Effect of Vibration Frequency on Serratus Anterior Muscle Activity during Performance of the Push-up Plus with a Redcord Sling

[Purpose] We investigated the effect of vibration at various frequencies on serratus anterior (SA) muscle activity. [Subjects] Ten male subjects were recruited. [Methods] The subjects performed the push-up plus exercise supported by straps above the surface and vertical ropes in the Redcord sling. During the push-up plus, vibrations of 0, 30, 50, or 90 Hz were applied to the Redcord sling using a mechanical vibration apparatus attached to the rope. SA muscle activity was recorded using electromyography. [Results] SA muscle activity at the 50 Hz vibration frequency was significantly higher than that of no vibration. [Conclusion] Performing the push-up plus using a Redcord sling with mechanical vibration of 50 Hz effectively increased SA muscle activity.Key words: Push-up plus, Mechanical vibration, Serratus anterior     

The effects of shoulder joint abduction angles on the muscle activity of the serratus anterior muscle and the upper trapezius muscle while vibrations are applied

[Purpose] The purpose of this study was to examine the ratio between the upper trapezius and the serratus anterior muscles during diverse shoulder abduction exercises applied with vibrations in order to determine the appropriate exercise methods for recovery of scapular muscle balance. [Subjects and Methods] Twenty-four subjects voluntarily participated in this study. The subjects performed shoulder abduction at various shoulder joint abduction angles (90°, 120°, 150°, 180°) with oscillation movements. [Results] At 120°, all the subjects showed significant increases in the muscle activity of the serratus anterior muscle in comparison with the upper trapezius muscle. However, no significant difference was found at angles other than 120°. [Conclusion] To selectively strengthen the serratus anterior, applying vibration stimuli at the 120° shoulder abduction position is considered to be appropriate.Key words: Serratus anterior, Upper trapezius, Vibration     

Effect of a Multi-Air-Cushion Biofeedback Device (MABD) on Shoulder Muscles during the Dynamic Hug Exercise

[Purpose] We developed a multi-air-cushion biofeedback device (MABD) to assist the dynamic hug exercise, and investigated the effects of MABD on the shoulder muscles during the dynamic hug exercise. [Subjects] Twelve males aged 22–32 years were recruited. [Methods] We measured the right side serratus anterior, lower trapezius, and upper trapezius muscle activities during the dynamic hug exercise with and without MABD. [Results] The serratus anterior and lower trapezius muscles activities significantly increased during the dynamic hug exercise with MABD compared to without it. The upper trapezius muscle significantly decreased during the dynamic hug exercise with MABD compared to without it. [Conclusion] The results suggest that the dynamic hug exercise with MABD is an effective scapular stability exercise.Key words: Biofeedback, Dynamic hug exercise, Scapular stability     

Does proprioceptive system stimulation improve sit-to-walk performance in healthy young adults?

[Purpose] Sit-to-walk performance is linked to proper proprioceptive information processing. Therefore, it is believed that an increase of proprioceptive inflow (using muscle vibration) might improve sit-to-walk performance. However, before testing muscle vibration effects on a frail population, assessment of its effects on healthy young people is necessary. Thus, the aim of this study was to investigate the effects of muscle vibration on sit-to-walk performance in healthy young adults. [Subjects and Methods] Fifteen young adults performed the sit-to-walk task under three conditions: without vibration, with vibration applied before movement onset, and with vibration applied during the movement. Vibration was applied bilaterally for 30 s to the tibialis anterior, rectus femoris, and upper trapezius muscles bellies. The vibration parameters were as follows: 120 Hz and 1.2 mm. Kinematics and kinetic data were assessed using a 3D motion capture system and two force plates. The coordinates of reflective markers were used to define the center-of-mass velocities and displacements. In addition, the first step spatiotemporal variables were assessed. [Results] No vibration effect was observed on any dependent variables. [Conclusion] The results show that stimulation of the proprioceptive system with local muscle vibration does not improve sit-to-walk performance in healthy young adults.     

Influence of pelvic position and vibration frequency on muscle activation during whole body vibration in quiet standing

[Purpose] The purpose of this study was to investigate muscle activation related to postural stability depending on the pelvic position and frequency of whole body vibration (WBV) during quiet standing, and to identify the most effective training conditions that elicit the highest neuromuscular responses. [Subjects and Methods] Eighteen healthy subjects voluntarily participated in this single-group, repeated-measures study in which surface electromyography (EMG) data for the upper trapezius, rectus abdominis, external oblique abdominis, erector spinae, gluteus maximus, rectus femoris, semitendinosus, and medial gastrocnemius were collected at three frequencies (0 Hz, 10 Hz, and 20 Hz) of WBV and three pelvic positions (neutral, anterior tilt, posterior tilt) for each subject during quiet standing. [Results] The EMG activities of all the recorded muscles showed significant differences between the three frequencies of WBV and three pelvic positions during quiet standing. [Conclusion] The study findings suggest that a higher WBV frequency (20 Hz) should be used to strengthen most muscles, and that using the posterior pelvic tilt during WBV is much more effective at strengthening and training muscles related to core stability.Key words: Whole body vibration, Frequency, Pelvic tilt     

The Effects of Sling Exercise Using Vibration on Trunk Muscle Activities of Healthy Adults

[Purpose] This study compared the effects of sling exercises with and without vibration on the muscular activity of the internal oblique (IO), rectus abdominis (RA), multifidus (MF), and erector spinae (ES) muscles of healthy adults. [Methods] Eleven healthy university students (11 men) with a mean age of 22.8 years were enrolled in this study. Subjects performed supine and prone bridge exercises with the knees flexed using a sling suspension system with and without vibration. The amplitudes of the EMG activities of selected trunk muscles (internal oblique, rectus abdominis, erector spinae, multifidus) were recorded. Two types of exercise conditions were executed in a random sequence for 5 seconds each. The signals detected from the middle 3 seconds (after discarding the signals of the first and the last one seconds) were used in the analysis. A 3-minute break was given after each exercise to minimize muscle fatigue. [Results] During the supine bridge exercise with vibration, the activities of the IO, RA, MF, and ES muscles were significantly higher than those of the supine bridge exercise without vibration. Additionally, during the prone bridge exercise with vibration, the activities of the IO, RA, MF, and ES were significantly higher than those of the prone bridge exercise without vibration. [Conclusion] Sling exercises with vibration improved the trunk muscle activities of healthy adults compared to the sling exercises without vibration. The information presented here is important for clinicians who use lumbar stabilization exercises as an evaluation tool or a rehabilitation exercise.Key words: Sling exercise, Vibration, Trunk muscle     

Comparisons of shoulder stabilization muscle activities according to postural changes during flexi-bar exercise

[Purpose] The purpose of this study was to compare shoulder stabilization muscle activities according to postural changes during flexi-bar exercise. [Subjects] The subjects included 18 students (10 males, 8 females) at B University. [Methods] The subjects performed the following flexi-bar exercises: 1) medio-lateral oscillation with the 90° shoulder abduction, with the hand in the neutral position; 2) dorso-ventral oscillation with 90° shoulder flexion, with the hand in the neutral position; 3) superior-inferior oscillation with 90° shoulder flexion, with the 80° hand pronation. [Results] The activity of the serratus anterior showed significant differences between each position; however, activities of the upper trapezius and middle trapezius were not significantly different. [Conclusion] The results of this study indicate that posture control is important for selective strengthening of the serratus anterior muscle during flexi-bar exercises.Key words: Flexi-bar exercise, Shoulder stabilization, Muscle activity     

Effect of the Shoulder Flexion Angle in the Sagittal Plane on the Muscle Activities of the Upper Extremities when Performing Push-up plus Exercises on an Unstable Surface

[Purpose] The purpose of this study was to investigate the effect of the shoulder flexion angle on the muscle activities of the upper extremities when performing the push-up plus exercise (PUPE) on an unstable surface with the forearm in the external rotation position. [Subjects] The subjects were conducted on 15 normal male adults. [Methods] A sling device was used for the unstable surface, and PUPE was performed with the forearm in the external rotation position. The shoulder flexion angles measured in the sagittal plane were 110°, 90°, and 70°. Electromyography was used for a comparitive analysis of the muscle activities of the serratus anterior (SA), the pectoralis major (PM), and the upper trapezius (UT). [Results] In the intra-group comparison, the muscle activity of SA was statistically the highest when the shoulder-flexion angle was 110°. [Conclusion] performing PUPE on an unstable surface, the muscle activity of the SA is activated the most when the shoulder flexion angle is 110° and the forearm is in the external rotation position.     

Effects of Vibratory Stimulations on Maximal Voluntary Isometric Contraction from Delayed Onset Muscle Soreness

[Purpose] The aim of this study was to investigate the effect of vibratory stimulation on maximal voluntary isometric contraction (MVIC) from delayed onset muscle soreness (DOMS). [Subjects] Sixty healthy adults participated in this study. The exclusion criteria were orthopedic or neurologic disease. [Methods] The researchers induced DOMS in the musculus extensor carpi radialis longus of each participant. Subjects in the control group received no treatment. The ultrasound group received ultrasound treatment (intensity, 1.0 W/cm^2; frequency 1 MHz; time, 10 minutes). The vibration group received vibration stimulation (frequency, 20 MHz; time, 10 minutes). Maximal voluntary isometric contraction (MVIC) was recorded at baseline, immediately after exercise, and 24, 48, and 72 hours after exercise. [Results] MVIC measurements showed statistically significant differences in the vibration group compared with the control group. [Conclusion] Vibratory stimulation had a positive effect on recovery of muscle function from DOMS.Key words: Vibratory stimulation, Ultrasound, Isometric contraction     

Effects of Various Gait Speeds on the Latissimus Dorsi and Gluteus Maximus Muscles Associated with the Posterior Oblique Sling System

[Purpose] This study investigated the effect of different gait speeds on the muscle activities of the latissimus dorsi and gluteus maximus muscles in relation to the posterior oblique sling system. [Subjects] We recruited 14 young adult males. [Methods] We measured the left latissimus dorsi muscle activity and right gluteus maximus muscle activity of all subjects while they walked on a treadmill at speeds of 1.5 km/h, 3.5 km/h and 5.5 km/h. [Results] There was a significant increase in latissimus dorsi muscle activity with a treadmill speed of 5.5 km/h compared with 1.5 km/h and 3.5 km/h. The gluteus maximus muscle activity significantly increased in the order of 1.5 km/h < 3.5 km/h < 5.5 km/h. [Conclusion] The present results indicate that arm swing connected to increasing gait speed influences the muscle activity of the lower limbs through the posterior oblique sling system.Key words: Electromyography, Gait speed, Posterior oblique sling system     

Effect of conscious abdominal contraction on the activation of periscapular muscles in individuals with subacromial pain syndrome

BackgroundSynergism between shoulder and trunk muscles seems to be effective to increase periscapular muscle activation in asymptomatic subjects. The influence of conscious contraction of the abdominal muscles has not yet been studied in non-athlete subjects with pain. The study aimed to investigate the effect of the instruction for conscious activation of the abdominal muscles on the activity of the scapulothoracic muscles during shoulder exercises in subjects with subacromial pain syndrome.MethodThirty subjects with unilateral pain (mean age 52 ± 11 years) participated in this study. Three isometric and five dynamic exercises for the scapulothoracic muscles were assessed. The group without instruction just repeated the exercises, while the instruction group was evaluated before and after conscious abdominal training. The linear mixed model analysis was used to compare the muscle activation between groups.FindingsDifferences between groups after the conscious abdominal contraction for activation of middle and lower trapezius on the symptomatic side in the “Full can”(p = 0.03; effect size:0.92 middle trapezius); (p = 0.02; effect size:0.96 lower trapezius) and “Knee Push” (p = 0.01; effect size:0.75 lower trapezius). For asymptomatic side, the exercises “External Rotation Kneeling” (p = 0.04; effect size: 0.81 lower trapezius); (p = 0.00; effect size: 2.09 serratus anterior), “Knee Push” (p = 0.04; effect size:1.24 serratus anterior) and “Wall Slide” (p = 0.01; effect size: 1.03 serratus anterior).InterpretationConscious contraction of the abdominal muscle immediately alter the activation of the serratus anterior muscle during closed kinetic chain exercises on the asymptomatic side and increased activation of trapezius on the symptomatic side during shoulder open kinetic chain exercise.     

Effects of squats accompanied by hip joint adduction on the selective activity of the vastus medialis oblique

[Purpose] This study evaluated the effective selective activation method of the vastus medialis oblique for knee joint stabilization in patients with patellofemoral pain syndrome. [Subjects and Methods] Fifteen healthy college students (9 males, 6 females); mean age, height, and weight: 22.2 years, 167.8 cm, and 61.4 kg, respectively) participated. The knee angle was held at 60°. Muscle activities were measured once each during an ordinary squat and a squat accompanied by hip joint adduction. The muscle activities of the vastus medialis oblique and vastus lateralis were measured by electromyography for five seconds while maintaining 60° knee flexion. Electromyography signals were obtained at a sampling rate of 1,000 Hz and band pass filtering at 20–50 Hz. The obtained raw root mean square was divided by the maximal voluntary isometric contraction and expressed as a percentage. The selective activity of the vastus medialis oblique was assessed according to the muscle activity ratio of the vastus medialis oblique to the vastus lateralis. [Results] The activity ratio of the vastus medialis oblique was higher during a squat with hip joint adduction than without. [Conclusion] A squat accompanied by hip joint adduction is effective for the selective activation of the vastus medialis oblique.Key words: Patellofemoral pain syndrome, Vastus medialis oblique, Squat     

The Effects of Cervical Stabilization Exercises on the Electromyographic Activity of Shoulder Stabilizers

[Purpose] The purpose of the present study was to examine the effects of cervical stabilization exercises on the electromyographic activity of the shoulder stabilizers in normal adults. [Subjects] In the present study, 20 normal adults were divided into an experimental group (EG, n=10) that performed cervical stabilization exercises and shoulder stabilization exercises and a control group (CG, n=10) that performed shoulder stabilization exercises. [Methods] The EG and CG performed their exercises three times per week for four weeks. The cervical stabilization exercises consisted of Craniocervical flexion exercises (CCFEs) that were performed using pressure biofeedback units (PBUs). The shoulder stabilization exercises consisted of scapula-setting exercises, wall stretching, and external rotation exercises. To examine the electromyographic activity of the upper trapezius (UT) muscle, lower trapezius (LT) muscle, and serratus anterior (SA) muscle, the electromyograms for these muscles were compared and analyzed. [Results] In comparisons within the groups, the EG showed statistically significant differences in the UT, the LT and the SA. The CG did not show any significant differences. [Conclusion] Cervical stabilization exercises and shoulder stabilization exercises are considered to be an effective intervention for the electromyographic activity of the shoulder stabilizers, the UT, LT, and SA.Key words: Cervical stabilization, Stabilizer, Electromyographic activity     

Changes in Pressure Pain Threshold of the Upper Trapezius,Levator Scapular and Rhomboid Muscles during Continuous Computer Work

[Purpose] This study investigated the changes in pressure pain threshold of the upper trapezius, levator scapular, and rhomboid muscles during continuous computer work. [Subjects] Fourteen males and females aged 26–32 years, were recruited. [Methods] A dolorimeter pressure algometer was used to measure the pressure pain threshold of the upper trapezius, levator scapular, and rhomboid muscles, respectively, before computer work and after 15 min, 30 min, and 60 min of computer work. [Results] The pressure pain threshold of the upper trapezius was significantly decreased after 15 min or more of computer work. The pressure pain threshold of the levator scapular was significantly decreased after computer work for 30 min and 60 min. The pressure pain threshold of the rhomboid muscle was significantly decreased after 60 min of computer work. [Conclusion] Continuous computer work could produce much more pain in the levator scapular and rhomboid muscle than the upper trapezius.Key words: Computer worker, Pressure pain threshold, Rhomboid muscle     

Surface EMG during the Push-up plus Exercise on a Stable Support or Swiss Ball: Scapular Stabilizer Muscle Exercise

[Purpose] Scapular stabilizer strengthening exercise is crucial for shoulder rehabilitation. The purpose of this study was to compare two types of push-up plus exercises, on a stable and unstable bases of support, using surface electromyography (EMG), to suggest an effective shoulder rehabilitation program. [Subjects and Methods] Ten healthy men volunteered for this study. All volunteers performed two sets of push-up plus exercise (standard push up and knee push up) on stable and unstable bases of support. The muscle activities of five important scapular stabilizer muscles (upper trapezius, middle trapezius, lower trapezius, serratus anterior, latissimus dorsi) were recorded during the exercise. [Results] The upper trapezius showed greater mean electric activation amplitude in the scapular retraction posture than in the scapular protraction posture, and the serratus anterior showed greater mean electric activation amplitude in the scapular protraction posture than in the scapular retraction posture. The root-mean-square normalized EMG values of the muscles were greater during the exercise performed on the unstable support than those on the stable support. [Conclusion] The standard push-up plus exercise on an unstable base of support helps to increase muscle activity, especially those of the upper/middle trapezius and serratus anterior.Key words: Scapular stabilizer, Push-up plus, Surface EMG     

The effect of single extremity-vibration on the serum sclerostin level

[Purpose] Sclerostin is mechanosensitive protein that is produced exclusively by osteocytes. It was reported that the plasma sclerostin level increases in the 10th minute after the application of Whole-Body Vibration. The aim of this study was to determine whether single extremity-vibration induces any change in the serum sclerostin level. [Subjects and Methods] Eight healthy young-adult volunteers were recruited for this pilot study. The participants sat on a chair with their left hip and knee joints flexed at 90 degrees. The lower leg was exposed to vibration: 40 Hz, 4 mm, 60 s. Blood samples were collected before and after the vibration. The serum sclerostin levels were blindly measured in dual-controlled blood samples. [Results] The serum sclerostin level before vibration was 328.2±589.9 pg/ml, and it showed no significant change after vibration. [Conclusion] Unlike Whole-Body Vibration, Single-Extremity Vibration did not affect the serum sclerostin level significantly. This finding can be explained by the limited bone volume exposed to vibration. Bone volume exposed to vibration is less during Single-Extremity Vibration than during Whole-Body Vibration.Key words: Sclerostin, Whole-Body Vibration, Bone     

Changes in upper-extremity muscle activities due to head position in subjects with a forward head posture and rounded shoulders

[Purpose] This study investigated upper-extremity muscle activities in natural, ideal, and corrected head positions. [Subjects and Methods] Forty subjects with a forward head posture and rounded shoulder were recruited and randomly assigned to the natural head position group (n = 13), ideal head position group (n = 14), or corrected head position group (n = 13). Muscle activities were measured using a four-channel surface electromyography system at the sternocleidomastoideus, upper and lower trapezius, and serratus anterior muscles on the right side during an overhead reaching task. [Results] The muscle activities of the upper trapezius and serratus anterior differed significantly among head positions. Post hoc tests revealed significant differences between natural and ideal head positions, and natural and ideal head positions for both the upper trapezius and serratus anterior. [Conclusion] Recovery of normal upper trapezius and serratus anterior muscle functions plays an important role in correcting forward head posture and rounded shoulders.Key words: Forward head posture, Muscle activity, Round shoulder     

Comparison of Upper Trapezius,Anterior Deltoid,and Serratus Anterior Muscle Activity during Push-up plus Exercise on Slings and a Stable Surface

[Purpose] The purpose of this study was to identify effects of push-up plus exercise on different support surfaces on upper extremity muscular activity. [Subjects] The subjects were 28 students (10 males, 18 females) at B University. [Methods] The subjects performed push-up plus exercises either on slings or on a fixed support. [Results] Push-up plus exercises on slings showed significant increases in the muscle activity of the trapezius (upper fiber), deltoid (anterior fiber), and serratus anterior muscles compared with stabilization exercises on a fixed support. [Conclusion] Based on these results, it is considered that performance of the push-up plus exercise on slings will increase scapular muscle activity.Key words: Push-up plus exercise, Sling, Muscle activity     

Rehabilitation Exercises to Induce Balanced Scapular Muscle Activity in an Anti-gravity Posture

[Purpose] The purpose of this study was to compare the intramuscular balance ratios of the upper trapezius muscle (UT) and the lower trapezius muscle (LT), and the intermuscular balance ratios of the UT and the serratus anterior muscle (SA) among prone extension (ProExt), prone horizontal abduction with external rotation (ProHAbd), forward flexion in the side-lying position (SideFlex), side-lying external rotation (SideEr), shoulder flexion with glenohumeral horizontal abduction load (FlexBand), and shoulder flexion with glenohumeral horizontal adduction load (FlexBall) in the standing posture. [Methods] The electromyographic (EMG) activities of the UT, LT and SA were measured during the tasks. The percentage of maximum voluntary isometric contraction (%MVIC) was calculated for each muscle, and the UT/LT ratios and the UT/SA ratios were compared among the tasks. [Results] The UT/LT ratio with the FlexBand was not significantly different from those of the four exercises in the side-lying and prone postures. The UT/SA ratio with the FlexBall demonstrated appropriate balanced activity. [Conclusion] In an anti-gravity posture, we recommend the FlexBand and the FlexBall for inducing balanced UT/LT and UT/SA ratios, respectively.Key words: Scapular muscle exercise, Balanced scapular muscle activity, Electromyography     

Morphological changes in the long axis of the lower leg muscles during isometric contraction in the sitting position

[Purpose] To compare the changes in the muscle cross-sectional area (MCSA) along the long axis of the lower leg muscles at rest and during ankle plantar flexors isometric contraction and to obtain basic information regarding the movement of lower leg muscles during ankle plantar flexors contraction. [Participants and Methods] Sixteen healthy young female participants (20.9 ± 1.2 years) were asked to sit with their ankles in a neutral ankle position. Images were obtained at rest and during isometric contraction of the ankle plantar flexors using gravity magnetic resonance imaging. The MCSAs of the triceps surae and tibialis anterior were measured. [Results] The middle region of the soleus muscle had a lower MCSA on contraction than at rest. In addition, the medial head of the gastrocnemius had a lower MCSA on contraction than at rest in the distal quarter. Moreover, the tibialis anterior had a lower MCSA at rest than on contraction in the middle region. [Conclusion] The area to be used as an indicator and the movement to be induced differ depending on the muscle during isometric contraction of the triceps surae.Key words: Muscular dynamics, MRI, Lower leg muscle