• The Korean Journal of Physiology
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• 제14권2호
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• pp.7-16
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• 1980

The effects of various inotropic interventions on the shape of the steady state length tension relation and the length-dependent activation process in cardiac muscle were studied. The influence of inotropic interventions upon the action potential was also observed. The range of varying muscle length was from the optimal length$(l_{max})$, where the active tension production is maximal, to 0.85 $l_{max}$. Changes in stimulus frequency or in external bathing Ca concentration constituted the inotropic interventions in this experiment. The papillary muscles were isolated from the rabbit right ventricles and perfused with $HCO-_3\;-buffered$ normal Tyrode solution which was aerated with $3%\;CO_2-97%\;O_2$ mixed gas and kept at $35^{\circ}C$. Resting Passive tension at $l_{max}$ was approximately 30% of the total tension and appeared from the muscle length of 0.90 $l_{max}$. The effect of stimulus frequency on the steady state level of developed tension was: As the stimulus frequency was increased from 0.1 to 0.5 Hz, there was little change in developed tension. As the frequency was increased further, to a value of about 3 Hz, tension increased steeply. Further increase of the frequency to 5 Hz had little additional effect on the developed tension. The length-tension curves for isometric peak tension became more steeper with the degree of potentiation by inotropic interventions. The relative steepness of the normalized length-tension curves where tension production was expressed as a percentage of maximal tension developed at $l_{max}$, varied inversely with the level of inotropic state and these curves were not superimposable one another. Thus at the stimulus frequency of 2 Hz or at the external Ca concentration of 8 mM, the relative decline in the developed tension for a given change in muscle length was considerably less than the decline observed at the frequency of 0.5 Hz or at the concentration of 2 mM Ca. Action potential duration was prolonged significantly as the frequency increased from 0.2 to 2 Hz, and this change in action potential duration was not observable on the changes in muscle length. There was a tendency of the hyperpolarization of membrane potential when the muscle length was shortened from $l_{max}$ to 0.95 $l_{max}$. These results support the hypothesis that there is a length-dependence of the activation process.

• 대한통합의학회지
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• 제7권2호
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• pp.39-47
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• 2019

Purpose : This study was investigated effects of vibration on scapular winging of knee push-up plus exercise. Methods : Twenty-eight female subjects with scapular winging were evaluated after performing knee push-up plus exercise, with or without vibration, three times a week for four weeks. Muscle activation of the serratus anterior and upper trapezius, and the ratio of activation of the upper trapezius to serratus anterior were measured using surface EMG; and scapular winging length was measured by using the caliper. Results : The findings showed that knee push-up plus exercise -with and without- vibration induced a significant increase in muscle activation of serratus anterior (p<.05) and a significant decrease in muscle activation of the upper trapezius (p<.05), the ratio of muscle activation of the upper trapezius to the serratus anterior (p<.05) and scapular winging length (p<.05). There was also a significant difference in muscle activation of the serratus anterior (p<.05) and upper trapezius (p<.05) between control and experimental group at post-test. Conclusion : This study suggests positive clinical effects of knee push-up plus exercise with vibration which enhanced muscle activation of serratus anterior and reduced muscle activation of upper trapezius in person with scapular winging. However, vibration had no effectiveness to improve muscle imbalance between serratus anterior and upper trapezius, and reduce the scapular winging length.

• Advances in pediatric surgery
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• 제5권1호
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• pp.64-68
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• 1999

The length, diameter and muscle thickness of the pylorus were measured by ultrasonograms in 15 infants with infantile hypertrophic pyloric stenosis(IHPS). These measurements were compared to assemble measurements of infants who came in for the routine vaccination and underwent ultrasonogram. This study also studied by ultrasound the changes in the pylorus of patients who underwent pyloromyotomy 4 weeks and 8 weeks postoperatively. According to $Carver^5$, the pyloric muscle volume(PMV) and pyloric muscle index(PMI) were calculated in each case. The pyloric muscle volume, PMI and the thickness of pyloric muscle proved to be a more reliable guide to diagnose IHPS than length and diameter of pylorus. The pyloric muscle length, diameter, thickness and pyloric muscle volume were not normalized at 4 and 8 weeks after pyloromyotomy. However, pyloric muscle index was normalized at 4 weeks postoperatively perhaps as the result of rapid weight gain after pyloromyotomy.

• 국제물리치료학회지
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• 제10권1호
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• pp.1739-1745
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• 2019

Background: There have been many studies on self-myofascial release (SMR) stretching, but there are few comparative studies on the effects of massages using a release ball, which is a type of the SMR method. Objective: To investigate the immediate effects of release ball massage and self-stretching on proprioceptive sensory, hamstring's temperature, range of motion (ROM) muscle strength,. Design: Crossover study. Methods: Thirty women in 20's at S University in Busan voluntarily participated in the study. Participants were random to release ball group (n=15) or self-stretching group (n=15). Both groups performed 3 sets of exercises, stretching for 30 seconds and resting for 15 seconds in each position. The proprioceptive sensory, temperature of the hamstring muscle, ROM, and strength were measured before exercise, 5 minutes after exercise, and 30 minutes after exercise. Results: Release ball group showed significant differences in muscle length and temperature over time (p<.05). The comparison between two group over time showed significant differences in muscle length, temperature, and muscle strength (p<.05). Conclusions: These results demonstrate that release ball massage and self-stretching are beneficial for improving hamstring's temperature, ROM and muscle strength.

• 한국운동역학회지
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• 제22권4호
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• pp.413-419
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• 2012

The purpose of this study was to investigate the effects of increased saddle height on the length and activity pattern of vastus lateralis (VL) and biceps femoris (BF) muscle. To compare the effects of increased saddle height, Preferred (self-selected height of subject) and High saddle height (approximately 5% higher saddle height than self-selected) were used. Seven elite cyclists (career: $16.1{\pm}8.5years$) participated in 3 min. sub-maximal pedaling tests under the same cadence (90 RPM) and pedaling power (150 W). Hip and knee joint angles, and the length and activity of VL and BF were compared by measuring 3D motion and electromyography (EMG) data. Results showed that there were significant differences in peak extension timing of the hip joint angle and the range of motion of the hip and knee joint between different saddle heights. Although there were significant differences in muscle length of both muscles with increasing saddle height, the timing and amount of muscle activity differed only at the BF. These findings suggest that the timing and amount of bi-articular muscle activity (i.e. BF) can be altered by changing the saddle height. For practically applying these results, further study is necessary to evaluate the effects of various cadence and the pedaling power with various saddle heights.

• 한국전문물리치료학회지
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• 제11권3호
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• pp.85-90
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• 2004

The purpose of this study was to find the difference in muscle firing rate between each muscle according to the knee angle with the quadriceps femoris which is a representative action muscle of the lower extremity. Seven normal healthy subjects were recruited. The median frequency (MDF) of muscle contraction was recorded from vastus lateralis, vastus medialis, and rectus femoris muscles using the surface EMG, in 5 seconds, during maximal isometric knee extension. The data were analyzed by the two-way repeated ANOVA. The results of the study were as follows: 1) median frequency of muscle contraction was significantly higher at the vastus lateralis, vastus medialis, and rectus femoris in descending order. 2) median frequency of muscle contraction was significantly higher at the $30^{\circ}$, $60^{\circ}$, and $90^{\circ}$ in descending order. Consequently, muscle recruitment at the knee decreases the EMG activity of the lengthened muscle. This study suggests that the change in EMG activity at different muscle lengths resulted in affecting the muscle firing rate during the knee extension.

• Asian-Australasian Journal of Animal Sciences
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• 제5권2호
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• pp.229-235
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• 1992

The usefulness of a portable linear electronic scanner. B-mode ultrasonic machine, was evaluated for estimating the longissimus muscle area from ultrasonic measurement of the muscle depth in 22 live pigs. The electronic scanner was easy to operate for muscle measurements in live pigs, which did not have to be held but were caged. The cross-sectional images of longissimus muscle and covering muscles and fat appeared on the monitor with grey scale in real time. It was easy to identify the ultrasonograms of fat and muscular tissues because the images differed in the degree of the grey scale. The longissimus muscle had less echogenic image than the other muscles. The boundary lines between first, second or third layers of backfat and the longissimus muscle were distinct on the ultrasonogram. The ultrasonic measurement at the shoulder was not acceptable because of the unstable measurements and the complex tissue structure. The repeatabilities for the measurements of longissimus muscle depth at one-half body length and last rib were acceptable. The simple correlation coefficients between ultrasonic estimates of the muscle depth in live pigs and the actual areas in the carcass, were 0.50 and 0.55 at the last rib and the one-half body length, respectively. Therefore, those positions were similarly suitable to measure. The method of electronic scanner for determining longissimus muscle area from the muscle depth was suitable for practical use in the field because of the simple and inexpensive technique.

• Biomaterials and Biomechanics in Bioengineering
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• 제2권4호
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• pp.225-235
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• 2015

Treatments for asthma are largely pharmaceutical, with some therapies also utilising alternative breathing techniques. The objective of both medical and alternative methods is to relax contracted airway smooth muscle (ASM). In normal subjects, tidal breathing- and deep inspiration-oscillations are believed to have a bronchodilatory effect. Similarly, application of length oscillations to isolated, contracted ASM also elicits muscle relaxation. As a means of investigating more-effective alternative treatment methods for contracted airways, we analyse the combined effects of bronchodilators and length oscillations on isolated, contracted ASM. The contractile state of the muscle tissue prior to treatment is of primary interest. Thereafter, the effect of applying a combination of small superimposed length oscillations with tidal breathing-like oscillations to ASM is studied alone and in combination with a common bronchodilator, isoproterenol (ISO). This work suggests that relaxation of isolated, contracted ASM following application of combined oscillations and ISO is larger than treatments of either combined oscillations or ISO alone. Further, the observed oscillation-associated relaxation is found to be amplitude- rather than frequency-dependent. This study gives additional insight into the role of oscillations and bronchodilators on contracted airways.

• 대한의용생체공학회:의공학회지
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• 제22권2호
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• pp.151-156
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• 2001

기능적 전기자극(FES)에 의한 사지운동의 효과적인 제어를 위해서는, 전기자극을 입력으로 하여 근력 및 운동을 정확히 출력하는 근골격모델이 요망된다. 이 연구에서는 FES에 의한 근력 및 운동을 보다 정확히 예측할 수 있는 모델을 작성하기 위하여, 기존의 근육모델에서는 포함되지 않았던 근력의 점진적 강화현상에 대한 기초적 성질을 조사하는 것을 목적으로 한다. 구체적으로는, 일정강도의 표면자극에 대한 근력의 강화현상이 주파수, 자극이력, 근육길이에 어떻게 의존하는지를 조사하였다. 실험결과로부터, 자극의 주파수가 높을수록 초기근력에 대한 자극중의 근력의 증가도는 작아지고 근력의 피크에 도달하는 시간이 짧아지는 것을 알 수 있었다. 선행 자극에 의해 근육의 내부적인 강화상태가 포화되면 근력은 추가적인 자극에 대해서도 더 이상 증가하지 않았다. 자극시의 근육의 길이는 근력강화에 큰 영향을 미쳤으며, 근육의 길이가 짧을수록 증가도가 컸다. 장래에는 이러한 결과를 토대로 한 새로운 근력강화의 모델이 요망된다.

• Physical Therapy Rehabilitation Science
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• 제7권3호
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• pp.127-133
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• 2018

Objective: The purpose of this study was to investigate the effects of foam roller (FR) stretching, kinesiotaping (KT), and dynamic stretching (DS) on gait parameters after inducing muscle fatigue in the ankle joint. Design: Cross-sectional study. Methods: The subjects were thirty healthy young adults between the ages of 20 and 31 years at Baekseok University who voluntarily participated in this study. The participants were randomly assigned to either the FR group, KT group, or the DS group after inducing muscle fatigue of the ankle joint. Fatigue induction of the ankle joint muscles was performed by alternating a heel up and down exercise with the standing posture on the ground. The speed was maintained at 40 beats/minute using a metronome. Subsequently, the respective intervention was applied to each group. Gait parameters were measured before and after ankle muscle fatigue induction, and after intervention using the GAITRite system. One-way ANOVA was used to compare gait parameters among groups, while repeated measures ANOVA was used to compare gait parameters within each intervention group. Results: The FR group increased significantly in velocity, step length, and stride length except for cadence after intervention compared to after ankle muscle fatigue induction (p<0.01). Furthermore, the KT group showed significant increases in velocity, cadence, step length, and stride length after intervention, especially in cadence group (p<0.05). All intervention groups showed significant increases in stride length after intervention, especially the DS group (p<0.05). Conclusions: Therefore, we suggest that KT, FR, and DS can be an effective intervention on gait parameters when the ankle joint is unstable and injured.