• Journal of the Korean Society of Physical Medicine
• /
• v.4 no.1
• /
• pp.15-21
• /
• 2009

Purpose : The purpose of this study was to find the effect of ankle joint angle on knee extensor electromyographic activity following knee extension exercise. Methods : Ten male university students participated in the study. The subjects performed isometric maximal voluntary knee extensor contractions (MVC) and knee extensor EMG activity measured in with three different ankle joint angle. The EMG activity of rectus femoris(RF), vastus medialis(VM), vastus lateralis(VL) were measured using surface electromyography. Results : EMG activity of vastus lateralis following the change of ankle joint angle was shown statistically significant difference. Conclusion : Ankle plantar flexion position increase EMG activity of vastus lateralis during knee extension exercise.

• PNF and Movement
• /
• v.14 no.3
• /
• pp.177-183
• /
• 2016

Purpose: The purpose of this study was to investigate the effects of neck patterns in proprioceptive neuromuscular facilitation (PNF) for neck movement and the neck disability index (NDI) among adults with forward head posture. Methods: Thirty-nine subjects were randomly assigned into two groups. Subjects in the proprioceptive neuromuscular facilitation exercise group (PNFG, n = 20) received 20 minutes of PNF neck pattern (flexion-Rt. lateral flexion-Rt. rotation followed by extension-Lt. lateral flexion-Lt. rotation) 3 times weekly for 4 weeks. Outcomes were measured using absolute rotation angle (ARA), anterior weight bearing (AWB), range of flexion and extension motions (RFEM), and neck disability index (NDI) methods before and after the 4-week intervention period. Results: There were significant effects for the PNFG, pre- and post-intervention, in ARA, AWB, RFEM, and NDI. There were significant differences in ARA, AWB, RFEM, and NDI compared with CG. Conclusion: The results of this study suggest the PNF neck pattern could be beneficial for adults with forward head posture.

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

• Journal of Internet Computing and Services
• /
• v.21 no.6
• /
• pp.41-50
• /
• 2020

The consequences of wearing high heels can be different according to the heel height, gait speed, shoe design, heel base area, and shoe size. This study aimed to focus on the knee extension and flexion range of motion (ROM) during gait, which were challenged by wearing five different shoe heel types and two different self-selected gait speeds (comfortable and fast) as experimental conditions. Measurement standards of knee extension and flexion ROM were individually calibrated at the time of heel strike, mid-stance, toe-off, and stance phase based on the 2-minute video recordings of each gait condition. Seven healthy young women (20.7 ± 0.8 years) participated and they were asked to walk on a treadmill wearing the five given shoes at a self-selected comfortable speed (average of 2.4 ± 0.3 km/h) and a fast speed (average of 5.1 ± 0.2 km/h) in a random order. All of the shoes were in size 23.5 cm. Three of the given shoes were 9.0 cm in height, the other two were flat shoes and sneakers. A motion capture software (Kinovea 0.8.27) was used to measure the kinematic data; changes in the knee angles during each gait. During fast speed gait, the knee extension angles at heel strike and mid-stance were significantly decreased in all of the 3 high heels (p<0.05). The results revealed that fast gait speed causes knee flexion angle to significantly increase at toe-off in all five types of shoes. However, there was a significant difference in both the knee flexion and extension angles when the gait in stiletto heels and flat shoes were compared in fast gait condition (p<0.05). This showed that walking fast in high heels leads to abnormal knee ROM and thus can cause damages to the knee joints. The findings in this preliminary study can be a basis for future studies on the kinematic changes in the lower extremity during gait and for the analysis of causes and preventive methods for musculoskeletal injuries related to wearing high heels.

• PNF and Movement
• /
• v.20 no.2
• /
• pp.179-187
• /
• 2022

Purpose: The purpose of this study was to determine the asymmetrical difference between the use of leg muscles on the surgical and non-surgical sides during initial lower extremity ergometer exercise after unilateral knee arthroplasty. Methods: Twelve elderly patients diagnosed with degenerative arthritis of the knee and who underwent unilateral arthroplasty were included in this study. The leg length of each subject was taken into account when setting the application distance of the lower extremity ergometer. The same pedal resistance, strength, and speed were used for all the subjects. The total angle of use of the ergometer (360°) was analyzed by dividing it into an extension section and a flexion section. Using a surface electromyography system, the activities of the muscles of the surgical and non-surgical sides were converted into maximal voluntary isometric contraction (MVIC) and analyzed using the paired t-test. Results: When the activities of the muscles on the surgical and non-surgical sides were compared, it was found that the rectus femoris and biceps femoris had significant differences in the flexion and extension sections (p < .05), and that the tibialis anterior significantly differed in the flexion section (p < .05). There was no significant difference in the extension section of the tibialis anterior muscle, or in the flexion and extension sections of the gastrocnemius (p >.05). Conclusion: The results of this study confirm that the rectus femoris, tibialis anterior, biceps femoris, and gastrocnemius on the surgical side act in an opposite manner to those on the non-surgical side during pedaling in the same section.

• Korean Journal of Applied Biomechanics
• /
• v.16 no.3
• /
• pp.33-41
• /
• 2006

This study was to analysis three dimension angle of the upper extremity segment and trunk to putting the protector in women bowlers. For this study, the subjects selected 4 players of national and university team. All subjects putted in the same wrist support to satisfy the experiment conditions. To get three dimensions position coordination of swing motion used for 6 ProReflex MCU 240 camera produced by Qualisys. After position coordination calculation, Three dimension angle of the trunk and the upper extremity segment calculated for Matlab 6.5. the result is following; In the trunk motion, there were little differences among the subjects in a flexion and extension change. There were a lot of differences in motion change of the abduction-adduction and internal-external rotation, but the motion types translated to the adduction-abduction-adduction and from the internal rotation toward the external rotation. In the upper arm segment the Flexion and extension showed a consistent motion in the down swing and up swing phase. And the motion change of abduction-adduction and pronation-supination showed a abduction-adduction-abduction and pronation-supination change during swing phase. In the forearm segment changes, it showed a lot of differences among the subjects and a similar change with the upper arm segment. Especially, the hand segment showed a supination motion from the backswing apex to release phase, but for increasing a rotation velocity of ball, the hand segment translated toward pronation in follow throw phase.

• Journal of Digital Convergence
• /
• v.17 no.3
• /
• pp.463-471
• /
• 2019

The purpose of this study was to investigate the effect of muscle imbalance on motion of back squat. The isokinetic muscle strength of the 8 subjects was recorded for the knee flexion/extension by the cybex 770 dynamometer. Each subject performed 3 back squats with the long barbell with an intensity of 25% body weight(BW), 50%BW, 100%BW, 125%BW. During the back squat through the recorded kinematic data the subjects' maximum flexion and extension knee angle, center of mass displacement and V-COP were calculated for evaluation of the stability of the movement. For the statistical analysis independent t-test was used. Knee flexion angle and COM displacement are dominated by the reciprocal muscle ratio. V-COP factor was dominated by bilateral extension deficit. Based on the results we can know that as the intensity of the squat increased to a level control was difficult because the muscles' imbalance influenced the movement.

• Journal of Biomedical Engineering Research
• /
• v.22 no.4
• /
• pp.359-368
• /
• 2001

A new knee-ankle-foot-orthosis(KAFO) which uses an automatically-controlled electromechanical wrap spring clutch for the knee joint was developed in the present study. It was found that the output voltage from the foot switches of the developed KAFO was proportionally increased with respect to the applied load. The output voltage from the infrared sensor also decreased as the knee flexion angle increased. The knee joint system for the new KAFO weighs only 780g lighter than any other commercially available developed system. In addition, the solenoid reduces the reaction time for the automatic control of the knee joint. The static torque of the clutch was measured for three persons, and it satisfied the normal knee extension moment during the pre-swing. Three-dimensional gait analyses for three different gait patterns (normal gait, locked-knee gait, controlled-knee gait) from five normal subjects were conducted. Controlled-knee gait showed the maximum knee flexion angle of 40.56$\pm9.55^{\circ}$ and the maximum knee flexion moment of 0.20$\pm$0.07Nm/kg at similar periods in the normal gait. Our KAFO system satisfies both stability during stance phase and free knee flexion during the swing phase at the proper period during the gait cycle. Therefore, our KAFO system would be very useful in various low extremity orthotic applications.

• The Journal of Korean Physical Therapy
• /
• v.29 no.4
• /
• pp.158-163
• /
• 2017

Purpose: The purpose of this study was to investigate the relationship among pain, range of motion of the neck, neck disability index and grip strength after thoracic manipulation and cervical stabilization training in patients with chronic neck pain. Methods: In this study, twelve subjects with chronic neck pain were included. All participants had thoracic manipulation and cervical stabilization training. Intervention was conducted three times per a week, for 4 weeks. The visual analogue scale (VAS), range of motion of neck, neck disability index (NDI), as well as the grip strength before and after intervention were measured in all participants. Paired t-test was used to compare variables before and after intervention. Pearson correlation analysis was used to identify the correlations between the variables. Results: All variables after the intervention were significantly improved. There was a significant negative correlation between VAS and flexion angle of the neck (r=-0.669, p<0.05). Moreover, there was a significant positive correlation between NDI and VAS (r=0.636, p<0.05), and a significant negative correlation between NDI and flexion angle of the neck (r=-0.692, p<0.05). Conclusion: Patients with reduced pain following therapeutic intervention illustrated that there would be an improvement in the flexion angle rather than the extension angle of the neck, and that those with increased flexion angle would have less restriction of activities in daily living.

• Korean Journal of Applied Biomechanics
• /
• v.21 no.5
• /
• pp.551-560
• /
• 2011

The purpose of this study was to perform the kinematic analyses of the men's pole vault skills in IAAF World Championships Daegu 2011. Subjects were the 1st through 8th place finishers in the pole vault. The kinematic analyses were divided into four phases: two dimensional run up analysis, and three dimensional analyses for the remaining plant, swing up, and extension phases. Run-up variables consisted of run up distance, number of steps, average step length, the ratio of step length to his height, average velocity at the final 6~11 m, approach position. Three variables were analyzed during plant: pole angle, center of gravity (COG) velocity, and takeoff angle of COG. Swing up phase variables included: pole flexion angle, COG velocity (horizontal, vertical, resultant), COG trajectory and bar approach angle of COG. Compared to the 2009 World Championships in Berlin, the average vault height, run up velocity and approach position increased. However, horizontal velocity during the last two steps of the final approach decreased dramatically compared to speeds from 1990. These results reflect the change in both technique and improved physical fitness in pole vaulters. During extension, the peak height of COG averaged 0.3m higher then COG height when the pole was released. These specific results can help coaches and athletes modify training and improve performance.