• PNF and Movement
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• v.22 no.1
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• pp.113-128
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• 2024

Purpose: This study aimed to investigate the effects of eccentric training applied to the calf muscles on muscle tone, muscle strength, and gait variables in patients with chronic stroke. Methods: Twenty-two participants were divided into experimental (n=12; eccentric training) and control (n=10; static stretching and stretching board) groups. The participants completed 30-minute physical therapy sessions five times a week for three weeks. Calf muscle tone, muscle strength, and gait variables were measured using MyotonPRO, a hand-held dynamometer, and Optogait, respectively, before and after each intervention. Results: Two-way analysis of variance (ANOVA) indicated a significant interaction effect between measurement points and groups in frequency, stiffness, and decrement of the lateral gastrocnemius, medial gastrocnemius, and soleus muscles (p<.05). Paired t-tests showed that the experimental group exhibited significantly decreased frequency and stiffness scores for the lateral gastrocnemius, medial gastrocnemius, and soleus muscles (p<.05), as well as significantly increased decrement and muscle strength scores, gait speed, step length, and stride length (p<.05). Conclusion: The application of eccentric training to the calf effectively reduced muscle tone, increased muscle strength, and improved the gait speed, step length, and stride length of patients with chronic stroke.

• The Korean Journal of Physiology
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• v.30 no.1
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• pp.43-51
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• 1996

This study was aimed to elucidate the changes in heart rate variability during treadmill exercise at various speeds and grades by spectral analysis. Thirty-three untrained male college students aged $20{\sim}26\;yr $were employed to exercise on a treadmill using 4 speeds (4.02, 5.47, 6.76 and 8.05 km/h) and 6 grades (0, 4, 8, 12, 16 and 20%). A fixed speed was selected for each session with the grade increased every 3 min. The electrocardiogram, respiration and the stepping activity were continuously recorded through an A/D converter system on the computer disk. Power spectra of heart rate variability (RRV) were obtained by use of a fast Fourier transform algorithm. The frequency domain was divided into 3 bands: $VLF\;(0{\sim}0.04\;Hz),\;LF\;(0.04 {\sim}0.15\;Hz)\;and\;HF\;(0.15{\sim}1.00\;Hz).$ Heart rate was $74.4{\pm}2.1\;beats/min$ at rest and showed a steady increase during treadmill exercise with increasing speed and grade up to $196.7{\pm}5.0\;beats/min.$ Total power of HRV was $35.0{\pm}6.7\;(beats/min)^{2}$ at rest and progressively decreased during exercise down to $1.9{\pm}0.3\;(beats/min)^{2}.$ The %VLF power of HRV was $34.5{\pm}3.7\; %$ at rest and showed no significant change during exercise except for a decrease observed at the highest intensity of exercise. The %LF power was $44.1{\pm}3.0\;%$ at rest and showed a progressive decrease down to $4.5{\pm}1.0\;%$ during those stages of exercise where heart rate was over 135 beats/min. The %HF power was $21.4{\pm}2.9\;%$ at rest and showed a progressive increase up to $87.1{\pm}6.7\;%$ during higher intensity exercise where heart rate was over 165 beats/min. Peak frequency of HF band was $0.200{\pm}0.018\;Hz$ at rest and was shifted to higher frequencies up to $0.909{\pm}0.048\;Hz$ at heart rates greater than 135 beats/min. Respiratory frequency was $18.0{\pm}1.5$ breaths/min at rest and significantly increased during exercise up to $53.0{\pm}3.7$ breaths/min. Stride frequency during treadmill exercise showed an increasing tendency with increasing speed from $55.6{\pm}0.9$ steps/min at 4.02 km/h to $81.2{\pm}0.6$ at 8.05 km/h. It was concluded that total power of HRV decreased progressively with increasing exercise intensity due to the withdrawal of parasympathetic activity. At higher exercise intensity, % LF power decreased and %HF power increased with its peak frequency shifted to higher values in a progressive mode with increasing speed and grade, reflecting a readjustment in the cardiovascular system and the increased respiration and its rate, respectively.

• Journal of Convergence for Information Technology
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• v.10 no.4
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• pp.160-167
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• 2020

This study analyzes the effects of changes in running velocity and slope on the biomechanical factors of the lower limb joints. For this purpose, 15 adult males in their 20s ran according to changes in running speed (2.7, 3.3 m/s) and slope ( -9°, -6°, 0°, 6°, 9°) on the treadmill, and their running characteristics (stride length, stride frequency). The range of motion of the lower limb joint and the vertical ground reaction force were greater in UR (p <.05), and the moment of the lower limb joint, braking force, thrust and load factor was large in DR (p <.05). In joint power, the ankle joint was greater in DR, and hip joint was greater in the UR (p <.05). These results show that the injuries of the ankle joint will be greater than other cases when running DR at a speed of 3.3 m/s.

• Korean Journal of Applied Biomechanics
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• v.34 no.2
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• pp.81-92
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• 2024

Objective: The purpose of this study was to analyze the impact acceleration, shock attenuation and biomechanical variables at various running speed. Method: 20 subjects (height: 176.15 ± 0.63 cm, weight: 70.95 ± 9.77 kg, age: 27.00 ± 4.65 yrs.) participated in this study. The subjects ran at four different speeds (2.5 m/s, 3.0 m/s, 3.5 m/s, 4.0 m/s). Three-dimensional accelerometers were attached to the distal tibia, sternum and head. Gait parameters, biomechanical variables (lower extremity joint angle, moment, power and ground reaction force) and acceleration variables (impact acceleration, shock attenuation) were calculated during the stance phase of the running. Repeated measures ANOVA was used with an alpha level of .05. Results: In gait parameters, decreased stance time, increasing stride length and stride frequency with increasing running speed. And at swing time 2.5 m/s and 4.0 m/s was decreased compared to 3.0 m/s and 3.5 m/s. Biomechanical variables statistically increased with increasing running speed except knee joint ROM, maximum ankle dorsiflexion moment, and maximum hip flexion moment. In acceleration variables as the running speed increased (2.5 m/s to 4.0 m/s), the impact acceleration on the distal tibia increased by more than twice, while the sternum and head increased by approximately 1.1 and 1.2 times, respectively. And shock attenuation (tibia to head) increased as the running speed increased. Conclusion: When running speed increases, the magnitude and increasing rate of sternum and head acceleration are lower compared to the proximal tibia, while shock attenuation increases. This suggests that limiting trunk movement and increasing lower limb movement effectively reduce impact from increased shock. However, to fully understand the body's mechanism for reducing shock, further studies are needed with accelerometers attached to more segments to examine their relationship with kinematic variables.

• The Transactions of the Korea Information Processing Society
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• v.7 no.7
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• pp.2196-2203
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• 2000

As processor's operational frequency increases and processors execute multiple instructions per cycle, the processor performance becomes more dependent on the load operand referencing latency and the data dependency. To reduce the operand fetch latency and to increase ILP by breaking the data dependency, we propose a value-address hybrid predictor using a reasonable size prediction buffer and analyse the performance improvement by the proposed predictor. Through the extensive simulation of 5 benchmark programs, the proposed hybrid prediction scheme accurately predicts 62.72% of all loads which are 12.64% higher than the value prediction scheme and show its cost-effectiveness compared to the address predition scheme. In addition, we analyse the performance improvement achieved by the stride management and the history of previous predictions.

• The Korean Journal of Physiology
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• v.4 no.1
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• pp.1-11
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• 1970

Studies on the analysis of walking were performed on 33 male subjects. A prescription of physical exercise (walking at a speed of greater than 6 km/hr for more than one hour daily) for the promotion of individual health is presented on the basis of walking analysis. Presumptions were made that adequate physical exercise does promote health and is beneficial for the healthy life and increases the life span. These presumptions were derived from the numerous experimental literatures. The literatures support indirectly the presumptions. The following results were obtained and prescription of physical exercise is presented. 1. Oxygen uptake in a walking on a treadmill at a speed of 4 km/hr was only 3 times of the resting oxygen uptake. This kind of moderate exercise did not stimulate the cardiopulmonary system adequately. Heart rate at a 4 km/hr walking was 101 beats/min in boys of less than 20 years old and 83 beats/min in adults. Oxygen uptake at a 6 km/hr walking exceeded 4 times of the resting oxygen uptake. It was interpreted that walking at 6 km/hr stimulated the cardiopulmonary system for the promotion of health. Heart rate at this speed was greater than 110 beats/min in boys and greater than 100 beats/min in adults. 2. Heart rates in a walking of 10 km/hr were 172 beats/min in boys, and 143 beats/min in adults, respectively. Maximal heart rates were 185 beats/min in boys, 180 in office clerks, and 168 beats/min in construction site laboreres. 3. The correlation between heart rate and oxygen uptake was high, namely, r>0.95. Subsequently heart rate could be used as a measure of degree of intensity of physical exercise instead of the cumbersome oxygen uptake measurement. 4. The prescription of physical exercise for the promotion of health is: Daily walking for more than one hour at a speed of greater than 6 km/hr. Bodily functions in this daily walking are in boys (body weight, 50 kg): heart rates of 110 beats/min; breathing frequency, 28/min; oxygen uptake, greater than 4 times of the resting uptake; pulmonary ventilation, 351/min; stride, 124 strides/min; cumulative number of strides for one hour, 7,440 strides, and energy expenditure of more than 300 kcal. In adults (body weight, 60 kg) the bodily functions are: heart rates of 100 beats/min, breathing frequency, 28/min; oxygen uptake, greater than 4 times of the resting uptake; Pulmonary ventilation, 301/min; stride, 127 strides/min; cumulative number of strides for one hour, 7,670 strides, and energy expenditure of more than 300 kcal.

• Structural Engineering and Mechanics
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• v.46 no.2
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• pp.179-196
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• 2013

An experimentally measured single footfall trace (SFT) from a walking subject needs to be extended into a continuous force curve, which can then be used as load for floor vibration serviceability assessment, or on which further analysis like discrete Fourier transform can be conducted. This paper investigates the accuracy, applicability and parametrical sensitivity of four extension methods, Methods I to IV, which extends the SFT into a continuous time history by the walking step rate, stride time, double support proportion and the double support time, respectively. Performance of the four methods was assessed by comparing their results with the experimentally obtained reference footfall traces in the time and frequency domain, and by comparing the vibrational response of a concrete slab subjected to the extended traces to that of reference traces. The effect of the extension parameter on each method was also explored through parametrical analysis. This study finds that, in general, Method I and II perform better than Method III and IV, and all of the four methods are sensitive to their extension parameter. When reliable information of walking rate or gait period is available in the test, Methods I or II is a better choice. Otherwise, Method III, with the suggested extension parameter of double support time proportion, is recommended.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.7
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• pp.767-772
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• 2011

Trajectory generation is important because it determines the walking stability, continuity, and performance of a body in motion. Generally, the Linear Inverted Pendulum Mode is used for trajectory generation; however, for the sake of simplicity, the trajectory in this mode does not allow vertical motions and pitching motions of the body. This paper proposes a new trajectory generation method called Extended Linear Inverted Pendulum Mode (ELIPM) that allows vertical motion as well as pitching motion. This method can also improve the performance of locomotion by controlling the stride and locomotion frequency of a body.

• Korean Journal of Applied Biomechanics
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• v.29 no.3
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• pp.167-172
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• 2019

Objective: The aim of this study was to investigate the effect of midsole hardness of running shoe on muscle fatigue and impact force during distance running. Method: Ten healthy college recreational runners who were performing distance running at least three times a week participated in this experiment. They were asked to run for 15 minutes in the treadmill at 10 km/h with running shoes having three different types of midsole hardness (Soft, Medium, Hard). EMG signal and insole pressure were collected during the first and last one minute for each running trials. Data were analyzed using a one-way analysis of variance (ANOVA) with repeated measures. Results: Midsole hardness did not affect the consistency of stride length. For the median frequency of the EMG signal, only VL was affected by midsole hardness; that of medium was greater than other midsoles (p<.05). The loading rate of impact forces increased by midsole hardness (p<.01). Conclusion: Although soft midsole could attenuate impact forces at heel contact, it might have a negative effect on the fatigue of muscle which could decelerate the body after heel contact. Therefore, it is necessary to select the optimum hardness of midsole carefully for both reduction impact forces and muscle fatigue.

• Korean Journal of Applied Biomechanics
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• v.26 no.2
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• pp.167-174
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• 2016

Objective: The purpose of this study was to determine the interrelationship between ranges of motion of the knee and ankle joints on the sagittal plane and the attenuation magnitude of impact shock at high frequency (9~20 Hz) in the support phase during downhill running. Method: Fifteen male heel-toe runners with no history of lower extremity injuries were recruited for this study (age, $25.07{\pm}5.35years$; height, $175.4{\pm}4.6cm$; mass, $75.8{\pm}.70kg$). Two uniaxial accelerometers were mounted to the tuberosity of tibia and sacrum, respectively, to measure acceleration signals. The participants were asked to run at their preferred running speed on a treadmill set at $0^{\circ}$, $7^{\circ}$, and $15^{\circ}$ downhill. Six optical cameras were placed around the treadmill to capture the coordinates of the joints of the lower extremities. The power spectrum densities of the two acceleration signals were analyzed and used in the transfer function describing the gain and attenuation of impact shock between the tibia and the sacrum. Angles of the knee and ankle joints on the sagittal plane and their angle ranges were calculated. The Pearson correlation coefficient was used to test the relationship between two variables, the magnitude of impact shock, and the range of joint angle under three downhill conditions. The alpha level was set at .05. Results: Close correlations were observed between the knee joint range of motion and the attenuation magnitude of impact shock regardless of running slopes (p<.05), and positive correlations were found between the ranges of motion of the knee and ankle joints and the attenuation magnitude of impact shock in $15^{\circ}$ downhill running (p<.05). Conclusion: In conclusion, increased knee flexion might be required to attenuate impact shock during downhill and level running through change in stride or cadence while maintaining stability, and strong and flexible ankle joints are also needed in steeper downhill running.