• The Korean Journal of Physiology and Pharmacology
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• v.15 no.3
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• pp.171-177
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• 2011

Tonic smooth muscle exhibit the latch phenomenon: high force at low myosin regulatory light chains (MRLC) phosphorylation, shortening velocity (Vo), and energy consumption. However, the kinetics of MRLC phosphorylation and cellular activation in phasic smooth muscle are unknown. The present study was to determine whether $Ca^{2+}$-stimulated MRLC phosphorylation could suffice to explain the agonist- or high $K^+$-induced contraction in a fast, phasic smooth muscle. We measured myoplasmic [$Ca^{2+}$], MRLC phosphorylation, half-time after step-shortening (a measure of Vo) and contractile stress in rabbit urinary bladder strips. High $K^+$-induced contractions were phasic at both $22^{\circ}C$ and $37^{\circ}C$: myoplasmic [$Ca^{2+}$], MRLC phosphorylation, 1/half-time, and contractile stress increased transiently and then all decreased to intermediate values. Carbachol (CCh)-induced contractions exhibited latch at $37^{\circ}C$: stress was maintained at high levels despite decreasing myoplasmic [$Ca^{2+}$], MRLC phosphorylation, and 1/half-time. At $22^{\circ}C$ CCh induced sustained elevations in all parameters. 1/half-time depended on both myoplasmic [$Ca^{2+}$] and MRLC phosphorylation. The steady-state dependence of stress on MRLC phosphorylation was very steep at $37^{\circ}C$ in the CCh- or $K^+$-depolarized tissue and reduced temperature flattend the dependence of stress on MRLC phosphorylation compared to $37^{\circ}C$. These data suggest that phasic smooth muscle also exhibits latch behavior and latch is less prominent at lower temperature.

• Archives of Pharmacal Research
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• v.23 no.6
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• pp.535-547
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• 2000

Recent findings indicate that mechanical strain (deformation) exerted by the extracellular matrix modulates activation of airway smooth muscle cells. Furthermore, cytoskeletal organization in airway smooth muscle appears to be dynamic, and subject to modulation by receptor activation and mechanical strain. Mechanosensitive modulation of crossbridge activation and cytoskeletal organization may represent intracellular feedback mechanisms that limit the shortening of airway smooth muscle during bronchoconstriction. Recent findings suggest that receptor-mediated signal transduction is the primary target of mechanosensitive modulation. Mechanical strain appears to regulate the number of functional G-proteins and/or phospholipase C enzymes in the cell membrane possibly by membrane trafficking and/or protein translocation. Dense plaques, membrane structures analogous to focal adhesions, appear to be the primary target of cytoskeletal regulation. Mechanical strain and receptor-binding appear to regulate the assembly and phosphorylation of dense plaque proteins in airway smooth muscle cells. Understanding these mechanisms may reveal new pharmacological targets for control1ing airway resistance in airway diseases.

• The Journal of Korea CHUNA Manual Medicine
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• v.4 no.1
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• pp.99-109
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• 2003

Dr. Lawrence H Jones developed innovative approach for the treatment of neuromuscular and musculo-skeletal disorders such as fibromyalgia, myofacial pain syndrome, any other muscle pain. This technique is called Strain/Counterstrain technique which uses effect of neuromuscular reflex for treatment of strain. First, Relieving spinal or other joint pain by passively putting the joint into its position of greatest comfort; secondly relieving pain by reduction and arrest of the continuing inappropriate proprioceptor activity. This was accomplished by markedly shortening the muscle that contains the malfunctioning muscle spindle by applying. mild strain to its antagonists. In other words, the inappropriate strain reflex is inhibited by application of counterstrain. Many other techniques have been developed for treating of muscle pain due to somatic dysfunction, but we want to introduce you to strain/counterstrain technique because this is basic concept and theory of Chum therapy for controling motor system.

• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.611-613
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• 1998

A structure of musculotendon model with a fatigue profile is investigated. The Hill-type musculotendon model can predicts the decline in muscle force for a given fatigue profile. It consists of nonlinear activation and contraction dynamics based on the physiological concepts. It is normalized for generalization to deal with the various muscles. Muscle force generated by continuous tetanic electrical monophasic pulsewidth modulation stimulation is decreased in time. A fatigue profile is expressed by a function of intramuscular acidification and applied to the relationship between muscle force and shortening velocity in contraction dynamics. The results of computer simulation are well matched with data in a literature which are isometrically performed for knee extension muscles. Also change in optimal fiber length has an effect only on muscle time, constant not on the steady-state tetanic force.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.27 no.2
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• pp.1-8
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• 2021

Background: Chronic neck pain (CNP) is associated with weakness in the deep neck flexor muscles, a shortening of the neck extensors, and a reduction in endurance. In addition, muscle imbalance can lead to neck pain and musculoskeletal dysfunction. This study compared neck extensor muscle fatigue, muscle strength, and muscle endurance time between patients with CNP and healthy adults during isometric neck extension. Methods: Thirty participants (15 patients with CNP and 15 healthy adults) were recruited in this research. The outcome measures included splenius capitis (SC) muscle fatigue, isometric neck extensor strength, and muscle endurance. The independent T-test was used to compare the continuous dependent variables between the CNP group and the healthy group. Results: The independent T-test indicated that muscle fatigue in the left SC differed significantly between the CNP group and the healthy group. A significant difference was also noted in the isometric neck extensor and neck extensor strength between the groups. Conclusion: Our results provided promising clinical evidence that patients with CLP have reduced neck extensor strength and endurance and increased SC muscle fatigue, which results in neck pain.

• Journal of Veterinary Clinics
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• v.37 no.3
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• pp.163-167
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• 2020

A 13-month-old, 3.3 kg castrated male Shih-tzu presented with right hindlimb lameness. The physical examination revealed atrophy of the right thigh muscles, hyperextension of the stifle joint and external torsion of the tibia. On the radiographic examination, patella alta and genu recurvatum were observed. A biapical deformity of the tibia and external torsion of the distal tibia were detected by computed tomography (CT). A three-dimensional (3D) printed bone model was designed and constructed for the preoperative plan prior to surgery. Rectus femoris muscle transposition, femoral shortening ostectomy and open wedge osteotomy of the distal tibia were performed using hybrid external skele/t0al fixation (hybrid-ESF). A dynamic stifle flexion apparatus was used to prevent recurrence of a quadriceps contracture (QC). Intense physiotherapy was administered postoperatively. The dog began to use the affected limb one week after surgery. Functional improvement in the affected limb was observed, and full weight-bearing was possible at 3 months after surgery. Union of the osteotomy lines was observed at 3 months, and the stifle joint was fully movable at 7 months after surgery. Regarding the treatments for QC, these methods may be excellent candidates, as they do not lead to severe damage to the limb or amputation.

• Korean Journal of Food Science and Technology
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• v.31 no.4
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• pp.1005-1010
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• 1999

To study the shortening of rigor mortis and changes in the morphological properties of gamma-irradiated pre-rigor bovine muscle (M). Sternomandibularis during post mortem, this experiment was performed with a test of shear force and the observation of the ultrastucture of raw muscle. The time elapsed until maximum shear force values was shortened by gamma irradiation, depending upon the dose. The release of rigor mortis started earlier than control (non-irradiated muscle). A shortening of the length of the Z-line and the maintenance of the sarcomere length by gamma irradiation was observed. The breakdown of the perimysium of muscle bundles was observed more in irradiated samples than in the control. In conclusion, it is considered that gamma irradiation on pre-rigor beef shortens aging-period, improves tenderness and enhances the beef quality.

• Korean Journal of Applied Biomechanics
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• v.22 no.4
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• pp.421-428
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• 2012

The purpose of this study was to verify the effects of developed assisting wear which maximize trunk(back) muscle's stretch-shortening effect during backswing and downswing for increasing golf ball carrying distance. Design and fabrication of assistive wear were performed based on the results of analyzed data of trunk EMG activity from the golf drive swings of elite professional male golfers during back swing and downswing phases. After the prototype of wear was produced, surface EMG and Flight scope tests were conducted to verify the effectiveness of the wear for increasing distance to the professional golfers. Results indicated that wearing trial showed significant longer carry distance than the non-wearing trial(p<.001). The carry distance of wearing trial showed an average 229 m compared to the non-wearing trial, the average 225 m. The swing with wearing also produced significantly faster ball speed than the trial without wearing(p<.05). Average 245 Km/h and 244 Km/h were produced for the swing with and without wearing trails, respectively. EMG results also indicated that the muscle activity of left psoas was significantly increased for wearing trial during downswing and near the impact. Thus, this may affect positively to increase club head speed. The activity of the left latissimus dorsi was dramatically increased during the final stage of swing. This generates elongation effect for longer follow-through and increased impulse between club and ball so eventually valid assistance to increase carry distance. Therefore, the developed assisting wear was proved to be effective tool for increasing golf ball carry distance with maximizing trunk(back) muscle's stretch-shortening effect during backswing and downswing.

• Physical Therapy Rehabilitation Science
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• v.12 no.2
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• pp.149-154
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• 2023

Objective: This study is designed to investigate the effect of ankle joint position on hip extensor muscle activity when bridging exercise in sagittal plane. Design: Cross-sectional study Methods: The subjects were recruited from 20 healthy adult men. The subjects performed three types of bridging exercises (normal bridging, ankle dorsiflexion bridging, ankle plantar flexion bridging) three times for five seconds with a rest of 15 seconds between measurements and two minutes of rest between each motion. The target muscles were the gluteus maximus, biceps femoris, soleus, and tibialis anterior. A surface electromyography was used to measure the muscle activity of these muscles. Results: The results show there was no statistically significant difference between the three types of exercise in the gluteus maximus muscle activity. However, the biceps femoris showed a significant difference between the three types of exercises (p<0.05). Conclusions: In conclusion, when the three different bridging exercises were performed by adding ankle motion to normal bridging exercise, there was a significant difference in the muscle activity of the gluteus maximus relative to the biceps femoris muscle activity in the order of the ankle dorsiflexion bridging, normal bridging, and ankle plantar flexion bridging exercise. Therefore, this could be an effective option for a bridging exercise if applied to patients with a weak gluteal muscle and shortening of the hamstring muscle in further studies.

• Korean Journal of Exercise Nutrition
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• v.25 no.2
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• pp.8-14
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• 2021

[Purpose] The purpose of this study was to investigate the effects of a high-fat high-sucrose (HFHS) diet on previously reported adaptations of cardiac morphological and contractile properties to resistance training. [Methods] Twelve-week-old rats participated in 12-weeks of resistance exercise training and consumed an HFHS diet. Echocardiography and skinned cardiac muscle fiber bundle testing were performed to determine the structural and mechanical adaptations. [Results] Compared to chow-fed sedentary animals, both HFHS- and chow-fed resistance-trained animals had thicker left ventricular walls. Isolated trabecular fiber bundles from chow-fed resistance-trained animals had greater force output, shortening velocities, and calcium sensitivities than those of chow-fed sedentary controls. However, trabeculae from the HFHS resistance-trained animals had greater force output but no change in unloaded shortening velocity or calcium sensitivity than those of the chow-fed sedentary group animals. [Conclusion] Resistance exercise training led to positive structural and mechanical adaptations of the heart, which were partly offset by the HFHS diet.