The Effects of Vibration Stimuli Applied to the Shoulder Joint on the Activity of the Muscles Around the Shoulder Joint

[Purpose] The present study compared the muscle activity of the upper trapezius with those of the serratus anterior and the lower trapezius when slings, unstable surfaces, were laterally vibrated, to examine the effects of vibration during sling exercises on shoulder stabilization muscles. [Methods] The subjects performed push-up exercises on a sling and maintained isometric contraction in the final stage, while vibration was manually administered to the rope of the sling during the isometric-contraction stage. Vibration within a range of 10 cm was delivered for five seconds at a frequency of 1 Hz in time with a metronome. Vibrations were applied for five seconds at 3 Hz and 3.5 Hz, respectively. [Results] The serratus anterior showed a significant differences between isometric contraction with vibration of 3 Hz and isometric contraction with vibration of 3.5 Hz. [Conclusion] The upper trapezius and the lower trapezius showed prominent changes in muscle activity at 3.5 Hz, and the serratus anterior showed prominent changes in muscle activity at 3 Hz and 3.5 Hz. Therefore, as vibration frequency increased, making the load-bearing surface more unstable, the recruitment of the upper trapezius, the lower trapezius, and the serratus anterior increased. To perform exercises that selectively strengthen the serratus anterior, the exercises should be performed at a vibration frequency of 3 Hz.Key words: Vibration, Shoulder joint, Muscle activity     

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.     

Effect of the application of local vibration in scaption on joint stability

[Purpose] The aim of this study was to determine the initial effect of local vibration on the stability of the shoulder joints by applying local vibration to the shoulder joints. [Subjects and Methods] For the test, the subjects held a FlexBar with one hand, at about 10 cm from one end, and performed the oscillation movement with the shoulder at 90° flexion and the elbow in the full-extension position in scaption; the vibration stimulus was set to 5 Hz. Then, the subjects underwent the Upper Quarter Y Balance Test to evaluate the stability of the shoulder joints. [Results] The moving distances in the left, right, and upper directions after the oscillation movement were increased significantly compared with the results before the oscillation movement. [Conclusion] A vibration stimulus is effective as an exercise method to increase the stability of the shoulder joints.Key words: Local vibration, Shoulder joint, Stability     

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     

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     

Whole-body vibration-induced muscular reflex: Is it a stretch-induced reflex?

[Purpose] Whole-body vibration (WBV) can induce reflex responses in muscles. A number of studies have reported that the physiological mechanisms underlying this type of reflex activity can be explained by reference to a stretch-induced reflex. Thus, the primary objective of this study was to test whether the WBV-induced muscular reflex (WBV-IMR) can be explained as a stretch-induced reflex. [Subjects and Methods] The present study assessed 20 healthy males using surface electrodes placed on their right soleus muscle. The latency of the tendon reflex (T-reflex) as a stretch-induced reflex was compared with the reflex latency of the WBV-IMR. In addition, simulations were performed at 25, 30, 35, 40, 45, and 50 Hz to determine the stretch frequency of the muscle during WBV. [Results] WBV-IMR latency (40.5 ± 0.8 ms; 95% confidence interval [CI]: 39.0–41.9 ms) was significantly longer than T-reflex latency (34.6 ± 0.5 ms; 95% CI: 33.6–35.5 ms) and the mean difference was 6.2 ms (95% CI of the difference: 4.7–7.7 ms). The simulations performed in the present study demonstrated that the frequency of the stretch signal would be twice the frequency of the vibration. [Conclusion] These findings do not support the notion that WBV-IMR can be explained by reference to a stretch-induced reflex.Key words: Skeletal muscle function, Gravitational physiology, Tonic vibration reflex     

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     

Analysis of the pulmonary functions of normal adults according to pillow height

[Purpose] The purpose of this study is to examine changes in pulmonary functions in relation to the sleeping positions of the experimental subjects. [Subjects and Methods] The subjects for this study were twenty randomly selected males and females from K University. Measurements were taken in the supine position at three different pillow heights: 0 cm, 5 cm, and 10 cm. Pulmonary functions (vital capacity, tidal volume, inspiratory reserve volume, and expiratory reserve volume) were evaluated using a Fit mate. [Results] These findings suggest that a pillow height of 5 cm makes a significant difference in vital capacity (VC). When the three pillow heights were compared, significant differences were seen between 0 cm and 5 cm, and between 5 cm and 10 cm, in terms of vital capacity for the pulmonary functions among the three positions. [Conclusion] In conclusion, changing the positions of the subjects produces changes in pulmonary functions. The greatest change occurred in the 5 cm pillow height. Presumably, ventilation is affected by the body structures. The results will provide objective data to establish the most suitable positions for stroke patients when they perform respiratory exercises.Key words: Pulmonary function, Pillow, Height     

Antioxidant effect of Phyllanthus amarus after moderate-intensity exercise in sedentary males: a randomized crossover (double-blind) study

[Purpose] We aimed to evaluate the effects of Phyllanthus amarus (PA) on oxidative stress and damage, inflammation, and soreness in muscle after a single session of moderate-intensity exercise. [Subjects and Methods] Twelve men randomly participated in 2, three-day phases with a one-week washout period. On the first day, participants consumed two capsules of PA or placebo control (CTL) before 20 min of cycling. They then consumed four capsules on the same day after exercise and six capsules/day for the next two days. Blood samples were obtained before, immediately after exercise and 24 h and 48 h after exercise. The pain tolerance was measured at both legs. [Results] Plasma vitamin C levels in the PA group were higher than those in the CTL group after exercise. At 48 h after exercise, vitamin C levels were higher in the PA group, but those in the CTL group were lower than the pre-exercise levels. However, plasma levels of creatine kinase were increased in both groups after exercise compared with the pre-exercise levels. The neutrophil count was higher immediately after exercise than the pre-exercise levels in the CTL group. [Conclusion] Acute supplementation with PA improves antioxidant status after a single session of moderate-intensity exercise.     

Effect of a Dynamic Air Cushion on the Development of Leg Edema during Wheelchair Sitting

[Purpose] To clarify how a novel dynamic cushion affects the leg edema evoked by wheelchair sitting, we measured the changes in leg volume induced during wheelchair sitting with the dynamic air cushion or a static cushion. [Subjects and Methods] Nine healthy male subjects participated in this study. Leg edema during wheelchair sitting was evaluated with strain gauge plethysmography (the gauge was placed around the middle portion of the lower thigh). Following a period of rest, each subject was asked to sit on a wheelchair containing the dynamic cushion for 15 min. Then, the protocol was repeated with a static cushion. The angles of the knee and ankle joints were set to 90 degrees, and no footrests were used. [Results] The change in leg volume observed during sitting on the dynamic cushion (0.00 ± 0.03 mL/100 mL) was smaller than that observed during sitting on the static cushion (0.02 ± 0.02 mL/100 mL). [Conclusion] These results suggested that the dynamic cushion relieved leg edema during wheelchair sitting.Key words: Wheelchair cushion, Leg volume, Healthy human     

Effect of Muscle Vibration on Postural Balance of Parkinson’s Diseases Patients in Bipedal Quiet Standing

[Purpose] The purpose of this study was to investigate the effect of muscle vibration applied to the lower extremities on static postural balance of patients with Parkinson’s disease (PD). [Subjects] Seven subjects with Parkinson’s disease participated in this study. [Methods] The oscillators of vibration were attached to the muscle bellies of the tibialis anterior, gastrocnemius, biceps femoris, and rectus femoris on both sides of the lower extremities with adhesive tape. A vibration frequency of 60 Hz was used to induce static postural reactions. Subjects’ center of pressure (COP) sway and peak ground reaction force (GRF) were measured with their eyes open with and without vibration. COP sway and peak GRF (Fx, Fy, Fz) were measured using a force plate (AMTI, Newton, USA), which provides x, y and z coordinates of body movement. [Results] The area of COP sway with vibration was significantly smaller than that with no vibration, but the length of COP sway showed no difference between two conditions. Peak medial-lateral maximum force (Fy) with vibration was significantly higher than that with no vibration, but peak anterior-posterior force (Fx) and peak vertical force (Fz) showed no differences. [Conclusion] These results suggest that vibration applied to the lower extremities can help PD patients control postural balance during quiet standing.Key words: Vibration, Postural balance, Parkinson’s disease     

Changes in corticospinal excitability with short-duration high-frequency electrical muscle stimulation: a transcranial magnetic stimulation study

[Purpose] Afferent input caused by electrical stimulation of a peripheral nerve or a muscle modulates corticospinal excitability. However, a long duration of stimulation is required to induce these effects. The purpose of this study was to investigate the effect of short-duration high-frequency electrical muscle stimulation (EMS) on corticospinal excitability through the measurement of motor evoked potentials (MEP) in young healthy subjects. [Subjects] Eleven healthy right-handed subjects participated in this study. [Methods] EMS was applied to the abductor pollicis brevis (APB) muscle at 100 Hz with a pulse width of 100 μs for 120 s. The intensity of stimulation was just below the motor threshold. Transcranial magnetic stimulation was applied over the motor cortex, and MEP were recorded from the APB before, and immediately, 10, and 20 min after EMS. [Results] In the APB muscle, the MEP amplitude significantly decreased after EMS, and this effect lasted for 20 min. [Conclusion] The excitability of the corticospinal tract decreased after short-duration high-frequency EMS, and the effect lasted for 20 min. These results suggest that even short duration EMS can change the excitability of the corticospinal tract.Key words: Electrical muscle stimulation, Transcranial magnetic stimulation, Corticospinal excitability     

The effect of static stretching on key hits and subjective fatigue in eSports

[Purpose] To explore the effects of static stretching for 20 s on key hits and subjective fatigue in an eSports-like setting. [Participants and Methods] The participants comprised of 15 healthy males who were instructed to hit a particular key on a computer keyboard using the left ring finger to achieve the maximum number of hits possible over a period of 30 s. Subjective fatigue of the forearm was assessed using a visual analog scale (VAS) before the experiment and after each trial. Trials 1, 2, and 3 were conducted in succession, with an inter-trial interval of 60 s to ensure a loaded state. Static stretching for 20 s preceded Trial 4. [Results] Over the first three trials, the number of key hits in the first 10 s gradually decreased, while the feeling of subjective fatigue gradually increased. After stretching, the number of key hits in the first 10 s of Trial 4 was similar to that observed in Trial 1, and there was no increase in subjective fatigue. [Conclusion] Static stretching for 20 s restored the number of key hits for 10 s after stretching to that before the load application and suppressed the increase in subjective fatigue.     

The Influence of “wuqinxi” exercises on the Lumbosacral Multifidus

[Purpose] To investigate the effect of the five animals (wuqinxi) exercises on the lumbosacral multifidus. [Subjects and Methods] This study enrolled two groups of volunteers, 15 volunteers who did the five animals exercises, the experimental group, and 15 volunteers who did aerobic exercise (walking), the control group. Both before and after the 1 year exercise intervention, the average surface electromyography (ASEMG) of the two groups in the process of flexion and extension was recorded and analyzed using DASYLab10.0 software, and the flexion extension ratio (FER) was calculated. [Results] The ASEMG in the process of flexion was lower than the ASEMG in the process of extension both before and after the 1 year exercise intervention on both sides of all volunteers. There was no significant difference in FER between the experimental group and control group before the 1 year exercise intervention; however, the FER of experimental group was lower than that of the control group after the 1 year exercise intervention. There was no significant difference between the two sides in any individual both before and after the 1 year exercise intervention in both groups. [Conclusion] The “wuqinxi” exercises improved the function of the lumbosacral multifidus, and might be an alternative method of reducing low back pain.Key words: Wuqinxi exercises, Flexion extension ratio (FER), Low back pain     

Does whole-body vibration training in the horizontal direction have effects on motor function and balance of chronic stroke survivors? A preliminary study

[Purpose] The objective of this study was to investigate the effects of whole-body vibration (WBV) in the horizontal direction on the motor function and balance of chronic stroke survivors. [Subjects and Methods] This study was a randomized controlled trial. Twenty-one individuals with chronic stroke from an inpatient rehabilitation center participated in the study. The participants were allocated to either the WBV training group or the control group. The WBV training group (n = 12) received whole-body vibration delivered in the horizontal direction (15 min/day, 3 times/week, 6 wks) followed by conventional rehabilitation (30 min/day, 5 times/week, 6 wks); the control group (n = 9) received conventional rehabilitation only (30 min/day, 5 times/week, 6 wks). Motor function was measured by using the Fugl-Meyer assessment, and balance was measured by using the Berg Balance Scale (BBS) and the Timed Up and Go (TUG) test before and after the interventions. [Results] After the interventions, all variables improved significantly compared with the baseline values in the WBV training group. In the control group, no significant improvements in any variables were noted. In addition, the BBS score in the WBV training group increased significantly compared with that in the control group. [Conclusion] WBV training with whole-body vibration delivered in the horizontal direction may be a potential intervention for improvement of motor function and balance in patients who previously experienced a stroke.Key words: Stroke, Whole-body vibration, Motor function     

Brain Activity Associated with the Illusion of Motion Evoked by Different Vibration Stimulation Devices: An fNIRS Study

[Purpose] A number of different stimulation devices are used in basic and clinical research studies, and their frequencies of use vary. However, whether or not they are equally effective has not been investigated. The purpose of the present study was to investigate neural activity in the brain during the illusion of motion evoked by stimulating the tendons of the wrist extensor muscles using various vibration devices. [Subjects] Twelve right-handed university students with no history of nervous system disorder or orthopedic disease participated in the study. [Methods] The wrist extensor tendon was stimulated using 3 different devices: 1) a vibration stimulation device (SL-0105 LP; Asahi Seisakusho Co., Ltd., Saitama, Japan), frequency 80 Hz; 2) a handy massager (YCM-20; Yamazen Corporation, Osaka, Japan), frequency 70 Hz; and 3) a handy massager (Thrive MD-01; Thrive Co., Ltd., Osaka, Japan), frequency 91.7 Hz. Brain activity was recorded during stimulation by using functional near-infrared spectroscopy. [Results] Increased neural activity was observed in both the premotor cortices and the parietal region in both hemispheres in all 3 cases. The level and localization of neural activity was comparable for all 3 stimulation devices used. [Conclusion] This suggests that subjects experience the illusion of motion while the tendon is being stimulated using any vibration device.Key words: Illusion of motion, Tendon vibration, fNIRS     

The Relationship between Physical Function and Postural Sway during Local Vibratory Stimulation of Middle-aged People in the Standing Position

[Purpose] The purpose of this study was to examine the relationship between physical function and postural sway during local vibratory stimulation of middle-aged subjects in an upright position. [Subjects] The subjects were 25 healthy community-dwelling middle-aged people. [Methods] We measured postural sway using a Wii board while vibratory stimulations of 30, 60, or 240 Hz were applied to the subjects’ lumbar multifidus or gastrocnemius muscles. Physical function was evaluated by 5-m usual gait speed and grip strength. [Results] Gait speed was strongly correlated to the anteroposterior body sway in the upright position during 30 Hz gastrocnemius muscles vibration (GMV). [Conclusion] Postural sway during 30 Hz GMV was strongly associated with gait speed and showed a posterior displacement. These findings show that the lower leg’s response to balance control under 30 Hz proprioceptive stimulation might be a good indicator of declining gait function.     

Effects of Local Muscle Vibration on the Displacement of Center of Pressure during Quiet Standing

[Purpose] The purpose of this study was to investigate the effect of local vibration stimuli on body balance (trace area, trace length, and velocity) in healthy adults during double-leg standing. [Subjects and Methods] Thirty-nine subjects (10 male, 29 female) participated in this study. They were asked to keep their balance while holding four positions: standing with their eyes open, with and without vibration stimuli, and standing with their eyes closed, with and without vibration stimuli. The vibration stimuli, which had a duration of 30 sec, and a frequency of 60–80 Hz, were applied to the tibialis anterior and gastrocnemius muscle belly during double-leg standing. Balance measurement was performed using the Balance Trainer 4 (HUR Labs Oy, Tampere, Finland). All subjects provided informed consent prior to participation in this study. [Results] In the open-eyes position, there were no significant differences in trace area, trace length, and velocity of the center of pressure (COP) either with or without vibration stimuli. However, in the closed-eyes position, the vibration stimuli significantly decreased trace area, trace length, and velocity of the COP compared with when no vibration stimuli were applied. [Conclusion] These results suggest that vibration stimuli applied to the lower leg improve balance when a person’s eyes are closed during double-leg quiet standing.Key words: Vibration, Center of pressure, Quiet standing     

The Effects of Aerobic Exercise and Strengthening Exercise on Pain Pressure Thresholds

[Purpose] We assessed the effects of aerobic exercise and strengthening exercise on pain pressure thresholds (PPTs) over time. [Subjects and Methods] Fifteen healthy participants were recruited and randomly divided into 3 groups: aerobic exercise, strengthening exercise, and control. The subjects in the aerobic group walked on a treadmill for 40 min at 6.5 km/h. The subjects in the strength group performed circuit training that included bench press, lat pull down, biceps curl, triceps extension, and shoulder press based on the perceived exertion for 40 min. The subjects in the control group rested without any exercise in a quiet room for 40 min. The PPTs of 5 potential muscle trigger points before exercise, and immediately after 10 and 40 min of exercise or rest were measured using an electronic algometer (JTECH Medical, USA). The Friedman’s, Kruskal-Wallis, and Mann-Whitney tests were performed using SPSS 18.0 (IBM, Korea). [Results] The PPTs of all subjects decreased after 10 min of exercise, but the difference was not statistically significant. The PPTs of the control group decreased after 40 min. Furthermore, the PPTs of 3 muscles increased after 40 min of aerobic exercise and of 6 muscles after 40 min of strengthening exercise. No significant difference in PPTs was noted among the groups. [Conclusion] The results show that 40 min is a more appropriate exercise time, although the efficacy of controlling pain did not differ between strengthening exercise and aerobic exercise.Key words: Aerobic exercise, Strengthening exercise, Pain pressure thresholds     

Effects of orthosis on balance and gait in healthy adults

[Purpose] This study evaluated the effects of an oral orthosis that can change body alignment on the balance ability and gait of healthy adults. [Subjects and Methods] The subjects of this study were 21 University students. A gait analyzer was used to analyze the subjects’ balance ability and gait quality. Two walking speeds were used: 2 km/h, a comfortable speed, and 4 km/h, a slightly faster walking speed. [Results] The step length, and base of gait at 2 km/h differed significantly after the intervention. The total step time and step length increased significantly after the intervention. Furthermore, the total base of gait decreased significantly after the intervention. The step times of the left lower limb at 4 km/h differed significantly after the intervention. [Conclusion] The oral orthosis tested positively affects the balance ability and gait of healthy adults.Key words: Orthosis, Balance, Gait