• Journal of Biomedical Engineering Research
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• v.33 no.2
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• pp.98-103
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• 2012

The purpose of this study was to compare premotor time(PMT) and electro-mechanical delay(EMD) between sitting and standing posture. Twenty four healthy young subjects(12 women and 12 men) participated in this study. Subjects were instructed to perform maximal, voluntary, isometric contraction of ankle muscle(tibialis anterior and gastrocnemius muscles) in reaction to auditory stimulus. PMT and EMD, calculated from stimulus, EMG and torque profile were compared between sitting and standing postures. As statistical analysis, paired t-test was performed to assess difference between sitting and standing posture. In both tibialis anterior and gastrocnemius muscles, EMD was found to be significantly longer for standing than sitting. However, PMT in standing posture was longer than that in sitting posture only in gastrocnemius muscles. These result indicate that increased reaction time, particularly, increased EMD of ankle muscles in standing posture may be caused by co-contraction of ankle muscles for postural control in standing posture.

• Journal of Korean Neurosurgical Society
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• v.43 no.2
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• pp.97-104
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• 2008

Objective: Transient receptor potential vanilloid subfamily type 1 (TRPV1), a most specific marker of the nociceptive primary afferent, is expressed in peptidergic and non-peptidergic primary afferents innervating skin and viscera. However, its expression in sensory fibers to skeletal muscle is not well known. In this study, we studied the neurochemical characteristics of TRPV1-positive primary afferents to skeletal muscles. Methods: Sprague-Dawley rats were injected with total $20{\mu}l$ of 1% fast blue (FB) into the gastrocnemius and erector spinae muscle and animals were perfused 4 days after injection. FB-positive cells were traced in the L4-L5 (for gastrocnemius muscle) and L2-L4 (for erector spinae muscle) dorsal root ganglia. The neurochemical characteristics of the muscle afferents were studied with multiple immunofluorescence with TRPV1, calcitonin gene-related peptide (CGRP) and $P2X_3$. To identify spinal neurons responding to noxious stimulus to the skeletal muscle, 10% acetic acids were injected into the gastrocnemius and erector spinae muscles and expression of phospho extracellular signal-regulated kinase (pERK) in spinal cords were identified with immunohistochemical method. Results: TRPVl was expressed in about 49% of muscle afferents traced from gastrocnemius and 40% of erector spinae. Sixty-five to 60% of TRPV1-positive muscles afferents also expressed CGRP. In contrast, expression of $P2X_3$ immnoreaction in TRPV1-positive muscle afferents were about 20%. TRPV1-positive primary afferents were contacted with spinal neurons expressing pERK after injection of acetic acid into the muscles. Conclusion: It is consequently suggested that nociception from skeletal muscles are mediated by TRPV1-positive primary afferents and majority of them are also peptidergic.

• PNF and Movement
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• v.17 no.2
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• pp.207-214
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• 2019

Purpose: Although multi-directional reaching exercises are commonly used clinically, the effects of specific movement directions on the muscle systems of the lower extremities have not been explored. We therefore investigated lower extremity muscle activity during reaching exercises with different sagittal and horizontal plane movements. Methods: The surface electromyography responses of the bilateral rectus femoris, tibialis anterior, peroneus longus, and gastrocnemius muscles were measured during reaching exercises in three directions in the horizontal plane (neutral, $45^{\circ}$ horizontal shoulder adduction, and $45^{\circ}$ abduction) and three directions in the sagittal plane (neutral, $120^{\circ}$ flexion, and $60^{\circ}$ flexion). A total of 20 healthy, physically active participants completed six sets of reaching exercises. Two-way repeated ANOVA was performed: body side (ipsilateral and contralateral) was set as the intra-subject factor and direction of reach as the inter-subject factor. Results: Reaching at $45^{\circ}$ horizontal shoulder adduction significantly increased the activity of the contralateral rectus femoris and gastrocnemius muscles, while $45^{\circ}$ horizontal shoulder abduction activated the ipsilateral rectus femoris and gastrocnemius muscles. The rectus femoris activity was significantly higher with reaching at a $120^{\circ}$ shoulder flexion compared to the other conditions. The gastrocnemius activity decreased significantly as the shoulder elevation angle increased from $60^{\circ}$ to $120^{\circ}$. Conclusion: Our results suggest that multi-directional reaching stimulates the lower extremity muscles depending on the movement direction. The muscles acting on two different joints responded to the changes in reaching direction, whereas the muscles acting on one joint were not activated with changes in reaching direction.

• Preventive Nutrition and Food Science
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• v.8 no.4
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• pp.377-382
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• 2003

This study investigated the effects of green tea on the muscle antioxidative defense system in the white & red gastrocnemius muscles of rats after aerobic exercise. Male Sprague-Dawley rats weighing 150 10 g were randomly assigned to a control group, non-exercise with green tea group (G group), and exercise training group. The exercise training group was then further classified as the training (T) group and training with green tea (TG) group, the latter of which was supplemented with green tea in the drinking water during the experimental period. The rats in the exercise training groups (T and TG) were subjected to aerobic exercise on a treadmill 30 min/day at a speed of 28 m/min (7% incline) 5 days/week, while the other groups (control and G group) were cage confined for 4 weeks. Thereafter, the rats were sacrificed with an injected overdose of pentobarbital just after running. In the white muscle, the xanthine oxidase (XOD) activities were 71 % higher in the T group compared to control group, whereas the TG group had the same activity as the control group. The XOD activities in the red gastrocnemius muscle exhibited the same tendency as in the white muscle. The superoxide dismutase (SOD) activity in the white muscle was lower in the T group compared with the control group, yet significantly higher in the TG group compared with the T group. The SOD activities in the red gastrocnemius muscle exhibited the same tendency as in the white gastrocnemius muscle. The glutathione peroxidase (GSHpx) activities in the white & red gastrocnemius muscles were 43 % lower in the T group compared with the control group, yet the activities in the TG group remained at control levels. The glutathione S-transferase (GST) activity in the white muscle was not significantly different among any of the three groups, but in the red gastrocnemius muscle, the TG group had the same activity as in the control group. The thiobarbituric acid reactive substance (TBARS) contents in the white & red gastrocnemius muscles were higher in the T group than in the control but the control and TG groups had the same concentrations of TBARS. In conclusion, the supplementation of green tea in rats subjected to aerobic exercise was found to reduce the peroxidation of muscle lipids by enhancing the antioxidative defense mechanism.

• The Korean Journal of Physiology
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• v.28 no.1
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• pp.61-70
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• 1994

A new method is used to record the actual shortening produced during the auxotonic activity of the sartorius (SAR), gastrocnemius (CAS) and rectus abdominis (RAB) muscles of a lizard Uromastix. The auxotonic twitch and tetanus records thus obtained were used for the first time to calculate the coefficient of linear shortening (COLS). This coefficient represent the relative Index between change in length $(\Delta\;L=L_0-L_1)$ and tension $({\Delta}P\;P_0-P_1)$ due to shortening at the steepest rising phase of the twitch and tetanus, recorded at resting length. In addition to this, maximum shortening $(S_{max})$ and auxotonic tensions were also determined at resting lengths of these muscles. The COLS was found to express the speed of shortening and auxotonic tensions are suggested to be of value to express the internal architecture of SAR, GAS & RAB muscles. The results are discussed in terms of contractile and elastic elements of the muscles alongwith the importance of shortening at resting lengths in skeletal muscles.

• Korean Journal of Exercise Nutrition
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• v.23 no.2
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• pp.1-6
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• 2019

[Purpose] Strenuous exercise often induces skeletal muscle damage, which results in impaired performance. Sphingolipid metabolism contributes to various cellular processes, including apoptosis, stress response, and inflammation. However, the relationship between exercise-induced muscle damage and ceramide (a key component of sphingolipid metabolism), is rarely studied. The present study aimed to explore the regulatory role of sphingolipid metabolism in exercise-induced muscle damage. [Methods] Mice were subjected to strenuous exercise by treadmill running with gradual increase in intensity. The blood and gastrocnemius muscles (white and red portion) were collected immediately after and 24 h post exercise. For 3 days, imipramine was intraperitoneally injected 1 h prior to treadmill running. [Results] Interleukin 6 (IL-6) and serum creatine kinase (CK) levels were enhanced immediately after and 24 h post exercise (relative to those of resting), respectively. Acidic sphingomyelinase (A-SMase) protein expression in gastrocnemius muscles was significantly augmented by exercise, unlike, serine palmitoyltransferase-1 (SPT-1) and neutral sphingomyelinase (N-SMase) expressions. Furthermore, imipramine (a selective A-SMase inhibitor) treatment reduced the exercise-induced CK and IL-6 elevations, along with a decrease in cleaved caspase-3 (Cas-3) of gastrocnemius muscles. [Conclusion] We found the crucial role of A-SMase in exercise-induced muscle damage.

• The Korean Journal of Physiology
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• v.26 no.2
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• pp.159-166
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• 1992

The present study was designed to evaluate effects of intermittent electrical stimulation of the sciatic nerve on the atrophic response of antigravity muscles, such as the soleus (slow m.) and medial gastrocnemius (fast m.) muscles. Rats (Sprague-Dawley, 245-255g) were subjected to a hindlimb suspension and divided into three groups : one was with hindlimb suspension (MS) and another with hindlimb suspension plus intermittent electrical stimulation of the sciatic nerve (HS ES). Control group (CONT) was kept free without strain of the hindlimb. After 7 days of hindlimb suspension, the soleus and medial gastrocnemius muscles were cut at their insertion sites, and were then connected to the force transducer to observe their mechanical properties. Optimal pulse width and frequency of electrical stimulation were 0.2ms, 20Hz for the soleus muscle and 0.3ms, 40Hz for the medial gastrocnemius muscle under supramaximal stimulation. Body weight and circumference of the hindlimb were significantly decreased in HS and HS-ES groups compared with the control group. In HS-ES group, however, the weight of the soleus muscle was not different from that in the control group while the weight of the medial gastrocnemius muscle was lower than that in the control group. In HS group, mechanical properties of muscle contraction including contraction time, half relaxation time, twitch tension, tetanic tension, and fatigue index of both muscles were significantly decreased compared with the control group except for twitch tension and tetanic tension of medial gastrocnemius muscle. The degree of atrophy of the soleus muscle in HS group was more prominent than that of the medial gastrocnemius muscle. Twitch tension and fatigue index of the soleus muscle and fatigue index of the medial gastrocnemius muscle in HS-ES group were not different from those of the control group. While mechanical properties of the soleus muscle examined were all significantly increased in HS-ES group compared with HS group, only contraction time and fatigue index of the medial gastrocnemius muscle were significantly increased in HS-ES group. These data indicate that intermittent electrical stimulation may be useful in prevention of muscle atrophy.

• Journal of Korean Academy of Nursing
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• v.28 no.4
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• pp.893-907
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• 1998

The purpose of this study was to determine the effect of regular exercise during dexamethasone injection on the body weight, weight of hindlimb muslces, myofibrillar protein content and glutamine synthetase activity. 180-200g female Wistar rats were divided into four groups : control, exercise, dexamethasone injection (dexa), and exercise during dexamethasone injection(D+E) group. The dexa group received daily subcutaneous injection of dexamethasone at a dose of 4mg/kg body weight for 7 days. The exercise group ran on a treadmill for 60min/day(20minutes every 4 hours) at 10m/min and a 10$^{\circ}$grade. The control group received daily subcutaneous injection of normal saline at a dose of 4mg/kg body weight for 7 days. The D+E group ran on a treadmill for 60min/day(20minutes every 4 hours) at 10m/min and a 10$^{\circ}$ grade during dexamethasone injection. Body weight of the control group increased significantly from days of experiment, that of the dexa group decreased significantly from day 4 of the experiment resulting in a 82.4% decrease compared to the first day of the experiment. Body weight of the D+E group decreased significantly from day 5 of experiment resulting in a 81.77% decrease comprared to the first day of the experiment. Body weights, muscle weight and myofibrillar protein content of the plantaris and gastrocnemius decreased significantly and muscle weight of the soleus tended to decrease with dexamethasone injection. Glutamine synthetase activity of the hindlimb muscles increased significantly with the dexamethasone injection. The relative weight of the soleus was comparable to the control group and that of plantaris decreased significantly and that of gastrocnemius tended to decrease compared to that of the control in the dexa group. Body weight and muscle weight of the plantaris and gastrocnemius of the excrcise group were comparable to the control group, and the muscle weight of soleus showed a tendencey to increase. The relative weight of the soleus increased significantly and that of the plantaris and gastrocnemius were comparable to the control in the exercise group. Myofibrillar protein content of the soleus and plantaris increased significantly and there was no change of GS activity of the hindlimb muscles compared to the control in the exercise group. Body weight of the D+E group was comparable to the dexa group, muscle weight of the plantaris increased significantly and that of the soleus and gastrocnemius showed a tendency to increase. The relative weight of the hindlimb muscles increased significantly. Myofibrillar protein content of the soleus and plantaris increased significantly and that of the gastrocnemius tended to increase compared to the dexa group. Body weight and muscle weight of the plantaris and gastrocnemius of the D+E group did not recover to that of the control group. Muscle weight of the soleus recovered to that of the control group. The relative weight and of myofibrillar protein content of the hindlimb muscles recovered to that of the control group. From these results, it is suggested that regular exercise during dexamethasone injection might attenuate the muscle atrophy of the hindlimb muscles.

• Herbal Formula Science
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• v.25 no.4
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• pp.499-508
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• 2017

Objectives : Skeletal muscle atrophy occurs in response to a variety of conditions. The unloading to muscle occurs clinically in limb immobilization, bed rest, spinal cord injury and peripheral nerve damage, resulting in significant loss of muscle mass and force production. Muscle disuse is accompanied by an increase in apoptotic signaling, which mediates some of the responses to unloading in the muscle. In this study we tested the hypothesis that Daeyeoung-jeon extract would improve muscle recovery after reloading following disuse. Method : Twenty young male Sprague-Dawley rats were used for the studies. The hindlimb immobilization was performed with casting tape to keep the left ankle joint in a fully extended position. No intervention was performed on the right leg and used as intact region. The Rats in Daeyeoung-jeon treated group (DYJ) were orally administrated Daeyeoung-jeon water extract, and rats of Control group were given with saline only. After 2 weeks of immobilization, all animals were sacrificed, and the whole gastrocnemius muscles were dissected from both legs. The morphology of right and left gastrocnemius muscles in both DYJ and Control groups were assessed by hematoxylin and eosin staining. Moreover, to investigate the immobilization-induced muscular apoptosis, the immunohistochemical analysis of Bax and Bcl-2 was carried out. Results : Daeyeoung-jeon represented the significant protective effects against the reductions of the left gastrocnemius muscles weight and average cross section area to compared with Control group. The treatment with Daeyeoung-jeon extract significantly reduced the immunoreactivity of BAX and increased the immunoreactivity of Bcl-2 in gastrocnemius muscle compared with Control group. Conclusion : Daeyeoung-jeon has protective effects against immobilization-induced muscle atrophy by regulating the activities of apoptosis-associated BAX/Bcl-2 proteins in gastrocnemius muscle.

• Journal of Korean Academy of Nursing
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• v.41 no.4
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• pp.520-527
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• 2011

Purpose: The purpose of this study was to examine effects of nitric oxide synthase (NOS) inhibitor on muscle weight and myofibrillar protein content of affected and unaffected hindlimb muscles in rats with neuropathic pain induced by unilateral peripheral nerve injury. Methods: Neuropathic pain was induced by ligation and cutting of the left L5 spinal nerve. Adult male Sprague-Dawley rats were randomly assigned to one of two groups: The NOSI group (n=19) had NOS inhibitor (L-NAME) injections daily for 14 days, and the Vehicle group (n=20) had vehicle injections daily for 14 days. Withdrawal threshold, body weight, food intake and activity were measured every day. At 15 days all rats were anesthetized and soleus, plantaris and gastrocnemius muscles were dissected from hindlimbs. Muscle weight and myofibrillar protein content of the dissected muscles were determined. Results: The NOSI group showed significant increases as compared to the Vehicle group for body weight at 15 days, muscle weight and myofibrillar protein content of the unaffected soleus and gastrocnemius. The NOSI group demonstrated a higher pain threshold than the vehicle group. Conclusion: NOSI for 14 days attenuates unaffected soleus and gastrocnemius muscle atrophy in neuropathic pain model.