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At least 397 records · Page 22Linked to original sources
PubMed2004

Zebrafish slow muscle cell migration induces a wave of fast muscle morphogenesis.

The specification and morphogenesis of slow and fast twitch muscle fibers are crucial for muscle development. In zebrafish, Hedgehog is required for slow muscle fiber specification. However, less is known about signals that promote development of fast muscle fibers, which constitute the majority of somitic cells. We show that when Hedgehog signaling is blocked, fast muscle cell elongation is disrupted. Using genetic mosaics, we show that Hedgehog signal perception is required by slow muscle cells but not by fast muscle cells for fast muscle cell elongation. Furthermore, we show that slow muscle cells are sufficient to pattern the medial to lateral wave of fast muscle fiber morphogenesis even when fast muscle cells cannot perceive the Hedgehog signal. Thus, the medial to lateral migration of slow muscle fibers through the somite creates a morphogenetic signal that patterns fast muscle fiber elongation in its wake.

Animals↗
PubMed1978

Turnover of muscle protein in the fowl. Collagen content and turnover in cardiac and skeletal muscles of the adult fowl and the changes during stretch-induced growth.

The collagen content and the rate of collagen synthesis were measured in the anterior and posterior latissimus dorsi muscles and in heart from fully grown fowl. This was done by measuring the proline/hydroxyproline ratios in the muscle and by a constant infusion of [(14)C]proline. These measurements were also made during the hypertrophy of the anterior muscle in response to the attachment of a weight to one wing of the fowl. In the non-growing muscles the collagen content was higher in the anterior muscle (22.8% of total protein) than in the posterior muscle (9.5% of total protein) and lowest in the heart (3.8% of total protein). In the two skeletal muscles a little over half of the collagen was accounted for by internal collagen (i.e. perimysium and endomysium). Collagen synthesis in these non-growing muscles occurred at 0.59%/day in each of the two skeletal muscles and at 0.88%/day in the cardiac muscle. During hypertrophy the collagen content of the anterior muscle increased, but not as fast as intracellular protein, so that after 58 days the concentration had fallen from 22.8 to 14.4% of total protein. This may have resulted from an incomplete production of the epimysial sheath, since the concentration of internal collagen did not fall and as a result accounted for over 80% of the total in the enlarged muscle. Collagen synthesis increased 8-fold during the first week of the hypertrophy, but never amounted to more than 4% of the total muscle protein synthesis. When the net accumulation of collagen is compared with the increased rate of synthesis it is concluded that between 30 and 70% of the newly synthesized collagen may have been degraded.

Animals↗
PubMed2000

Positional relationships between the masticatory muscles and their innervating nerves with special reference to the lateral pterygoid and the midmedial and discotemporal muscle bundles of temporalis.

For an accurate assessment of jaw movement, it is crucial to understand the comprehensive formation of the masticatory muscles with special reference to the relationship to the disc of the temporomandibular joint. Detailed dissection was performed on 26 head halves of 14 Japanese cadavers in order to obtain precise anatomical information of the positional relationships between the masticatory muscles and the branches of the mandibular nerve. After complete removal of the bony elements, the midmedial muscle bundle in all specimens and the discotemporal muscle bundle in 6 specimens, derivatives of the temporalis, which insert into the disc were observed. On the anterior area of the articular capsule and the disc of the temporomandibular joint, the upper head of the lateral pterygoid, the midmedial muscle bundle of temporalis and the discotemporal bundle of temporalis were attached mediolaterally, and in 3 specimens the posterosuperior margin of the zygomaticomandibularis was attached to the anterolateral area of the disc. It is suggested that these muscles and muscle bundles contribute to various mandibular movements. Although various patterns of the positional relationships between the muscles and muscle bundles and the their innervating nerves are observed in the present study, relative positional relationships of the muscles and muscle bundles and of nerves of the mandibular nerve are consistent. A possible scheme of the developmental formation of the masticatory muscles based on the findings of the positional relationships between the muscles and the nerves is presented.

Female↗
PubMed2006

Autologous bone marrow-derived cells enhance muscle strength following skeletal muscle crush injury in rats.

Insufficient post-traumatic skeletal muscle regeneration with consecutive functional deficiency continues to be a serious problem in orthopedic and trauma surgery. Transplantation of autologous muscle precursor cells has shown encouraging results in muscle trauma treatment but is associated with significant donor site morbidity. In contrast to this, bone marrow-derived (BMD) cells can be obtained without any functional deficit by puncture. The goal of this study was to examine whether regular muscle regeneration can be improved by local application of autologous BMD cells in a rat model of blunt skeletal muscle trauma. One week after standardized open blunt crush injury to the left soleus muscle, 10(6) autologous BMD cells were injected into the traumatized muscle of male Sprague Dawley rats. Rats of the control group received saline solution as treatment. Three weeks after application, the fast twitch and tetanic contraction capacity of the soleus muscles was measured bilaterally by stimulating the sciatic nerves. Contraction forces of injured soleus muscles in control animals recovered to 39 +/- 10% (tetanic) and 59 +/- 12% (fast twitch) of the contralateral noninjured soleus muscles (p < 0.001). In contrast, autologous BMD cell injection significantly restored contractile forces to 53 +/- 8% (tetanic) and 72 +/- 13% (fast twitch) compared to those observed in contralateral noninjured soleus muscles. Thus, muscle function was significantly increased by BMD cell treatment (tetanic, p = 0.014; fast twitch, p = 0.05). In conclusion, autologous BMD cell grafting leads to an increase in contraction force, 14% in tetanic and 13% in fast twitch stimulation, demonstrating its potential to improve functional outcome after skeletal muscle crush injury.

Animals↗
PubMed2001

Neck muscles in the rhesus monkey. I. Muscle morphometry and histochemistry.

Morphometric methods were used to describe the musculotendinous lengths, fascicle lengths, pennation angles, and cross-sectional areas of neck muscles in adult Macaca mulatta monkeys. Additionally, muscles were frozen, sectioned, and stained for ATPase activity to determine fiber-type composition. Individual rhesus muscles were found to vary widely in their degree of similarity to feline and human muscles studied previously. Suboccipital muscles and muscles supplied by the spinal accessory nerve were most similar to human homologs, whereas most other muscles exhibited architectural specializations. Many neck muscles were architecturally complex, with multiple attachments and internal aponeuroses or tendinous inscriptions that affected the determination of their cross-sectional areas. All muscles were composed of a mixture of type I, IIa, and IIb fiber types the relative proportions of which varied. Typically, head-turning muscles had lower proportions of type II (fast) fibers than homologous feline muscles, whereas extensor muscles contained higher proportions of type II fibers. The physical and histochemical specializations described here are known to have a direct bearing on functional properties, such as force-developing capacity and fatigue-resistance. These specializations must be recognized if muscles are to be modeled accurately or studied electrophysiologically.

Adenosine Triphosphatases↗
PubMed1997

Appearance of complex branched muscle fibers is associated with a shift to slow muscle characteristics.

To examine the effects of numerous complex branched fibers (CBF) on whole muscle contractile properties, we established a model of myopathic muscles containing a large number of CBF by repeated local injection of bupivacaine hydrochloride (Marcaine) into the plantaris (PLA) muscle. Marcaine injections were administered once weekly for 10 weeks into the right PLA muscles of Wistar male rats. The in situ contractile properties of Marcaine-injected PLA muscles (I-PLA) were examined under urethane anesthesia, and compared with the contralateral (control) PLA muscle (C-PLA). Numerical and morphological examination using the modified nitric acid fiber digestion method and scanning electron microscopy showed that Marcaine resulted in an 8-fold increase in the number of branched fibers in the I-PLA muscles and about 70% of these fibers were CBF. The latter were composed of ten or more muscle fibers fused together along with many thin and thick, long and short daughter branches. The time to peak tension of twitch and tetanus, and 1/2 relaxation time were significantly longer in I-PLA muscles, representing a shift to slow muscle characteristics. However, the total area of slow fibers/muscle cross-sectional area was similar in I-PLA and C-PLA muscles. Aggregates of same-type fibers (slow fibers) with small and large diameters were observed, reflecting an expected cross-sectional property of CBF. Our results suggest that the appearance of several CBF in a muscle is associated with a shift towards slower contractile properties in the affected muscle.

Anesthetics, Local↗
PubMed2005

A dual fate of the hindlimb muscle mass: cloacal/perineal musculature develops from leg muscle cells.

The cloaca serves as a common opening to the urinary and digestive systems. In most mammals, the cloaca is present only during embryogenesis, after which it undergoes a series of septation events leading to the formation of the anal canal and parts of the urogenital tract. During embryogenesis it is surrounded by skeletal muscle. The origin and the mechanisms regulating the development of these muscles have never been determined. Here, we show that the cloacal muscles of the chick originate from somites 30-34, which overlap the domain that gives rise to leg muscles (somites 26-33). Using molecular and cell labelling protocols, we have determined the aetiology of cloacal muscles. Surprisingly, we found that chick cloacal myoblasts first migrate into the developing leg bud and then extend out of the ventral muscle mass towards the cloacal tubercle. The development of homologous cloacal/perineal muscles was also examined in the mouse. Concordant with the results in birds, we found that perineal muscles in mammals also develop from the ventral muscle mass of the hindlimb. We provide genetic evidence that the perineal muscles are migratory, like limb muscles, by showing that they are absent in metd/d mutants. Using experimental embryological procedures (in chick) and genetic models (in chick and mouse), we show that the development of the cloacal musculature is dependent on proximal leg field formation. Thus, we have discovered a novel developmental mechanism in vertebrates whereby muscle cells first migrate from axially located somites to the pelvic limb, then extend towards the midline and only then differentiate into the single cloacal/perineal muscles.

Animals↗
PubMed2026

Effects of exercise on muscle strength and characteristics in rheumatic diseases and sarcopenia: Protocol for the Care for Muscle (C4M) Study.

OBJECTIVE: Muscle weakness is prevalent in rheumatoid arthritis (RA), osteoarthritis (OA) and sarcopenia (SARC). Endurance exercises may improve mitochondrial function and oxidative capacity, while strength exercises are thought to stimulate myofibrillar protein synthesis. This study aims to compare the effects of strength and endurance exercise and explore the association between muscle characteristics and exercise outcomes in patients with RA, OA and SARC. We hypothesize that responses to endurance and strength exercises in patients with muscle weakness are influenced by intramuscular pathology including muscle morphology, mitochondrial function, and systemic inflammation, based on their disease pathology, potentially requiring personalized training schedules. METHODS: This two-arm, parallel-group exploratory trial will enroll 69 patients (23 RA, 23 OA, 23 SARC), randomized to endurance (n&#x2009;=&#x2009;35) or muscle strength exercises (n&#x2009;=&#x2009;34), using minimization to balance disease type and gender. The 8-week intervention includes two supervised sessions per week using a controlled cable pulley device (Reforter&#x2122;) and fitness equipment, plus one weekly home-based session. The primary outcome is isokinetic muscle strength (peak torque), measured with the Biodex system&#xae;. Secondary outcomes include muscle morphology, mitochondrial function, systemic inflammation and muscle endurance (by Biodex and 6 Minute Walk test). Muscle morphology will be assessed via 3D ultrasound imaging of the vastus lateralis. Mitochondrial function will be analyzed using high-resolution respirometry on muscle biopsies. Systemic inflammation will be measured using multiplex assays or ELISA on serum samples. DISCUSSION: This study will explore differential responses to muscle endurance and muscle strength exercises in patients with RA, OA, and SARC, offering novel insights into the molecular mechanisms of muscle weakness. The findings may help identify potential mechanisms underlying variability in exercise response and provide effect size estimates to guide future confirmatory studies and more targeted exercise interventions. TRIAL REGISTRATION: ClinicalTrials.gov NCT06480643 (date of registration28-06-24).

Humans↗
PubMed2004

Determination of muscle architecture and fiber characteristics of the superficial and deep digital flexor muscles in the forelimbs of adult horses.

OBJECTIVE: To provide a quantitative description of the architecture of superficial digital flexor (SDF) and deep digital flexor (DDF) muscles in adult horses to predict muscle-tendon behavior and estimate muscle forces. SAMPLE POPULATION: 7 forelimb specimens from 7 adult Thoroughbreds. PROCEDURE: Muscle and tendon lengths and volumes were measured from 6 fixed forelimbs. After processing, fiber bundle and sarcomere lengths were measured. Optimal fascicle lengths and muscle length-to-fascicle length, muscle length-to-free tendon length, and fascicle length-to-tendon length ratios were calculated, as were tendon and muscle physiologic cross-sectional areas (PCSAs). Pennation angles were measured in 1 embalmed specimen. RESULTS: The SDF optimal fascicle lengths were uniformly short (mean +/- SD, 0.8 +/- 0.1 cm), whereas DDF lengths ranged from 0.9 +/- 0.2 cm to 10.8 +/- 1.6 cm. The DDF humeral head had 3 architectural subunits, each receiving a separate median nerve branch, suggestive of neuromuscular compartmentalization. Pennation angles were small (10 degrees to 25 degrees). The PCSAs of the SDF and DDF muscle were 234 +/- 51 cm2 and 259 +/- 30 cm2, with estimated forces of 4,982 +/- 1148 N and 5,520 +/- 544 N, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: The SDF muscle appears to provide strong tendinous support with little muscle fascicular shortening and fatigue-resistance properties. The DDF muscle combines passive and dynamic functions with larger tension development and higher shortening velocities during digital motion. Architectural parameters are useful for estimation of forces and have implications for analysis of muscle-tendon function, surgical procedures involving muscle-tendon lengthening, and biomechanical modeling.

Age Factors↗
PubMed2000

Acute effects of the skeletal muscle-specific immunotoxin ricin-mAb 35 on extraocular muscles of rabbits.

PURPOSE: To determine the acute histologic and ultrastructural effects of a recently developed muscle-specific immunotoxin, ricin-mAb 35. METHODS: Graduated doses of ricin-mAb 35, composed of ricin conjugated to a monoclonal antibody against the nicotinic acetylcholine receptor of skeletal muscle, were injected into one superior rectus muscle in rabbits. After 3, 7, and 14 days, both superior rectus muscles were removed and prepared for electron microscopy and histologic examination, by using a number of immunohistochemical markers to identify inflammatory cell infiltration, muscle fiber loss, and muscle regeneration. RESULTS: Myotoxicity of the ricin-mAb 35 was focal and dose related. At the highest dose tested, there was substantial inflammatory cell infiltrate by 3 days, which largely disappeared by 7 days. Significant muscle loss was apparent by 7 days after ricin-mAb 35 treatment. Both the inflammatory reaction and muscle fiber loss were confined to the immediate injection site. Surrounding muscle appeared to be normal. At 14 days after treatment, early signs of muscle regeneration were evident within the tissue sections. No evidence of orbital or systemic toxicity was seen in any animal. CONCLUSIONS: Direct injection of ricin-mAb 35 into the extraocular muscles of rabbits results in a dose-related focal injury to the muscles, with a self-limited inflammatory component and significant muscle fiber loss. This novel immunotoxin may be useful in the treatment of strabismus if chronic studies show a sustained histologic and electrophysiologic effect.

Animals↗
PubMed2002

Morphometric evaluation of muscle fiber types in different skeletal muscles of rats.

The purpose of the present work was to study some morphological differences of similar muscle fiber types--classified by ATPase reactions in different muscles of rats. Morphological parameters were used as stereological techniques at light and electron microscopic level. There was a great variation in the diameter of each muscle fiber type of different muscles. The smallest diameter of type 1 myofibers of the soleus was greater than the diameter of type 1 myofibers of other muscles. The diameter of type 1 myofibers of the soleus and of the lateral part of the gastrocnemius was almost twice the diameter of type 1 myofibers of sternocleidomastoid. The lateral and medial parts of gastrocnemius had the largest 2A and 2B muscle fibers. As a whole, among the studied muscles, myofibers of postural muscles of the posterior parts of the posterior limbs had the greatest diameter. Stereological analysis at electron microscopic level revealed that there were differences in the volume density of mitochondria in the different muscles. The quantity of mitochondria was greater in the diaphragm than in the gastrocnemius, soleus and sternocleidomastoid muscles. Our results suggested that the diameter of muscle fibers is more related to the resistance the muscle is submitted than to the continuous necessity of contraction. However, the quantity of mitochondria of oxidative fibers of the diaphragm would be related to continuous necessity of contraction and high oxidative necessity of this muscle.

Adenosine Triphosphatases↗
PubMed1995

Muscle fatigue and muscle length interaction: effect on the EMG frequency components.

Muscle fatigue can be identified by a decrease in the frequency components of the EMG signal, typically represented by a fall in the center frequency (fc). In addition, changes in muscle length have been demonstrated to independently alter the EMG fc. What remains unknown is the interaction between muscle fatigue and muscle length changes on the EMG fc. To address this question, a human biceps model of muscle fatigue, consisting of repetitive non-isometric contractions until task failure was studied. EMG signals from the biceps brachii were acquired via surface electrodes, and muscle length was determined by recording elbow angle. Five subjects developed biceps fatigue by repeating contractions of 50% maximal force until task failure. Fatigue produced a decrease in EMG fc at all muscle lengths. For the first three quarters of fatigue development there was a similar degree of reduction in EMG fc at all muscle lengths. But as task failure approached, there was a greater reduction in EMG fc at the shortest muscle length relative to the longest muscle length (41% reduction from baseline versus 30% reduction from baseline, respectively). The effect of muscle length independent of fatigue was such that a 20% increase in length would result in approximately an 18% fall in EMG fc. In conclusion, during fatigue development muscle length significantly influences the EMG fc, and it may be an important factor to consider when utilizing the EMG fc to detect muscle fatigue.

Adult↗
PubMed2002

Differentiation of original and regenerated skeletal muscle fibres in mdx dystrophic muscles.

The differentiation of both original muscle fibres and the regenerated muscle fibres following necrosis in mdx muscles was investigated using immunoblotting and immunocytochemical procedures. Before the onset of necrosis, postnatal skeletal muscles in mdx mouse differentiated well with only a slight delay in differentiation indicated by the level of developmental isoforms of troponin T. Prior to the onset of apparent myopathic change, both fast and slow skeletal muscle fibre types in mdx leg muscles also differentiated well when investigated by analysis of specific myosin heavy chain expression pattern. While the original muscle fibres in mdx leg muscles developed well, the differentiation of regenerated myotubes into both slow and distinct fast muscle fibre types, however, was markedly delayed or inhibited as indicated by several clusters of homogeneously staining fibres even at 14 weeks of age. The number of slow myosin heavy chain-positive myotubes amongst the regenerated muscle clusters was quite small even in soleus. This study thus established that while muscle fibres initially develop normally with only a slight delay in the differentiation process, the differentiation of regenerated myotubes in mdx muscles is markedly compromised and consequently delayed.

Animals↗
PubMed1979

Muscle spindle supply to the masticatory muscles in the Japane ermine (Carnivora).

Histological examination of the jaw muscles of the Japanese ermine showed that 4 jaw-closing muscles have 13 muscle spindles on one side of the face. The temporal muscle has 99 muscle spindles, 68 being in the anterior vertical and 31 in the posterior horizontal belly. The masseter muscle has 33 muscle spindles, 23 being in the profound and 10 in the superficial belly. The medial pterygoid muscle has 7 muscle spindles and the zygomaticomandibular muscle contains 4 muscle spindles. The lateral pterygoid and the jaw-opening muscles have no spindles.

Animals↗
PubMed1995

Changes in acetylcholine receptor number in muscle from critically ill patients receiving muscle relaxants: an investigation of the molecular mechanism of prolonged paralysis.

OBJECTIVE: Previous reports have described prolonged paralysis after the administration of muscle relaxants in critically ill patients. The purpose of this study was to examine possible pathophysiologic causes for this paralysis by measuring muscle-type, nicotinic acetylcholine receptor number in necropsy muscle specimens from patients who had received muscle relaxants to facilitate mechanical ventilation before death. DESIGN: Prospective laboratory study of human muscle collected at autopsy. SETTING: Medical and surgical intensive care units (ICUs) at a university hospital and a research laboratory. PATIENTS: Fourteen critically ill patients, with a variety of diagnoses, all of whom required mechanical ventilatory support before their deaths in the ICU and who underwent post mortem examination. Patients were arbitrarily divided into three groups, according to their total vecuronium dose and number of days mechanically ventilated before death. Three patients were in the control group (defined as dying within 72 hrs of initiation of ventilatory support and receiving a total dose of < 5 mg of vecuronium). Six patients were in the low-dose group (defined as requiring ventilatory support for > 3 days before death and receiving a total vecuronium dose of < or = 200 mg). Five patients were in the high-dose group (defined as requiring ventilatory support for > 3 days before death and receiving a total vecuronium dose of > 200 mg). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Nicotinic acetylcholine receptor numbers as measured by specific 125I-alpha-bungarotoxin binding to human rectus abdominis muscle obtained at autopsy were determined. In general, receptor number reflected the clinical requirements for the muscle relaxants of each patient. Patients who had increasing requirements for muscle relaxants before death had increases in receptor number, as compared with control values. CONCLUSIONS: The increase in nicotinic acetylcholine receptor number in muscle from patients with an increasing requirement for muscle relaxants before death suggests that nicotinic acetylcholine receptor up-regulation may underlie the increased requirements for muscle relaxants seen in some patients. Furthermore, these findings suggest that muscle relaxant-induced, denervation-like changes may at least be partially responsible for prolonged muscle paralysis after the long-term administration of muscle relaxants. This study may provide the first information into the molecular mechanisms underlying prolonged paralysis.

Adult↗
PubMed1996

Contributions of structure and innervation pattern of the stick insect extensor tibiae muscle to the filter characteristics of the muscle-joint system

It is shown that the low-pass filter characteristics of the muscle&shy;joint system of the femur&shy;tibia joint of the stick insect Cuniculina impigra result from co-contraction of the extensor and flexor tibiae muscles. The most distal region of the extensor muscle, which contains a high percentage of slow muscle fibres, is involved in this co-contraction. This conclusion results from the following evidence. (1) Inertial and friction forces do not affect the characteristics of the low-pass filter of the muscle&shy;joint system. (2) There is some co-contraction of the extensor and flexor muscles during sinusoidal stimulation of the femoral chordotonal organ at high stimulus frequencies. Both muscles generate tonic forces that increase with increasing stimulus frequency and also increase with time from the beginning of stimulation until a plateau is reached. (3) For the extensor muscle, this tonic force is produced by its most distal portion only. (4) Electrical stimulation of the common inhibitory motoneurone (CI1) reduces the tonic force generated in this most distal portion of the extensor muscle. Therefore, CI1 stimulation reduces the amplitude of tibial movement in response to sinusoidal stimulation of the femoral chordotonal organ at stimulus frequencies below 0.5 Hz (over this frequency range, the tibial movement amplitude is a function of the force amplitude produced by the whole extensor muscle and there is no co-contraction), but at chordotonal organ stimulus frequencies of 1 Hz and above, CI1 stimulation increases the tibial movement amplitude (in this case, movement amplitude is limited by the degree of co-contraction of the extensor and flexor muscles). With repeated chordotonal organ stimulation at higher stimulus frequencies, the tibial movement amplitude steadily decreases. This must be a consequence of increasing levels of co-contraction of the extensor and flexor muscles, since at low stimulus frequencies (no co-contraction) there is no reduction in movement amplitude during repeated stimulations. It is concluded that co-contraction of the extensor and flexor tibiae muscles prevents instability in the reflex loop in spite of the high gain necessary for the generation of catalepsy. Therefore, the mechanism described can be considered to be an adaptation to the ecological niche occupied by this animal. The contribution of the distal part of the extensor muscle to this system can be switched off by the CI1 during active movements.

Journal Article↗
PubMedDate not supplied

Effects of massage on delayed-onset muscle soreness, swelling, and recovery of muscle function.

CONTEXT: Delayed-onset muscle soreness (DOMS) describes muscle pain and tenderness that typically develop several hours postexercise and consist of predominantly eccentric muscle actions, especially if the exercise is unfamiliar. Although DOMS is likely a symptom of eccentric-exercise-induced muscle damage, it does not necessarily reflect muscle damage. Some prophylactic or therapeutic modalities may be effective only for alleviating DOMS, whereas others may enhance recovery of muscle function without affecting DOMS. OBJECTIVE: To test the hypothesis that massage applied after eccentric exercise would effectively alleviate DOMS without affecting muscle function. DESIGN: We used an arm-to-arm comparison model with 2 independent variables (control and massage) and 6 dependent variables (maximal isometric and isokinetic voluntary strength, range of motion, upper arm circumference, plasma creatine kinase activity, and muscle soreness). A 2-way repeated-measures analysis of variance and paired t tests were used to examine differences in changes of the dependent variable over time (before, immediately and 30 minutes after exercise, and 1, 2, 3, 4, 7, 10, and 14 days postexercise) between control and massage conditions. SETTING: University laboratory. PATIENTS OR OTHER PARTICIPANTS: Ten healthy subjects (5 men and 5 women) with no history of upper arm injury and no experience in resistance training. INTERVENTION(S): Subjects performed 10 sets of 6 maximal isokinetic (90 degrees x s(-1)) eccentric actions of the elbow flexors with each arm on a dynamometer, separated by 2 weeks. One arm received 10 minutes of massage 3 hours after eccentric exercise; the contralateral arm received no treatment. MAIN OUTCOME MEASURE(S): Maximal voluntary isometric and isokinetic elbow flexor strength, range of motion, upper arm circumference, plasma creatine kinase activity, and muscle soreness. RESULTS: Delayed-onset muscle soreness was significantly less for the massage condition for peak soreness in extending the elbow joint and palpating the brachioradialis muscle (P < .05). Soreness while flexing the elbow joint (P = .07) and palpating the brachialis muscle (P = .06) was also less with massage. Massage treatment had significant effects on plasma creatine kinase activity, with a significantly lower peak value at 4 days postexercise (P < .05), and upper arm circumference, with a significantly smaller increase than the control at 3 and 4 days postexercise (P < .05). However, no significant effects of massage on recovery of muscle strength and ROM were evident. CONCLUSIONS: Massage was effective in alleviating DOMS by approximately 30% and reducing swelling, but it had no effects on muscle function.

Journal Article↗
PubMed1998

Distribution of muscle spindles in a simply structured muscle: integrated total sensory representation.

BACKGROUND: The distribution of muscle spindles (Sps) in a small muscle of simple architecture, the capsularis at the cat's hip joint, was quantified to reveal the patterns of proprioceptive representation in the transverse and sagittal planes as well as to model the effect a local disturbance in muscle length would have on total Sp discharge. METHODS: Locations in serial cross-sections of the 32 and 38 Sps in 2 muscles, 1 perfused with the hip joint flexed and the other extended, were plotted, and their patterns of integrated sensitivity calculated assuming that (1) the discharge rate of a Sp afferent varies linearly with change in length along the Sp's axis, and (2) that within a local disturbance produced by contraction of a motor unit (MU), lengths decrease either linearly or as the square of the distance from its center. RESULTS: The isomeric pattern of "integrated, total Sp representation on cross-section" showed two peaks of sensitivity in the half of the muscle that had been next to the joint capsule, offset by low representation in a small, central area and along the extensive zone bordering the laterally facing "superficial surface." The equivalent radius of an idealized symmetrical MU territory was estimated from distributions of the few fast, oxidative-glycolytic fibers found in two muscles, and the effect of a MU's contraction on net Sp discharge predicted when the unit was positioned at distinctive sites within the pattern. As an index of Ia and II afferent representation in the sagittal plane, the distribution of the nucleated regions of Sps and the summed lengths of segments of Sp axial bundles and capsules, respectively, within successive 1-mm segments of the muscle were graphed. CONCLUSIONS: The longitudinal representation and structure of the muscle are not suited for reflex adjustment of differences in length along the muscle. The isomeric pattern of high relief in the transverse plane suggests that in this approximately 0.2 g muscle, the localization of myotatic reflexes might be accommodated but the need for adjustment in activation of MUs seems minimal. This is because the muscle is not compartmentalized, its fibers extend between the muscle's origin and insertion, their angle of pinnation is low, and greater than 90% are of slow type. The distribution of Sps is consistent with gauging length of the entire muscle and hence angulation at the hip joint.

Animals↗