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Toxins Apr 2021The simple definition of tone as the resistance to passive stretch is physiologically a complex interlaced network encompassing neural circuits in the brain, spinal... (Review)
Review
The simple definition of tone as the resistance to passive stretch is physiologically a complex interlaced network encompassing neural circuits in the brain, spinal cord, and muscle spindle. Disorders of muscle tone can arise from dysfunction in these pathways and manifest as hypertonia or hypotonia. The loss of supraspinal control mechanisms gives rise to hypertonia, resulting in spasticity or rigidity. On the other hand, dystonia and paratonia also manifest as abnormalities of muscle tone, but arise more due to the network dysfunction between the basal ganglia and the thalamo-cerebello-cortical connections. In this review, we have discussed the normal homeostatic mechanisms maintaining tone and the pathophysiology of spasticity and rigidity with its anatomical correlates. Thereafter, we have also highlighted the phenomenon of network dysfunction, cortical disinhibition, and neuroplastic alterations giving rise to dystonia and paratonia.
Topics: Animals; Brain; Dystonia; Humans; Muscle Contraction; Muscle Hypertonia; Muscle Rigidity; Muscle Spasticity; Muscle Tonus; Muscle, Skeletal; Neural Pathways; Spinal Cord
PubMed: 33923397
DOI: 10.3390/toxins13040282 -
European Journal of Physical and... Aug 2018The Modified Ashworth Scale is the most widely clinical scale used to measure the increase of muscle tone. Reliability is not an immutable property of a scale and can... (Meta-Analysis)
Meta-Analysis Review
INTRODUCTION
The Modified Ashworth Scale is the most widely clinical scale used to measure the increase of muscle tone. Reliability is not an immutable property of a scale and can vary as a function of the variability and composition of the sample to which it is administered. The best method to examine how the reliability of a test scores varies is by conducting a systematic review and meta-analysis of the reliability coefficients obtained in different applications of the test with the data at hand. The objectives of this systematic revision are: what is the mean inter- and intra-rater reliability of the Modified Ashworth Scale's scores in upper and lower extremities? Which study characteristics affect the reliability of the scores in this scale?
EVIDENCE ACQUISITION
The PubMed, Embase and CINAHL databases were searched from 1987 to February 2015. Two reviewers independently selected empirical studies published in English or in Spanish that applied the Modified Ashworth Scale and reported any reliability coefficient with the data at hand in children, adolescents or adults with spasticity.
EVIDENCE SYNTHESIS
Thirty-three studies reported any reliability estimate of Modified Ashworth Scale scores (N.=1065 participants). For lower extremities and inter-rater agreement, the mean intraclass correlation was ICC+=0.686 (95% CI: 0.563 and 0.780) and for kappa coefficients, κ+=0.360 (95% CI: 0.241 and 0.468); for intra-rater agreement: ICC+=0.644 (95% CI: 0.543 and 0.726) and κ+=0.488 (95% CI: 0.370 and 0.591). For upper extremities and inter-rater agreement: ICC+=0.781 (95% CI: 0.679 and 0.853) and κ+=0.625 (95% CI: 0.350 and 0.801); for intra-rater agreement: ICC+=0.748 (95% CI: 0.671 and 0.809) and κ+=0.593 (95% CI: 0.467 and 0.696). The type of design, the study focus, and the number of raters presented statistically significant relationships with ICC both for lower and upper extremities.
CONCLUSIONS
Inter- and intra-rater agreement for Modified Ashworth Scale scores was satisfactory. Modified Ashworth Scale' scores exhibited better reliability when measuring upper extremities than lower. Several characteristics of the studies were statistically associated to inter-rater reliability of the scores for lower and upper extremities.
Topics: Disability Evaluation; Evidence-Based Medicine; Female; Humans; Male; Muscle Spasticity; Muscle Tonus; Observer Variation; Physical and Rehabilitation Medicine; Severity of Illness Index
PubMed: 28901119
DOI: 10.23736/S1973-9087.17.04796-7 -
Journal of Sports Science & Medicine Mar 2019Dynamic stretching (DS) is often performed during warm-up to help avoid hamstring muscle injuries, increase joint flexibility, and optimize performance. We examined the...
Dynamic stretching (DS) is often performed during warm-up to help avoid hamstring muscle injuries, increase joint flexibility, and optimize performance. We examined the effects of DS of the hamstring muscles on passive knee extension range of motion (ROM), passive torque (PT) at the onset of pain (as a measure of stretch tolerance), and passive stiffness of the muscle-tendon unit over an extended period after stretching. Twenty-four healthy subjects participated, with 12 each in the experimental and control groups. Stretching was performed, and measurements were recorded using an isokinetic dynamometer pre-intervention, and at 0, 15, 30, 45, 60, 75, and 90 min post-intervention. DS consisted of ten 30-s sets of 15 repetitions of extension and relaxation of the hamstrings. ROM increased significantly (range, 7%-10%) immediately after DS, and the increase was sustained over 90 min. PT at the onset of pain also increased immediately by 10% but returned to baseline by 30 min. Passive stiffness decreased significantly (range, 7.9%-16.7%) immediately after DS, and the decrease was sustained over 90 min. Post-DS values were normalized to pre-DS values for the respective outcomes in both groups. ROM was significantly higher (range, 7.4%-10%) and passive stiffness was significantly lower (range, 5.4%-14.9%) in the experimental group relative to the control group at all time points. Normalized PT values at the onset of pain were significantly higher in the experimental group at 0-15 min than in the controls, but the differences were smaller at 30-45 min and not significant thereafter. We conclude that DS increases ROM and decreases passive stiffness in a sustained manner, and increases PT at the onset of pain for a shorter period. Overall, our results indicate that when performed prior to exercise, DS is beneficial for the hamstring muscles in terms of increasing flexibility and reducing stiffness.
Topics: Female; Hamstring Muscles; Humans; Knee; Male; Muscle Stretching Exercises; Muscle Tonus; Myalgia; Range of Motion, Articular; Torque; Young Adult
PubMed: 30787647
DOI: No ID Found -
The Cochrane Database of Systematic... Jun 2017Exercise training is commonly recommended for individuals with fibromyalgia. This review is one of a series of reviews about exercise training for people with... (Review)
Review
BACKGROUND
Exercise training is commonly recommended for individuals with fibromyalgia. This review is one of a series of reviews about exercise training for people with fibromyalgia that will replace the "Exercise for treating fibromyalgia syndrome" review first published in 2002.
OBJECTIVES
• To evaluate the benefits and harms of aerobic exercise training for adults with fibromyalgia• To assess the following specific comparisons ० Aerobic versus control conditions (eg, treatment as usual, wait list control, physical activity as usual) ० Aerobic versus aerobic interventions (eg, running vs brisk walking) ० Aerobic versus non-exercise interventions (eg, medications, education) We did not assess specific comparisons involving aerobic exercise versus other exercise interventions (eg, resistance exercise, aquatic exercise, flexibility exercise, mixed exercise). Other systematic reviews have examined or will examine these comparisons (Bidonde 2014; Busch 2013).
SEARCH METHODS
We searched the Cochrane Library, MEDLINE, Embase, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), the Physiotherapy Evidence Database (PEDro), Thesis and Dissertation Abstracts, the Allied and Complementary Medicine Database (AMED), the World Health Organization International Clinical Trials Registry Platform (WHO ICTRP), and the ClinicalTrials.gov registry up to June 2016, unrestricted by language, and we reviewed the reference lists of retrieved trials to identify potentially relevant trials.
SELECTION CRITERIA
We included randomized controlled trials (RCTs) in adults with a diagnosis of fibromyalgia that compared aerobic training interventions (dynamic physical activity that increases breathing and heart rate to submaximal levels for a prolonged period) versus no exercise or another intervention. Major outcomes were health-related quality of life (HRQL), pain intensity, stiffness, fatigue, physical function, withdrawals, and adverse events.
DATA COLLECTION AND ANALYSIS
Two review authors independently selected trials for inclusion, extracted data, performed a risk of bias assessment, and assessed the quality of the body of evidence for major outcomes using the GRADE approach. We used a 15% threshold for calculation of clinically relevant differences between groups.
MAIN RESULTS
We included 13 RCTs (839 people). Studies were at risk of selection, performance, and detection bias (owing to lack of blinding for self-reported outcomes) and had low risk of attrition and reporting bias. We prioritized the findings when aerobic exercise was compared with no exercise control and present them fully here.Eight trials (with 456 participants) provided low-quality evidence for pain intensity, fatigue, stiffness, and physical function; and moderate-quality evidence for withdrawals and HRQL at completion of the intervention (6 to 24 weeks). With the exception of withdrawals and adverse events, major outcome measures were self-reported and were expressed on a 0 to 100 scale (lower values are best, negative mean differences (MDs)/standardized mean differences (SMDs) indicate improvement). Effects for aerobic exercise versus control were as follows: HRQL: mean 56.08; five studies; N = 372; MD -7.89, 95% CI -13.23 to -2.55; absolute improvement of 8% (3% to 13%) and relative improvement of 15% (5% to 24%); pain intensity: mean 65.31; six studies; N = 351; MD -11.06, 95% CI -18.34 to -3.77; absolute improvement of 11% (95% CI 4% to 18%) and relative improvement of 18% (7% to 30%); stiffness: mean 69; one study; N = 143; MD -7.96, 95% CI -14.95 to -0.97; absolute difference in improvement of 8% (1% to 15%) and relative change in improvement of 11.4% (21.4% to 1.4%); physical function: mean 38.32; three studies; N = 246; MD -10.16, 95% CI -15.39 to -4.94; absolute change in improvement of 10% (15% to 5%) and relative change in improvement of 21.9% (33% to 11%); and fatigue: mean 68; three studies; N = 286; MD -6.48, 95% CI -14.33 to 1.38; absolute change in improvement of 6% (12% improvement to 0.3% worse) and relative change in improvement of 8% (16% improvement to 0.4% worse). Pooled analysis resulted in a risk ratio (RR) of moderate quality for withdrawals (17 per 100 and 20 per 100 in control and intervention groups, respectively; eight studies; N = 456; RR 1.25, 95%CI 0.89 to 1.77; absolute change of 5% more withdrawals with exercise (3% fewer to 12% more).Three trials provided low-quality evidence on long-term effects (24 to 208 weeks post intervention) and reported that benefits for pain and function persisted but did not for HRQL or fatigue. Withdrawals were similar, and investigators did not assess stiffness and adverse events.We are uncertain about the effects of one aerobic intervention versus another, as the evidence was of low to very low quality and was derived from single trials only, precluding meta-analyses. Similarly, we are uncertain of the effects of aerobic exercise over active controls (ie, education, three studies; stress management training, one study; medication, one study) owing to evidence of low to very low quality provided by single trials. Most studies did not measure adverse events; thus we are uncertain about the risk of adverse events associated with aerobic exercise.
AUTHORS' CONCLUSIONS
When compared with control, moderate-quality evidence indicates that aerobic exercise probably improves HRQL and all-cause withdrawal, and low-quality evidence suggests that aerobic exercise may slightly decrease pain intensity, may slightly improve physical function, and may lead to little difference in fatigue and stiffness. Three of the reported outcomes reached clinical significance (HRQL, physical function, and pain). Long-term effects of aerobic exercise may include little or no difference in pain, physical function, and all-cause withdrawal, and we are uncertain about long-term effects on remaining outcomes. We downgraded the evidence owing to the small number of included trials and participants across trials, and because of issues related to unclear and high risks of bias (performance, selection, and detection biases). Aerobic exercise appears to be well tolerated (similar withdrawal rates across groups), although evidence on adverse events is scarce, so we are uncertain about its safety.
Topics: Adult; Exercise; Fatigue; Female; Fibromyalgia; Humans; Male; Middle Aged; Muscle Tonus; Pain Measurement; Patient Dropouts; Quality of Life; Randomized Controlled Trials as Topic
PubMed: 28636204
DOI: 10.1002/14651858.CD012700 -
Lakartidningen Dec 2021Paroxysmal sympathetic hyperactivity (PSH) is a condition mainly described in patients after traumatic brain injury and it is also known under the terms "autonomic...
Paroxysmal sympathetic hyperactivity (PSH) is a condition mainly described in patients after traumatic brain injury and it is also known under the terms "autonomic storm" and "dysautonomia". It affects between 8-10% of patients after traumatic brain injury and can also affect patients after other neurological diseases, such as anoxic brain injury, stroke, tumors or infections. PSH manifests with six main symptoms: tachycardia, tachypnea, hypertension, hyperthermia, hyperhidrosis and increased muscle tonus. It is of outmost importance to exclude other causes for the symptoms and there are diagnostic criteria established to identify and diagnose PSH. The treatment is pharmacological and non-pharmacological and often multimodal. PSH is probably underdiagnosed and increased awareness is needed.
Topics: Autonomic Nervous System Diseases; Brain Injuries; Brain Injuries, Traumatic; Humans; Hypertension; Tachycardia
PubMed: 34914088
DOI: No ID Found -
Mechanisms of Development Apr 2017Muscles are the major force producing tissue in the human body. While certain muscle types specialize in producing maximum forces, others are very enduring. An extreme... (Review)
Review
Muscles are the major force producing tissue in the human body. While certain muscle types specialize in producing maximum forces, others are very enduring. An extreme example is the heart, which continuously beats for the entire life. Despite being specialized, all body muscles share similar contractile mini-machines called sarcomeres that are organized into regular higher order structures called myofibrils. The major sarcomeric components and their organizational principles are conserved throughout most of the animal kingdom. In this review, we discuss recent progress in the understanding of myofibril and sarcomere development largely obtained from in vivo models. We focus on the role of mechanical forces during muscle and myofibril development and propose a tension driven self-organization mechanism for myofibril formation. We discuss recent technological advances that allow quantification of forces across tissues or molecules in vitro and in vivo. Although their application towards muscle development is still in its infancy, these technologies are likely to provide fundamental new insights into the mechanobiology of muscle and myofibril development in the near future.
Topics: Actins; Animals; Biomechanical Phenomena; Connectin; Drosophila melanogaster; Gene Expression Regulation, Developmental; Humans; Integrins; Muscle Development; Muscle Tonus; Myofibrils; Signal Transduction; Tendons
PubMed: 27913119
DOI: 10.1016/j.mod.2016.11.003 -
Cureus Aug 2021Pseudomyopia is an inappropriately excessive accommodation of the eye due to overstimulation or ciliary spasm, which leads to a marked approximation of the far point.... (Review)
Review
Pseudomyopia is an inappropriately excessive accommodation of the eye due to overstimulation or ciliary spasm, which leads to a marked approximation of the far point. Common symptoms of pseudomyopia include eye strain or fatigue, and it is classified as organic or functional. The latter is due to eye strain and functional increase in the ciliary tonus. Pseudomyopia can vary from being a transient condition or continue to progress to myopia. Head trauma is the most common cause followed by psychiatric illnesses, neurologic diseases, and drug-induced causes. There is an association between psychological stress-inducing events and pseudomyopia as it affects the autonomic nervous system. The human body counteracts anxiety by activating the parasympathetic nervous system, causing ciliary muscle contraction. Underlying psychiatric diseases in pseudomyopia patients have been reported in the past in multiple studies. Generalized anxiety disorder is the most common psychiatric illness associated with pseudomyopia with a positive correlation between anxiety-somatization scores and accommodation amount of the eye. It is strongly advised that a psychiatric consultation should be included in the multidisciplinary evaluation of every case. If patients have coexisting anxiety disorders, a multidisciplinary approach using psychiatric consultations, work environment changes, ocular exercises, and cycloplegic drugs can be used. This review aims to shed light on the association of psychiatric disorders such as anxiety with pseudomyopia.
PubMed: 34589322
DOI: 10.7759/cureus.17411 -
Journal of Biomechanics May 2023The classical view of muscles as independent motors has been challenged over the past decades. An alternative view has emerged in which muscles are not isolated but... (Review)
Review
The classical view of muscles as independent motors has been challenged over the past decades. An alternative view has emerged in which muscles are not isolated but embedded in a three-dimensional connective tissue network that links them to adjacent muscles and other non-muscular structures in the body. Animal studies showing that the forces measured at the distal and proximal ends of a muscle are not equal have provided undisputable evidence that these connective tissue linkages are strong enough to serve as an extra pathway for muscular force transmission. In this historical review, we first introduce the terminology and anatomy related to these pathways of muscle force transmission and provide a definition for the term epimuscular force transmission. We then focus on important experimental evidence indicating mechanical interactions between synergistic muscles that may affect force transmission and/or influence the muscles' force generating capacity. We illustrate that there may exist different expressions of the highly relevant force-length properties depending on whether the force is measured at the proximal or distal tendon and depending on the dynamics of surrounding structures. Changes in length, activation level or disruption of the connective tissue of neighboring muscles, can affect how muscles interact and produce force on the skeleton. While most direct evidence is from animal experiments, studies on humans also suggest functional implications of the connective tissues surrounding muscles. These implications may explain how distant segments, which are not part of the same joint system, affect force generation at a given joint, and, in clinical conditions, explain observations from tendon transfer surgeries, where a muscle transferred to act as an antagonist continues to produce agonistic moments.
Topics: Humans; Muscle, Skeletal; Animals; Connective Tissue; Muscle Tonus; Muscle Strength
PubMed: 37120913
DOI: 10.1016/j.jbiomech.2023.111575 -
American Journal of Physiology. Lung... Oct 2019
Topics: Animals; Bronchiectasis; Mice; Muscle Tonus; Respiratory System
PubMed: 31508977
DOI: 10.1152/ajplung.00363.2019 -
American Journal of Physiology.... Jul 2021Aging can lead to rectoanal incontinence due to internal anal sphincter (IAS) dysfunction, which is characterized by a decrease in IAS tone and contractility and an...
Aging can lead to rectoanal incontinence due to internal anal sphincter (IAS) dysfunction, which is characterized by a decrease in IAS tone and contractility and an increase in nonadrenergic noncholinergic (NANC) relaxation. We aimed to determine whether brain-derived neurotropic factor (BDNF) rescues this aging-associated IAS dysfunction (AAID). To do so, we studied the effects of BDNF on the basal and G protein-coupled receptors (GPCR)-stimulated IAS smooth muscle tone and on NANC relaxation in Fischer 344 rats representing different age groups [26-mo-old (aging) vs. 6-mo-old (young)], before and after tyrosine kinase receptor B (TrkB) antagonist K252a. We also used isolated smooth muscle cells (SMCs) to determine the effects of BDNF before and after different agonists. For some studies, we monitored NO release using smooth muscle perfusates. BDNF reversed AAID by rescuing the basal IAS tone and agonists [thromboxane A analog (U46619) and angiotensin II (ANG II)]-induced contractility, and NANC relaxation. These rescue effects of BDNF were selective as K252a attenuated the changes in the IAS without modifying the effects of Kdepolarization. Because of the direct association between the basal and GPCR-stimulated IAS tone and RhoA/ROCK activation, we speculate that this pathway in the rescue effects of BDNF. Conversely, our data suggest that aging-associated increased NANC relaxation is reversed by decreased release of NO and decrease in the sensitivity of the released inhibitory neurotransmitter. In summary, BDNF rescue of AAID involves RhoA/ROCK and inhibitory neurotransmission. These data have direct implications for the role of BDNF in the pathophysiology and therapeutic targeting of aging-associated rectoanal motility disorders. These studies demonstrate that brain-derived neurotropic factor (BDNF) rescues the aging-associated internal anal sphincter (IAS) dysfunction, characterized by a decrease in IAS tone, and increase in non-adrenergic noncholinergic relaxation. We determined the effects of BDNF on the basal and GPCR (TXA and ANG II)-stimulated IAS tone, and on NANC relaxation, before and after TrkB inhibitor K252a. BDNF may have an important role in the pathophysiology and therapeutic targeting of certain rectoanal motility disorders.
Topics: Aging; Animals; Brain; Brain-Derived Neurotrophic Factor; Male; Muscle Contraction; Muscle Relaxation; Muscle Tonus; Muscle, Smooth; Myocytes, Smooth Muscle; Rats; Rats, Inbred F344; Signal Transduction; rho-Associated Kinases
PubMed: 34075793
DOI: 10.1152/ajpgi.00090.2021