Effects of Low-Frequency Whole-Body Vibration on Muscle Activation, Fatigue, and Oxygen Consumption in Healthy Young Adults: A Single-Group Repeated-Measures Controlled Trial.

CONTEXT: Whole-body vibration (WBV) training improves muscle strength and balance. Few studies have focused on the effects of WBV frequencies below 30 Hz. We aimed to investigate the effect of low-frequency WBV training on muscle activity, fatigue recovery, and oxygen consumption (VO2). DESIGN: Prospective single-group, repeated-measures study. METHODS: In this controlled laboratory setting study, 20 healthy adults (age 23.26 [1.66] y) performed half squats at 0, 4, 6, 8, 12, 16, 20, 24, and 30-Hz WBV. Muscle activity was evaluated using the root mean square and peak electromyography amplitude of 6 muscles (iliocostalis, rectus abdominis, rectus femoris, biceps femoris, tibialis anterior, and gastrocnemius) obtained via surface electromyography. VO2 was measured during the squats using a gas analyzer, and fatigue recovery was evaluated using measurements of lactate after the squats and after a recovery period. Statistical significance was set at P < .05, and analysis of variance was conducted to determine differences in muscle activity, fatigue, recovery, and VO2, with post hoc analyses as appropriate. RESULTS: Of the 6 muscles measured, the muscle activity of the gastrocnemius alone significantly increased from 0 Hz at 4, 8, 12, 16, 24, and 30 Hz based on the root mean square values and at 4, 8, 12, and 30 Hz based on the peak electromyography amplitude values. There were no significant differences in the other muscles. There were no significant differences in VO2 or in lactate levels. CONCLUSIONS: Low-frequency WBV during squat exercises significantly increased the activity of the gastrocnemius medialis only at specific frequencies in healthy young adults. Low-frequency WBV is safe and has the potential to increase muscle activity.

Does the Periprosthetic Fracture Pattern Depend on the Stem Fixation Method in Total Hip Arthroplasty?

Background: Management of periprosthetic femoral fractures (PFFs) is reportedly challenging. Different patterns of PFFs would occur based on whether stem fixation was primarily cemented or cementless and whether these patterns would be associated with clinical outcomes, such as subsidence, fracture union, and complications, after stem revision. Methods: A retrospective comparative study was performed, involving 52 PFF patients treated with tapered fluted modular stems (TFMSs). In the 52 patients with Vancouver B2 or B3, including 21 cemented stems and 31 cementless stems, fracture patterns and bone stock were analyzed. Clinical outcomes after revision surgery using the TFMSs were compared between the two groups. Results: Transverse or short oblique type PFFs occurred around the cemented stem with loosening at the bone-cement interface. The Paprosky type III femoral deficiency and Vancouver type B3 fracture were observed more frequently in the cemented stem group. Otherwise, spiral fractures occurred more frequently in the cementless group (p < 0.001). Excessive subsidence of > 5 mm was observed more frequently in the cemented stem group (p < 0.001). The re-revision rates were higher in the cemented group than in the cementless group (p = 0.047). Conclusions: In our study, it was found that the patterns of transverse or oblique PFFs were more frequently produced with cemented stems, while long spiral fractures were more frequent with cementless stems. Stem subsidence and reoperation related to complications were more common in patients with PFFs around cemented stems than those with PFFs around cementless stems.

The development of split-treadmill with a fall prevention training function.

BACKGROUND: The weakening of the ability of the elderly to perform gait is becoming a major cause of the increase in the frequency of falls. OBJECTIVE: In this study, we designed and manufactured a treadmill capable of restraining walking by providing a sudden repulsive force on the left and right legs of a pedestrian when walking for the fall prevention training of the elderly. Through this, it is possible for the elderly person to strengthen the lower extremity muscles to prevent and prepare for falling through the fall prevention training similar to the fall environment that may occur in daily life. METHOD: The development system includes a motor for generating a driving force in the form of a left and a right driving system and a belt separated from each other, an electromagnetic clutch for rapidly stopping the running belt of the motor transmitted to the running belt to stop the running belt, and a controller for controlling the driver. RESULTS: In order to evaluate the development system, the motor driving ability test and the power transmission, connection and shut-off performance of the electromagnetic clutch were carried out. The subject's muscle activity of the lower extremity muscles was evaluated when the running belt stopped at the beginning of the right folding. CONCLUSION: It is expected that the developed dual function system would be helpful for the fall prevention exercise as well as the rehabilitation exercise for patients who have recovered from surgery or hemiplegic patients.

Effectiveness of Whole-Body Vibration Training to Improve Muscle Strength and Physical Performance in Older Adults: Prospective, Single-Blinded, Randomized Controlled Trial.

Whole-body vibration training (WBVT) is emerging as an alternative exercise method that be easily performed by older adults. This clinical trial investigates the efficacy of WBVT in improving muscle strength and physical performance before resistance exercise, in comparison to conventional resistance exercise after stretching exercise in older adults. The WBVT group (n = 20) performed WBVT using a vibrating platform (SW-VC15™), followed by strengthening exercises. The control group (n = 20) performed stretching instead of WBVT. Both groups underwent a total of 12 sessions (50 min per session). The primary outcome was isokinetic dynamometer. The secondary outcomes were grip strength, short physical performance battery (SPPB), a 36-Item Short Form Survey (SF-36), and body composition analysis. In all results, only the time effect was significant, and the group effect or time x group effect was not. Both groups showed a significant increase in isokinetic dynamometer. Although there was no significant group effect, the increase in mean peak torque was greater in the WBVT group. The only WBVT group showed significant improvement in SPPB. In SF-36, only the control group showed significant improvements. WBVT can be safely performed by older adults and may be an alternative exercise method to boost the effect of strengthening exercise.

Clinical evaluation of the effectiveness of a new orthotic device for the non-operative treatment of scoliosis.

BACKGROUND: Bracing is one of the oldest non-operative treatments for patients with scoliosis. However, a wide variety of braces is used, and some show no effect, while others show conflicting results. OBJECTIVE: We aimed to evaluate the effectiveness of a new orthotic device for the treatment of adult scoliosis. METHODS: Twenty adult patients who were diagnosed with scoliosis and qualified for the study were selected and all participants were treated for 12 hours/day for 12 weeks using a new orthotic device. Various efficacy assessments (Cobb's angle, spine length, pelvic angle, shoulder angle, thoracic angle, lumbar angle, pelvic sacral angle) were performed before and after the 12-week treatment. The values at each time point were compared. RESULTS: There were significant treatment effects in a time-dependent manner on every efficacy assessment (p< 0.05) after 12 weeks of bracing. CONCLUSION: In this clinical study, it was demonstrated that a new brace that is more comfortable for the wearer reduced scoliosis and may be a useful option for non-operative treatment of scoliosis.

The effect of exercise load deviations in whole body vibration on improving muscle strength imbalance in the lower limb.

BACKGROUND: The amount of patients with muscle imbalance of the left and right side increases rapidly due to an incorrect lifestyle. OBJECTIVE: We investigated the optimal exercise load required to improve muscle imbalance. METHODS: Thirty participants were enrolled in the study. They performed squat exercises according to a whole body vibration (WBV) frequency protocol over a period of eight weeks. The exercises were performed three days a week and comprised five sets of fifteen trials per set per day. We validated muscle imbalance improvement using WBV by comparing and analyzing the results at different vibration frequencies. The participants were divided into three WBV protocol groups: no WBV, low-frequency WBV (25 Hz and 5 mm amplitude), and high-frequency WBV (50 Hz and 5 mm amplitude). We estimated the isokinetic muscle functions of the hip, knee, and ankle joints using BIODEX system 3. Ultimately, low-frequency WBV improved balance 10.2 ∼ 26.5% more than high-frequency WBV. RESULTS: Continuous load-deviation motions during low-frequency WBV were more effective at improving muscle imbalance than high-frequency WBV. WBV load variation methods improved muscle function and contractility more than external weights or loads by directly transferring kinetic energy into the body. CONCLUSION: In this clinical study, we demonstrated that low-frequency WBV was more effective at improving muscle imbalance. The WBV protocol can be used in rehabilitation programs to improve imbalance without requiring elderly or physically decompensated patients to participate in excessive exercise.

A study on trunk muscle activation patterns according to tilt angle during whole body tilts.

BACKGROUND: Lower back pain has a lifetime prevalence of 80% for people in a modern society, and in recent years, spinal stabilization movement has been highlighted as a method to treat lower back pain and an unbalanced position. OBJECTIVE: The objectives of this study were to assess the trunk muscle activities in accordance with the tilt angles (10∘, 20∘, 30∘, 40∘) during trunk tilt exercises with a 3D dynamic exercise device. METHODS: Active tilt mode (a self-generated active movement in the angle and direction steered by the user) was used in this study. The rotation capability enabled the investigation of the anterior (A), anterior right (AR), right (R), posterior right (PR), posterior (P), posterior left (PL), left (L), and anterior left (AL) tilt directions. EMG signals of the trunk (3 global muscles: rectus abdominis, RA, external obliques, EO, latissimus dorsi, LD, and 1 local muscle: multifidus, MF) muscles were obtained. RESULTS: The MF muscle activity was higher while the anterior tilt was maintained, and the abdominal muscle activity was higher while the posterior tilt was maintained. Also, as the tilt angle increased, the activity of the muscles opposite the tilt direction increased. CONCLUSIONS: The results indicate that to maintain equilibrium through posture stabilization during whole body tilting, the human body maintains a proper interaction among the body segments as well as between the body and the execution environment. Moreover, stability is maintained through the co-contraction of antagonistic and agonistic muscles. In future studies, it will be important to conduct research on improving imbalance in the trunk muscles.

Effect of whole body vibration on lactate level recovery and heart rate recovery in rest after intense exercise.

OBJECTIVE: In this paper, we investigated the recovery of the lactate level, muscular fatigue, and heart rate recovery (HRR) with respect to whole body vibration (WBV) during the rest stage after a gait exercise. METHODS: A total of 24 healthy subjects with no medical history of exercise injury participated. The participants were divided into a training group with vibration during rest and a control group with the same conditions but without vibration. The subjects performed a gait exercise with a slope of 15% and velocity of 4 km/h to consume 450 kcal in 30 min. Then, they rested on a vibrating chair or on a chair without vibrations for 30 min. The vibration protocol consists of a frequency of 10 Hz and amplitude of 5 mm. To estimate the recovery effect, we measured the lactate levels in blood, spectral edge frequency (SEF) of MVIC, and HRR before, immediately after exercise, and after rest. RESULTS: The results showed that the lactate level in the training group decreased more (93.8%) than in the control group (32.8%). Also, HRR showed a similar trend with a recovery of 88.39% in the training group but 64.72% in the control group. We considered that whole-body vibrations during rest would help remove lactic acid by improving the level of lactic acid oxidation with stimulated blood vessels in the muscles and by helping to maintain blood flow. Also, WBV would lead to compensation to actively decrease the fast excess post-exercise oxygen consumption from blood circulation. CONCLUSIONS: We suggest that whole-body vibrations during rest can provide fast, efficient fatigue recovery as a cool down exercise for women, the elderly, and patients without other activity after intense exercise.

Effect of vibration on muscle strength imbalance in lower extremity using multi-control whole body vibration platform.

This study shows the improvement of muscle activity and muscle strength imbalance in the lower extremities through independent exercise loads in vibration platform. Twenty females of age 20 participated in this study. The subjects were divided into WBV group, with more than 10% of muscle strength imbalance between left and right the lower extremities, and control group, with less than 10% of muscle strength imbalance between left and right the lower extremities. As the prior experiment showed, different exercise postures provide different muscular activities. As a result, the highest muscular activity was found to be in the low squat posture. Therefore, the LS posture was selected for the exercise in this experiment. Vibration intensities were applied to dominant muscle and non-dominant muscle, and the vibration frequency was fixed at 25Hz for the WBV group. The control group was asked to perform the same exercise as the WBV group, without stimulated vibration. This exercise was conducted for a total of 4 weeks. As a result, the WBV group which showed an average deviation of 16% before the experiment, tended to decrease approximately to 5%. In this study, vibration exercise using load deviation is shown to be effective in improving the muscle strength imbalance.

Preliminary study on verifying the detection of gait intention based on knee joint anterior displacement of gait slopes.

This study investigated the feasibility of the Infrared (IR) sensor-based walking aids for detecting the gait intention. To compensate for the defects of Force Sensing Resistors (FSRs) or force sensors, such as the velocity control problem on gait slopes, we used IR sensors to investigate knee joint anterior displacement in order to recognize the gait intention. We also measure leg muscle activities and foot pressure, in order to verify our investigation. We placed two IR sensors on the rollator center to sense left and right leg walking intentions. We took EMG signals of four leg muscles, and analyzed them. Foot pressure analysis parameters were the measured force and mean pressure. We conducted experiments on twenty young healthy adults. The results show that knee joint anterior displacement increases according to gait slope and velocity. We confirm similar results of knee joint anterior displacement through the IR sensors.

Fundamental study of lower limb muscle activity using an angled whole body vibration exercise instrument.

This research was performed to assess the effects of angled whole body vibration on muscle activity of the lower limbs, by examining adults in their twenties during squat exercises, taking into account two variables of exercise intensity (vibration frequency and gradient). Twenty healthy males in their twenties with previous experience of more than 6 month's weight training and no past medical history were included in this study. The experiment was performed by participating in squat exercises which consisted of 3 sets (1 set = 5 seconds x 3 repetitions of exercise), and the muscle activities of the Rectus Femoris, Vastus Lateralis, Vastus Medialis were measured with variation in the gradients of 0°, 10°, and 20°, and vibration frequencies of 20, 30, and 40 Hz. At 30 and 40 Hz, the vastus lateralis showed the highest change in muscle activity, while activity of the vastus medialis also increased significantly. Analysis of muscle activity according to the gradient showed a significant increase of the vastus lateralis at 20°, while the highest muscle activity at 20° was observed for the vastus medialis. In comparison of the change in lower limb muscle activity according to simultaneous stimulation, at a gradient of 10°, high activity was shown in muscle, while at 20°, high muscle activities were produced at 40 Hz in the vastus lateralis, 40 Hz in the rectus femoris, and both 30 and 40 Hz in the vastus medialis.

Analysis of basal physical fitness and lumbar muscle function according to indoor horse riding exercise.

The aim of this study is to verify the effect of indoor horse riding exercise on basal physical exercise and lumbar muscular function. The subjects included were 20 healthy females, who participated in the horse riding exercise using SRider (Rider Co. & ChonbuK National Univ, Korea) for 30 minutes per day, 3 days per week, over a period of 8 weeks. The subjects were divided into 4 groups as follows, with 10 subjects in each group: Postural Balance Exercise mode (PBE), Abdomen Exercise mode (ADE), Whole body Exercise mode (WBE), and Multiple Exercise (MTE). Isokinetic muscular function test was performed before and after the horse riding exercise, to assess the effect of horse riding on basal physical exercise and lumbar muscular function. The test result on basal physical exercise and isokinetic muscular function showed improvements with variable degree in the back muscle strength, maximum joint torque, total work, and muscular acceleration time. The result signifies that the horse riding is an antagonistic exercise mainly performed on waist and abdomen area, and the machine induces persistent muscle contraction and causes myotonic induction enhancing the muscle strength. Indoor horse riding exercise proved its effectiveness for senior or the disabled people who need muscle exercises but have difficulties performing outdoor activities.

Comparative analysis of basal physical fitness and muscle function in relation to muscle balance pattern using rowing machines.

The purpose of this study was to evaluate muscle function and basal physical fitness in relation to muscle balance pattern using rowing machines. Twenty four subjects participated in this study, using three different rowing machines. Rowing exercises were performed for twenty-five times a set, four sets a day, 3 days a week, for 8 weeks. Biodex system 3(Biodex Medical Systems Co., New York, USA) was used to measure joint torques in the elbow, shoulder, lumbar and knee of subjects, for analyzing muscle function. The evaluation of basal physical fitness included body composition, muscle strength, muscle endurance, muscle reaction, agility, flexibility and explosive power. Before the experiment, significant differences of joint torques in the elbow, shoulder, lumbar and knee were present between subjects in the group. After the rowing exercise, significant improvement in every joint was witnessed. All aspects of basic fitness increased significantly, and the most improvement was observed in muscle strength from the joint torque results. As shown in the following results, every joint it was evident to have improved by more than 30% with the use of dependent load deviation type over the previously used water load method. This means that it is more effective for enhancing muscle strength and endurance to keep the muscle balance using dependent load deviation. The human body maintains motor coordination of muscle contraction during exercise. The muscle balances in the upper-lower and left-right arms could assist with effective activation of motor coordination. In this paper, an exercise method using dependent load deviation was demonstrated to be more efficient for improving muscle imbalance and strengthening muscles.

Effect of recovery from muscle strength imbalance in lower limb using four point weight bearing reduction system.

This study was performed to assess the improvement of muscle strength imbalance in the lower limbs using a four point weight bearing reduction system with a two-belt treadmill. Participants, each having differences in muscle function of the left and right legs of over 20%, were divided into two groups of ten. The participants were involved in experiments progressing 40 minutes per day, 3 days per week, during a period of 4 weeks. The maximal peak torque and average power were measured for testing joint torque in the hip, knee and ankle. The results showed the improvement of muscle imbalance as assessed by the maximal muscle strength was the most effective in the hip joint, while the improvement of muscular reaction was the most effective in the knee joint. We suggest that the method of weight bearing reduction could be sufficient to reduce muscle imbalance in the lower limbs.