Managing Vibration Training Safety by Using Knee Flexion Angle and Rating Perceived Exertion.

Whole-body vibration (WBV) is commonly applied in exercise and rehabilitation and its safety issues have been a major concern. Vibration measured using accelerometers can be used to further analyze the vibration transmissibility. Optimal bending angles and rating of perceived exertion (RPE) evaluations have not been sufficiently explored to mitigate the adverse effect. Therefore, the aims of this study were to investigate the effect of various knee flexion angles on the transmissibility to the head and knee, the RPE during WBV exposure, and the link between the transmissibility to the head and the RPE. Sixteen participants randomly performed static squats with knee flexion angles of 90, 110, 130, and 150 degrees on a WBV platform. Three accelerometers were fixed on the head, knee, and center of the vibration platform to provide data of platform-to-head and platform-to-knee transmissibilities. The results showed that the flexion angle of 110 degrees induced the lowest platform-to-head transmissibility and the lowest RPE (p < 0.01). A positive correlation between RPE and the platform-to-head transmissibility was observed. This study concluded that a knee flexion of about 110 degrees is most appropriate for reducing vibration transmissibility. The reported RPE could be used to reflect the vibration impact to the head.

Augmented reality-assisted training with selected Tai-Chi movements improves balance control and increases lower limb muscle strength in older adults: A prospective randomized trial.

BACKGROUND: Tai-Chi benefits older adults by enhancing balance control and increasing the muscle strength of the lower limbs. However, a complete set of traditional Tai-Chi exercises is sometimes too difficult for beginners. We investigated whether practicing augmented reality-assisted training with selected Tai-Chi movements tailored to the practitioner's ability (selected Tai-Chi, or sTC) is as effective as performing a complete set of Tai-Chi sequences (complete traditional Tai-Chi, or tTC). METHODS: In this prospective randomized trial carried out in the Beitou District of Taipei City, Taiwan, community-dwelling adults aged ≥65 and without any debilitating diseases (n = 28) were included. Participants were randomly assigned to the sTC group (n = 14) or the tTC group (n = 14). Participants in the sTC group practiced selected Tai-Chi movements using the augmented reality Tai-Chi training system. Participants of the tTC group were asked to complete the 24-form Yang-style Tai-Chi following the instructions of Tai-Chi masters. Each training session lasted 30 min, with 3 sessions per week for 8 weeks. Pre- and post-intervention evaluations included functional balance tests, comprising the Berg Balance Scale (BBS), Timed Up and Go test (TUG), and Functional Reach Test (FRT), as well as muscle strength measurements of the lower extremities. RESULTS: Pre-intervention evaluations showed significant differences in FRT (p = 0.034) and left hip abductor muscle strength (p = 0.046) between the sTC and tTC groups. After 8 weeks of training, the BBS, TUG, and FRT scores in the sTC group showed significant improvement overall. Although all three functional balance test scores improved in the tTC group, only the improvement in BBS was statistically significant (p = 0.001). After 8 weeks, all muscle strength measurements increased by an average of 3.1 ± 1.0 kgw in the sTC group and 1.6 ± 0.8 kgw in the tTC group. CONCLUSIONS: The augmented reality-assisted training with selected Tai-Chi movements, designed based on objective measurements of the practitioner's capability, improved balance control and muscle strength of lower limbs at least as effectively as the complete sequence of traditional Tai-Chi exercises. TRIAL REGISTRATION: This study was approved by the Institutional Review Board of National Yang-Ming University (IRB number: 1000087). Written informed consent was obtained from all participants.

Feasibility and outcome of an individualized Tai Chi program for improving balance and strength in the elderly: A pilot study.

BACKGROUND: Traditional Tai Chi is too complex for most elderly individuals. There have been few reports regarding the development of simplified Tai Chi programs to suit the physical needs of elderly adults. However, these programs were not individualized according to the participants' balance control abilities. OBJECTIVE: Purpose of this study is to develop an individualized Tai Chi program and report the feasibility of the program. METHODS: Phase 1: Five Tai Chi masters performed the Tai Chi movements on a force platform. Based on the results of center of pressure displacement and the individual's balance abilities, an individualized program was developed.Phase 2: Ten community-dwelling older adults received 24 half-hour-sessions, using the individualized Tai Chi exercise program. The Berg Balance Scale (BBS) score, Timed Up & Go (TUG) test, forward reach, and strength of the knee extensor were determined before and after intervention. RESULTS: Participants achieved improved performance on balance control as measured with BBS (p≤0.001), TUG (p = 0.004) and forward reach (p = 0.035) as well as knee extensor strength (p = 0.002) after the program. CONCLUSIONS: This preliminary result suggests that the individualized Tai Chi program is potentially effective to improve balance function and knee extensor strength of the elderly.

Chronic effects of whole-body vibration on jumping performance and body balance using different frequencies and amplitudes with identical acceleration load.

UNLABELLED: Previous studies on vibration training have all been based on protocols at different combinations of frequencies and amplitudes without controlling the loading intensity. OBJECTIVES: This study investigated the effect of an 8-week vibration training program, under identical acceleration loads with various frequencies and amplitudes, on jumping performance, muscle activation and body balance. DESIGN: Fifty young adults were randomly assigned to an high-frequency (32 Hz, 1mm, and 4 g), low-frequency (18 Hz, 3 mm, and 4 g), or a control group. The high-frequency and low-frequency groups underwent 60 s of squats exercise on the specific vibration platform three times a week, whereas the control group was trained without vibration. METHODS: A force platform was used to measure the center of pressure of a static single leg stance, and the heights and impulse of two consecutive countermovement jumps before and after intervention. The activation of the rectus femoris and biceps femoris were also measured synchronously by surface electromyography. RESULTS: The heights and impulse of both the first and second countermovement jumps were significantly increased and the area of center of pressure was significantly decreased after training in both the high-frequency and low-frequency groups (P<.05). Consequently, activation of the rectus femoris during the first countermovement jump was significantly lower than the pre-training value in the HF group but increased in the low-frequency group after training (P<.05). CONCLUSIONS: An 8-week identical acceleration vibration training regimen with various frequencies and amplitudes can significantly improve jumping performance and body balance, but the specific neuromuscular adaptation is possibly induced by different training settings.

The effects of tai chi chuan combined with vibration training on balance control and lower extremity muscle power.

The aim of this study was to determine whether performing Tai Chi Chuan on a customized vibration platform could enhance balance control and lower extremity muscle power more efficiently than Tai Chi Chuan alone in an untrained young population. Forty-eight healthy young adults were randomly assigned to the following three groups: a Tai Chi Chuan combined with vibration training group (TCV), a Tai Chi Chuan group (TCC) or a control group. The TCV group underwent 30 minutes of a reformed Tai Chi Chuan program on a customized vibration platform (32 Hz, 1 mm) three times a week for eight weeks, whereas the TCC group was trained without vibration stimuli. A force platform was used to measure the moving area of a static single leg stance and the heights of two consecutive countermovement jumps. The activation of the knee extensor and flexor was also measured synchronously by surface electromyography in all tests. The results showed that the moving area in the TCV group was significantly decreased by 15.3%. The second jump height in the TCV group was significantly increased by 8.14%, and the activation of the knee extensor/flexor was significantly decreased in the first jump. In conclusion, Tai Chi Chuan combined with vibration training can more efficiently improve balance control, and the positive training effect on the lower extremity muscle power induced by vibration stimuli still remains significant because there is no cross-interaction between the two different types of training methods. Key pointsEight weeks of Tai Chi Chuan combined with vibration training can more efficiently improve balance control for an untrained young population.The positive training effect on the lower extremity muscle power induced by vibration stimuli during Tai Chi Chuan movements still remains significant because of SSC mechanism.Combining Tai Chi Chuan with vibration training is more efficient and does not decrease the overall training effects due to a cross-interaction of each other.