• 한국체육학회지인문사회과학편
• /
• v.57 no.3
• /
• pp.345-356
• /
• 2018

Objective: The purpose of this study was to investigate the local stability of the lower extremity joints and muscle activation patterns of the lower extremity during walking between falling and non-falling group in the elderly women. Method: Forty women, heel strikers, were recruited for this study. Twenty subjects (age:72.55±5.42yrs; height:154.40±4.26cm; mass:57.40±6.21kg; preference walking speed:0.52±0.17m/s; fall frequency=1.70±1.26 times) had a history falls(fall group) within two years and Twenty subjects (71.90±2..90yrs; height:155.28±4.73cm; mass:56.70±5.241kg; preference walking speed: 0.56±0.13m/s) had no history falls(non-fall group). While they were walking on a instrumented treadmill at their preference speed for a long while, kinematic and EMG signals were obtained using 3-D motion capture and wireless EMG electrodes, respectively. Local stability of the ankle and knee joint were calculated using Lyapunov Exponent (LyE) and muscles activation and their co-contraction index were also quantified. Hypotheses were tested using one-way ANOVA and Mann-Whitey. Spearman rank was also used to determine the correlation coefficients between variables. Level of significance was set at p<.05. Results: Local stability in the knee joint adduction-abduction was significantly greater in fall group than non-fall group(p<.05). Activation of anterior tibials that acts on the foot segment dorsal flexion was greater in non-fall group than fall group(p<.05). CI between gastrocnemius and anterior tibials was found to be significantly different between two groups(p<.05). In addition, there was significant correlation between CI of the leg and LyE of the ankle joint flexion-extention in the fall group(p<.05). Conclusion: In conclusion, muscles that act on the knee joint abduction-adduction as well as gastrocnemius and anterior tibials that act on the ankle joint flexion-extention need to be strengthened to prevent from potential fall during walking.

• Journal of the Korea Convergence Society
• /
• v.10 no.9
• /
• pp.63-68
• /
• 2019

The purpose of this study was to investigate the effect of hyper-extended knee and asymmetric standing posture on knee joint position and lower extremity muscle activity. Thirty-three voluntary participants participated and included sixty legs in the study. The sixty legs were divided into two groups: hyper-extended knee and normal group. The muscle activity and knee extension angle were measured. In the asymmetric standing posture, the knee joint extension angle and the muscle activity of the gastrocnemius were statistically significant between the normal group and the hyper-extended knee group. Based on the results, we confirmed that the asymmetric standing posture increases the hyper-extended knee. Therefore, it will contribute to the establishment of therapeutic guide for the subjects with hyper-extended knee to maintain the symmetrical standing posture, and future studies need to be conducted including the effects of the hip joint and ankle joints.

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

• Korean Journal of Applied Biomechanics
• /
• v.28 no.3
• /
• pp.159-164
• /
• 2018

Objective: The aims of this study were to determine the impact peak force and kinematic variables in running speed and investigate the relationship between them. Method: Thirty-nine male heel strike runners ($mean\;age=21.7{\pm}1.6y$, $mean\;mass=72.5{\pm}8.7kg$, $mean\;height=176.6{\pm}6.1cm$) were recruited in this investigation. The impact peak forces during treadmill running were assessed, and the kinematic variables were computed using three-dimensional data collected using eight infrared cameras (Oqus 300, Qualisys, Sweden). One-way analysis of variance ANOVAwas used to investigate the influence of the running speed on the parameters, and Pearson's partial correlation was used to investigate the relationship between the impact peak force and kinematic variables. Results: The running speed affected the impact peak force, stride length, stride frequency, and kinematic variables during the stride phase and the foot angle at heel contact; however, it did not affect the ankle and knee joint angles in the sagittal plane at heel contact. No significant correlation was noted between the impact peak force and kinematic variables in constantrunning speed. Conclusion: Increasing ankle and knee joint angles at heel contact may not be related to the mechanism behind reducing the impact peak force during treadmill running at constant speed.

• The Journal of Korean Physical Therapy
• /
• v.34 no.4
• /
• pp.168-174
• /
• 2022

Purpose: The purpose of this study was to analyze the correlation between balance control ability and leg circumference, proprioception, range of motion (ROM), and muscle strength in young adults. Methods: The subjects of this study were 30 university students who were enrolled in D university in Gyeongbuk province. We measured the dynamic balance and static balance using the Biorescue. The muscular strengths of the hip, knee, and ankle joints were measured using a muscle contraction dynamometer. The ROM and proprioception were measured using an inclinometer. Pearson correlation analysis was used to test the correlations between balance control ability and variables. Results: Sway length was significantly correlated with knee and hip joint muscle strength, ROM, and proprioception of hip and ankle joints (p<0.05). Sway speed was significantly correlated with ROM and proprioception in hip joints (p<0.05). Limit of stability was significantly correlated with muscle strength and ROM in ankle joints, and proprioception in hip, knee, and ankle joints (p<0.05). Conclusion: The sway length was most related to hip extension and ankle joint plantar flexion in the range of motion and ankle joint plantar flexion in proprioception. Overall, balance training for young adults will be of effective help if the treatment focuses on the knee and hip joints, range of motion and the ankle and hip joints' proprioception.

• Korean Journal of Applied Biomechanics
• /
• v.29 no.4
• /
• pp.255-261
• /
• 2019

Objective: The purpose of this study was to investigate differences of shock attenuation strategies between double-leg and single-leg landing on sagittal plane using statistical parametric mapping. Method: Nine healthy female professional soccer players (age: 24.0±2.5 yrs, height: 164.9±3.3 cm, weight: 55.7±6.6 kg, career: 11.2±1.4 yrs) were participated in this study. The subjects performed 10 times of double-leg and single-leg landing from the box of 30 cm height onto force plates respectively. The ground reaction force, angle, moment, angular velocity, and power of the ankle, knee, and hip joint on sagittal plane was calculated from initial contact to maximum knee flexion during landing phase. Statistical parametric mapping was used to compare the biomechanical variables of double-leg and single-leg landing of the dominant leg throughout the landing phase. Each mean difference of variables was analyzed using a paired t-test and alpha level was set to 0.05. Results: For the biomechanical variables, significantly increased vertical ground reaction force, plantarflexion moment of the ankle joint, negative ankle joint power and extension moment of the hip joint were found in single-leg landing compared to double-leg landing (p<.05). In addition, the flexion angle and angular velocity of the knee and hip joint in double-leg landing were observed significantly greater than single-leg landing, respectively (p<.05). Conclusion: These findings suggested that negative joint power and plantarflexion moment of the ankle joint can contribute to shock absorption during single-leg landing and may be the factors for preventing the musculoskeletal injuries of the lower extremity by an external force.

• Korean Journal of Applied Biomechanics
• /
• v.18 no.1
• /
• pp.179-190
• /
• 2008

The purpose of this study was to identify whether or not in one-leg vertical jump of each limb asymmetry between both sides is present and to identify how the discrepancies between both limbs affect two-leg jumping performance, that is bilateral deficit. We had 13 healthy subjects perform one-leg jump for both sides and two-leg countermovement jump. The result of biomechanical analysis showed significantly difference of 4-7% in net impulses and work output between dominant and non-dominant one-leg jump and bilateral deficit of 24% when sum of those of each one-leg jump was compared with two-leg jump. But asymmetry in lower extremity was not significantly correlated with bilateral deficit. Two-leg jump could be characterized by relatively short propulsion time, long propulsion distance and high joint angular velocity compared with one-leg jump. These factors seemed to contribute to decreased performance in two-leg jump. Furthermore bilateral deficit was attributed to lower activities of extensor muscles found in two-leg jump.

• Journal of the Korean Burn Society
• /
• v.23 no.2
• /
• pp.31-36
• /
• 2020

Purpose: Scar contracture influence the outcome of burn patients significantly. This study aims to investigate the feasibility of robot-assisted training for the lower extremity rehabilitation of burn patients. Methods: This pilot study was conducted on 7 burn patients for 8 weeks between January 2019 and November 2019. Two of 7 patients withdrew from this study because one had skin abrasion on the legs which thigh fastening devices were applied on and the other was not participate in the assessment at 4 weeks after training. Final 5 patients received gait training with SUBAR^® and numeric rating scale (NRS), 6-minutes walking test, and range of motion in flexion and extension of knee and ankle joint were evaluated before training, 4 weeks and 12 weeks after training. Results: The subjects had a mean age of 51.8±98 years, mean total burn surface area of 30.8±13.7%, mean duration from injury to 1^st assessment of 102.8±39.3 days. Anyone of 5 patients did not have musculoskeletal or cardiovascular side effects such as increased or decreased blood pressure or dizziness. The significant improvement in NRS, gait speed, and range of motion in knee extension and ankle plantarflexion after robotic training (all P<0.05). Conclusion: Robot-assisted training could be feasible for the rehabilitation of burn patients and it could improve muscle strength and range of motion in lower extremities, and gait function.

• Journal of Korean Physical Therapy Science
• /
• v.4 no.1
• /
• pp.229-242
• /
• 1997

This study was performed to figure out effects of stroke rehabilitation on education using isokinetic exercise on physical function recovery. It is considered isokinetic exercise will playa primary role in muscle strength, ROM of joint, and body balance recovery for stroke rehabilitation and so far can be used as a basic references to increase the health of all people. The study consisted of 42 stroke patient(21 training group, 21 control group) diagnosed as cerebral hemorrhage from Oriental Rehabilitation Department of Kyung Hee University. Upper extremity and lower extremity exercise was performed in the training group using isokinetic ergometer. The recovery of physical function(muscle strength, ROM of joint, body balance) data between the two groups were compared and ana lysed by paired t-test are as followed. 1. Muscle testing record showed increased in the strength of elbow flexion, knee flexion, knee extension, ankle extension of the training group com paired to control group(p < .05). In the measurement of ROM, however other parts of the body motion showed no significant changes, only shoulder extension of the training group was increased(p < .05). 2. Body balance increase was highly significant in all training group compaired to control group(p<001). Based on these findings, stroke rehabilitation education with isokinetic ergometer showed available effects on recovery of physical function rehabilitation program with isokinetic exercise will play a primary role in the recovery of physical function of stroke or brain injury patients as well as to promote the health of all people.

• Korean Journal of Applied Biomechanics
• /
• v.18 no.1
• /
• pp.97-105
• /
• 2008

The kinematic variables for swimming and fin-swimming start motions were analyzed and compared using 3-dimensional cinematography. For the swimming start, the arm segment moved towards the upper rear and trunk towards the upper front followed by a descent towards the lower front, while the fin-swimming start motion showed movement towards the lower front for all segments. The total body center of gravity for the swimming start showed horizontal movement far to the front followed by a rapid descent while the fin-swimming start showed close movement towards the lower front in a short period of time. Upon entering the water, the center of gravity for swimming showed high vertical velocities while fin swimming had high horizontal velocities. For both swimming and fin swimming, the upper extremity velocity had more influence on the total center of gravity velocity than the lower extremities. Flexion of the hip joint was observed before the jump for the fin swimming start while the swimming start showed two flexions in mid-air succeeding the jump. The flexion and extension movements at the knee joint during the fin-swimming start motion were shown to be larger and more rapid than those of fin-swimming.