| Summary: | 博士 === 中山醫學大學 === 醫學研究所 === 104 === Purpose: The aim this study was to investigate the effects of whole-body vibration training with different frequencies on the balance and flexibility of the healthy elderly. And according to the result of vibration frequencies parameters that add to a visual feedback-deprived plus WBV (VFDWBV) on balance and lower-extremity muscle strength in the elderly.
Study design: A single-blind randomized trial.
Subject: In different vibration frequency group: A total of 45 subjects, with a mean age of 69.6 ± 3.9 years, were randomly divided into three groups. The subjects were randomly divided into three groups: a high-frequency vibration group (40 Hz, n=15), a low frequency vibration group (20 Hz, n=15), and a no vibration control group (0Hz, n=15). In vibration training without visual feedback A total of 45 elderly subjects with an average age of 69.22±3.97 years, divided into a WBV group (n=14), a VFDWBV group (n=17), and a control group (n=14), completed the trial. The WBV training last for 3 months, and the subjects received WBV training 3 times per week for 5 min each time.
Parameter: In different vibration frequency training: The participants in the experiment all received assessments at Pre-training, Mid-training (Month 1), Post-training (Month 3), and Follow-up (Month 6). The assessment included the limits of stability test and the sit and reach test. In VFDWBV: The evaluation items included the limits of stability (LOS) test and evaluation of the strength of the knee extensor/flexor muscles.
Result: There was a significant inter action in the limits of stability test and the sit and reach test of the different groups at the four time points (F = 25.218, p < 0.001, F = 12.235, p < 0.001, respectively), showing that the 20 Hz group experienced a more positive effect on balance and flexibility than those in the 40 Hz and control groups at the four different measured time points. Post hoc analysis and comparison indicated significant differences in balance performance among the 20 Hz group, the 40 Hz group, and the control group at Month 1, Month 3, and Month 6 (p < 0.001). There was a significant difference between the 40 Hz group and the control group upon termination of the 3-months vibration training (p = 0.033); however, the differences at other time points did not reach statistical significant. The flexibility performances of the 20 Hz group improved more than those of the 40 Hz group and the control group at Month 1, Month 3, and Month 6. However, the difference did not reach statistical significant (p > 0.05). The within group effect of the improvement on the sit and reach test of the 20 Hz vibration training group was the most significant, and lasted to Month 6 (F = 33.280, p < 0.001). The within-group effect of the 40 Hz vibration training group lasted to Month 6 (F = 7.623, p = 0.005). Within the study period, it was found that the probability of medical appointments due to falls in the 20 Hz group was 0% (0/15), that in the 40 Hz group was 6.7% (1/15), and that in the control group was 20% (3/15). The number of medical appointments due to falls in the 20 Hz group was lower than that in the other two groups. However, the difference did not reach statistical significance (p = 0.302).
There were statistically significant differences in balance performance among the 3 groups at different time points (time X group interaction: F = 13.213,p < 0.001). In addition, the post hoc comparison showed that balance performance was better in the VFDWBV group and the WBV group than in the control group at Month 3 and Month 6 (p < 0.001). The strength of the knee extensor and knee flexor muscles had time x group interactions: F = 29.604, p < 0.001 and F = 4.684, p = 0.015, respectively. Relative to the pre-training performance, the post-training knee extensor strength of the VFDWBV group improved by 37.89% (p < 0.001), and the post-training knee flexor strength improved by 19.40% (p = 0.002). However, only the knee extensor strength of the WBV group showed improvement, with an increase of 15.40% (p < 0.001). There was no significant improvement in the control group. At the 6-month follow-up, 0 subject from the WBV group (0%, 0/14), 0 subject from the VFDWBV group (0%, 0/17), and 4 subjects from the control group (28.57%, 4/14) reported hospital visits due to falls. Fisher exact test found that the incidence of falls was higher in the control group than in the other groups (p = 0.013).
Conclusion: Whole-body vibration training at 20 Hz has significant benefit to the balance and flexibility of the elderly who do not engage in habitual exercise. WBV training at 20 Hz without visual feedback can significantly improve the balance performance and lower-extremity muscle strength of the elderly.
Key words: whole-body vibration; balance; flexibility; elderly
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