Sang-Yeol Lee

Effect of the Mandibular Orthopedic Repositioning Appliance on Trunk and Upper Limb Muscle Activation during Maximum Isometric Contraction.

[Purpose] The purpose of this study was to measure the muscle activities of the trunk muscles and upper limb muscles during maximum isometric contraction when temporomandibular joint alignment was achieved with a mandibular orthopedic repositioning appliance in order provide basic data on the effects of mandibular orthopedic repositioning appliance on the entire body. [Subjects] The present study was conducted with healthy Korean adults in their 20s (males=10, females=10). [Methods] An 8 channel surface electromyography system was used to measure the muscle activities of the upper limb muscles and neck muscles of the subjects during maximum isometric contraction with and without use of a mandibular orthopedic repositioning appliance. [Results] The maximum isometric contractions of the trunk and upper limb muscles when mandibular orthopedic repositioning appliance were used were compared with those when no mandibular orthopedic repositioning appliance was used. The results showed that the sternocleidomastoid muscle, cervical and lumbar erector spinae, upper trapezius, biceps, triceps, rectus abdominis and internal oblique and external oblique muscles all showed significant increases in maximum isometric contractions with a mandibular orthopedic repositioning appliance. [Conclusion] The use of a mandibular orthopedic repositioning appliance is considered to be a method for normal adults to improve the stability of the entire body with the improvement of the stability of the TMJ. The proximal improvement in stability improves of the proximal thereby improving not only muscle strength with increased muscle activation but also stability during exercises.

Gluteus medius muscle activation on stance phase according to various vertical load.

BACKGROUND AND OBJECTIVESnThis study aims to analyze muscle activity of the lower limbs during stance phase of gait in accordance with the application of various vertical loadings.nnnMATERIAL AND METHODSnParticipants who met the criterion for this study (n=11). During their gait, various vertical loadings (0 kg, 0.5 kg, 1 kg) were provided and their muscle activities in the lower limbs during stance phase were measured. In order to accurately measure their gait, they were instructed to walk 5 gait cycles, and 3 gait cycles excluding the front and back 1 cycle were used for analysis. For the objectivity of data, measurements were made three times under each condition and average values were employed for statistic analysis.nnnRESULTSnThe intervention of applying various vertical loadings of 0 kg, 0.5 kg, 1 kg to the lower limbs during swing phase in order to compare muscle activities of the lower limbs during stance phase of gait resulted in the following outcomes. Tibialis anterior and peroneus longus muscle activities did not significantly differ with the application of various vertical loadings to the lower limbs during swing phase, while gluteus medius muscle activities significantly differed according to the levels of loadings applied. There were significant differences in muscle activities between the loading of 0 kg and the loading of 0.5 kg.nnnCONCLUSIONSnClinicians may use these results to effectively progress strengthening for gluteus medius in the rehabilitation of lower extremity injuries.

Effect of the Mandibular Orthopedic Repositioning Appliance (MORA) on Forearm Muscle Activation and Grasping Power during Pinch and Hook Grip.

[Purpose] This study verified the changes in muscle activities and grasping power during maximal isometric exercise of the forearm and masseter muscle with and without a mandibular orthopedic repositioning appliance (MORA). It also offers basic data for defining the correlation of function of hand with mouth. [Methods] EMG was used to measure masticatory muscle, flexor bundle and extensor bundle activities with or without MORA while subjects performed the hook grip and pinch grip. The measuring tool used for measuring grip strength was the same as that used for measuring pinch and hook strength. The subjects were 28 healthy young adults. [Result] Muscle activity and grasping power significantly increased when wearing the MORA. [Conclusion] The result indicates that wearing MORA can increase muscle activity and grasping power of forearm and masseter muscle. We think wearing MORA might help improve the function of the forearm because it activates the function of the masseter.

Comparison of shoulder and back muscle activation in caregivers according to various handle heights.

[Purpose] This study aims to improve the safety for caregivers and avoid musculoskeletal diseases by examining the shoulder and trunk muscle activity depending on wheelchair handle height as the caregiver provides propulsion to a wheelchair for wheelchair-bound patients. [Subjects] The participants were caregivers who met the criteria for this study (n=30). [Methods] To determine the activity of the shoulder and trunk muscles of caregivers depending on the handle height, the muscle activity was measured as a wheelchair was being pushed under three height conditions. [Results] According to the study results, the deltoid middle fiber, serratus anterior muscle, rhomboid muscle, and erector spinalis of lumbar part showed significantly low muscle activity at a height that produced an elbow joint flexion angle of 30°. Caregivers are highly likely to develop musculoskeletal disease if the handle height is excessively low. In addition, the burden on the shoulder and back muscles can be reduced at heights that lead to flexion of 30°. [Conclusions] As a caregiver pushes a wheelchair, the handle height has a close relationship with the burden on the shoulder and back muscles. If the handle height is excessively low, the caregiver is highly likely to develop musculoskeletal disease.

Peroneus Longus activity according to various angles of a ramp during cross-ramp walking and one-legged standing

BACKGROUNDnAnkle sprain are one of the most common injuries in sports and public health in general. Cross-slope may creat a risk for ankle sprain and are commonly found in both urban and rural environment.nnnOBJECTIVEnThe purpose of study was to clarify the environmental risk factor that can be easily occurred ankle sprain during walking (stance phase) and one leg standing at various ramp environment.nnnMETHODSnParticipants was measured muscle activation on peroneus longus during both conditions (walk across the ramp and one leg stand in the transverse direction) of seven different angle (0∘, 2∘, 5∘, 10∘, 15∘, 20∘, 25∘). The measured data were analyzed using one-way ANOVA to investigate the effect of muscle activation on the each condition.nnnRESULTSnAnkle sprain can be easily occurred when cross walk and one-leg stand on a ramp from higher than 10∘, and highest risk was angle of 25∘ or more. As a people with peroneus longus weakness walks a ramp, the ramp angle has a cross relationship with the sprain on the ankle.nnnCONCLUSIONSnIf people with peroneus longus weakness walk on the more than 10∘ of ramp angle, they will need a lot of attention for prevent ankle sprain.

Muscle Activity of the Gluteus Medius at Different Gait Speeds

[Purpose] The present study aimed to determine the changes in the muscle activities of the gluteus medius, latissimus dorsi, and gluteus maximus at different gait speeds, to collect basic data for the study of the gluteus medius. [Subjects and Methods] The subjects were 18 young and healthy male adults whose mean age, height, and weight were 26.4u2005years, 173.37u2005cm, and 72.5u2005kg, respectively. Electromyograpy was used to measure the maximum voluntary isometric contraction of each muscle three times and the values averaged. Then, the subjects walked on a treadmill at gait speeds of 1.5 m/s, 2.5 m/s, and 3.5 m/s and the muscle activity of each muscle was measured. [Results] The gluteus medius showed no significant difference in muscle activity among the different gait speeds. [Conclusion] For selectively strengthening the gluteus medius, to establish the external stability of the pelvis during walking, weight loading or sloped treadmills are effective interventions. However, different gait speeds exert no significant effect on the selective strengthening of the gluteus medius.

Muscle activities of the rectus abdominis and rectus femoris and their ratio during leg raises performed by healthy adults.

[Purpose] The purpose of this study was to analyze muscle activation during hip flexion in the supine position to examine the activation characteristics of the rectus abdominis and rectus femoris. [Subjects] The subjects of this study were 20 healthy adults (10 males and 10 females). [Methods] Muscle activities of the rectus abdominis and rectus femoris while raising the leg from 0°–60° were measured in 15-degree divisions and their ratio was calculated. [Results] Statistically significant differences were found in the muscle activities of the rectus femoris and rectus abdominis were found among each division of during hip flexion in the supine position. The rectus abdominis and rectus femoris ratios increased as the angle of hip flexion increased. [Conclusion] During hip flexion from 0°–45° in the supine position, femur motion caused hip flexion. At angles greater than or equal to 45° hip flexion was accompanied by pelvic motion.

The effects of wearing high heels while pressing a car accelerator pedal on lower extremity muscle activation

[Purpose] The purpose of this study was to determine the effects of wearing high heels while driving on lower extremity muscle activation. [Subjects] The subjects of this experimental study were 14 healthy women in their 20s who normally wear shoes with high heels. [Methods] The subjects were asked to place their shoes on an accelerator pedal with the heel touching the floor and then asked to press the pedal with as much pressure as possible for 3 seconds before removing their feet from the pedal. A total of 3 measurements were taken for each heel height (flat, 5u2005cm, 7u2005cm), and the heel height was randomly selected. [Results] The levels of muscle activity, indicated as the percentage of reference voluntary contraction, for gastrocnemius muscle in the flat, 5u2005cm, and 7u2005cm shoes were 180.8±61.8%, 285.4±122.3%, and 366.2±193.7%, respectively, and there were significant differences between groups. Those for the soleus muscle were 477.3±209.2%, 718.8±380.5%, and 882.4±509.9%, and there were significant differences between groups. [Conclusion] To summarize the results of this study, it was found that female drivers require greater lower extremity muscle activation when wearing high heels than when wearing low heels. Furthermore, instability and muscle fatigue of the ankle joint, which results from wearing high heels on a daily basis, could also occur while driving.

The effects of ratio in the multifidus muscle thickness according to various angle of mediolateral ramp during double stance

[Purpose] This study was conducted to predict the risks of standing on mediolateral ramps by identifying the ratios of the multifidus muscles on the two sides of the spine when standing postures are maintained on mediolateral ramps of diverse angles. [Subjects and Methods] The study was conducted with 15 healthy adult males. All subjects participated voluntarily. Mediolateral ramps at five angles (0°, 5°, 10°, 15°, and 20°) were used. Ultrasonography was used to determine the thicknesses of the multifidus muscles under individual conditions. [Results] The ratio of the left/right multifidus muscles showed statistically significant differences as the angle of the mediolateral ramp increased. Post-hoc test results showed that the use of the two multifidus muscles was asymmetric on mediolateral ramps at angles equal to or larger than 10°. [Conclusion] The asymmetric use of the multifidus muscles began on a mediolateral ramp at an angle of 10°, suggesting that subjects with instability in body control might have risk factors such as falls on mediolateral ramps with angles equal to or larger than 10°. Therefore, caregivers must be attentive and/or assist patients and older adults when they are walking on ramps at angles of approximately 10° and up in their daily lives.

The effects of exercise using PNF in patients with a supraspinatus muscle tear

[Purpose] The aim of this study was to examine the effects of proprioceptive neuromuscular facilitation techniques and simple exercise on subjective pain reduction and blood flow velocity in supraspinatus tear patients and to evaluate muscle recovery. [Subjects and Methods] The 20 subjects of this study were diagnosed with supraspinatus tears by MRI. The subjects have performed PNF techniques and Simple exercise for 12 weeks. [Results] After 12 weeks of proprioceptive neuromuscular facilitation techniques and simple exercise, the blood flow velocity, Visual Analogue Scale, and disabilities of the arm, shoulder, and hand score showed statistically significant difference. Also, the difference between the proprioceptive neuromuscular facilitation techniques and simple exercise was statistically significant. [Conclusion] In conclusion, 12 weeks of proprioceptive neuromuscular facilitation treatment and simple exercise therapy had no effect on pain reduction in patients with supraspinatus tear, but in terms of functionality, the proprioceptive neuromuscular facilitation treatment was effective.