
The aim of this study is to investigate the effects of whole body vibratory stimulation on muscle strength, balance, and fall efficacy among super-aged women.
Randomized controlled trial.
Twenty-eight super-aged women over 80 years of age were assigned to either the experimental group (n=14) and control group (n=14). The experimental group received an exercise program that used the whole body vibratory stimulation with a frequency of 30 Hz and amplitude of 3 mm, and the control group received an exercise program without vibratory stimulation. Intervention was provided for 4 weeks, 3 sessions per week, and 30 minutes per session. In order to measure lower extremity muscle strength the 30-second chair stand test (CST) was used. The Berg Balance Scale (BBS) was used to measure dynamic balance. Static balance was measured by tracking the path length, velocity, and area of the center of pressure (CoP). The Falls Efficacy Scale (FES) was used to measure the subjects’ fear of falling.
Both the experimental and control group demonstrated statistically significant increase in muscle strength, dynamic balance, and fall efficacy (p<0.05). Only the experimental group showed significant improvements in static balance before and after the intervention (p<0.05). The experimental group showed significantly greater improvements in CST, BBS, and CoP (path length, velocity) than control group (p<0.05).
Whole body vibratory stimulation exercise is shown to be a safe and appropriate physical therapy intervention method to enhance muscle strength, balance, and fall efficacy of super-aged women.
According to Statistics Korea, the number of people over 65 years of age was 7.38 million, constituting 14.3% of the total population in 2018 [1], and it is prospected that 1 out of 5 people will be over the age of 65 years, entering a super-aged society in 2025. The increase in the elderly population is not only a social problem, but also becomes a health issue. One of the health issues that may arise due to decrease in physical function in the elderly population is falls. According to Statistics Korea [2], 21.0% of the population over 65 years of age has experienced falls in 2016, and the hospital admission rate due to falls was 72.4%, where 47.4% have experienced residual effects due to falls. This illustrates the point that fall incidents are increasing along with the increase in the elderly population. Falls are a serious events that jeopardizes the health of the elderly population, and it is declared as the cause of increase in morbidity death rates [3,4].
Physical disability acquired through falls is difficult to recover, and it is considered as a serious health issue because of the high risk for complications when compared with the younger population [5,6]. In addition, normal activities are limited by not only physical impairments, but also by fear of falling, and furthermore, there is a decrease in physical function, resulting in a high risk for falls [7]. Muscle mass decreases due to aging and subsequently leads to decreased muscle strength, endurance, muscle atrophy, and contraction [8]. Additionally, degeneration of somatic senses, visual, vestibular, and central nervous impairments, and other deteriorations are factors that increase the risk of falls by causing problems in balance and gait abilities [9,10].
Gradual resistance exercises may improve the functional status of an elderly person apart from improving the heart function, and muscle strengthening exercises may prevent muscle deterioration [11]. Therefore, various exercise programs have been developed and implemented to decrease the incidence of falls among the elderly population. Some of the most emphasized targets within the programs for fall prevention are increasing lower extremity muscle strength, endurance, and balance [12]. Improvements in balance, muscle strength, and gait are reported to have significant correlations with the quality of life of the elderly population [13].
Recently, the whole body vibrator has been introduced as a method of enhancing muscle function by applying new stimuli to the muscles through synthetic and quantitative control of gravity without putting too much pressure on the body [14,15]. The whole body vibrator provides various frequencies of vibration to stimulate the somatic senses of the participant, and is effective in increasing muscle strength and bone density. There are previous studies that report significant increases in muscle contraction and strength when the whole body vibrator is used in young adults and the elderly [16-18]. Other literature reports effectiveness in postural stability and decreased risk of falls in the elderly [19,20]. Specifically, Cheung
Prior Korean studies that have used the whole body vibrator reports various participant groups, such as athletes [22,23], stroke patients [24], obese women [25], children with cerebral palsy [26], and people with spinal cord injury [27,28], but there are no studies on the effects of the whole body vibrator for the super-aged population over 80 years of age. Therefore, this study aims to investigate the effects of muscle strength, balance, and fall efficacy of super-aged women in their 80s who used the whole body vibrator and clinical implications, and recommend it as a fall prevention intervention method by increasing balance and muscle strength.
Seventy-six women who were over 80 years of age who lived in Jung Hwa nursing facility located in Iksan were recruited for this study. The inclusion criteria were super-aged elderly over 80 years of age, able to perform independent activities of daily living, able to walk 15 minutes or more without any assistance, able to perform a semi-squat for 10 seconds, and scored 24 or higher on the Korean version of the Mini-Mental State Examination. The exclusion criteria were women who were diagnosed with nephrotic, hepatic, or cognitive problems, used a pacemaker, any osteopathic issues that may affect the study outcomes, intends to drop out from the study, and participated less than 80% of the intervention. All of the participants were given full explanation of the study purpose, content, procedures, participant rights, and safety issues. The participants agreed and signed the written consent before participating in the study. This study was approved by the Ethical Committee of Daejeon University (IRB No. 1040647-201804-HR-017-01). Written informed consent.
This study was a before-after controlled trial and used G-Power ver. 3.1 (Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany) to determine the number of participants. Based on the main effect outcomes from the preceding research [29] the effect size was set to d=0.938, significance level
The whole body vibration system (SW-VH11; SONIX, Wonju, Korea) was used for the whole body vibration exercise program. The exercise program modified the intervention methods of the preceding study by Bautmans
In order to measure lower extremity muscle strength, the 30-second chair stand test (CST) was conducted [32]. It was measured by counting the number of sit to stands performed within 30 seconds with both arms across the chest. The average was obtained after three measurements.
To assess dynamic balance, the Berg Balance Scale (BBS) was utilized. The BBS is a balance test that can predict the risk of falls of the elderly population in the community and consists of 14 components, each scored from 0 to 4, with a total score of 56. The average value was obtained after three measurements. For static balance ability, the movement distance, speed, and moving area of the center of pressure (CoP) were assessed by using the Wii balance board while maintaining static posture with the subject standing comfortably for 30 seconds. The collected data was analyzed using the Balancia software. The fear of falling during performance of activities of daily living was evaluated by using the Falls Efficacy Scale (FES) [33]. It assesses the subjects’ fear of falling during the performance of 10 different types of actions required for the performance of daily living activities, each scored from 1 to 10. The point system ranges from the minimum of 10 points to a maximum of 100 points, where the lower score, the greater the fear of falling.
The collected data was analyzed using PASW Statistics ver. 18.0 (IBM Co., Armonk, NY, USA). The general characteristics of the participants are provided through descriptive statistics and standard deviation values, and the Shapiro-Wilk test was conducted to test for normality. The general characteristics and the homogeneity test of pre- measured values were analyzed for differences within groups using the independent t-test. Comparisons of effects before and after the interventions within groups were analyzed using the paired t-test. Statistical significance of this study was set to
Within the experimental and control groups, 1 participant in each group withdrew from the study due to not fulfilling the participation rate criteria. Ultimately, the data of 14 participants in the experimental group and 14 participants in the control group were collected for analysis. The general characteristics of participants are described in Table 1, and homogeneity between the groups was determined.
The results of the 30-second CST that was used to determine the changes in lower extremity muscle strength showed significant improvements (
The BBS results showed significant improvements in the before and after intervention measurements for both groups (
The path length, velocity, and area 95% were measured for static balance. The results showed that only the experimental group demonstrated a significant decrease (
The FES was used to measure fall efficacy of the participants, and both groups showed significant improvements for before and after intervention measurements. However, the before and after intervention FES values between the two groups were not statistically significant (Table 3).
Whole body vibration is a new form of exercise that stimulates the muscles with the mechanism of tonic vibration reflex to resist vibration stimuli while maintaining a position. Different muscles may be targeted depending on various positions made on top of the whole body vibrator, and it is an exercise applicable by only maintaining the position without any excessive pressure or resistance. Specifically, this method of training may be provided to the elderly as a safe and easy exercise without any risk of potential danger of involving the cardiovascular system or producing muscle overuse [32]. Over the years, whole body vibration was introduced as a training method for various geriatric diseases and the elderly. This study investigated the effects of whole body vibration on lower extremity muscle strength, balance, and fall efficacy of super-aged elderly women over 80 years of age. The results confirmed that this training method is effective in enhancing balance.
Functional muscle strength of the lower extremities was measured using the 30-second CST. Compared with the results from before the intervention, the experimental group showed an increase of 40.2% (Cohen’s d =1.770) and 18.6% (Cohen’s d=0.639) for the control group. Both groups showed a statistically significant increase (
Prior to the study, the intensity of the exercise program for the super-aged elderly over the age of 80 years was an immense consideration. Many participants reported that the vibration stimuli that they have never experienced were difficult to adjust. Regardless of the difficulties, there was only 1 participant that dropped out from each group. Unlike the study by Bautmans
Along with lower extremity muscle strength, both groups showed a significant increase in dynamic balance before and after the intervention. The BBS results showed 19.7% (Cohen’s d=2.050) improvement in the experimental group and 6.9% (Cohen’s d=0.510) for the control group illustrating that the two groups resulted in significant difference in before and after the intervention measurements. Additionally, the experimental group showed a greater significant difference than the control group.
The application of the whole body vibration exercise also showed a significant difference between groups in static balance ability. The measurement results of the path length and velocity of the CoP showed a significant difference only in the experimental group (path length=6.5%, Cohen’s d=0.660; velocity=6.5%, Cohen’s d=0.670), and there was a greater significant contribution to postural stability than the control group. The BBS is a gold standard clinical tool that allows the anticipation of fall risks and assesses dynamic balance. This study supports the study by Pollock
Increases in muscle strength and postural control after whole body vibration are also related to decreased frequency of falls. Bruyere
Factors that decide the effects of whole body exercise are frequency, amplitude, and velocity, with the most important factor being frequency. Many studies of the effects of various frequencies of whole body vibration show different results. This study utilized the frequency of 30 Hz and the amplitude of 3 mm as suggested by Rittweger [40] and Di Giminiani
These results may suggest that whole body vibration exercise is an effective program for super-aged elderly participants over the age of 80 years when appropriately constructed and frequency and amplitude are considered. However this study had a few limitations. First, participants without any particular issues with physical function were selected; thereby it is difficult to generalize the result to all super-aged elders over 80 years of age. The second limitation is that individual lifestyle habits, environmental factors, and nutritional status were difficult to control due to various dwelling habits in a nursing facility. Thirdly, the durability of the intervention effects cannot be confirmed. Further studies need to minimize these limitations along with other problems that may rise and investigate the long-term effects of whole body vibration exercise in super-aged elders with geriatric conditions by designing an appropriate exercise program.
In conclusion, this study aimed to investigate the effects of applying a whole body vibrator on muscle strength, balance, and fall efficacy of super-aged women over 80 years of age. The results showed that the whole body vibrator is a safe and applicable exercise method to increase muscle strength and balance. Future studies are warranted to confirm the effects of the whole body vibrator on other impairments from a wider range of subjects, and the results may need to be reviewed for clinical usability.
This work was supported by the Korea Foundation for the Advancement of Science & Creativity (KOFAC), and funded by the Korean Government (MOE) (No. 20180217).
The authors declared no potential conflicts of interest with respect to the authorship and/or publication of this article.
General characteristics of participants (N=28)
Variable | Experimental group (n=14) | Control group (n=14) | t ( |
---|---|---|---|
Age (y) | 83.14 (3.92) | 84.00 (3.80) | −0.587 (0.562) |
Height (cm) | 146.39 (5.97) | 148.64 (5.16) | −1.067 (0.296) |
Weight (kg) | 55.82 (11.29) | 58.50 (9.40) | −0.682 (0.501) |
Body mass index (kg/m2) | 25.96 (4.48) | 26.49 (3.98) | −0.332 (0.742) |
Values are presented as mean (SD).
Comparison of lower extremity muscle strength and dynamic balance ability between groups (N=28)
Variable | Experimental group (n=14) | Control group (n=14) | t ( |
---|---|---|---|
CST (score) | |||
Pre | 6.920 (1.660) | 7.300 (2.100) | −0.530 (0.601) |
Post | 9.700 (1.460) | 8.660 (2.150) | |
Pre-post | −2.790 (1.290) | −1.360 (1.200) | 2.925 (0.007) |
t ( | −8.053 (<0.001) | −4.241 (0.001) | |
BBS (scores) | |||
Pre | 39.500 (4.740) | 41.500 (5.320) | −1.051 (0.303) |
Post | 47.290 (2.490) | 44.360 (5.930) | |
Pre-post | 7.780 (4.020) | 2.860 (3.010) | 3.671 (0.001) |
t ( | −7.242 (<0.001) | −3.553 (0.004) |
Values are presented as mean (SD).
CST: 30-second chair stand test, BBS: Berg Balance Scale.
Comparison of static balance ability and fall efficacy between groups (N=28)
Variable | Experimental group (n=14) | Control group (n=14) | t ( |
---|---|---|---|
CoP path length (cm) | |||
Pre | 87.270 (8.110) | 87.180 (7.150) | 0.030 (0.976) |
Post | 81.580 (9.030) | 87.450 (11.705) | |
Pre-post | 5.690 (6.690) | −0.260 (7.830) | 2.162 (0.040) |
t ( | 3.180 (0.007) | −0.126 (0.902) | |
CoP velocity (cm/s) | |||
Pre | 2.910 (0.270) | 2.910 (0.240) | 0.044 (0.965) |
Post | 2.720 (0.300) | 2.910 (0.390) | |
Pre-post | 0.180 (0.220) | −0.010 (0.260) | 2.130 (0.043) |
t ( | 3.193 (0.007) | −0.123 (0.904) | |
CoP area 95% | |||
Pre | 5.420 (1.820) | 4.940 (1.950) | 0.664 (0.512) |
Post | 6.480 (2.150) | 5.520 (1.910) | |
Pre-post | −1.070 (2.310) | −0.570 (2.130) | −0.584 (0.564) |
t ( | −1.724 (0.108) | −1.012 (0.330) | |
FES (scores) | |||
Pre | 74.290 (17.830) | 74.500 (14.550) | −0.035 (0.972) |
Post | 86.140 (16.990) | 83.360 (15.590) | |
Pre-post | −11.860 (10.305) | −8.860 (8.500) | 0.838 (0.410) |
t ( | –4.286 (0.001) | −3.898 (0.002) |
Values are presented as mean (SD).
CoP: center of pressure, FES: Falls Efficacy Scale.