Background: For instance, forward head posture (FHP), characterized by the forward movement of the head relative to the spine, places significant stress on the neck and upper back muscles, disrupting the biomechanical balance of the body. Objects: The objective of this study was to probe the biomechanical effects of FHP on musculoskeletal health through a relative analysis of 26 adults diagnosed with FHP and 26 healthy controls. Methods: In this study, we evaluated the biomechanical impacts of FHP. Participants adjusted their head positions and underwent muscle strength tests, including electromyography assessments and the Biering-Sørensen test for trunk muscle endurance. Data analysis was conducted using Kinovea (Kinovea) and IBM SPSS software ver. 26.0 (IBM Co.) to compare muscle activities between groups with normal and FHPs. Results: The study shows that individuals with FHP have significantly lower muscle activity, endurance, and spinal extension in the erector spinae compared to those without, highlighting the detrimental effects of FHP on these muscles. Conclusion: This study underscores the impact of FHP on erector spinae function and emphasizes the need for posture correction to enhance musculoskeletal health and guide future research on intervention strategies.

Background: Forward head posture affects many individuals and can cause pain and dysfunction in the muscles and joints of the head, neck, and shoulders. Objectives: This study aimed to assess muscle activity and onset time of cervical and scapular muscles during 180° shoulder flexion and abduction in individuals with normal head posture (NHP) and in those with forward head posture (FHP), both before and after correction. Design: Cross-sectional study. Methods: Thirty-six individuals were divided into FHP and NHP groups. Muscle activity and muscle contraction onset time of the splenius capitis, sternocleidomastoid, upper middle and lower trapezius, and serratus anterior muscles were measured during shoulder flexion and abduction using wireless surface electromyography. Results: The FHP group exhibited increased muscle activity compared to the NHP group (P<.05), notably in the sternocleidomastoid and middle trapezius muscles, more so during shoulder abduction than flexion (P<.05). Regarding muscle contraction onset time, sternocleidomastoid onset was fastest during shoulder abduction in the FHP group (P<.05), while serratus anterior onset was slowest during both shoulder abduction and flexion (P<.05). Conclusion: These findings highlight distinct muscle activity and muscle contraction onset time patterns based on head posture and shoulder movement. Selective muscle activation strategies may help reduce heightened sternocleidomastoid and trapezius activity and enhance serratus anterior engagement in individuals with FHP.

Background: Individuals with pes planus tend to overuse the extrinsic foot muscles, such as the tibialis anterior (TA) and peroneus longus (PL), to compensate for the weakened intrinsic foot muscles, such as the abductor hallucis (AbdH). Furthermore, differences in weight-bearing can affect the activity of muscles in both the intrinsic and extrinsic foot muscles. To date, no study has compared the effects of the short foot exercise (SFE) and toe spread-out exercise (TSO) on intrinsic and extrinsic foot muscle activity and the corresponding ratios in different weight-bearing positions. Objects: To compare the effects of the SFE and TSO on AbdH, TA, and PL activity and the AbdH/TA and AbdH/PL activity ratios in the sitting and standing positions in individuals with pes planus. Methods: Twenty participants with pes planus were recruited. Surface electromyography was used to assess the amplitudes of AbdH, TA, and PL activity. Participants performed both exercises while adopting both the sitting and standing positions. Results: No significant interaction between exercise and position was found regarding the activity of any muscle or ratio of the activity, except for PL activity. We observed a significant increase in AbdH activity during the TSO compared to the SFE, and no significant difference in TA and PL activity between the two exercises. AbdH, TA, and PL activity were significantly higher in the standing position than in the sitting position. Furthermore, the AbdH/PL activity ratio significantly increased in the sitting position, although there was a significant increase in AbdH activity in the standing position. Conclusion: In individuals with pes planus, we recommend performing the TSO in the sitting position, which may increase the activity of the AbdH while concurrently decreasing the activity of the TA and PL, thus strengthening the AbdH.

Background: The serratus anterior (SA) is a muscle that performs protraction of the scapulothoracic joint and plays a role in stabilizing the scapula. Imbalances or weaknesses in SA activation are associated with a variety of shoulder dysfunctions, making selective SA strengthening important for rehabilitation. Objects: We aimed to compare the muscle activation of the pectoralis major (PM), SA, external oblique (EO), and internal oblique (IO) during the push-up plus (PUP) exercise with isometric hip adduction (HA) and abdominal drawing-in maneuver (ADIM). Methods: Nineteen healthy male participants performed three PUP exercises: standard PUP, PUP with ADIM, and PUP with HA. Surface electromyography was used to measure and analyze the muscle activity for PM, SA, EO, and IO. Results: PUP with HA showed the lowest PM activity and highest SA activity, and no significant difference was observed between PUP and PUP with ADIM. PUP with ADIM showed significantly the highest EO and IO activity, followed by PUP with HA and PUP. Additionally, PUP with HA showed the lowest PM/SA ratio, and no significant difference was noted between PUP and PUP with ADIM. Conclusion: PUP with HA was able to show high SA muscle activity while reducing PM muscle activity. In addition, PUP with HA can lead to higher EO and IO muscle activity than standard PUP. This exercise could be used as a practical exercise method to selectively strengthen SA and improve scapular muscle stability during early shoulder rehabilitation.

Background: Interventions for acute low back pain include exercise therapy such as stretching, aerobic exercise, and sling exercise. Another treatment method for back pain is soft tissue release. Soft tissue release is a relaxation method that improves balance while allowing tension tissues to relax as much as possible. Objectives: To investigated the effect of acute low back pain on the massage ball exercise. Design: Randomized controlled trial. Methods: The twenty-eight subjects were randomly allocated to the Massage ball exercise with TENS group (MBETG, n=14) and the transcutaneous electrical nerve stimulation group (TG, n=14). For MBETG, massage ball exercise (BALLance Dr. Tanja Kühne method) was applied for 25 minutes followed by TENS for 15 minutes. The TG group applied TENS for 40 minutes. Each group conducted the intervention three sessions. The results were analyzed by measuring the numeric pain rating scale (NPRS), surface electromyography (%MVIC), and Oswestry disability index (ODI) before and after the intervention in each group. Results: Significant reduction was observed for NPRS and ODI in the MBETG (P<.05). And Significant higher was observed for %MVIC of the Erector spinae in the MBETG (P<.05). The NPRS and ODI in the MBETG were decreaed than the TG (P<.05). Conclusion: Massage ball exercise to patients with acute back pain will be effective in reducing pain, increasing muscle activity, and improving functional disability.

Background: This study investigated quadriceps femoris muscle activity by comparing concentric and eccentric contractions with self-selective squat speed. Objectives: Study participants agreed in advance and included 30 male college students in their 20s without musculoskeletal system disease. Design: A randomized controlled trial. Methods: Participants who participated in this study agreed in advance and recruited 30 male college students in their 20s who had no disease with musculoskeletal system to conduct this study. When squatting at a self-selected speed, the subjects were evaluated using one-way ANOVA to compare concentric and eccentric contraction muscle activity. Results: There were significant differences between the rectus femoris, vastus medialis, and vastus lateralis regarding concentric contractions.contractions. There was a significant difference in vastus medialis but no significant difference between rectus femoris and vastus lateralis for eccentric contractions. Conclusion: During concentric contraction, all muscles and eccentric contractions indicated significant improvement in the vastus medialis. Therefore, to minimize knee joint injury and maximize efficient muscle activity, self-selected slow and moderate speeds based on self-selection speed when performing the sit-down motion during a squat and moderate speed with fast motions when performing the standing motion should be considered as high muscle activities.

Background: The Nordic hamstring exercise is effective as a representative exercise for strengthening eccentric contraction that can activate the hamstring at high levels, improve eccentric contraction strength and ability, and significantly reduce injury rates. Objectives: To investigated a comparison with the lunge exercise to determine the effect of the Nordic hamstring exercise on muscle activity and balance ability in a sample of adult amateurs and football players. Design: Randomized controlled trials. Methods: The subjects of the study were stratified samples of 28 professional and amateur football players and two groups (Nordic hamstring group and lunge group) of 14 people each were studied. Surface electromyography using, was performed to measure the hamstring muscle activity, and the good morning exercise was selected as the measurement exercise. For balance ability, the surface area ellipse and length were measured with BioRescue, while for static balance, the posture of closing the eyes and single-limb standing was measured, and for dynamic balance the one-legged squat was measured. Results: The %MVIC of the semitendinosus and the biceps femoris improved in the Nordic hamstring exercise group and showed statistically significant increase (P<.05). The static and dynamic balance improved in the Nordic hamstring exercise group and showed statistically significant decrease (P<.05). Conclusion: The Nordic hamstring exercise can be useful as an exercise to improve the hamstring muscle activity and balance ability of professional and amateur football players.

Background: Choosing to perform squats on an unstable surface potentially offers advantages surpassing those of their stable counterpart. Objectives: The purpose of this study was to compare muscle activation during squats on stable and unstable surfaces and investigate the relationship among thigh muscles. Design: Observational study. Methods: Nineteen adults participated in this study. The stable surface consisted of a flat floor. The unstable surface involved the use of an air cushion. An air cushion was positioned beneath each foot of the study participants. Surface electromyography was employed to measure muscle activation. %MVC was calculated by measuring muscle activation during squat execution and manual muscle testing. Results: The comparison of muscle activation during squats between stable and unstable surfaces revealed a significant difference in the rectus femoris and biceps femoris (P<.05). On stable surfaces, positive correlations were observed in the rectus femoris, vastus lateralis, and vastus medialis (P<.05). On unstable surfaces, positive correlations were found between the rectus femoris and vastus medialis (P<.05). Conclusion: This study observed an increase in muscle activation of the rectus femoris and biceps femoris during squats on an unstable support surface compared to a stable support surface.

Background: In modern society, the use of computers accounts for a large proportion of our daily lives. Although substantial research is being actively conducted on musculoskeletal diseases resulting from computer use, there has been a recent surge in interest in improving the working environment for prevention. Objects: This study aimed to examine the effects of posture correction feedback (PCF) on changes in neck posture and muscle activation during computer typing. Methods: The participants performed a computer typing task in two sessions, each lasting 16 minutes. The participant’s dominant side was photographed and analyzed using ImageJ software to verify neck posture. Surface electromyography (EMG) was used to confirm the participant’s cervical erector spinae (CES) and upper trapezius muscle activities. The EMG signal was analyzed using the percentage of reference voluntary contraction and amplitude probability distribution function (APDF). In the second session, visual and auditory feedback for posture correction was provided if the neck was flexed by more than 15° in the initial position during computer typing. A 20-minute rest period was provided between the two sessions. Results: The neck angle (p = 0.014), CES muscle activity (p = 0.008), and APDF (p = 0.015) showed significant differences depending on the presence of the PCF. Furthermore, significant differences were observed regarding the CES muscle activity (p = 0.001) and APDF (p = 0.002) over time. Conclusion: Our study showed that the feedback system can correct poor posture and reduces unnecessary muscle activation during computer work. The improved neck posture and reduced CES muscle activity observed in this study suggest that neck pain can be prevented. Based on these results, we suggest that the PCF system can be used to prevent neck pain.

Background: In terms of physical performance, elastic tape (ET) is known to contribute to injury prevention and performance enhancement. Objects: This study aimed to compare and analyze the effect on lower extremity muscle activity of young adult women with and without ET during squats. Methods: In this study, six healthy, young women were recruited as participants in a university laboratory. Participants were allocated to two groups of three after measuring muscle activity in a pre-test, and the experiment was conducted for a total of two weeks (two sessions). First, 10 half squats were taped once in the first week, and 10 half squats were performed without taping in the second week. The other group did this in reverse and measured muscle activity after the squat was over. Results: As a result of this study, there was no significant difference in the quadriceps with or without ET (Z = –0.11, p > 0.05). Similarly, no significant difference was found in hamstring (Z = –0.31, p > 0.05). Conclusion: No beneficial effect was found on changes in muscle activity following ET application during squats. Further studies require randomized controlled trials that increase the number of participants and the intensity of the intervention, and measure pain, function, and performance rather than muscle properties depending on the biomechanical lifting mechanism.

Background: Mobilization movements was applied with different forces and frequencies for different clinicians. Force transmission varies with frequency. Objectives: The purpose of this study was to examine the effects of frequency- specific application of grade III PA movement on muscle tone and muscle activity around the lumbar vertebrae. Design: A one group pretest-posttest design. Methods: Twenty study subjects applied grades III of PA movement exercise of 0.5 Hz and 1 Hz with a force of 13 N around the 1st and 3rd lumbar vertebrae, and muscle tone and muscle activity were measured and compared before and after. Results: This study showed that 0.5 Hz grade III PA activity exerted an effect on the decrease in muscle tone of the 1st and 3rd right and left lumbar muscles. It was found that 0.5 Hz affected the right side of L1 and 1.0 Hz affected the left side of L1 in near-activity when applying the grade III PA movement by frequency. Conclusion: In the future, it will be necessary to investigate the effect of applying frequency according to various grades of PA movement.

Background: Individuals with scapular winging have a weak serratus anterior (SA) muscle, and to compensate, the pectoralis major (PM) and upper trapezius (UT) muscles excessively activate, which can cause upper extremity dysfunction. This study aimed to compare the effects of isometric horizontal abduction (IHA) on SA, PM, and UT muscle activity, as well as the SA/PM and SA/UT muscle activity ratios during knee push-up plus (KPP) at 90° and 120° of shoulder flexion. Objects: This study aimed to compare the effects of IHA on SA, PM, and UT muscle activity, as well as the SA/PM and SA/UT muscle activity ratios during KPP at 90° and 120° of shoulder flexion. Methods: This study, conducted at a university research laboratory, included 20 individuals with scapular winging. Participants performed KPP with and without IHA at 90° (KPP90) and 120° (KPP120) of shoulder flexion. SA, PM, and UT muscle activity were measured using surface electromyography. Results: PM activity in KPP90 with IHA was significantly lower than KPP90 and in KPP120 was significantly lower than KPP90. UT activity was significantly greater with IHA than without IHA and at 120° than 90° of shoulder flexion. SA/PM muscle activity ratio was significantly higher in KPP90 with IHA than without IHA and in KPP120 than in KPP90. SA/UT muscle activity ratio was significantly lower with IHA than without IHA. Conclusion: KPP90 with IHA and KPP120 are effective exercises to reduce PM activity and increase SA/PM muscle activity ratio. However, applying IHA in KPP90 also reduces SA/UT muscle activity ratio, implying that it would be preferable to apply KPP120 in individuals overusing their UT muscles.

Background: Osteoarthritis is a common condition with an increasing prevalence and is a common cause of disability. Osteoarthritic pain decreases the quality of life, and simple gait training is used to alleviate it. Knee osteoarthritis limits joint motion in the sagittal and lateral directions. Although many recent studies have activated orthotic research to increase knee joint stabilization, no study has used patellar tendon straps to treat knee osteoarthritis. Objects: This study aimed to determine the effects of patellar tendon straps on kinematic, mechanical, and electromyographic activation in patients with knee osteoarthritis. Methods: Patients with knee osteoarthritis were selected. After creating the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), leg length difference, Q-angle, and thumb side flexion angle of the foot were measured. Kinematic, kinetic, and muscle activation data during walking before and after wearing the orthosis were viewed. Results: After wearing the patellar tendon straps, hip adduction from the terminal stance phase, knee flexion from the terminal swing phase, and ankle plantar flexion angle increased during the pre-swing and initial swing phases. The cadence of spatiotemporal parameters and velocity increased, and step time, stride time, and foot force duration decreased. Conclusion: Based on the results of this study, the increase in plantar flexion after strap wearing is inferred by an increase due to neurological mechanisms, and adduction at the hip joint is inferred by an increase in adduction due to increased velocity. The increase in cadence and velocity and the decrease in gait speed and foot pressure duration may be due to joint stabilization. It can be inferred that joint stabilization is increased by wearing knee straps. Thus, wearing a patellar tendon strap during gait in patients with knee osteoarthritis influences kinematic changes in the sagittal plane of the joint.

목적 : 세 가지 컴퓨터 마우스 작업 시 보조기 유형(미착용, 손목보조기, 팔꿉보조기)에 따른 근활성도 차이를 비교하는 것이다. 연구방법 : 부산광역시에서 근무하는 20∼40대 사무직 근로자 36명을 대상으로 보조기 유형(미착용, 손목보조기, 팔꿉보 조기)에 따라 세 가지 컴퓨터 마우스 작업에 대한 근활성도를 비교하였다. 세 가지 마우스 작업은 과제 1(8개의 칸에 마우 스 왼쪽 버튼을 이용하여 지그재그 클릭하기), 과제 2(검지를 이용하여 6페이지 분량의 문서를 마우스 휠을 돌려서 가장 마지막 페이지로 이동하였다가 다시 되돌아 오기), 과제 3(모니터 바탕화면에 깔린 아이콘 별로 폴더에 드래그하여 옮기기 로 구성하였다. 과제 수행 중 대상자의 근활성도는 표면 근전도 장비를 사용하여 등세모근, 손가락굽힘근, 긴노쪽손목폄 근, 자쪽손목폄근을 측정하였고, 결과분석은 반복측정 분산분석을 사용하였다. 결과 : 과제 1에서 손목보조기 착용 시 긴노쪽손목폄근의 근활성도가 유의하게 감소되었고, 팔꿉보조기 착용 시에는 긴노 쪽손목폄근 및 자쪽손목폄근의 근활성도가 유의하게 감소되었다. 과제 2에서는 손목보조기 착용 시 및 팔꿉보조기 착용 시 모두 긴노쪽손목폄근과 자쪽손목폄근의 근활성도가 유의하게 감소되었다. 과제 3에서는 미착용, 손목보조기 착용, 팔 꿉보조기 착용 간 통계학적으로 유의한 근활성도 차이가 없었다. 결론 : 과제 유형에 따라 손목보조기 또는 팔꿉보조기의 착용 효과가 근육별로 다르게 나타났으며, 일부 과제에서 보조기 착용이 긴노쪽손목폄근 또는 자쪽손목폄근의 근활성도 감소에 효과가 있는 것으로 사료된다.

Background: Inspiratory muscle training can improve inspiratory strength and endurance through threshold loading. In addition, trunk stabilization exercises can improve trunk strength and respiratory function. Objectives: The purpose of this study is to investigate the effect of application of inspiratory muscle training and trunk stabilization exercise on pulmonary function and inspiratory muscle activation in college students. Design: Randomized controlled trials. Methods: In this study, 24 college students were randomly divided into two groups: inspiratory muscle training and trunk stabilization exercise (experimental group, n=12), and trunk stabilization exercise (control group, n=12). Inspiratory muscle activity was measured using a surface electromyography. Pulmonary function was measured using a spirometer and a peak expiratory flow meter. Results: In the experimental group, the muscle activity of both upper trapezius and latissimus dorsi muscles increased significantly after the intervention. In the experimental group, both upper trapezius muscle activity was significantly increased than in the control group. In the experimental group, all the pulmonary function significantly increased after the intervention. Conclusion: In this study, when the inspiratory muscle training was additionally applied to the trunk stabilization exercise in college students in their twenty, it was possible to improve the inspiratory muscle activity and pulmonary function.

Background: Older adults use different ankle muscle activation patterns during difficult static balance conditions. It has been suggested that this is related to a decline in proprioception with age, resulting in reduced postural balance. However, the association between proprioception and ankle muscle activity during quiet standing has not been directly assessed. Objects: This study aimed to investigate the effects of age and sensory condition on ankle muscle activity and the association between ankle proprioception and ankle muscle activity. Methods: We recruited 10 young women and 9 older women. Ankle proprioception was evaluated using joint position sense (JPS) and force sense (FS) divided by dorsiflexion and plantarflexion. The electromyographic activity of the tibialis anterior (TA) and gastrocnemius (GCM) muscles was collected during quiet standing. Results: Older women activated GCM muscle more than young during quiet standing and when performing difficult tasks. Older women had more errors in JPS dorsiflexion and FS plantarflexion than did young. The GCM muscle activity is related to JPS dorsiflexion and FS plantarflexion. Conclusion: Lower proprioception of the GCM with age leads to increased muscle activity, resulting in reduced postural balance. There was no difference in TA proprioception or muscle activity among older women with frequent physical activity.

Background: Gluteus medius muscle is important for the stability of hip joint. The sufficient core stability can be contributed to the performance of gluteus medius muscle in standing position. In addition, the external support may affect core stability in standing position. Objects: The purpose of this study was to investigated the effectiveness of the external support on the strength and muscle activity of hip abductor muscle during hip abduction in standing position in subjects without core stability. Methods: Fifteen subjects participated in this study. The subjects were evaluated by using the double-leg lowering with bent knees to measure the core stability. The strength and muscle activity of hip abductors was measured in standing position with the condition with and without external support using the tensiometer sensor and the surface electromyography. The paired t-test was used to investigate the difference between hip abductor strength and activity according to external support. The level of statistical significance was set at α = 0.05. Results: The hip abductor strength and muscle activity of gluteus medius muscle with external support were significantly greater than those without external support during hip abduction in standing position (p < 0.05). Conclusion: During hip abduction in standing position, the external support may be contributed to the improvement of the hip abductor strength and muscle activity of gluteus medius especially in the subjects without core stability.

Background: Individuals with scapular winging may have proprioceptive dysfunction which is important for motor control and causes shoulder instability. Reduced serratus anterior (SA) and lower trapezius (LT) muscle activity accompanied by over-active upper trapezius (UT), and pectoralis major (PM) may be contributing factors. Flexi-bar (FB) exercise may be used to increase joint position sense (JPS) and alter the target muscle activities. Objects: This study aimed to investigate the immediate effects of flexi-bar exercise prior to knee push-up plus (FPK) versus knee push-up plus (KPP) on JPS and muscle activity of SA, LT, UT, and PM in subjects with scapular winging. Methods: Eighteen subjects with scapular winging were recruited. JPS was investigated at baseline, after KPP and after FPK. Passive and active JPS errors were calculated by isokinetic equipment. Surface electromyography was used to record muscle activities during KPP and FPK. One-way repeated-measures analysis of variance and post hoc analyses were used to analyze the JPS error measured at baseline, after KPP and after FPK. Paired t-tests were used to compare muscle activities between KPP and FPK. Results: Passive JPS error was significantly decreased after KPP (p = 0.005) and after FPK (p = 0.003) compared to the baseline. Active JPS error was also significantly decreased after KPP (p = 0.016) and after FPK (p = 0.012) compared to the baseline. There was no significant difference in the passive and active JPS errors between KPP and FPK. SA activity during FPK was significantly increased (p = 0.024), and LT activity during FPK was significantly increased (p = 0.006). There were no significant differences in the UT and PM activity. Conclusion: FB might be recommended to immediately improve passive and active JPS and to selectively increase SA and LT muscle activities during KPP in individuals with scapular winging.

Background: Stroke patients have weak trunk muscle strength due to brain injury, so a single type of exercise is advised for restoring functionality. However, even after intervention, the problem still lies and it is suggested that another intervention method should be applied with exercise in order to deal with such problem. Objectives: To Investigate the effect of bridge exercise combined with functional electrical stimulation (FES) on trunk muscle activity and balance in stroke patients. Design: Randomized controlled trial. Methods: From July to August 2020, twenty stroke patients was sampled, ten patients who mediated bridge exercises combined with functional electrical stimulation were assigned to experiment group I, and ten patients who mediated general bridge exercises were assigned to experiment groupⅡ. For the pre-test, using surface EMG were measured paralyzed rectus abdominis, erector spinae, transverse abdominis/internal oblique muscle activity, and using trunk impairment scale were measured balance. In order to find out immediate effect after intervention, post-test was measured immediately same way pre-test. Results: Change in balance didn’t show significant difference within and between groups, but muscle activity of trunk was significant difference rectus abdominis and erector spinae within groups I (P<.01), also between groups was significant difference (P<.05). Conclusion: Bridge exercise combined with FES could improve trunk function more effectively than general bridge exercise due to physiological effect of functional electrical stimulation.