Individual Responses to Different Vibration Frequencies Identified by Electromyography and Dynamometry in Different Types of Vibration Application

Effects of whole-body vibration training combined with KAATSU training on lower limb joint muscle strength in older women

Objective: This study aimed to investigate the effect of whole-body vibration training (WBVT) combined with KAATSU training (KT) on lower limb joint muscle strength and to provide a reference for improving muscle strength in older women. Methods: A total of 86 healthy older people was randomly divided into WBVT group (WG, n = 21), KT group (KG, n = 22), combined intervention group (CIG, n = 20) and control group (CG, n = 23). WG and CIG subjects underwent WBVT, and KG and CIG subjects underwent 150 mmHg and lower limb joint and local compression intervention for 16 weeks (three times per week, about 15 min/time). The peak torque (PT) and endurance ratio (ER) of joint flexion or extension were tested for all subjects. Results: 1) Results at 16 weeks were compared with the baseline data. The knee extension and ankle flexion PT (60°/s) in CIG increased by 14.3% and 15.3%, respectively (p < 0.05). The knee extension PT (180°/s) increased by 16.9, 18.4% and 33.3% in WG, KG and CIG (p < 0.05), respectively, and the ankle extension PT (180°/s) in CIG increased by 31.1% (p < 0.05). The hip, knee extension and ankle flexion ER increased by 10.0, 10.9% and 5.7% in CIG (p < 0.05), respectively. 2) Results were compared among groups at 16 weeks. The relative changes were significantly lower in WG, KG and CG compared to CIG in the knee extension and ankle flexion PT (60°/s) (p < 0.05). The relative changes were significantly greater in WG, KG and CIG compared to CG in the knee extension PT (180°/s) (p < 0.05). The relative changes were significantly lower in WG, KG and CG compared to CIG in the ankle extension PT (180°/s) (p < 0.05). The relative changes were significantly lower in WG, KG and CG compared to CIG in the hip extension ER (p < 0.05). The relative changes were significantly lower in CG compared to CIG in the knee extension ER (p < 0.05). Conclusion: Sixteen-week WBVT and KT increased the knee extensor strength in older women. Compared with a single intervention, the combined intervention had better improvements in the knee extensor and ankle flexor and extensor strength and hip extension muscle endurance. Appears to be some additional benefit from combined intervention above those derived from single-interventions.

The Effects of Vibration Exposure on Lower-Limb Extensor Muscles' Stiffness, Elasticity, and Strength Responses in Untrained Young Individuals: A Randomized Controlled Trial

OBJECTIVES

The whole-body vibration (WBV) effects on muscle strength show inconsistent results. Moreover, there is no study about the WBV effect on stiffness, elasticity, and muscle strength. Therefore, the study aimed to examine the effect of WBV exposure with static squat posture on the stiffness, elasticity, and strength of the lower-limb extensor muscles.

MATERIAL AND METHODS

Forty healthy untrained young adults were divided into WBV and control groups. The experimental group received WBV exposure on 2 nonconsecutive days of the week, for 6 weeks. The MyotonPRO device was used for the assessment of the knee extensor and the ankle dorsiflexors' stiffness and elasticity. Isometric muscle strength was evaluated with a hand-held dynamometer. All measurements were done by the same assessor at baseline, and the following 6 weeks.

RESULTS

Significant group-by-time interactions were found for the elasticity scores of the right (d = 0.84, P = .01) and left (d = 0.77, P = .02) ankle dorsiflexors. Similar to the elasticity measurements, significant group-by-time interactions were observed in the muscle strength scores of the right (d = 0.45, P = .046) and left (d = 1.25, P < .001) ankle dorsiflexors. No significant effects were observed in any of the evaluated muscle stiffness measurements (P > .05), and there was no significant group-by-time interaction in knee-extensor muscle strength and elasticity scores (P > .05).

CONCLUSIONS

The study results indicate that if the ankle dorsiflexor strength and elasticity are desired to be increased, the 6-week WBV exposure in a static squat posture can be used in healthy individuals.

Effect of Multi-Frequency Whole-Body Vibration on Muscle Activation, Metabolic Cost and Regional Tissue Oxygenation

Prolonged immobilization from a critical illness can result in significant muscle atrophy. Whole-body vibration (WBV) could potentially attenuate the issue of muscle atrophy; however, there exists no device that could potentially provide WBV in supine position that is suitable for critically ill patients. Hence, the purpose of this study was to develop a new wearable suit, called therapeutic vibration device (TVD), that can provide WBV in supine position and test its effects on physiologic markers of physical activity including muscle activation, oxygen consumption (VO₂), and regional hemoglobin oxygen saturation (rSO₂). The prototype TVD delivered multi-frequency WBV axially to 19 healthy participants in supine position for 10 minutes simultaneously at 25 Hz/4.2 g_rms on the feet and 15 Hz/0.7 g_rms on the shoulders. Muscle activation was recorded by electromyography (EMG), VO₂ was measured by indirect calorimetry and rSO₂ was recorded by near-infrared spectroscopy. Recordings were collected from each participant from multiple body locations, on three separate days, at baseline and during the intervention. Acceleration was also recorded to gain insight into transmissibility and coherence. Repeated-measures ANOVA using Bonferroni correction revealed that the muscle activity significantly increased by 4% - 62% (p < 0.05), VO₂ improved by 22.3% (p < 0.05) and rSO₂ increased by 1.4% - 4.5% (p < 0.05) compared to baseline. WBV provided by the TVD is capable of producing physiologic responses consistent with mild physical activity. Such effects could potentially be valuable as an adjunct to physical therapy for early mobilization to prevent atrophy occurring from prolonged immobilization.