• PNF and Movement
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• v.20 no.1
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• pp.115-123
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• 2022

Purpose: The aim of this study was to investigate the effects of sit-to-stand training with various foot positions combined with visual feedback on muscle onset time and balance in stroke patients. Methods: Thirty stroke patients were randomly assigned into three standing groups: one with a symmetrical foot position (SSF; n = 10), one with an asymmetrical foot position with the affected foot at the rear (SAF; n = 10), and one with visual feedback and an asymmetrical foot position (SVAF; n = 10). Sit-to-stand training with different foot positions was performed for 30 minutes a day, 5 times a week, for a total of 4 weeks. The effects on muscle onset time and balance were assessed. Results: In a comparison of the onset time of muscle contraction, the onset time of the affected side tibialis anterior and less-affected side gastrocnemius muscle and tibialis anterior was significantly shortened in the SAVF group. And onset time of the less-affected side tibialis anterior was shortened in the SAF group. There was a significant difference in the result of functional reach testing in the SVAF group. Conclusion: VRG was effective in improving muscle activity and balance in elderly women aged 65 and older. In this study, sit-to-stand training with visual feedback and asymmetrical foot position showed significant functional improvement.

• The Journal of Korean Physical Therapy
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• v.24 no.1
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• pp.7-14
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• 2012

Purpose: The purpose of this study was to investigate the effect of motor imagery on the onset time of the leg muscle and ankle injury score of patients with functional ankle instability. Methods: The study included 16 patients with ankle instability after their ankle sprains. Motor imagery was performed 3 times a week for 4 weeks. The onset time of leg muscles was measured by using the surface EMG in one leg standing position on tibialis anterior, peroneous longus and medial, lateral gastrocnemius. The pre- and post-intervention was measured by using the ankle injury score. Data was analyzed by a paired t-test. Results: The onset time was reduced but there was no significant difference (p>0.05). The order of muscle recruitment was changed. Anke injury score increased significantly after motor imagery (p<0.05). Conclusion: The results suggest that motor imagery was effective by showing delayed onset time of peroneal muscle in patients with functional ankle instability. In future studies, various conditions and disorders should all be considered for the effective analysis of motor imagery.

• Physical Therapy Korea
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• v.13 no.4
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• pp.56-63
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• 2006

This study examined the effects of the abdominal drawing-in (ADI) maneuver using a pressure biofeedback on muscle recruitment pattern of erector spinae and hip extensors and anterior pelvic tilt during hip extension in the prone position. Fourteen able-bodied volunteers, who had no medical history of lower extremity or lumbar spine disease, were recruited for this study. The muscle onset time of erector spinae, gluteus maximus, and medial hamstring and angle of anterior pelvic tilt during hip extension in prone position were measured in two conditions: ADI maneuver condition and non-ADI maneuver condition. Muscle onset time was measured using a surface electromyography (EMG). Kinematic data for angle of anterior pelvic tilt were measured using a motion analysis system. The muscle onset time and angle of anterior pelvic tilt were compared using a paired t-test. The study showed that in ADI maneuver during hip extension in prone position, the muscle onset time for the erector spinae was delayed significantly by a mean of 43.20 ms (SD 43.12), and the onset time for the gluteus maximus preceded significantly by a mean of -4.83 ms (SD 14.10) compared to non-ADI maneuver condition (p<.05). The angle of anterior pelvic tilt was significantly lower in the ADI maneuver condition by a mean of 7.03 degrees (SD 2.59) compared to non-ADI maneuver condition (15.01 degrees) (p<.05). The findings of this study indicated that prone hip extension with the ADI maneuver was an effective method to recruit the gluteus maximus earlier than erector spinae and to decrease anterior pelvic tilting.

• PNF and Movement
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• v.21 no.1
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• pp.47-52
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• 2023

Purpose: This study aims to examine the functional difference in the long and short heads of the biceps brachii by investigating the onset time of muscle contractions in the biceps brachii in the supination motion according to whether the flexor of the elbow joint is excluded. Methods: This study was conducted with 21 healthy men aged in their 20s. While performing forearm pronation at an elbow flexion angle of 90 degrees, the onset time of muscle contractions in the long and short heads of the biceps brachii was measured and compared in a posture where the humerus is placed on a table and the posture is lifted against gravity. Using an independent samples t-test, the difference in the onset time of muscle contractions in the long and short heads of the biceps brachii was analyzed. Results: The onset time of the long head was shorter if the flexor activity of the elbow joint was excluded, while that of the short head of the biceps brachii was shorter if it was not excluded. Conclusion: It is noted that the long head of the biceps brachii mainly functions as a supinator muscle, while the short head of the biceps brachii plays a role in stabilizing and maintaining flexion of the elbow joint.

• Journal of the Korean Society of Physical Medicine
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• v.10 no.2
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• pp.55-61
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• 2015

PURPOSE: The purpose of this study was to investigate recruiting order and onset time around shoulder muscle during the push-up according to the body tilting angle. METHODS: Twenty healthy young adult subjects were recruited for this study. They had no neurological and musculoskeletal disease. We used the sEMG for recording onset time of shoulder muscles. Shoulder Muscles were anterior deltoid(AD), posterior deltoid(PD), pectoralis major(PM), upper trapezius(UT). Body tilting angle were measured at 0 degree, 30 degree and 60 degree by using tilting table. Muscles contraction onset time were set by the push-up performed 3 times respectively. Mean of 3 measurements were used. And initiate onset time was decided by the Mean ${\pm}2$ SD in the threshold, more than 25ms. RESULTS: There were significant difference at 0 degree, 30 degree and 60 degree(p<.05). Muscles onset time were same order at 0 degree, 30 degree. UT occurred first of all contraction at 0 degree and 30 degree. And then contracted AD, PD, PM. But, at 60 degree, AD was the first contraction, and PM, UT, PD. CONCLUSION: Muscle recruitment order and onset time according to the body tilting was shown the difference when you do push-up. Therefore, this result, shoulder muscle recruitment pattern of according to the body tilting is different and it has to make effective shoulder exercise program.

• PNF and Movement
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• v.21 no.1
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• pp.107-117
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• 2023

Purpose: The aim of this study is to compare the immediate effects of weight-assisting methods on vastus medialis oblique (VMO) and vastus lateralis (VL) muscle activation, on the VMO/VL muscle activation ratio, and on muscle onset time in healthy subjects when ascending stairs. Methods: Healthy participants were randomly assigned to the belt group (n = 11), hand group (n = 11), and control group (n = 11). In the belt group, a belt was wrapped around the sacrum and pulled forward with both hands, moving the center of weight forward, while ascending stairs. The hand group grasped the hips with both hands and climbed stairs, assisting their weight from the rear and moving the center of weight backward, and the control group climbed the stairs without any intervention. Results: Muscle activation of the VMO decreased significantly after the intervention in the belt and hand groups, and activation of the VL muscle in both groups showed a greater decrease than that of the VMO muscle. Further, the VMO/VL muscle activation ratio increased significantly, with an improvement shown in the order of the belt group, hand group, and control group, while muscle onset time also improved in the order of the belt group, hand group, and control group. Conclusion: The belt group demonstrated the greatest effect across all dependent variables, confirming that in clinical practice, these two weight-assisting methods are more effective interventions during stair ascent for patients with knee joint instability, pain, and imbalance than no assistance.

• PNF and Movement
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• v.15 no.3
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• pp.291-302
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• 2017

Purpose: The purpose of this study was to describe the effects of neck and trunk stabilization exercise on the onset time of trunk muscle contraction in the elderly. Methods: Elderly subjects were divided into 2 groups: a neck and trunk stabilization exercise group (NTSG) and a control group (CG). The NTSG performed both neck and trunk stabilization exercises and the CG performed gait training on a treadmill, at 30 min per session, 3 times per week, over 8 weeks. Surface electromyography was employed to measure the onset times of trunk muscle contractions in the right anterior deltoid, rectus abdominis, external oblique abdominis, internal oblique abdominis, and erector spinae muscles. Results: The NTSG subjects showed earlier and statistically significant onset of contraction in trunk muscles as compared to the CG. Conclusion: The combination of neck and trunk stabilization exercises may more effectively improve the onset of muscle contractions in the elderly than other types of exercise. The present study's findings may be used as basic data for the development of exercise programs suitable to the elderly, specifically for the design of home exercise programs.

• The Journal of Korea Robotics Society
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• v.18 no.4
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• pp.496-504
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• 2023

This paper recognizes the motion intention of the wearer using a muscle stiffness sensor and proposes a control system for a wearable robot based on this. The proposed system recognizes the onset time of the motion using sensor data, determines the assistance mode, and provides assistive torque to the hip flexion/extension motion of the wearer through the generated reference trajectory according to the determined mode. The onset time of motion was detected using the CUSUM algorithm from the muscle stiffness sensor, and by comparing the detection results of the onset time with the EMG sensor and IMU, it verified its applicability as an input device for recognizing the intention of the wearer before motion. In addition, the stability of the proposed method was confirmed by comparing the results detected according to the walking speed of two subjects (1 male and 1 female). Based on these results, the assistance mode (gait assistance mode and muscle strengthening mode) was determined based on the detection results of onset time, and a reference trajectory was generated through cubic spline interpolation according to the determined assistance mode. And, the practicality of the proposed system was also confirmed by applying it to an actual wearable robot.

• Journal of Korean Physical Therapy Science
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• v.8 no.2
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• pp.1065-1071
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• 2001

Delayed onset muscle soreness is a sensation of discomfort that occurs 24 h after exercise, and it is associated with the performance of unfamiliar and high force muscle work, such as eccentric contractions. The injury to the muscle has been well described but the mechanism underlying the injury is not fully understood. Although the pathophysiological processes underlying delayed onset muscle soreness are not completely understood, many researchers have investigated various treatments in a attempt to reduce the soreness. Physical therapy is the most importance techniques to reduce delayed onset muscle soreness. The purpose of this study is to investigate the effect of a cryotherapt on DOMS. Thirty subjects were randomly assigned to experimental group : control, cryotherapy, and placebo group. Elbow flexion range, mechanical pain threshold. and subjective pain were measured 30 min before DOMS was induced and 24, 48, 72 hours after DOMS was induced. The results of this study were as follows: 1. Elbow flexion range showed significant difference each time, especially at 48 and 72 hours 2. Mechanical pain thershold and subjectively pain showed no significant difference between group.

• The Journal of Korean Physical Therapy
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• v.15 no.4
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• pp.488-497
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• 2003

The purpose of this study was to compare the muscle onset time of sternocleidomastoid (SCM) and rectus abdominalis (RA) muscle activity during head lift in supine position between cerebral palsy and healthy children. Ten cerebral palsy children and 10 age, sex-matched healthy children were recruited for this study. Muscle activity of the SCM and RA were collected by surface electromyography (MP100SWS). Results demonstrated that the muscle onset time order was not significantly different between cerebral palsy children and healthy children. However, the DMHT and ST between SCM and RA during head lift in supine position were significantly shorter in healthy children than in cerebral palsy children. Further studies are needed to clarify the mechanism of differences in muscle activation patterns during head lift in supine position in cerebral palsy children compared with healthy children.