• Journal of the Korean Society for Precision Engineering
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• v.24 no.1 s.190
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• pp.85-92
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• 2007

In the present study, three-dimensional motion analyses were performed to determine biomechanics of the lower extremity in unexpected missing foot steps for ten healthy young volunteers. In unexpected missing foot steps, the whole plantar surface of the foot or the heel contacted to the ground. A rapid ankle dorsiflexion was found right after missing foot steps and an increased plantarflexion moment was noted during loading response. After the unexpected situation, the breaking force increased rapidly. At this time, both tibialis anterior and soleus were simultaneously activated. Moreover, the range of motion at ankle, knee and hip significantly decreased during stance. In pre-swing, rectus femoris and biceps femoris prevented the collapse of the lower limbs. During late stance, propulsive forces decreased and thus, both plantarflexion moment and power generation were significantly reduced. On the opposite side, hip extension and pelvic upward motion during terminal swing were significant. Due to the shortened pre-swing, the energy generation at the ankle to push sufficiently off the ground was greatly reduced. This preliminary study would be helpful to understand the biomechanics of unexpected dynamic perturbations and valuable to prevent frequent falling of the elderly and patients with gait disorders.

• The Journal of Korean Physical Therapy
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• v.34 no.6
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• pp.321-325
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• 2022

Purpose: Temporomandibular disorder (TMD) is a condition defined as pain and dysfunction of temporomandibular joints and masticatory muscles. Abnormal interconnections between temporomandibular muscles and cervical spine structures can cause the changes of postural alignment and balance ability. The aim of this study was to investigate changes in static balance ability in subjects with painrelated TMD. Methods: This study conducted on 25 subjects with TMD and 25 control subjects with no TMD. Pressure pain thresholds (PPTs) of the masseter and temporalis muscles were measured using a pressure algometer. Static balance ability was assessed during one leg standing using an Inertial Measurement Unit (IMU) sensor. During balance task, the IMU sensors measured motion and transfer movement data for center of mass (COM) motion, ankle sway and hip sway. Results: PPTs of masseter and temporalis muscles were significantly lower in the TMD group than in the control group (p<0.05). One leg standing, hip sway, and COM sway results were significantly greater in the TMD group (p<0.05), but ankle sways were not different between group. Conclusion: We suggest pain-related TMD is positively related to reduced PPTs of masticatory muscles and to static balance ability. These results should be considered together with global body posture when evaluating or treating pain-related TMD.

• Korean Journal of Applied Biomechanics
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• v.27 no.2
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• pp.133-140
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• 2017

Objective: The purpose of this study was to determine the relationship between center of pressure (CoP) and local stability of the lower joints, which was calculated based on approximate entropy (ApEn) during walking in elderly women. Method: Eighteen elderly women were recruited (age: $66.4{\pm}1.2yrs$; mass: $55.4{\pm}8.3kg$; height: $1.56{\pm}0.04m$) for this study. Before collecting data, reflective marker triads composed of 3 non-collinear spheres were attached to the lateral surface of the thigh and shank near the mid-segment to measure motion of the thigh and shank segments. To measure foot motion, reflective markers were placed on the shoe at the heel, head of the fifth metatarsal, and lateral malleolus, and were also placed on the right anterior-superior iliac spine, left anterior-superior iliac spine, and sacrum to observe pelvic motion. During treadmill walking, kinematic data were recorded using 6 infrared cameras (Oqus 300, Qualisys, Sweden) with a 100 Hz sampling frequency and kinetic data were collected from a treadmill (Instrumented Treadmill, Bertec, USA) for 20 strides. From kinematic data, 3D angles of the lower extremity's joint were calculated using Cardan technique and then ApEn were computed for their angles to evaluate local stability. Range of CoP was determined from the kinetic data. Pearson product-moment and Spearman rank correlation coefficient were applied to find relationship between CoP and ApEn. The level of significance was determined at p<.05. Results: There was a negative linear correlation between CoP and ApEn of hip joint adduction-abduction motion (p<.05), but ApEn of other joint motion did not affect the CoP. Conclusion: It was conjectured that ApEn, local stability index, for adduction/abduction of the hip joint during walking could be useful as a fall predictor.

• Journal of Korean Physical Therapy Science
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• v.8 no.2
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• pp.961-965
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• 2001

The aim of this study is to present the basic reference data of age and specipic gait parameters for Korean Adult. The basic gait parameters were extracted from 20 Adult, 10 men and 10 women, 21 to 24 years of age using VICON 512 Motion Analyzer. The temporal gait parameters and kinematic parameters of Korean Adult similar to other western reference data. The results were as follows: 1) The mean Cadence of the male to the female were 113.5 steps/min to 117.6 steps/min. 2) The mean Walking Speed of the male to the female were 1.30 m/s, to 1.27 m/s. 3) The mean Stride Length of the male to the female were 1.35 m, to 1.30 m. 4) The mean maximal angles of pint on the pelvic tilt motion for different male to the female were $9.80^{\circ}$ to $7.75^{\circ}$. (p<0.05) 5) The mean maximal angles of pint on the hip flexion motion for different male to the female were $22.62^{\circ}$ to $27.65^{\circ}$. (p<0.05) 6) The mean maximal angles of pint on the knee flexion motion for different male to the female were $55.78^{\circ}$ to $55.49^{\circ}$. (p>0.05) 7) The mean maximal angles of pint on the ankle dorsiflexion motion for different male to the female were $12.47^{\circ}$ to $13.39^{\circ}$. (p>0.05).

• The Journal of Korean Physical Therapy
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• v.14 no.3
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• pp.129-135
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• 2002

The aim of this study is to present the basic reference data of age and specipic gait parameters for Hemiplegia Patients. The basic gait parameters were extracted from 30 Adult Hemiplegia Patients and 30 normal adult, 50 to 60 years of age using VICON 512 Motion Analyzer. The results were as follows; 1) The mean Cadence of the adult to the hemiplegia were $108.50\pm11.67$ steps/min, to $77.57\pm22.71$ steps/min. 2) The mean Walking Speed of the adult to the hemiplegia were $1.07\pm0.18m/s$, to $0.44\pm0.14m/s.$. 3) The mean Stride Length of the adult to the hemiplegia were $1.17\pm0.12m$, to $0.69\pm0.21m.$ 4) The mean maximal angles of joint on the pelvic tilt for different adult or hemiplegia Were $7.60\pm3.91.,\;to\;9.63\pm4.94.\;(P<0.05)$ 5) The mean maximal angles of joint on the hip flexion motion for different adult or hemiplegia were $29.53\pm5.03.,\;to\;25.30\pm9.94.\;(p<0.05)$ 6) The mean maximal angles of joint on the knee flexion motion for different adult or hemiplegia were $56.36\pm5.81.,\;to\; 41.64\pm17.21.(P<0.05)$ 7) The mean maximal angles of joint on the ankle dorsiflexion motion for different adult or hemiplegia were $16.65\pm2.72.,\;to\;16.53\pm7.45$(P>0.05) 8) The mean maximal angles of joint on the ankle plantarflexion motion for different adult or hemiplegia were $7.11\pm5.42.,\;to\;2.81\pm6.14.$(p<0.05)

• Journal of Korean Physical Therapy Science
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• v.9 no.1
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• pp.129-134
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• 2002

The aim of this study is to present the basic reference data of age and specipic gait parameters for Hemiplegia Patients. The basic gait parameters were extracted from 10 Adult Hemiplegia Patients, 5 left Hemiplegia Patients and 5 right Hemiplegia Patients, 50 to 60 years of age using VICON 512 Motion Analyzer. The results were as follows; 1) The mean Cadence of the left to the right hemiplegia were $75.81{\pm}28.10\;steps/min$, to $68.47{\pm}9.93\;steps/min$. 2) The mean Walking Speed of the left to the right hemiplegia were $0.45{\pm}0.28\;m/s$, to $0.44{\pm}0.14\;m/s$. 3) The mean Stride Length of the left to the right hemiplegia were $0.66{\pm}0.31\;m$, to $0.76{\pm}0.17m$. 4) The mean. maximal angles of joint on the pelvic tilt for different right or left hemiplegia were $8.59{\pm}5.13^{\circ}$, to $11.85{\pm}5.23^{\circ}$.(p>0.05) 5) The mean maximal angles of joint on the hip flexion motion for different right or left hemiplegia were $23.98{\pm}8.45^{\circ}$, to $25.81{\pm}5.39^{\circ}$.(p>0.05) 6) The mean maximal angles of joint on the knee flexion motion for different right or left hemiplegia were $29.52{\pm}10.24^{\circ}$, to $28.38{\pm}14.48^{\circ}$.(p>0.05) 7) The mean maximal angles of joint on the ankle dorsiflexion motion for different right or left hemiplegia were $14.68{\pm}5.03^{\circ}$, to $9.90{\pm}7.26^{\circ}$.(p>0.05) 8) The mean maximal angles of joint on the ankle plantarflexion motion for different right or left hemiplegia were $2.10{\pm}5.17^{\circ}$, to $8.63{\pm}5.81^{\circ}$.(p>0.05)

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.28 no.2
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• pp.45-55
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• 2022

Background: This study compared the effects of trunk stabilization exercise and hip joint exercises on the range of motion of the lumbar spine, pain severity, and severity of disability in patients with chronic lower back pain. Methods: A total of 30 participants were enrolled and divided into group 1 (n=10), group 2 (n=10), and group 3 (n=10) were performed by each group thrice a week for a total of 8 weeks. Group 1 performed warm-up exercise (15 min), trunk stabilization exercise (25 min), finish-up exercise (15mins). Group 2 performed warm-up exercise (15 min), hip exercise (25 mins, finish-up exercise (15mins). Group 3 warm-up exercise (15 min), trunk stabilization and hip exercise (25 min), Finish-up exercise (15 min). Participants were assessed for the range of motion of the lumbar spine, pain severity (visual analog scale score; VAS), and severity of disability (Oswestry disability index score; ODI) before and after the interventions. Results: All three groups showed a significant increase in the range of motion of the lumbar spine, but there was no significant difference among the groups. Moreover, the severity of pain and ODI were significantly decreased in all groups; however, the intergroup differences were non-significant. Conclusion: The results from this study confirmed the effectiveness of trunk stabilization and hip joint exercise in improving the lumbar range of motion, pain severity, and chronic lower back pain in patients. Thus, trunk and pelvic stabilization exercises and hip joint exercise can be used as clinical practices to treat and prevent chronic lower back pain.

• Korean Journal of Applied Biomechanics
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• v.22 no.1
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• pp.65-73
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• 2012

The purpose of this study was to identify the saddle to pedal length contributing to successful performance in kayak using a kayak ergometer. Ten male elite kayak players participated in this study. players were tested on the kayak ergometer which was varied saddle to pedal length by the knee flexion angle(90deg; 120deg; 150deg) to measure stroke frequency, paddling amplitude, joint angle, RoM and angular velocity, foot pressure and force, iEMG using the 3D motion system, foot pressure system and EMG wireless system. At a results, rowing at 120deg on knee flexion angle showed higher stroke frequency and paddling amplitude than other knee flexion angles. RoM at upper extremity showed not significant difference between knee flexion angles. But there were significant differences in thorax and pelvis rotation RoM, knee flexion-extension RoM in each condition. In addition, foot pressure, force and iEMG were significantly different in knee flexion angles. Study showed that changed of saddle to pedal length affected rowing performance kinds of stroke frequency, paddling amplitude. The most important thing, increased range of motion in pelvic and thorax has occurred by force that generated foot-bar to seat. Not only that, but it seems to be attributed to a technical adaptation developed to maximum rowing performance.

• Korean Journal of Applied Biomechanics
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• v.24 no.1
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• pp.1-9
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• 2014

The purpose of this study was to investigate the muscle mechanical properties of the pelvic axial pre-rotational movement for the Jireugi in the Taekwondo Juchumseogi stance. Eleven elite Taekwondo Poomsae athletes participated. Each participant performed 5 right hand Jireugi in Juchumseogi stance as fast and strong as possible while their motion was recorded by a 3D motion analysis system and the ground reaction forces by two force plates. The power and work of the muscular group surrounding the waist were analyzed to verify the effect of the stretch-shortening cycle (SSC) theory. The cause of the greater power seems to be the application of the SSC by the muscles surrounding the waist during the preparation phase of the pre-rotation group. For the none pre-rotation group, they only used the concentric contraction of the muscles surrounding the waist. Because the pre-rotation group used the SSC theory, they had the effect of shortening of the range of movement, creating a fast and more powerful rotation, thus anticipating the increase the magnitude of impact.

• Journal of Korean Physical Therapy Science
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• v.15 no.3
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• pp.55-63
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• 2008

Background : The Purposes of this study were to understand difference between free walking and obstacle over walking through the naked eye and motion analysis device, and to review merits of obstacle walking training as item of functional assessment in clinical situations. Methods : All participants were male and performed 3 types of walking methods: free walking, obstacle over walking with low block(height=10cm, width=8cm), and obstacle over walking with high block(height=20cm, width=8cm). All walking were performed 3 trials respectively. Results : In the naked eye, initial contact with toes occurred more than heel strike in obstacle over walking, and the flexion angle of hip and knee were increased in obstacle over walking. On interpretations though motion analysis device, cadence, gait speed and weight accept were significant statistically(p<.05). Cadence and gait speed were decreased, and weight accept duration was increased in obstacle over walking. Rotation among three pelvic motions was significant statistically(p<.05), flexion among three hip motions was significant statistically(p<.05) and flexion among three ankle motions was significant statistically(p<.05). Rotation and flexion among three ankle motions was significant statistically(p<.05). Conclusion : Both the naked eye and interpretations of the device presented many difference between free walking and obstacle over walking. In overcrossing obstacles, many participants appeared walking strategy by perform initial contact with toes. Knee flexion was most significant statistically(p<.05) in obstacle over walking with 20cm block.