Facilitation and suppression of the patellar reflex by muscular exercises.
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Electromyography↗
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Results for “Muscle Stretching Exercises”
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Tennis shoulder.
A depression of the exercised shoulder was found in skilled tennis players, and in other athletes employing the overhand motion. The deformity is attributed to stretching of the shoulder elevating muscles and hypertrophy of the extremity. Most symptoms were over the anterior rotator cuff, and occurred on abduction of the arm. Shoulder depression results in a relative abduction and abduction causes impingement of the cuff. Shoulder droop may induce thoracic outlet syndrome and may simulate scoliosis in the athlete.
Adult↗
Acute and chronic adaptations of muscle proprioceptors in response to increased use.
Acute adaptations to use have been shown to occur in both the muscle spindle and Golgi tendon organ pathways. This short term activation adaptation increases the excitability of the motoneuron pool, thereby potentially providing a nonvoluntary increase in the excitation of subsequent contractions. It is thought that the intrafusal muscle fibres reset to a higher gain after contraction and that the tendon organ pathway undergoes a brief desensitisation. These phenomena could be important clinically when trying to stretch muscles, i.e. a contraction before a stretch should make the stretch more difficult. Also, this could affect the amount of muscle force generated, thereby altering motor behaviours requiring fine accuracy. Research on the adaptations of proprioceptors during free movement, using locomotion as a model, has found that the hypothesis of consistent alpha-gamma coactivation during motor behaviours is much more complicated and adaptable, depending on the environmental circumstance and the specific motor task. These research findings support the use of selective training, i.e. training to the task, for optimal motor learning. The results of the relatively limited research on chronic adaptations of proprioceptors due to exercise has shown that on a microlevel, the intrafusal muscle fibres may show some metabolic changes but do not show any hypertrophy. However, on a more macro level, with extended training, the latency of the stretch reflex response is found to be decreased and the amplitude is found to be increased in both animals and humans. Through classical conditioning research, proprioceptors may also be necessary for motor learning. Lastly, both primates and humans have been shown to be able to up- or down-grade their stretch reflex responses using operant conditioning techniques and many practice sessions. These findings have important implications both for rehabilitation of persons with abnormal reflex activity and in the training of athletes. This review provides some consolidation of the recent research findings, but much more research needs to be done in order to fully understand the purpose and importance of the proprioceptive sensory system.
Humans↗
Multisystem Proteinopathy
CLINICAL CHARACTERISTICS: Multisystem proteinopathy (MSP) is a genetically heterogeneous, multisystem degenerative disorder characterized by adult-onset proximal and distal muscle weakness (clinically resembling a limb-girdle muscular dystrophy syndrome), early-onset Paget disease of bone (PDB), and premature frontotemporal dementia (FTD). Muscle weakness progresses to involve other limb and respiratory muscles. PDB involves focal areas of increased bone turnover that typically lead to spine and/or hip pain and localized enlargement and deformity of the long bones; pathologic fractures occur on occasion. Early stages of FTD are characterized by dysnomia, dyscalculia, comprehension deficits, and paraphasic errors, with minimal impairment of episodic memory; later stages are characterized by inability to speak, auditory comprehension deficits for even one-step commands, alexia, and agraphia. Mean age at diagnosis for muscle disease is 43 years, PDB is 41 years, and FTD is 56 years. Dilated cardiomyopathy, amyotrophic lateral sclerosis, and Parkinson disease are now known to be part of the spectrum of findings associated with MSP. DIAGNOSIS/TESTING: The diagnosis of MSP is established in a proband with typical clinical findings and a heterozygous pathogenic variant in VCP, HNRNPA1, HNRNPA2B1, or SQSTM1 identified by molecular genetic testing. MANAGEMENT: Treatment of manifestations: Weight control to avoid obesity; physical therapy and stretching exercises to promote mobility and prevent contractures; occupational therapy and mechanical aids (canes, walkers, orthotics, wheelchairs) as needed for ambulation/mobility; surgical intervention for foot deformity and scoliosis as needed; respiratory aids when indicated; assisted living arrangements for muscle weakness and/or dementia; bisphosphonates to relieve pain and disability from PDB; social and emotional support; education regarding safety precautions. Surveillance: Echocardiogram and electrocardiogram with repeat cardiac evaluation every two to three years or earlier if symptomatic; annual pulmonary function studies; sleep studies as clinically indicated; annual alkaline phosphatase measurement; skeletal imaging as indicated for evaluation of PDB; neurologic and neuropsychological assessment every two to three years or more frequently as needed; multidisciplinary monitoring for respiratory, cardiac, musculoskeletal, and cognitive decline. GENETIC COUNSELING: MSP is inherited in an autosomal dominant manner. Most individuals diagnosed with MSP have an affected parent. Estimates based largely on VCP-MSP suggest that approximately 5% of individuals have a de novo pathogenic variant. Each child of an individual with MSP has a 50% chance of inheriting the MSP-related pathogenic variant. Marked intrafamilial variability may be observed among heterozygous family members, including differences in age at onset, severity, rate of progression, and the specific combination of manifestations. Once the MSP-related pathogenic variant has been identified in an affected family member, predictive testing for at-risk family members and prenatal/preimplantation genetic testing are possible.
Inclusion Body Myopathy with Early-Onset Paget Dis↗
Interaction between carotid baroreflex and exercise pressor reflex depends on baroreceptor afferent input.
Because arterial baroreceptor and skeletal muscle receptor afferents project to cardiovascular regions in the lower brain stem such as the nucleus tractus solitarii (NTS), it is likely that the level of baroreceptor afferent input will modify the excitatory cardiovascular responses evoked by contraction-sensitive skeletal muscle afferents. The purpose of this study was to determine the effect of carotid sinus baroreceptor afferent input (CSA) on reflex heart rate (HR) and mean arterial pressure (MAP) responses evoked by activation of skeletal muscle receptor afferents (SMA). CSA input was servo controlled at three levels of carotid sinus pressure using the isolated carotid sinus preparation, and SMA input was varied by induced muscle contraction (L7-S1 ventral root stimulation) or passive muscle stretch. Experiments were performed in alpha-chloralose-anesthetized and vagotomized dogs (n = 9). When CSA input was low (106 +/- 35 mmHg), electrically induced muscle contraction increased HR and MAP (30 +/- 8 beats/min and 42 +/- 12 mmHg, respectively, P < 0.05). However, when CSA input was high (221 +/- 9 mmHg), the reflex changes in HR and MAP during muscle contraction were attenuated (6 +/- 4 beats/min and 18 +/- 4 mmHg, respectively, P < 0.05). Similarly, the sympathoexcitatory responses evoked by passive muscle stretch were attenuated in a baroreceptor-dependent manner. These results suggest that changing CSA input from low (106 mmHg) to high (221 mmHg) shifts the interaction from facilitation to inhibition. Therefore, it is concluded that the nature of the interaction (i.e., facilitation or inhibition) between the baroreflex and the exercise pressor reflex is dependent on the level of baroreceptor input. Moreover, our findings substantiate early studies showing that the level of afferent input from arterial baroreceptors is a powerful modulator of sympatho-excitation evoked by mechanically and metabolically sensitive skeletal muscle receptors.
Animals↗
Static interaction between muscle mechanoreflex and arterial baroreflex in determining efferent sympathetic nerve activity.
Elucidation of the interaction between the muscle mechanoreflex and the arterial baroreflex is essential for better understanding of sympathetic regulation during exercise. We characterized the effects of these two reflexes on sympathetic nerve activity (SNA) in anesthetized rabbits (n = 7). Under open-loop baroreflex conditions, we recorded renal SNA at carotid sinus pressure (CSP) of 40, 80, 120, or 160 mmHg while passively stretching the hindlimb muscle at muscle tension (MT) of 0, 2, 4, or 6 kg. The MT-SNA relationship at CSP of 40 mmHg approximated a straight line. Increase in CSP from 40 to 120 and 160 mmHg shifted the MT-SNA relationship downward and reduced the response range (the difference between maximum and minimum SNA) to 43 +/- 10% and 19 +/- 6%, respectively (P < 0.01). The CSP-SNA relationship at MT of 0 kg approximated a sigmoid curve. Increase in MT from 0 to 2, 4, and 6 kg shifted the CSP-SNA relationship upward and extended the response range to 133 +/- 8%, 156 +/- 14%, and 178 +/- 15%, respectively (P < 0.01). A model of algebraic summation, i.e., parallel shift, with a threshold of SNA functionally reproduced the interaction of the two reflexes (y = 1.00x - 0.01; r(2) = 0.991, root mean square = 2.6% between estimated and measured SNA). In conclusion, the response ranges of SNA to baroreceptor and muscle mechanoreceptor input changed in a manner that could be explained by a parallel shift with threshold.
Anesthesia↗
The role played by elasticity in an exercise involving movements of small amplitude.
In an exercise consisting of repetitive small jumps on both feet at a frequency of 116/min, the mechanical work performed and the O2 consumption at steady state were measured. Of the positive work performed in the jump only 40% appears to be due to the chemical transformations taking place in the contractile componenet of the muscle fibres; the remaining 60% appears to be due to the elastic energy accumulated in the elastic elements of the contracted stretched muscles of the lower limbs during the falling phase of the previous jump, when the body hits the ground.
Elasticity↗
Muscle cramps.
Painful involuntary skeletal muscle contractions, or cramps, are common patient complaints and may be classified as examples of true cramp, tetany, contracture, or dystonia. The pathophysiologic and clinical features of each of these diagnoses are described. The approach to the patient with cramps should emphasize the history, physical examination, and, if the diagnosis is unclear, minimal routine laboratory data. Although many therapies have been proposed for ordinary cramps, the best evidence supports stretching exercises and quinine. Areas for future study of this common symptom are proposed.
Contracture↗
The effect of hamstring muscle stretching on standing posture and on lumbar and hip motions during forward bending.
BACKGROUND AND PURPOSE: The purpose of this study was to determine whether stretching the hamstring muscles affects extensibility, as indicated by straight leg raising (SLR), lumbopelvic posture, and the relative amounts of lumbar and hip motion during forward bending. SUBJECTS: Thirty-nine subjects without known musculoskeletal impairments of their spine or lower extremities and with tight hamstring muscles (ie, SLR of < or = 70 degrees) were randomly assigned to either a stretching group or a control group. METHODS: A three-dimensional digitizer was used to measure lumbar, pelvic, and hip positions while subjects were in a standing position and during partial and full forward bending. RESULTS: Straight leg raising and hip motion during late and total forward bending were increased after stretching. No changes occurred in standing posture or lumbar motion during forward bending. CONCLUSION AND DISCUSSION: The results of this study suggest that there is no relationship between hamstring muscle length and lumbopelvic posture. There was some indication, however, that stretching the hamstring muscles may affect motion during forward bending.
Adult↗
Acute and delayed neuromuscular adjustments of the triceps surae muscle group to exhaustive stretch-shortening cycle fatigue.
Stretch-shortening cycle (SSC)-type fatigue is associated with acute and delayed functional defects, and appears to be a useful model to reveal the flexibility of both central and reflex adjustments to the contractile failure. SSC fatigue was induced in an experimental (EXP) group (n=6) on a sledge ergometer with an exhaustive rebound exercise with submaximal effort. The acute (POST) and 2-day delayed (2D) neuromuscular changes with fatigue were examined in a short submaximal rebound task (REBOUND) and in a maximal isometric plantarflexion test (ISOM). The EXP group results were compared to those of a control group (n=6) who did not perform the exhaustive SSC exercise and did not present any change in the tests. In the EXP group, the ISOM test revealed mostly a large decrease in maximal plantarflexion force at 2D that was correlated with the reduced mean soleus muscle (SOL) activation. Indicating "task-dependent" fatigue effects on the neural changes, the REBOUND test revealed both acute and delayed increases in SOL activation. Supporting central neural changes, SOL preactivation increased in POST and 2D. The neural flexibility along time and across muscles was demonstrated by the shifted increase in SOL activation from the braking phase in POST to the push-off phase in 2D, and associated increased gastrocnemius medialis preactivation in 2D. In contrast, activation during the stretch-reflex period was constant in POST, and decreased in 2D. These results would support the influence of musculotendinous afferents on the flexible neural adjustments to the SSC-induced contractile failure.
Adaptation, Physiological↗
Intramuscular pressure, torque and swelling for the exercise-induced sore vastus lateralis muscle.
This study investigated changes in intramuscular fluid pressure (IMP), torque and swelling related to delayed onset muscle soreness (DOMS) of the vastus lateralis muscle. IMP was measured via catheterization in the unstretched (0 degree, full extension) and stretched (90 degrees of knee flexion) muscle at rest; then IMP and knee extension torque were determined during maximal contractions pre and 2 d after (post) repetitive eccentric activity in one leg for eight male subjects. DOMS of the vastus lateralis muscle was associated with a significant elevation in IMP at rest as indicated by pre (0 degree: 5.4 mmHg, 90 degrees: 80 mmHg) and post (0 degree: 8.4 mmHg, 90 degrees: 13.2 mmHg) comparisons (P = 0.02). Soreness symptoms were aggravated when the muscle was stretched and this was accompanied by a significantly higher post IMP at 90 degrees vs. 0 degree (P = 0.01). During maximal contractions, peak torque declined by 15% relative to pre and peak IMP declined by 26%; DOMS symptoms, however, were most severe during this manoeuvre. Biopsies from the sore vastus lateralis muscle revealed significantly larger fibre areas for all fibre types as compared with contralateral controls (P < 0.01); however, no differences were detected for extracellular volume percent comparisons. This study shows that DOMS of the vastus lateralis muscle is associated with extensive intracellular swelling and with elevated IMP. In line with previous studies, fibre swelling may be a common subsequence to repetitive eccentric activity; the ability of IMP measurements to detect this swelling at rest and during various manoeuvres for other muscles may depend on compartmental compliance.
Adult↗
Reflex effects following selective stimulation of J receptors in the cat.
1. Experiments carried out on anaesthetized cats showed that increasing blood flow, through the lobes of a lung, by 133% (S.E. 33%) generated an average of 0.75 impulses/sec (S.E. 0.3) in ten almost silent J receptors. Equivalent activity was produced by injecting 12-18 micrograms phenyl diguanide/kg into the right atrium. Such activity caused marked reflex effects, i.e. apnoea, rapid shallow breathing and reduction in the knee jerk. 2. The reflex effects of J receptors were studied after blocking the activity from cardiac receptors by intrapericardial injections of xylocaine. This was necessary because left atrial injections of phenyl diguanide produced reflex respiratory effects and inhibition of the knee jerk. 3. Hypoxia, but not hypercapnia, attenuated the reflex effects of J receptors, apnoea being abolished if the Pa,O2 fell below 35 mmHg. This was a central effect as it occurred in spite of increased activity of J receptors following phenyl diguanide, and effects of hypoxia persisted after cutting both carotid nerves. 4. The only invariable reflex effect of J receptors was a reduction in the total number and the average frequency of phrenic impulses in each breath. The changes in inspiratory time (ti) and expiratory time (te) following apnoea were variable although most frequently both were reduced. In about half the observations the first effect before the apnoea was a reduction in ti, in the other half it was a reduction in te. It was concluded that an input from J receptors inhibits inspiratory and expiratory mechanisms directly. 5. In some cats apnoea and rapid shallow breathing produced by J receptors continued after interrupting their activity by vagotomy and this did not diminish the reduction in ti or te; in other cats it did. The reduction in te was at times quite independent of changes in ti, i.e. pulmonary stretch receptor activity. 6. It was concluded that J receptors must be stimulated during moderate exercise to levels that produce marked respiratory reflex effects and inhibition of muscles.
Animals↗
The shoulder of the tennis player.
A depression of the exercised shoulder was found among highly trained tennis players, and in other athletes employing the overhand motion. This deformity is attributed to stretching of the shoulder elevating muscles, and to hypertrophy of the racket-holding extremity. Most symptoms in the shoulders studied were in the region of the rotator cuff, and occurred upon strokes requiring abduction. Shoulder dependency causes a relative abduction of the extremity, which may result in impingement of the rotator cuff. Shoulder droop may lead to thoracic outlet syndrome, and, in the athlete, may simulate scoliosis.
Adult↗
Influence of the contact time on coupling time and a simple method to measure coupling time.
The enhancement of performance in stretch shortening cycle (SSC) exercises has been attributed to the recoil of elastic energy stored during the stretching phase and depends on the duration of the coupling time (T(coupling)) i.e., the duration of the isometric phase occurring between the stretch and the shortening of the muscle. However, instead of T(coupling), the contact time (T(contact))--i.e., the sum of T(coupling) plus the duration of the stretching and shortening phases that precede and follow T(coupling)--is more easily and often measured. The aim of this study was to investigate the T(coupling) changes within a large range of T(contact), in order to propose a possible relationship between T(coupling) and T(contact), thus allowing the accurate measurement of T(coupling )only from a tachometer and force data obtained classically in vertical jumps, jumps on sledge apparatus and running on force treadmills. Eleven subjects performed SSC exercises on a sledge apparatus with a large range of T(contact) (400, 700, 1,000, 1,500, 2,000 and 2,500 ms). The T(coupling) and T(contact) values were measured individually, from force platform recordings and the velocity of the carriage seat obtained by a tachometer. For the longest T(contact) (i.e., from 850 to 2,500 ms), we observed a significant linear relationship between T(contact) and T(coupling). This transition between T(contact) shorter or longer than about 850 ms seems to be important and to correspond to T(coupling) close to 300 ms. This limit observed in the present study could be explained physiologically due to a possible modification of the cross-bridges formation.
Adult↗
The effect of delayed-onset muscle soreness on stretch reflexes in human low back muscles.
The aim of the study was to investigate the effect of moderate delayed-onset muscle soreness (DOMS) on the short latency stretch reflex (SLR) and long latency stretch reflex (LLR) response i.e. electromyographic (EMG) onset latencies and EMG amplitudes in erector spinae (ES). Nine males with muscle soreness (DOMS group) were tested 24, 48 h, and 7 days post-exercise. Eight males (control group) were tested likewise. EMG was measured from ES bilaterally at the level of L3/L4. The SLR was elicited by mechanically tapping the ES at L3/L4, and the LLR was elicited by sudden loadings of the spine. Significant reductions in force during maximal voluntary contractions and range of motion, and a significant increase in muscle soreness (measured by pressure algometry) and subjective experience of soreness in the low back indicated DOMS 24, and 48 h post-exercise in the DOMS group. No changes were observed in the control group. The SLR and LLR response were unaffected by DOMS, i.e. no changes in EMG latencies and amplitudes were observed. In conclusion, despite changes in DOMS indicators, the reflex system protecting the stability of the lumbar spine is apparently capable of maintaining an appropriate triggering of SLR and LLR.
Adult↗
Effect of submaximal contraction intensity in contract-relax proprioceptive neuromuscular facilitation stretching.
OBJECTIVE: To determine if submaximal contractions used in contract-relax proprioceptive neuromuscular facilitation (CRPNF) stretching of the hamstrings yield comparable gains in hamstring flexibility to maximal voluntary isometric contractions (MVICs). METHOD: Randomised controlled trial. A convenience sample of 72 male subjects aged 18-27 was used. Subjects qualified by demonstrating tight hamstrings, defined as the inability to reach 70 degrees of hip flexion during a straight leg raise. Sixty subjects were randomly assigned to one of three treatment groups: 1, 20% of MVIC; 2, 60% of MVIC; 3, 100% MVIC. Twelve subjects were randomly assigned to a control group (no stretching). Subjects in groups 1-3 performed three separate six second CRPNF stretches at the respective intensity with a 10 second rest between contractions, once a day for five days. Goniometric measurements of hamstring flexibility using a lying passive knee extension test were made before and after the stretching period to determine flexibility changes. RESULTS: Paired t tests showed a significant change in flexibility for all treatment groups. A comparison of least squares means showed that there was no difference in flexibility gains between the treatment groups, but all treatment groups had significantly greater flexibility than the control group. CONCLUSION: CRPNF stretching using submaximal contractions is just as beneficial at improving hamstring flexibility as maximal contractions, and may reduce the risk of injury associated with PNF stretching.
Adolescent↗
Does stretching induce lasting increases in joint ROM? A systematic review.
BACKGROUND AND PURPOSE: Stretching (that is, interventions that apply tension to soft tissues) induces increases in the extensibility of soft tissues, and is therefore widely administered to increase joint mobility and reverse contractures. However, it is not clear whether the effects of stretching are lasting. A systematic review was conducted to determine if stretching (either self-administered, administered manually by therapists or by some external device such as a splint) produces lasting increases in the mobility of joints not directly affected by surgery, trauma or disease processes. METHOD: In order to determine the lasting effects of stretching, only studies that measured joint range of motion (ROM) at least one day after the cessation of stretching were included. MEDLINE (from 1966 to June 2000), EMBASE (from 1988 to June 2000), the Cochrane Controlled Trials Register and PEDro databases were searched, and citation tracking was used to identify randomized studies that met the inclusion criteria. Each study was rated by two independent assessors on the PEDro scale, which rated trials according to criteria such as concealed allocation, blinding and intention-to-treat analysis. RESULTS: Thirteen studies satisfied the inclusion criteria. All examined the effect of stretching (median number of stretch sessions = eight) on joint ROM in healthy subjects without functionally significant contractures. Four studies were of 'moderate' quality and the remaining nine were of 'poor' quality. The 'moderate' quality studies suggest that regular stretching increases joint ROM (mean increase in ROM = 8 degrees; 95% CI 6 degrees to 9 degrees) for more than one day after cessation of stretching and possibly that the effects of stretching are greater in muscle groups with limited extensibility. CONCLUSIONS: The results of four 'moderate' quality studies show a convincing effect of stretching in people without functionally significant contracture. These findings require verification with high-quality studies. Lasting effects of intensive stretching programmes (for example, stretching applied for more than six weeks or for more than 20 minutes a day) or of stretching on people with functionally significant contracture have not yet been investigated with randomized studies.
Exercise Therapy↗
Dynamic exercise stimulates group III muscle afferents.
1. In decerebrate cats, we investigated the responses of group III muscle afferents to dynamic exercise. The cats performed low intensity dynamic exercise on a treadmill. Group III afferent activity from the dynamically exercising triceps surae muscles was recorded from L7-S1 dorsal root filaments. 2. Single-unit recordings were obtained from 15 group III afferent fibers whose receptive fields were in the triceps surae muscles and from one group III afferent whose receptive field was in the flexor digitorum longus muscle. Conduction velocities for the 16 group III afferents ranged from 3.0 to 27.9 m/s (15.6 +/- 1.9 m/s, mean +/- SE). 3. Ten of 16 group III muscle afferents were stimulated by dynamic exercise. Of the 10, 7 were strongly responsive and 3 were mildly responsive to dynamic exercise. Each of the 10 afferents displayed at least some activity that was synchronized to the contraction phase of the step cycle. The mean developed tensions for strongly responsive afferents, mildly responsive afferents, and afferents that did not respond were 0.8 +/- 0.3, 1.3 +/- 0.5, and 0.7 +/- 0.3 Kg, respectively (P > 0.05). Thus differences in the responsiveness of the afferents to exercise were not attributable to differences in developed tensions. 4. The group III afferents that were strongly responsive to dynamic exercise were also mechanically sensitive. Each strongly responsive afferent (n = 7) was stimulated by nonnoxious pressure applied to its receptive field. Most strongly responsive afferents (n = 5) were stimulated by stretch of the triceps surae muscles.(ABSTRACT TRUNCATED AT 250 WORDS)
Afferent Pathways↗