PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Muscle Stretching Exercises”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 541 records · Page 30Linked to original sources
PubMed1996

Decreased muscle GLUT-4 and contraction-induced glucose transport after eccentric contractions.

Eccentric exercise causes muscle damage and decreased muscle glycogen and glucose transporter isoform (GLUT-4) protein content. We investigated whether the contraction-induced increase in skeletal muscle glucose transport and muscle performance is affected by prior eccentric contractions. The calf muscles from rats were stimulated for eccentric (EC) or concentric (CC) contractions or were passively stretched (ST). Muscles from unstimulated control (CT) rats were also studied. Two days later, all rats had their isolated hindlimbs perfused either at rest or during 15 min of isometric muscle contractions. EC rats had a significantly lower total GLUT-4 protein content in the white gastrocnemius (GW) muscle (55%) and red gastrocnemius (GR) muscle (34%) compared with muscle from the CT, ST, and CC rats. In contrast, GLUT-1 protein content was approximately twofold higher in the GW muscle in EC rats than in CT rats. In the GW and GR muscle, prior eccentric exercise decreased contraction-induced stimulation of glucose transport compared with CT, ST, and CC rats despite no difference in tension development and oxygen uptake among the groups. There was no change in total GLUT-4 content and glucose transport in the soleus (S) muscle among the four group. It is concluded that the GLUT-4 and GLUT-1 protein contents in fast-twitch muscle are decreased and increased, respectively, 2 days after eccentric contractions. The functional consequence of these changes appears to be decreased contraction-induced increase in skeletal muscle glucose transport.

Animals↗
PubMed2005

Molecular mechanisms of vascular adaptations to exercise. Physical activity as an effective antioxidant therapy?

A lack of exercise training and/or regular physical activity is a known risk factor for cardiovascular disease. Exercise training induces marked vascular remodeling by increasing angiogenesis and arteriogenesis. These changes in the architecture of the vascular tree are likely associated with functional changes and improved organ blood flow. Physical forces such as shear stress, transmural pressure and cyclic stretch activate mechanotransduction mechanisms in endothelial and smooth muscle cells that are mediated by integrins and associated RhoA small GTPase. They stimulate various signal transduction pathways involving phosphorylation of kinases such as focal adhesion kinase, c-Src, Akt kinase, phosphatidylinositol 3-kinase, myosin light chain kinase and mitogen-activated protein kinases (MAPK) such as extracellular signal-regulated kinase (ERK). These mechanisms result in upregulation of genes mediating antiatherogenic effects by promoting antiapoptotic and antiproliferative signals, by increasing vascular NO bioavailability and by changing calcium handling and the vascular myogenic response to pressure. Exercise-induced increase of vascular eNOS expression and of eNOS Ser-1177 phosphorylation is most likely an important and potentially vasoprotective effect of exercise training. The underlying mechanisms involve cell membrane proteins such as integrins and products of vascular oxidative stress such as hydrogen peroxide. Exercise-induced eNOS expression is transient and reversible and regulated by factors such as angiogenesis, arteriogenesis and antioxidative effects including upregulation of superoxide dismutases (SOD1, SOD3) and downregulation of NAD(P)H oxidase, which likely blunts the effects of oxidative stress. Based on these observations, it appears reasonable to assume that exercise training can be viewed as an effective antioxidant and antiatherogenic therapy.

Adaptation, Physiological↗
PubMed2001

Exercise-induced neuromuscular dysfunction under reflex conditions.

The purpose of this research was to describe further the effects of exercise-induced muscle damage on reflex sensitivity. The subjects were eight physically active, but untrained males, between the ages of 18 and 29 years. The effects of eccentric and concentric exercise on patellar tendon reflex responses were determined. The 8 week experiment consisted of two, 5 day, test protocols with a 6 week wash-out period between test protocols. Each 5 day test protocol consisted of the following six test sessions: (1) day 1--baseline, (2) day 2 baseline, (3) day 2--immediate post-exercise, and (4-6) days 3-5: 24, 48, and 72 h post-exercise. On day 2, the subjects made either 100 fatiguing concentric or eccentric isotonic contractions using the right leg at 75% of the corresponding repetition maximum values. During each test session, the electromyogram (EMG) and force-time characteristics of basic and conditioned patellar tendon reflex responses were measured. The reflex amplitudes of basic and conditioned patellar tendon reflex responses were decreased following fatiguing concentric exercise. There were no immediate effects of fatiguing eccentric exercise on the basic and conditioned patellar tendon reflex responses, but the EMG amplitudes of these reflex responses were reduced on the days following eccentric exercise. The amount of conditioned patellar tendon reflex facilitation was decreased following the concentric exercise protocol and at 48 h post-eccentric exercise. Our conditioned reflex data suggest that post-exercise changes to the physiological mechanisms that modulate the recruitment gain of the alpha-motoneuron pool may depend upon the type of fatiguing exercise.

Adolescent↗
PubMed2003

Acute changes in neuromuscular excitability after exhaustive whole body vibration exercise as compared to exhaustion by squatting exercise.

The effects of hard squatting exercise with (VbX+) and without (VbX-) vibration on neuromuscular function were tested in 19 healthy young volunteers. Before and after the exercise, three different tests were performed: maximum serial jumping for 30 s, electromyography during isometric knee extension at 70% of the maximum voluntary torque, and the quantitative analysis of the patellar tendon reflex. Between VbX+ and VbX- values, there was no difference found under baseline conditions. Time to exhaustion was significantly shorter in VbX+ than in VbX- (349 +/- 338 s versus 515 +/- 338 s), but blood lactate (5.49 +/- 2.73 mmol l-1 versus 5.00 +/- 2.26 mmol l-1) and subjectively perceived exertion (rate of perceived exertion values 18.1 +/- 1.2 versus 18.6 +/- 1.6) at the termination of exercise indicate comparable levels of fatigue. After the exercise, comparable effects were observed on jump height, ground contact time, and isometric torque. The vastus lateralis mean frequency during isometric torque, however, was higher after VbX+ than after VbX-. Likewise, the tendon reflex amplitude was significantly greater after VbX+ than after VbX- (4.34 +/- 3.63 Nm versus 1.68 +/- 1.32 Nm). It is followed that in exercise unto comparable degrees of exhaustion and muscular fatigue, superimposed 26 Hz vibration appears to elicit an alteration in neuromuscular recruitment patterns, which apparently enhance neuromuscular excitability. Possibly, this effect may be exploited for the design of future training regimes.

Adult↗
PubMed2001

The stretch-shortening cycle of the internal rotators muscle group measured by isokinetic dynamometry.

BACKGROUND: The ability to measure the stretch-shortening cycle of isolated muscle groups has been limited. The purpose of this study was to measure the stretch-shortening cycle of the internal rotator muscle group. METHODS: Sixty-eight volunteer subjects, 35 men and 33 women, participated in one test session; eight men and eight women also participated in a retest session; to examine the reliability of the test. A concentric contraction of the dominant internal rotator was measured for peak torque, standardized peak torque, power, standardized power and acceleration time on a Cybex Norm isokinetic dynamometer under three conditions: 1) concentric contraction only, 2) isometric preload before a concentric contraction, and 3) eccentric preload before a concentric contraction. RESULTS: Condition 3 showed a significant increase in peak torque production compared to condition 1 (p=0.001). Conditions 2 and 3 showed a significant increase in power production compared to condition 1 (p=0.0001, p=0.003). A significant difference was found in all three conditions between the men and women, with the men producing greatest peak torques and powers. CONCLUSIONS: The testing protocol was found to have high reliability. This testing protocol could be used to further study the stretch-shortening cycle in the internal rotator muscle group.

Adult↗
PubMed2003

Subcutaneous tissue mechanical behavior is linear and viscoelastic under uniaxial tension.

Subcutaneous tissue is part of a bodywide network of "loose" connective tissue including interstitial connective tissues separating muscles and surrounding all nerves and blood vessels. Despite its ubiquitous presence in the body and its potential importance in a variety of therapies utilizing mechanical stretch, as well as normal movement and exercise, very little is known about loose connective tissue's biomechanical behavior. This study aimed to determine elastic and viscoelastic mechanical properties of ex-vivo rat subcutaneous tissue in uniaxial tension with incremental stress relaxation experiments. The elastic response of the tissue was linear, with instantaneous and equilibrium tensile moduli of 4.77 kPa and 2.75 kPa, respectively. Using a 5 parameter Maxwell solid model, material parameters micro(1) = 0.95 +/- 0.24 Ns/m and micro(2) = 8.49 +/- 2.42 Ns/m defined coefficients of viscosity related to time constants tau(1M) = 3.83 +/- 0.15 sec and tau(2M) = 30.15 +/- 3.16 sec, respectively. Using a continuous relaxation function, parameters C = 0.25 +/- 0.12, tau(1C) = 1.86 +/- 0.34 sec, and tau(2C) = 110.40 +/- 25.59 sec defined the magnitude and frequency limits of the relaxation spectrum. This study provides baseline information for the stress-strain behaviors of subcutaneous connective tissue. Our results underscore the differences in mechanical behaviors between loose and high-load bearing connective tissues and suggest that loose connective tissues may function to transmit mechanical signals to and from the abundant fibroblasts, immune, vascular, and neural cells present within these tissues.

Animals↗
PubMed1994

Physical conditioning in adolescents.

Exercise and physical conditioning or physical fitness play an important role in disease prevention. The three primary components of physical conditioning are endurance, flexibility, and strength training. Like adults, adolescents can improve their aerobic fitness by doing aerobic activity with achievement of 60% to 90% of the maximum heart rate for a minimum of 20 minutes at least three times per week. Flexibility should involve major muscle groups, using static stretching only, and be individually tailored for different sports. Stretching does not prevent injuries in persons without preexisting injuries. Strength training is associated with strength gains in adolescents, and is safe when supervised by knowledgeable adults. Areas for future research in regard to physical conditioning and adolescents include 1) the effects of physical education programs on youth fitness, 2) the relationship between flexibility or hypermobility and injury, and 3) the tracking of physical fitness and conditioning from adolescence into adulthood.

Adolescent↗
PubMed2005

Acute effects of passive muscle stretching on sprint performance.

The results of previous research have shown that passive muscle stretching can diminish the peak force output of subsequent maximal isometric, concentric and stretch-shortening contractions. The aim of this study was to establish whether the deleterious effects of passive stretching seen in laboratory settings would be manifest in a performance setting. Sixteen members (11 males, 5 females) of a Division I NCAA track athletics team performed electronically timed 20 m sprints with and without prior stretching of the legs. The experiment was done as part of each athlete's Monday work-out programme. Four different stretch protocols were used, with each protocol completed on a different day. Hence, the test period lasted 4 weeks. The four stretching protocols were no-stretch of either leg (NS), both legs stretched (BS), forward leg in the starting position stretched (FS) and rear leg in the starting position stretched (RS). Three stretching exercises (hamstring stretch, quadriceps stretch, calf stretch) were used for the BS, FS and RS protocols. Each stretching exercise was performed four times, and each time the stretch was maintained for 30 s. The BS, FS and RS protocols induced a significant (P < 0.05) increase (approximately 0.04 s) in the 20 m time. Thus, it appears that pre-event stretching might negatively impact the performance of high-power short-term exercise.

Adult↗
PubMed1997

Mitral valve prolapse and ventricular arrhythmias: observations in a patient with a 20-year history.

INTRODUCTION: Ventricular arrhythmias are a common feature in patients with mitral valve prolapse. In an attempt to determine the origin and underlying electrophysiologic mechanism, we describe a patient with ventricular fibrillation, exercise-induced ventricular tachycardia (VT), and, at the time of diagnosis, prolapse of the posterior mitral valve leaflet without mitral regurgitation. METHODS AND RESULTS: Treatment with beta-blockade and diphenylhydantoin prevented the occurrence of malignant ventricular arrhythmias for more than 17 years. Discontinuation of the therapy resulted in an immediate reappearance of the VT, which, despite the marked enlargement of the left ventricle (secondary to development of severe mitral valve regurgitation), had a strikingly similar morphology. For hemodynamic reasons, the patient was finally selected for valve replacement. Detailed pre-, peri-, and postoperative studies were performed, including administration of flunarizine, body surface mapping, construction of perioperative epicardial and endocardial maps, and studies of the excised muscles in vitro. CONCLUSIONS: Delayed afterdepolarization-induced triggered activity is the mechanism of VT in this mitral valve prolapse patient. The trigger is provided by isolated ventricular premature complexes elicited by a different electrophysiologic mechanism, possibly reentry, which is related to stretch and presumably to fibrosis of the papillary muscles.

Adult↗
PubMed2005

Lack of on-going adaptations in the soleus muscle activity during walking in patients affected by large-fiber neuropathy.

The aim of this study was to investigate the contribution of feedback from large-diameter sensory fibers to the adaptation of soleus muscle activity after small ankle trajectory modifications during human walking. Small-amplitude and slow-velocity ankle dorsiflexion enhancements and reductions were applied during the stance phase of the gait cycle to mimic the normal variability of the ankle trajectory during walking. Patients with demyelination of large sensory fibers (Charcot-Marie-Tooth type 1A and antibodies to myelin-associated glycoprotein neuropathy) and age-matched controls participated in this study. The patients had absent light-touch sense in the toes and feet and absent quadriceps and Achilles tendon reflexes, indicating functional loss of large sensory fibers. Moreover, their soleus stretch reflex response consisted of a single electromyographic (EMG) burst with delayed onset and longer duration (P < 0.01) than the short- and medium-latency reflex responses observed in healthy subjects. In healthy subjects, the soleus EMG gradually increased or decreased when the ankle dorsiflexion was, respectively, enhanced or reduced. In the patients, the soleus EMG increased during the dorsiflexion enhancements; however, the velocity sensitivity of this response was decreased compared with the healthy volunteers. When the dorsiflexion was reduced, the soleus EMG was unchanged. These results indicate that the enhancement of the soleus EMG is mainly sensitive to feedback from primary and secondary muscle spindle afferents and that the reduction may be mediated by feedback from the group Ib pathways. This study provides evidence for the role of sensory feedback in the continuous adaptation of the soleus activity during the stance phase of human walking.

Adaptation, Physiological↗
PubMed2001

Inhibition of maximal voluntary isokinetic torque production following stretching is velocity-specific.

Recent research has shown that a regimen of stretching provides an acute inhibition of maximal force production by the stretched muscle group. To further characterize this phenomenon, the effect of an acute stretching regimen on maximal isokinetic knee-extension torque at 5 specific movement velocities (1.05, 1.57, 2.62, 3.67, and 4.71 rad x s(-1)) was examined in 10 men and 5 women (22-28 years). Each person's 5 baseline maximal isokinetic knee-extension torques (dominant leg) were measured on a Cybex NORM dynamometer. Following the baseline torque measurements, the participants stretched the dominant quadriceps for 15 minutes using 1 active and 3 passive stretching exercises. Once the stretching exercises were completed, the maximal torque measurements were repeated. Poststretch maximal torque at 1.05 rad x s(-1) was significantly reduced (p < 0.05) from 218 +/- 47 Nm (mean +/- SD) to 199 +/- 49 Nm (7.2% decrease). At 1.57 rad x s(-1), a similar decrease (p < 0.05) was also seen (204 +/- 48 Nm vs. 195 +/- 47 Nm; 4.5% decrease), but at the other velocities (2.62, 3.67, and 4.71 rad x s(-1)), poststretch maximal torque was unaltered (p > 0.05). It appears, therefore, that the deleterious impact of stretching activities on maximal torque production might be limited to movements performed at relatively slow velocities.

Adult↗
PubMed1995

Attenuation of the exercise pressor reflex. Effect of opioid agonist on substance P release in L-7 dorsal horn of cats.

Using alpha-chloralose-anesthetized cats, we studied blood pressure and heart rate responses to static contraction and passive stretch of the triceps surae muscle before and after microdialyzing the mu-opioid agonist [D-Ala2]-methionine enkephalinamide (DAME, 200 mumol/L) into the L-7 dorsal horn of the spinal cord. In addition, we measured contraction-induced substance P release in the dorsal horn before and after drug delivery. After 92 +/- 3 minutes of dialyzing the opioid agonist, contraction-induced increases in mean arterial pressure and heart rate were attenuated from control values of 58 +/- 7 mm Hg and 17 +/- 3 beats per minute to postdrug values of 27 +/- 7 mm Hg and 10 +/- 2 beats per minute, respectively. A similar attenuation was observed for the passive muscle stretches after 97 +/- 5 minutes of dialysis (control, 38 +/- 4 mm Hg and 8 +/- 2 beats per minute; after drug, 23 +/- 4 mm Hg and 5 +/- 1 beats per minute). Prior microdialysis of naloxone (300 mumol/L), a mu-antagonist, blocked this effect, suggesting that the opioid agonist has a specific receptor action. Naloxone alone had no effect on the pressor or tachycardiac responses. The contraction-induced increase in substance P-like immunoreactivity was reduced from a control value of 0.119 +/- 0.024 to 0.047 +/- 0.010 fmol/100 microL by DAME. Time-control experiments revealed no decrease in the release of substance P-like immunoreactivity. Thus, activation of opioid receptors modulates the transmission of group III and IV muscle afferent nerve activity through the L-7 dorsal horn.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1992

No effect of piroxicam on achilles tendinopathy. A randomized study of 70 patients.

70 consecutive adult, nonrheumatic patients with a painful achilles tendinopathy were randomized to treatment with either a nonsteroid antiinflammatory drug (piroxicam) or placebo. Both groups received adjunct treatment with a period of rest combined with stretching and strengthening exercises. 52/70 cases were engaged in various sports, notably running. All subjects were evaluated on days 3, 7, 14, and 28 with respect to pain, tenderness, swelling, ankle joint movement and muscle strength. Results were judged from residual symptoms and an overall assessment of the efficacy. No differences were seen between the groups at any time during the study. The overall result was identical with a rate of success slightly better than 50 percent which corresponds to the placebo response reported in other studies.

Achilles Tendon↗
PubMedDate not supplied

Histochemical correlates of hamstring injuries.

This study reports the histochemical fiber type composition of the human hamstring muscles. Muscle specimens from necropsy specimens were obtained from seven locations in the hamstring, four locations in the quadriceps, and one location in the adductor magnus. The hamstring muscles are shown to have a relatively high proportion of Type II fibers. Type II fibers are more involved with exercise of higher intensity and force production and it is postulated that the hamstrings are capable of high intrinsic force production. The hamstrings are two-joint muscles and are, therefore, subject to increased stretch and force production extrinsically by motion at the hip and knee. It is proposed that high levels of tension in the hamstrings produced by intrinsic force production and extrinsic stretch may make them prone to injury in periods of intense muscular activity. This proposal is also relevant to other frequent athletic muscle injuries.

Adenosine Triphosphatases↗
PubMed1991

Influence of an active pre-stretch on fatigue of skeletal muscle.

In activities such as running, many muscles of the lower extremities appear to be actively stretched before they are allowed to shorten. In this study we investigated the effect of an active pre-stretch on the fatigability of muscles. Thus muscle contractions were compared in which shortening was preceded by an active isometric phase or by an active stretch. Rat medial gastrocnemius muscle-tendon complexes (with arrested blood flow) performed a series of ten repeated contractions (1.s-1) with either an active stretch or an isometric phase preceding the shortening. Contraction duration (0.45 s), and shortening duration (0.3 s), distance (6 mm) and velocity (20 mm.s-1) were the same in both types of contraction. Work output during the ten shortening phases was approximately 40% higher in the contractions with an active pre-stretch; in contrast, high-energy phosphate utilization was similar. Over the ten repeated contractions reduction of work output during the shortening phases of both types of contraction was similar in absolute terms (approx. 9.5 mJ). It is suggested that all the extra work performed during the shortening phases after a pre-stretch originated from sources other than cross-bridge cycling, which are hardly affected by fatigue. However, reduction of work output in relative terms, which is how the reduction is often expressed in voluntary exercise, was less after a pre-stretch (26% vs 32%), giving the impression of protection against fatigue by an active pre-stretch.

Animals↗
PubMed1985

Exercise testing and training of the elderly patient.

As an invariable accompaniment of the aging process, cardiac function declines, that is, cardiac output, stroke volume, heart rate, and maximum oxygen consumption all decrease. The vital capacity declines as residual volume increases, and ventilation-perfusion imbalance increases. Muscles atrophy and weaken, joints stiffen, and bones are demineralized. Certainly the aging process per se explains a portion of this functional deterioration. Disease states also account for some deterioration. However, inasmuch as approximately one half of the deterioration in function can be prevented or reversed by an exercise training program, it would seem that disuse or inactivity is responsible for at least a portion of the functional decline characteristic of aging. Special considerations in prescribing exercise training for the elderly include careful cardiovascular assessment; evaluation of orthopedic problems; consideration of heat intolerance; and careful attention to motivation. The exercise prescription should be specific and tailored to the subject's individual cardiovascular status, musculoskeletal limitations, and personal goals. Walking, stretching calisthenics, and other aerobic activities, if of reasonable intensity and duration, and when preceded and followed by an appropriate warm-up and cool-down period, respectively, can result in a substantial, positive training effect in the elderly. In response to such a training program, elderly subjects demonstrate an increase in stroke volume, cardiac output, and maximum heart rate. Respiratory function changes little, yet maximal oxygen consumption is increased. Fat may be replaced by lean muscle mass as muscle strength and endurance improve. Flexibility is improved and bone demineralization retarded or even reversed. Exercise has a tranquilizing effect on elderly subjects so that anxiety and depression may be prevented. The subject develops self-respect as effort tolerance improves. An excessively conservative attitude on the part of physicians, families, and elderly subjects has resulted in inappropriate activity limitations with a consequent decrement in effort tolerance. Elderly individuals can maintain a reasonable level of effort tolerance or can be rehabilitated to this level of activity with an appropriate exercise program. The decline in overall function expected with age can be substantially retarded. Consequently, physicians, families, and the subjects themselves should consider the potential advantages of an exercise program.

Aged↗
PubMed2005

Reduction of common synaptic drive to ankle dorsiflexor motoneurons during walking in patients with spinal cord lesion.

It is possible to obtain information about the synaptic drive to motoneurons during walking by analyzing motor-unit coupling in the time and frequency domains. The purpose of the present study was to compare motor-unit coupling during walking in healthy subjects and patients with incomplete spinal cord lesion to obtain evidence of differences in the motoneuronal drive that result from the lesion. Such information is of importance for development of new strategies for gait restoration. Twenty patients with incomplete spinal cord lesion (SCL) participated in the study. Control experiments were performed in 11 healthy subjects. In all healthy subjects, short-term synchronization was evident in the discharge of tibialis anterior (TA) motor units during the swing phase of treadmill walking. This was identified from the presence of a narrow central peak in cumulant densities constructed from paired EMG recordings and from the presence of significant coherence between these signals in the 10- to 20-Hz band. Such indicators of short-term synchrony were either absent or very small in the patient group. The relationship between the amount of short-term synchrony and the magnitude of the 10- to 20-Hz coherence in the patients is discussed in relation to gait ability. It is suggested that supraspinal drive to the spinal cord is responsible for short-term synchrony and coherence in the 10- to 20-Hz frequency band during walking in healthy subjects. Absence or reduction of these features may serve as physiological markers of impaired supraspinal control of gait in SCL patients. Such markers could have diagnostic and prognostic value in relation to the recovery of locomotion in patients with central motor lesions.

Action Potentials↗