) or duration (φ = 0.129, P = .712) were observed. Participants with comorbid NP also reported greater insomnia (d = 1.16, P = .003) and fatigue (d = 0.868, P = .040) as well as lower physical functioning (d = 0.802, P = .036) and greater bodily pain (d = 0.762, P = .012). There were no differences in anxiety, depression, mental health, emotional role limitations, vitality, or social functioning between those with and without comorbid NP (d ≤ 0.656, P ≥ .079). CONCLUSIONS A majority of veterans with mTBI and PTH in our sample reported comorbid NP that was associated with greater headache symptom severity and physical limitations, but not with mood or emotional limitations. Preliminary findings from this small convenience sample indicate that routine assessment of comorbid NP and associated physical limitations should be considered in veterans with mTBI and PTH.
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Affiliation(s)
- Bahar Shahidi
- Department of Orthopaedic Surgery, University of California San Diego, La Jolla, CA 92037, USA
| | - Robyn W Bursch
- Department of Physical Therapy, San Diego State University, School of Exercise and Nutritional Sciences, San Diego, CA 92182, USA
| | - Jennifer S Carmel
- Department of Physical Therapy, San Diego State University, School of Exercise and Nutritional Sciences, San Diego, CA 92182, USA
| | - Ashleigh C Carranza
- Department of Physical Therapy, San Diego State University, School of Exercise and Nutritional Sciences, San Diego, CA 92182, USA
| | - Kelsey M Cooper
- Department of Physical Therapy, San Diego State University, School of Exercise and Nutritional Sciences, San Diego, CA 92182, USA
| | - Jayme V Lee
- Department of Physical Therapy, San Diego State University, School of Exercise and Nutritional Sciences, San Diego, CA 92182, USA
| | - Colleen N O'Connor
- Department of Physical Therapy, San Diego State University, School of Exercise and Nutritional Sciences, San Diego, CA 92182, USA
| | - Scott F Sorg
- Veterans Association San Diego Healthcare System, Research Service, San Diego, CA 92161, USA.,Veterans Association San Diego Healthcare System, Center of Excellence for Stress and Mental Health, San Diego, CA 92161, USA
| | - Katrina S Maluf
- Department of Physical Therapy, San Diego State University, School of Exercise and Nutritional Sciences, San Diego, CA 92182, USA
| | - Dawn M Schiehser
- Veterans Association San Diego Healthcare System, Research Service, San Diego, CA 92161, USA.,Department of Psychiatry, University of California San Diego, La Jolla, CA 92037, USA
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Marker RJ, Campeau S, Maluf KS. Psychosocial stress alters the strength of reticulospinal input to the human upper trapezius. J Neurophysiol 2016; 117:457-466. [PMID: 27832595 DOI: 10.1152/jn.00448.2016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 10/31/2016] [Indexed: 11/22/2022] Open
Abstract
Psychosocial stress has been shown to influence several aspects of human motor control associated with the fight-or-flight response, including augmentation of upper trapezius muscle activity. Given the established role of the reticular formation in arousal, this study investigated the contribution of reticulospinal activation to trapezius muscle activity during exposure to an acute psychosocial stressor. Twenty-five healthy adults were exposed to startling acoustic stimuli (SAS) while performing a motor task during periods of low and high psychosocial stress. Acoustic startle reflexes (ASRs) were recorded in the upper trapezius during low intensity contractions using both surface and intramuscular electromyography. Exposure to the stressor increased subjective and physiological measures of arousal (P < 0.01). The majority of participants demonstrated inhibitory ASRs, whereas a small subgroup with significantly higher trait anxiety (n = 5) demonstrated excitatory ASRs in the low stress condition. Changes in synaptic input for inhibitory ASRs were confirmed by decreases in the discharge rate of single motor units in response to the SAS. ASRs decreased in magnitude for all participants during exposure to the acute psychosocial stressor. These findings suggest that the reticular formation has predominately inhibitory effects on the human upper trapezius during an ongoing motor task and that disinhibition caused by psychosocial stress may contribute to augmentation of trapezius muscle activity. Further research is required to investigate mechanisms underlying the complex ASRs characterized by this study, particularly the phase reversal to excitatory responses observed among more anxious individuals. NEW & NOTEWORTHY This study is the first to quantify stress-evoked changes in the acoustic startle reflex in the upper trapezius muscle of humans, and our findings reveal a complex pattern of inhibitory and facilitatory responses consistent with observations in nonhuman primates. We further demonstrate that psychosocial stress consistently reduces the amplitude of these responses. These findings have implications for the control of motor behaviors in response to stress.
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Affiliation(s)
- Ryan J Marker
- Rehabilitation Science Program, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Serge Campeau
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, Colorado; and
| | - Katrina S Maluf
- Rehabilitation Science Program, University of Colorado Anschutz Medical Campus, Aurora, Colorado; .,School of Exercise and Nutritional Sciences, San Diego State University, San Diego, California
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Marker RJ, Balter JE, Nofsinger ML, Anton D, Fethke NB, Maluf KS. Upper trapezius muscle activity in healthy office workers: reliability and sensitivity of occupational exposure measures to differences in sex and hand dominance. Ergonomics 2016; 59:1205-14. [PMID: 26924036 PMCID: PMC9333326 DOI: 10.1080/00140139.2015.1130860] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Patterns of cervical muscle activity may contribute to overuse injuries in office workers. The purpose of this investigation was to characterise patterns of upper trapezius muscle activity in pain-free office workers using traditional occupational exposure measures and a modified Active Amplitude Probability Distribution Function (APDF), which considers only periods of active muscle contraction. Bilateral trapezius muscle activity was recorded in 77 pain-free office workers for 1-2 full days in their natural work environment. Mean amplitude, gap frequency, muscular rest and Traditional and Active APDF amplitudes were calculated. All measures demonstrated fair to substantial reliability. Dominant muscles demonstrated higher amplitudes of activity and less muscular rest compared to non-dominant, and women demonstrated less muscular rest with no significant difference in amplitude assessed by Active APDF compared to men. These findings provide normative data to identify atypical motor patterns that may contribute to persistence or recurrence of neck pain in office workers. Practitioner Summary: Upper trapezius muscle activity was characterised in a large cohort of pain-free workers using electromyographic recordings from office environments. Dominant muscles demonstrated higher activity and less rest than non-dominant, and women demonstrated less rest than men. Results may be used to identify atypical trapezius muscle activity in office workers.
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Affiliation(s)
- Ryan J. Marker
- Rehabilitation Science Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Jaclyn E. Balter
- Physical Therapy Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Micaela L. Nofsinger
- Physical Therapy Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Dan Anton
- Department of Physical Therapy, Eastern Washington University, Spokane WA, USA
| | - Nathan B. Fethke
- Department of Occupational and Environmental Health, University of Iowa, Iowa City IA, USA
| | - Katrina S. Maluf
- Rehabilitation Science Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
- Physical Therapy Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
- School of Exercise and Nutritional Sciences, Doctor of Physical Therapy Program, San Diego State University, San Diego, CA, USA
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Gaffney BM, Maluf KS, Davidson BS. Evaluation of Novel EMG Biofeedback for Postural Correction During Computer Use. Appl Psychophysiol Biofeedback 2015; 41:181-9. [DOI: 10.1007/s10484-015-9328-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Marker RJ, Maluf KS. Associations Between Workday Heart Rate Variability, Trapezius Muscle Activity, And Anxiety In Office Workers. Med Sci Sports Exerc 2015. [DOI: 10.1249/01.mss.0000477684.68724.ad] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Shahidi B, Sannes T, Laudenslager M, Maluf KS. Cardiovascular responses to an acute psychological stressor are associated with the cortisol awakening response in individuals with chronic neck pain. Physiol Behav 2015; 150:93-8. [PMID: 25662023 DOI: 10.1016/j.physbeh.2015.02.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Revised: 02/02/2015] [Accepted: 02/03/2015] [Indexed: 10/24/2022]
Abstract
INTRODUCTION Dysregulation of the hypothalamic-pituitary-adrenal axis (HPA-axis) is common in individuals who experience chronic psychological stress, as well as individuals with chronic pain. Changes in cortisol availability in the presence of a chronic stressor such as pain may influence the sympathetic-adrenal-medullary (SAM) system, which contributes to cardiovascular responses to stress and also exhibits altered responsiveness in the presence of pain. The purpose of this study was to investigate the relationship between HPA activity during the cortisol awakening response and cardiovascular reactivity during exposure to an acute psychological stressor in individuals with chronic neck pain. METHODS Area under the curve (AUC) of the salivary cortisol awakening response was assessed in 41 individuals with chronic neck pain aged 19-80 years (22 men, 23 women). Slopes representing the change in mean arterial pressure and heart rate during a baseline quiet sitting condition, a low stress condition with mental concentration, and a high stress condition combining mental concentration with social evaluative threat were calculated for each individual as an index of cardiovascular responsiveness to the acute stressor. Cardiovascular responses were regressed on cortisol awakening AUC and pain duration, adjusting for age and sex. RESULTS Greater mean arterial pressure (β = -0.33, p = 0.02) and heart rate responses (β = -0.41, p = 0.007) to the acute psychological stressor were associated with lower cortisol awakening responses after adjusting for age and sex. Individuals with a shorter duration of chronic pain also demonstrated a larger increase in mean arterial pressure during the laboratory stressor (β = -0.39, p = 0.01), but there was no relationship between pain duration and changes in heart rate (p = 0.25). CONCLUSIONS Individuals with a shorter duration of chronic neck pain who demonstrate heightened cardiovascular responsiveness to an acute psychological stressor also exhibit lower cortisol awakening response. These results are consistent with time-dependent adaptations across the two major stress systems in the presence of chronic pain.
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Affiliation(s)
- Bahar Shahidi
- University of Colorado Denver, Rehabilitation Science Program, Department of Physical Medicine and Rehabilitation, Aurora, CO, USA
| | - Timothy Sannes
- University of Colorado Denver, Department of Psychiatry, Aurora, CO, USA
| | - Mark Laudenslager
- University of Colorado Denver, Department of Psychiatry, Aurora, CO, USA
| | - Katrina S Maluf
- University of Colorado Denver, Rehabilitation Science Program, Department of Physical Medicine and Rehabilitation, Aurora, CO, USA; San Diego State University, Physical Therapy Program, School of Exercise and Nutritional Sciences, San Diego, CA, USA.
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Umeda M, Corbin LW, Maluf KS. Examination of contraction-induced muscle pain as a behavioral correlate of physical activity in women with and without fibromyalgia. Disabil Rehabil 2014; 37:1864-9. [DOI: 10.3109/09638288.2014.984878] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Marker RJ, Stephenson JL, Kluger BM, Curran-Everett D, Maluf KS. Modulation of intracortical inhibition in response to acute psychosocial stress is impaired among individuals with chronic neck pain. J Psychosom Res 2014; 76:249-56. [PMID: 24529046 PMCID: PMC9288141 DOI: 10.1016/j.jpsychores.2013.12.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2013] [Revised: 12/01/2013] [Accepted: 12/02/2013] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Psychosocial stress has been associated with a variety of chronic pain disorders although the mechanisms responsible for this relationship are unknown. The purpose of this study was to compare the excitability of intracortical and corticospinal pathways to the trapezius muscle in individuals with and without chronic neck pain during exposure to low and high levels of psychosocial stress. METHODS Single and paired-pulse transcranial magnetic stimulation was used to assess motor evoked potentials (MEPs) and short-interval intracortical inhibition (SICI) during mental math performed in the presence and absence of social evaluative threat. RESULTS All participants demonstrated higher amplitude MEPs in the high stress compared to the low stress condition (p < 0.01). Participants with chronic neck pain had significantly greater SICI than healthy participants in the low stress condition (p = 0.03). During exposure to the stressor, healthy participants showed an increase in SICI, whereas participants with neck pain showed no change (group difference for change in SICI, p < 0.01). CONCLUSIONS These findings suggest that individuals with chronic neck pain inhibit motor output to the trapezius in the presence of minor stressors, and are unable to compensate for additional stress-evoked increases in corticospinal excitability through further modulation of SICI. This observation has potential implications for the management of patients who have difficulty relaxing painful muscles during times of stress.
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Affiliation(s)
- Ryan J. Marker
- Rehabilitation Science Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Jennifer L. Stephenson
- Clinical Science Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Benzi M. Kluger
- Department of Neurology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Douglas Curran-Everett
- Division of Biostatistics and Bioinformatics, National Jewish Health, Denver, CO, USA and Department of Biostatistics and Informatics, Colorado School of Public Health, University of Colorado Denver, Denver, CO, USA
| | - Katrina S. Maluf
- Rehabilitation Science Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
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Umeda M, Corbin LW, Maluf KS. Pain mediates the association between physical activity and the impact of fibromyalgia on daily function. Clin Rheumatol 2013; 34:143-9. [PMID: 24030630 DOI: 10.1007/s10067-013-2386-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Revised: 08/12/2013] [Accepted: 09/01/2013] [Indexed: 11/29/2022]
Abstract
This study quantified the association between recreational physical activity and daily function in women with fibromyalgia, and determined if this association is mediated by symptoms of pain, depression, or body mass. Twenty-three women diagnosed with fibromyalgia participated in an observational survey study. Recreational physical activity and the impact of fibromyalgia on daily function were assessed using the sport and leisure time physical activity subscales of the Baecke Physical Activity Questionnaire (BPAQ) and the Fibromyalgia Impact Questionnaire (FIQ), respectively. Potential mediators of the association between physical activity and daily function were assessed using the Visual Analogue Scale for pain intensity (VAS-Pain), the Beck Depression Inventory (BDI), and body mass index (BMI). BPAQ was inversely associated with FIQ (R (2) = 0.20) and VAS-Pain (R (2) = 0.39). VAS-Pain was positively associated with FIQ (R (2) = 0.23). The inverse association between BPAQ and FIQ was no longer significant after controlling for VAS-Pain. BDI was positively associated with FIQ (R (2) = 0.37), whereas BMI was not. BPAQ was not significantly associated with either BDI or BMI. These results indicate that the intensity of musculoskeletal pain, rather than depressive symptoms or body mass, mediates the association between physical activity and daily function among women with fibromyalgia.
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Affiliation(s)
- Masataka Umeda
- Department of Health, Exercise, and Sport Sciences, Texas Tech University, Lubbock, TX, USA
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Stephenson JL, Maluf KS. Dependence of the paired motor unit analysis on motor unit discharge characteristics in the human tibialis anterior muscle. J Neurosci Methods 2011; 198:84-92. [PMID: 21459110 PMCID: PMC3718290 DOI: 10.1016/j.jneumeth.2011.03.018] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Revised: 03/18/2011] [Accepted: 03/23/2011] [Indexed: 11/19/2022]
Abstract
The paired motor unit analysis provides in vivo estimates of the magnitude of persistent inward currents (PIC) in human motoneurons by quantifying changes in the firing rate (ΔF) of an earlier recruited (reference) motor unit at the time of recruitment and derecruitment of a later recruited (test) motor unit. This study assessed the variability of ΔF estimates, and quantified the dependence of ΔF on the discharge characteristics of the motor units selected for analysis. ΔF was calculated for 158 pairs of motor units recorded from nine healthy individuals during repeated submaximal contractions of the tibialis anterior muscle. The mean (SD) ΔF was 3.7 (2.5)pps (range -4.2 to 8.9 pps). The median absolute difference in ΔF for the same motor unit pair across trials was 1.8 pps, and the minimal detectable change in ΔF required to exceed measurement error was 4.8 pps. ΔF was positively related to the amount of discharge rate modulation in the reference motor unit (r² = 0.335; P<0.001), and inversely related to the rate of increase in discharge rate (r² = 0.125; P<0.001). A quadratic function provided the best fit for relations between ΔF and the time between recruitment of the reference and test motor units (r² = 0.229, P<0.001), the duration of test motor unit activity (r² = 0.110, P<0.001), and the recruitment threshold of the test motor unit (r² = 0.237, P<0.001). Physiological and methodological contributions to the variability in ΔF estimates of PIC magnitude are discussed, and selection criteria to reduce these sources of variability are suggested for the paired motor unit analysis.
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Affiliation(s)
- Jennifer L Stephenson
- Department of Physical Medicine & Rehabilitation, University of Colorado Denver, School of Medicine, Aurora, CO 80045, USA
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Stephenson JL, Christou EA, Maluf KS. Discharge rate modulation of trapezius motor units differs for voluntary contractions and instructed muscle rest. Exp Brain Res 2010; 208:203-15. [PMID: 21063691 DOI: 10.1007/s00221-010-2471-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2010] [Accepted: 10/19/2010] [Indexed: 10/18/2022]
Abstract
This study examined discharge rate modulation at respiratory (0-0.5 Hz) and beta (16-32 Hz) frequencies in trapezius motor units active during voluntary contractions and during periods of instructed rest under conditions of low and high psychosocial stress. In separate sessions, single motor unit activity was recorded from the trapezius muscle of healthy women during low-intensity voluntary contractions and during periods of instructed muscle rest that followed voluntary contractions. The level of psychosocial stress during periods of instructed muscle rest was manipulated using a verbal math task combined with social evaluative threat which increased perceived anxiety, heart rate, and blood pressure (P ≤ 0.002). Discharge rate modulation was quantified by the mean power of motor unit discharge rate profiles within frequency bands of interest. Under low stress conditions, motor units active during instructed rest had greater power at 0-0.5 Hz (P = 0.002) and less power at 16-32 Hz (P = 0.009) compared to those active during voluntary contraction. Exposure to the stressor increased the amount of motor unit activity during instructed rest (P = 0.021) but did not alter the power of discharge rate modulation at 0-0.5 Hz (P = 0.391) or 16-32 Hz (P = 0.089). These results indicate that sustained motor unit activity during periods of instructed muscle rest has a lesser contribution from inputs at beta frequencies and a greater contribution from inputs at respiratory frequencies than present during low-intensity voluntary contractions. Furthermore, increases in motor unit activity when exposed to stressors during periods of instructed rest are not caused by changes in inputs at respiratory or beta frequencies.
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Affiliation(s)
- Jennifer L Stephenson
- Department of Physical Medicine & Rehabilitation, Applied Neuromuscular Physiology Lab, Physical Therapy Program, University of Colorado Denver School of Medicine, Aurora, CO 80045, USA
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Van Dillen LR, Maluf KS, Sahrmann SA. Further examination of modifying patient-preferred movement and alignment strategies in patients with low back pain during symptomatic tests. ACTA ACUST UNITED AC 2007; 14:52-60. [PMID: 18032090 DOI: 10.1016/j.math.2007.09.012] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2006] [Revised: 08/13/2007] [Accepted: 09/14/2007] [Indexed: 10/22/2022]
Abstract
Our purpose was to examine the effect of modifying symptomatic movement and alignment tests in a sample of people with LBP referred to physical therapy. Fifty-one patients (19 males, 32 females; mean age 37+/-10.59 yr) with LBP and a mean Oswestry Disability Index score of 34+/-18% were examined. The examination included 28 primary tests in which patients used their preferred movement or alignment strategy and reported symptoms. Symptomatic tests were followed by a secondary test in which the patient's strategy was standardly modified to correct the spinal alignment or movement that occurred with the primary test. Symptoms and directions of movement or alignment modified were recorded. For 82% of the secondary tests, the majority of the patients' symptoms improved. For 54% of the secondary tests, some patients required modification of more than one direction of movement or alignment to eliminate symptoms. The findings suggest that the modifications described are generalizable across a number of tests with a moderately involved group of patients, and for individual tests there is variability in the numbers and directions of movements or alignments that appear to contribute to symptoms. Information obtained from the modifications is important because it can be used to confirm the patient's LBP classification and, within the context of the examination, immediately be used to teach the patient strategies to change movements and positions that appear to be contributing to his LBP.
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Affiliation(s)
- Linda R Van Dillen
- Program in Physical Therapy, Washington University School of Medicine, St. Louis, MO 63108, USA.
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Maluf KS, Barry BK, Riley ZA, Enoka RM. Reflex responsiveness of a human hand muscle when controlling isometric force and joint position. Clin Neurophysiol 2007; 118:2063-71. [PMID: 17646129 PMCID: PMC2020450 DOI: 10.1016/j.clinph.2007.06.009] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2007] [Revised: 05/08/2007] [Accepted: 06/12/2007] [Indexed: 11/25/2022]
Abstract
OBJECTIVE This study compared reflex responsiveness of the first dorsal interosseus muscle during two tasks that employ different strategies to stabilize the finger while exerting the same net muscle torque. METHODS Healthy human subjects performed two motor tasks that involved either pushing up against a rigid restraint to exert a constant isometric force equal to 20% of maximum or maintaining a constant angle at the metacarpophalangeal joint while supporting an equivalent inertial load. Each task consisted of six 40-s contractions during which electrical and mechanical stimuli were delivered. RESULTS The amplitude of short and long latency reflex responses to mechanical stretch did not differ significantly between tasks. In contrast, reflexes evoked by electrical stimulation were significantly greater when supporting the inertial load. CONCLUSIONS Agonist motor neurons exhibited heightened reflex responsiveness to synaptic input from heteronymous afferents when controlling the position of an inertial load. Task differences in the reflex response to electrical stimulation were not reflected in the response to mechanical perturbation, indicating a difference in the efficacy of the pathways that mediate these effects. SIGNIFICANCE Results from this study suggest that modulation of spinal reflex pathways may contribute to differences in the control of force and position during isometric contractions of the first dorsal interosseus muscle.
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Affiliation(s)
- Katrina S Maluf
- Department of Integrative Physiology, University of Colorado, Boulder, CO 80309-0354, USA.
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Mottram CJ, Maluf KS, Stephenson JL, Anderson MK, Enoka RM. Prolonged Vibration of the Biceps Brachii Tendon Reduces Time to Failure When Maintaining Arm Position With a Submaximal Load. J Neurophysiol 2006; 95:1185-93. [PMID: 16282200 DOI: 10.1152/jn.00807.2005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Vibration reduces the amplitudes of the tendon jerk response and the Hoffmann and stretch reflexes in the muscle exposed to the vibration, yet does not alter the time to task failure when the task involves exerting a submaximal force against a rigid restraint. Because the amplitude of the stretch reflex is greater when a limb acts against a compliant load than a rigid restraint, the purpose was to determine the influence of prolonged tendon vibration on the time to failure when maintaining limb position with the elbow flexor muscles. Twenty-five healthy men performed the fatiguing contraction by maintaining elbow angle at 1.57 rad until failure while supporting a load equal to 20% of maximal voluntary contraction (MVC) force. The fatiguing contraction was performed on 3 separate days with different levels of vibration applied to the biceps brachii tendon: no vibration, subthreshold for a tonic vibration reflex (TVR), and suprathreshold for a TVR. MVC force before the fatiguing contraction was similar across the three sessions (mean of 3 sessions: 313 ± 54 N, P = 0.83). Despite a similar decline in MVC force after the fatiguing contraction across conditions (–18.0 ± 8.0%, P > 0.05), the time to task failure was 3.7 ± 1.4 min for the suprathreshold TVR condition, 4.3 ± 2.1 min for the subthreshold TVR condition, and 5.0 ± 2.2 min for the no-vibration condition ( P < 0 0.001). The average EMG of the elbow flexor muscles was similar ( P = 0.22) during the fatiguing contractions. However, the fluctuations in limb acceleration at task onset were greater for the suprathreshold TVR condition ( P < 0.01), but were not different between the subthreshold TVR and no-vibration conditions ( P ≥ 0.22). Furthermore, the difference in the SD of limb acceleration between the no-vibration and vibration conditions was correlated with the difference in time to failure for the no-vibration and subthreshold TVR conditions ( P = 0.03; r2 = 0.22), but not for the no-vibration and suprathreshold TVR conditions ( P = 0.90; r2 = 0.001). These findings indicate that prolonged vibration reduced the time to failure of a sustained contraction when subjects maintained limb position, suggesting that peripheral inputs to the motor neuron pool play a significant role in sustaining a contraction during tasks that require active control of limb position.
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Affiliation(s)
- Carol J Mottram
- Department of Integrative Physiology, University of Colorado, Boulder, CO 80309-0354, USA
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Maluf KS, Shinohara M, Stephenson JL, Enoka RM. Muscle activation and time to task failure differ with load type and contraction intensity for a human hand muscle. Exp Brain Res 2005; 167:165-77. [PMID: 16044306 DOI: 10.1007/s00221-005-0017-y] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2005] [Accepted: 03/29/2005] [Indexed: 10/25/2022]
Abstract
Time to failure for sustained isometric contractions of the elbow flexors is briefer when maintaining a constant elbow angle while supporting an inertial load (position task) compared with exerting an equivalent torque against a rigid restraint (force task). Our primary purpose was to determine whether the effects of load type on time to task failure exist when motor unit recruitment cannot be enhanced during a sustained submaximal contraction of an intrinsic hand muscle. A second purpose was to determine whether a greater reserve remains in the muscle after early failure of the position task. Two groups of 10 strength-matched men performed the force and position tasks at either 20% or 60% of maximal force (MVC) with the first dorsal interosseus, followed by a second force task at the same relative intensity. The rate of increase in surface EMG was greater (P = 0.002) and time to failure was briefer (P = 0.005) for the position task (593 +/- 212 s) compared with the force task (983 +/- 328 s) at 20% MVC, whereas there were no task differences in these variables at 60% MVC (P >or= 0.200). Time to failure for the second force tasks did not differ at either contraction intensity (P>or=0.743). These results demonstrate that previously observed effects of load type generalize to a hand muscle, although only for low-intensity contractions. For the position task at low forces, muscle activity increased more rapidly and no additional reserve remained in the muscle at failure compared with the force task. We propose that the briefer time to failure for the position task during sustained, low-intensity contractions is due to earlier recruitment of the motor unit pool.
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Affiliation(s)
- Katrina S Maluf
- Department of Integrative Physiology, University of Colorado, Boulder, 80309-0354, USA.
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Tracy BL, Maluf KS, Stephenson JL, Hunter SK, Enoka RM. Variability of motor unit discharge and force fluctuations across a range of muscle forces in older adults. Muscle Nerve 2005; 32:533-40. [PMID: 15986419 DOI: 10.1002/mus.20392] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Variability of motor unit discharge is a likely contributor to the greater force fluctuations observed in old adults at low muscle forces. We sought to determine whether the variability of motor unit discharge rate underlies the fluctuations in force during steady contractions across a range of forces in young (n = 11) and old (n = 14) adults. The coefficient of variation (CV) for discharge rate and force were measured during a force-matching task as the first dorsal interosseous muscle performed isometric contractions. The recruitment thresholds of the 78 motor units ranged from 0.04% to 34% of maximal voluntary contraction (MVC) force. The CV for discharge rate ranged from 7.6% to 46.2% and was greater (P < 0.05) for old adults (21.5% +/- 7.7%) than young adults (17.3% +/- 8.1%). Although the CV for force was similar for young and old subjects (2.53% +/- 1.6%) across all target forces, it was greater for old adults at the lowest forces. Furthermore, there was a positive relation (r2 = 0.20, P < 0.001) between the CV for force and the CV for discharge rate across the range of recruitment thresholds. This relation was significant for old adults (r2 = 0.30, P < 0.001), but not for young adults (r2 = 0.06, P > 0.05). Thus, the normalized variability (CV) of motor unit discharge was greater in old adults and was related to the amplitude of force fluctuations across a broader range of forces than previously examined. These findings underscore the contribution of variability of motor unit activity to motor output in normal human aging.
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Affiliation(s)
- Brian L Tracy
- Department of Integrative Physiology, University of Colorado, Boulder, Colorado 80523-1582, USA.
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Abstract
By comparing the physiological adjustments that occur when two similar fatiguing contractions are performed to failure, it is possible to identify mechanisms that limit the duration of the more difficult task. This approach has been used to study two fatiguing contractions, referred to as the force and position tasks, which differed in the type of feedback given to the subject and the amount of support provided by the surroundings. Even though the two tasks required a similar net muscle torque during submaximal isometric contractions, the duration that the position task could be sustained was consistently much briefer than that for the force task. The position task involved a greater rate of increase in EMG activity and more marked changes in motor unit recruitment and rate coding compared with the force task. These observations are consistent with the hypothesis that the motor unit pool was recruited more rapidly during the position task. The difference in motor unit behavior appeared to be caused by variation in synaptic input, likely involving heightened sensitivity of the stretch reflex during the position task. Upon repeat performances of the two fatiguing contractions, some subjects were able to increase the time to failure for the force task but not the position task. Furthermore, the time to failure for the position task could be influenced by the postural demands associated with maintaining the position of the limb, and the difference in the two durations was enhanced when the postural activity evoked a pressor response. These observations indicate that the difference in the duration of the two fatiguing contractions was attributable to differences in the control strategy used to sustain the tasks and the magnitude of the associated postural activity.
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Affiliation(s)
- Katrina S Maluf
- Dept. of Integrative Physiology, University of Colorado, Boulder, CO 80309-0354, USA
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Lott DJ, Maluf KS, Sinacore DR, Mueller MJ. Relationship between changes in activity and plantar ulcer recurrence in a patient with diabetes mellitus. Phys Ther 2005; 85:579-88. [PMID: 15921478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
BACKGROUND AND PURPOSE Although pressure-reducing interventions have been effective in the healing of neuropathic foot ulcers, these ulcers frequently recur in people with diabetes mellitus (DM). This case report illustrates how sudden changes in weight-bearing activity may have affected ulcer recurrence in a patient with DM and how the physical stress theory (PST) relates to ulcer recurrence for this patient. CASE DESCRIPTION The patient was a 66-year-old man with a history of DM, peripheral neuropathy, and recurrent plantar ulcers. His plantar ulcer healed after total contact casting. OUTCOME Despite relatively low peak plantar pressure (9.3 N/cm(2)), the patient's ulcer recurred within 4 weeks of healing. Plantar pressure assessment and activity monitoring suggested that a rapid and sudden increase in weight-bearing activity (steps per day) contributed to cumulative plantar tissue stress that was 3.3 times higher on the day of ulcer recurrence than his average value. Although his cumulative plantar stress was high compared with his usual value, the cumulative value was similar to the amount of daily stress of individuals without a history of recurrent ulcers. DISCUSSION Within the context of the PST, rapid change in activity level may have an effect on cumulative stress and the risk of ulcer recurrence.
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Affiliation(s)
- Donovan J Lott
- Program in Physical Therapy, Washington University, Campus Box 8502, 4444 Forest Park Blvd, St Louis, MO 63108-2212, USA.
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Abstract
The purpose of the study was to quantify the influence of selected motor unit properties and patterns of activity on amplitude cancellation in the simulated surface electromyogram (EMG). The study involved computer simulations of a motor unit population with physiologically defined recruitment and rate coding characteristics that activated muscle fibers whose potentials were recorded on the skin over the muscle. Amplitude cancellation was quantified as the percent difference in signal amplitude when motor unit potentials were summed before and after rectification. The simulations involved varying the level of activation for the motor unit population, the recording configuration, the upper limit of motor unit recruitment, peak discharge rates, the amount of motor unit synchronization, muscle fiber length, the thickness of the subcutaneous tissue, and the motor unit properties that change with advancing age. The results confirmed a previous experimental report (Day SJ and Hulliger M, J Neurophysiol 86: 2144–2158, 2001) that amplitude cancellation in the surface EMG can reach 62% at maximal activation. A decrease in the range of amplitudes of the motor unit potentials, as can occur during fatiguing contractions, increased amplitude cancellation up to ∼85%. Differences in the amount of amplitude cancellation were observed across all simulated conditions, and resulted in substantial changes in the absolute magnitude of the EMG signal. The most profound factors influencing amplitude cancellation were the number of active motor units and the duration of the action potentials. The effects of amplitude cancellation were minimal (<5%) when the EMG amplitude was normalized to maximal values, with the exception of variations in peak discharge rate and recruitment range, which resulted in differences up to 17% in the normalized EMG signal across conditions. These results indicate the amount of amplitude cancellation that can occur in various experimental conditions and its influence on absolute and relative measures of EMG amplitude.
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Affiliation(s)
- Kevin G Keenan
- Dept. of Integrative Physiology, University of Colorado at Boulder, Boulder, CO 80309-0354, USA
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Maluf KS, Mueller MJ, Strube MJ, Engsberg JR, Johnson JE. Tendon Achilles lengthening for the treatment of neuropathic ulcers causes a temporary reduction in forefoot pressure associated with changes in plantar flexor power rather than ankle motion during gait. J Biomech 2004; 37:897-906. [PMID: 15111077 DOI: 10.1016/j.jbiomech.2003.10.009] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/29/2003] [Indexed: 11/24/2022]
Abstract
The purposes of this study were to determine the effects of tendon Achilles lengthening (TAL) on ambulatory plantar pressures and ankle range of motion, moment, and power, and to determine whether changes in forefoot pressure after treatment of a neuropathic ulcer are related to changes in ankle dorsiflexion range of motion (DFROM) or plantar flexor (PF) power during gait. Pressure and gait tests were performed before treatment, and at 3 weeks and 8 months after treatment in two randomly assigned groups of subjects with diabetes, equinus deformity, and a neuropathic forefoot ulcer treated with TAL and total contact casting (TAL group, n=14), or total contact casting alone (TCC group, n=14). The TAL group had an initial decrease in forefoot peak pressure (PP) (27%), forefoot pressure-time integral (PTI) (42%), PF moment (53%), and PF power (65%), along with an initial increase in rear foot PP (34%), rear foot PTI (48%), and DFROM (74%). Post-surgical changes in rear foot pressure and DFROM were maintained up to 8 months after treatment with TAL, whereas forefoot pressure and PF moment and power increased significantly. Changes in forefoot pressure after treatment in either group were correlated with changes in PF power (r=0.45-0.60), but not with changes in DFROM during gait (r=-0.02-0.08). Results suggest TAL causes a temporary reduction in forefoot pressure primarily by reducing PF power during gait. The initial decrease in forefoot pressure, followed by progressive reloading of forefoot tissues as PF muscles regain strength after TAL, may help reduce the risk of ulcer recurrence in patients with diabetes.
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Affiliation(s)
- K S Maluf
- Department of Integrative Physiology, University of Colorado at Boulder, USA
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Stephenson JL, Maluf KS, Tracy BL, Hunter SK, Enoka RM. Fluctuations in Isometric Force Are Associated With Motor Unit Discharge Rate Variability in Older Adults. Med Sci Sports Exerc 2004. [DOI: 10.1249/00005768-200405001-00587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Maluf KS, Morley RE, Richter EJ, Klaesner JW, Mueller MJ. Foot pressures during level walking are strongly associated with pressures during other ambulatory activities in subjects with diabetic neuropathy. Arch Phys Med Rehabil 2004; 85:253-60. [PMID: 14966710 DOI: 10.1016/j.apmr.2003.06.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To assess the relationship between foot pressures measured during level walking and other types of ambulatory activity in subjects with diabetes mellitus (DM) and peripheral neuropathy (PN). DESIGN Descriptive survey with repeated measures. SETTING University medical center. PARTICIPANTS Convenience sample of 16 ambulatory subjects with DM and PN. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Peak pressure and pressure-time integral (PTI) at the heel, great toe, first metatarsal head (MT1), and third metatarsal head (MT3) during level walking, ramp climbing, stair climbing, and turning at a self-selected speed. RESULTS Peak pressure and PTI during level walking correlated highly with pressures during ramp climbing (r range,.85-.97) and turning (r range,.75-.96) at all regions examined and with pressures during stair climbing at MT1 and MT3 (r range,.84-.91). Correlations between pressures during level walking and stair climbing were moderate at the great toe (r range,.46-.57) and poor at the heel (r range, -.12 to -.06). With few exceptions, pressures during ramp climbing, stair climbing, and turning were less than (P<.008) or equal to pressures during level walking. We found no activity-related differences in peak pressure or PTI independent of the effects of preferred walking speed. CONCLUSIONS Results support the clinical evaluation of peak pressure during level walking as an efficient method to screen for maximum levels of stress on the foot as patients with DM and PN perform their daily activities.
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Affiliation(s)
- Katrina S Maluf
- Department of Kinesiology and Applied Physiology, University of Colorado, Boulder, CO, USA
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Maluf KS, Mueller MJ. Novel Award 2002. Comparison of physical activity and cumulative plantar tissue stress among subjects with and without diabetes mellitus and a history of recurrent plantar ulcers. Clin Biomech (Bristol, Avon) 2003; 18:567-75. [PMID: 12880704 DOI: 10.1016/s0268-0033(03)00118-9] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVES To compare the amount of weight-bearing activity and estimates of cumulative plantar tissue stress between subjects with and without diabetes mellitus and a history of recurrent plantar ulcers. DESIGN Cross-sectional study with matched groups. BACKGROUND Weight-bearing activity among individuals with diabetes is likely to influence the amount of mechanical trauma accumulated by plantar tissues, yet activity levels have not been accounted for in previous measurements of plantar tissue stress or predictions of plantar tissue injury. METHODS Study groups included subjects with diabetes mellitus and peripheral neuropathy, either with or without a history of recurrent plantar ulcers, and non-diabetic control subjects (n=10 per group). Pressure on the plantar foot was assessed as subjects walked at their preferred speed in the shoes they reported wearing most often each day. Physical activity was monitored over seven consecutive days using an accelerometer. The product of mean daily strides and forefoot pressure-time integral was used to estimate daily cumulative stress on the plantar forefoot. RESULTS Subjects with diabetes and a history of recurrent plantar ulcers were 46% less active than subjects without diabetes (mean (SD)=2727 (1345) versus 5037 (2624) strides/day, P=0.04), and accumulated 41% less daily stress on the forefoot than non-diabetic and diabetic control subjects without a history of plantar ulcers (mean (SD)= 210 (134) versus 354 (118) and 354 (148) MPas/day respectively, P=0.03). CONCLUSIONS Subjects with diabetes and a history a previous ulcers may be susceptible to plantar tissue injury even at relatively low levels of cumulative tissue stress. RELEVANCE Changes in weight-bearing activity following plantar tissue injury in patients with diabetes may influence plantar tissue adaptation and the risk of ulcer recurrence.
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Affiliation(s)
- K S Maluf
- Washington University School of Medicine, Program in Physical Therapy, 4444 Forest Park Blvd, Campus Box 8502, Saint Louis, MO 63108-2212, USA
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Abstract
The purpose of this study was to compare muscle activity and joint moments in the lower extremities during walking between subjects with diabetic neuropathy (DN) and control subjects. Tests were performed on nine subjects with DN, and nine age, gender, and weight-matched controls. Onset and cessation times of lower extremity electromyographic (EMG) activity and joint moments were determined. Results demonstrated that subjects with DN had less ankle mobility, slower walking speeds, longer stance phases, and lower peak ankle dorsiflexion, ankle plantar flexion, and knee extension moments than control subjects. Onset times with respect to heel-strike (HS) for the soleus, medial gastrocnemius, and medial hamstring muscles were significantly earlier during the gait cycle (GC) in subjects with DN than in control subjects. The cessation times of soleus, tibialis anterior, vastus medialis, and medial hamstring muscles were significantly prolonged in subjects with DN. Subjects with DN showed more co-contractions of agonist and antagonist muscles at the ankle and knee joints during stance phase compared with control subjects. These gait changes and co-contractions may allow subjects with DN to adopt a safer, more stable gait pattern to compensate for diminished sensory information from the ankle and the foot. The premature activation of soleus and medial gastrocnemius muscles in subjects with DN could be contributing to abnormal forefoot plantar pressure distribution. Additional research is needed to clarify the relationship between the premature activation of triceps surae muscles and the forefoot plantar pressure parameters in subjects with DN.
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Affiliation(s)
- Oh-Yun Kwon
- Department of Rehabilitation, College of Health Science, Yonsei University, Wonju, South Korea
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Abstract
The purpose of this perspective is to present a general theory--the Physical Stress Theory (PST). The basic premise of the PST is that changes in the relative level of physical stress cause a predictable adaptive response in all biological tissue. Specific thresholds define the upper and lower stress levels for each characteristic tissue response. Qualitatively, the 5 tissue responses to physical stress are decreased stress tolerance (eg, atrophy), maintenance, increased stress tolerance (eg, hypertrophy), injury, and death. Fundamental principles of tissue adaptation to physical stress are described that, in the authors' opinion, can be used to help guide physical therapy practice, education, and research. The description of fundamental principles is followed by a review of selected literature describing adaptation to physical stress for each of the 4 main organ systems described in the Guide to Physical Therapist Practice (ie, cardiovascular/pulmonary, integumentary, musculoskeletal, neuromuscular). Limitations and implications of the PST for practice, research, and education are presented.
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Affiliation(s)
- Michael J Mueller
- Movement Science Laboratory, Program in Physical Therapy, Washington University School of Medicine, 4444 Forest Park Blvd, Campus Box 8502, St Louis, MO 63110-2212, USA.
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Maluf KS. A lesson from John Hughlings Jackson. J Orthop Sports Phys Ther 2002; 32:84-5. [PMID: 12168741 DOI: 10.2519/jospt.2002.32.3.84] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Maluf KS, Morley RE, Richter EJ, Klaesner JW, Mueller MJ. Monitoring in-shoe plantar pressures, temperature, and humidity: reliability and validity of measures from a portable device. Arch Phys Med Rehabil 2001; 82:1119-27. [PMID: 11494193 DOI: 10.1053/apmr.2001.24223] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE To investigate the reliability and validity of measures obtained from a portable electronic device used to monitor changes in plantar pressure, temperature, and humidity that occur within the shoe during prolonged activity. DESIGN Descriptive study comparing electronic sensor output with criterion values. SETTINGS Indoor level walkway for pressure data; uncontrolled, outdoor environment for step count data; enclosed environmental control chamber for humidity and temperature data. PARTICIPANTS Convenience sample of 4 healthy, sensate subjects. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Correlations between sensor output and criterion measures were determined for pressure and temperature data. The absolute differences between sensor output and criterion values of temperature, humidity, and step count were also determined. RESULTS Pressure measurements from electronic sensors correlated highly with criterion values (r > or =.82), both before and after prolonged use. Relative humidity sensor output were within 5% of hygrometer values. In-shoe temperature data correlated highly with criterion values (r > or =.99), and differed from known temperatures by.50 degrees +/-.84 degrees C and.96 degrees +/- 1.56 degrees C at the forefoot and heel, respectively. Electronic step counts recorded at the central forefoot were within 1 step of visual step counts. Pressure tracings obtained from the device during different weight-bearing activities revealed qualitatively distinct pressure patterns. CONCLUSION The device provides valid and reliable measures of in-shoe plantar pressures, temperature, and humidity during prolonged activity.
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Affiliation(s)
- K S Maluf
- Program in Physical Therapy, Washington University School of Medicine, St. Louis, MO 63108-2212, USA
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Abstract
Patients with diabetes and peripheral neuropathy are susceptible to unnoticed trauma on the foot that can cause skin breakdown. We have designed an electronic system in a shoe that monitors temperature, pressure, and humidity, storing the data in a battery-powered device for later uploading to a host computer for data analysis. The pressure sensors are located at the heel, and under three metatarsal heads. Temperature sensors are located under the medial metatarsal head and under the heel. The humidity sensor is located in the toe of the shoe. Correlations of data from pressure sensors with known values were high (r > 0.85), even after extended use. Although data currently are being collected for descriptive purposes, the design potentially can be used to provide feedback to patients.
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Affiliation(s)
- R E Morley
- Department of Electrical Engineering, Washington University, St Louis, MO 63130-4899, USA.
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Maluf KS, Sahrmann SA, Van Dillen LR. Use of a classification system to guide nonsurgical management of a patient with chronic low back pain. Phys Ther 2000; 80:1097-111. [PMID: 11046197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
BACKGROUND AND PURPOSE This case report describes the use of a classification system in the evaluation of a patient with chronic low back pain (LBP) and illustrates how this system was used to develop a management program in which the patient was instructed in symptom-reducing strategies for positioning and functional movement. CASE DESCRIPTION The patient was a 55-year-old woman with a medical diagnosis of lumbar degenerative disk and degenerative joint disease from L2 to S1. Rotation with extension of the lumbar spine was found to be consistently associated with an increase in symptoms during the examination. Instruction was provided to restrict lumbar rotation and extension during performance of daily activities. OUTCOMES The patient completed 8 physical therapy sessions over a 3-month period. Pretreatment, posttreatment, and 3-month follow-up modified Oswestry Disability Questionnaire scores were 43%, 16%, and 12%, respectively. DISCUSSION Daily repetition of similar movements and postures may result in preferential movement of the lumbar spine in a specific direction, which then may contribute to the development, persistence, or recurrence of LBP. Research is needed to determine whether patients with LBP would benefit from training in activity modifications that are specific to the symptom-provoking movements and postures of each individual as identified through examination.
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Affiliation(s)
- K S Maluf
- Movement Science Program, Program in Physical Therapy, Washington University School of Medicine, St Louis, MO, USA
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