733525
research-article2017
CRE0010.1177/0269215517733525Clinical RehabilitationLam et al.
CLINICAL REHABILITATION
Original Article
Effects of whole-body vibration on balance and mobility in institutionalized older adults: a randomized controlled trial
Clinical Rehabilitation 1–11 © The Author(s) 2017 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav https://doi.org/10.1177/0269215517733525 DOI: 10.1177/0269215517733525 journals.sagepub.com/home/cre
Freddy MH Lam1, Philip FL Chan2, LR Liao3, Jean Woo4, Elsie Hui4, Charles WK Lai2, Timothy CY Kwok5 and Marco YC Pang1
Abstract Objective: To investigate whether a comprehensive exercise program was effective in improving physical function among institutionalized older adults and whether adding whole-body vibration to the program conferred additional therapeutic benefits. Design: A single-blinded randomized controlled trial was conducted. Setting: This study was carried out in residential care units. Participants: In total, 73 older adults (40 women, mean age: 82.3 ± 7.3 years) were enrolled into this study. Interventions: Participants were randomly allocated to one of the three groups: strength and balance program combined with whole-body vibration, strength and balance program without whole-body vibration, and social and recreational activities consisting of upper limb exercises only. All participants completed three training sessions per week for eight weeks. Outcome measures: Assessment of mobility, balance, lower limb strength, walking endurance, and self-perceived balance confidence were conducted at baseline and immediately after the eight-week intervention. Incidences of falls requiring medical attention were recorded for one year after the end of the training period. Results: A significant time × group interaction was found for lower limb strength (five-times-sit-tostand test; P = 0.048), with the exercise-only group showing improvement (pretest: 35.8 ± 16.1 seconds; posttest: 29.0 ± 9.8 seconds), compared with a decline in strength among controls (pretest: 27.1 ± 10.4 seconds; posttest: 28.7 ± 12.3 seconds; P = 0.030). The exercise with whole-body vibration group had a
1Department
of Rehabilitation Sciences, The Hong Kong Polytechnic University, Kowloon, Hong Kong 2Physiotherapy Department, Shatin Hospital, Shatin, Hong Kong 3Department of Rehabilitation, Jiangsu Provincial Yixing Jiuru Rehabilitation Hospital, Yixing, China 4Medical and Geriatric Unit, Shatin Hospital, Shatin, Hong Kong
5Department
of Medicine and Therapeutics, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong
Corresponding author: Freddy MH Lam, Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong. Email: [email protected]
2
Clinical Rehabilitation 00(0)
significantly better outcome in balance confidence (pretest: 39.2 ± 29.0; posttest: 48.4 ± 30.6) than the exercise-only group (pretest: 35.9 ± 24.8; posttest: 38.2 ± 26.5; P = 0.033). Conclusion: The exercise program was effective in improving lower limb strength among institutionalized older adults but adding whole-body vibration did not enhance its effect. Whole-body vibration may improve balance confidence without enhancing actual balance performance. Keywords Exercise, aging, balance, mobility, whole-body vibration Received: 21 April 2017; accepted: 31 August 2017
Introduction Falls can have negative consequences on the psychological (i.e. fear of falling)1 and physical (i.e. fragility fractures)2 status of an individual. Therefore, developing effective interventions to modify the risk of falls among older adults is an important aim in geriatric medicine and rehabilitation. Exercise training is identified as an effective intervention to improve physical function and reduce falls among older adults.3 The exercise program, however, has to be sufficiently challenging to induce significant improvement in balance and mobility function if it is to reduce the risk of falls.3 Whole-body vibration (WBV) could be an effective intervention to increase the intensity of training. Vibration was found to activate the muscle spindles, thereby inducing reflex muscle activation (i.e. tonic vibration reflex) and potentially result in muscle strength benefits.4 WBV can hence potentially augment the strengthening benefits of exercise.5–8 The vibration platform also provides an unstable surface for exercise to further challenge balance control. Therefore, WBV could be effective to improve neuromotor function such as balance and gait.9 However, current evidence regarding the use of WBV training alone to improve balance and mobility in older adults remains largely inconclusive.10,11 Due to concerns about potential harmful effects of long-term exposure to vibrations, WBV treatment is typically limited to a short training duration (45°; absence of knee flexion contracture; ability to stand with support >1 minute; and provision of informed consent by the participant or his or her caregiver. Participants were excluded based on the following criteria: peripheral vascular disease; symptomatic vestibular disorder; contraindications to exercise, such as unstable angina; serious illnesses that would preclude participation, such as cancer; and previous lower limb fracture which required metal implant fixation.
Intervention Participants were randomly allocated to one of the three following groups: WBV + exercise group, exercise group, or control group. The allocation was completed by an off-site researcher who was not involved in other aspects of the trial, using an online randomization program with a ratio of 1:1:1. All three groups participated in three training sessions per week for a period of eight weeks. This intervention volume was based on previously published research reporting a positive effect of similar training
3 dosage on mobility function among communitydwelling older adults.17 The exercise group and the WBV + exercise group participated in a comprehensive exercise program that consisted of a warmup phase, followed by a combination of mobility, strengthening and balance training exercises, and a cool-down phase. Each training session was typically 1-hour long. The exercise protocol was designed according to the ability of the participants. For the WBV + exercise group, the following exercises were performed while receiving WBV: dynamic semi-squats; heel raise; and single-leg standing, on both right and left lower limbs. The purpose of these exercises was to provide multidirectional vibration input to the lower limbs in order to augment activation of the major lower limb muscle groups.5,18 Vertical WBV was delivered using the Fitvibe medical WBV system (GymnaUniphy NV, Bilzen, Belgium). Exposure to vibration was provided in 1-minute bouts, with a 1- to 2-minute rest period between bouts, for a total exposure to WBV of about 4 minutes per training session. Prior to each vibration bout, the duration had been preset using the automated function of the vibration device. The vibration would stop automatically when the predefined time was reached. The total duration of exposure (4 minutes per session) was selected based on previous studies which demonstrated that a brief period of WBV (1–15 minutes) was sufficient to induce positive effects on balance and mobility function17,19 and exercise tolerance of older adults. A frequency of 30 Hz (weeks 1–4) and 40 Hz (weeks 5–8), with a vertical displacement of 0.9 mm, was used. These parameters of WBV have commonly been used in previous research which evaluated the therapeutic benefits of WBV in older adults.19 Previous studies also reported that these WBV parameters significantly increased lower limb muscle activity in both younger and older adults.8,20–22 As measured by calibrated accelerometers (Dytran 7523A5; Dytran Instruments, Inc., Chatsworth, CA), the actual WBV delivered by the platform was at a peak acceleration of 3.40 units of Earth’s gravity (g) in the 30-Hz condition and at 4.7g in the 40-Hz condition. The exercise group performed the identical exercise program both in terms of the type of exercise and number of repetitions, but no WBV was imposed.
4 The control group engaged in social and recreational activities that only involved the upper limbs. The detailed training protocol for each group is provided in Supplemental Table 1. All sessions were supervised by a physiotherapist and a nursing home worker.
Outcome measures Two blinded assessors performed outcome assessments at baseline and at the end of the eight-week intervention. Exercise instructors were informed to not divulge participants’ group allocation to assessors. Study participants and exercise instructors were not blinded to group assignment. Relevant demographic information was obtained from the nursing home records, including sex, age, medications, important medical history, and fall history. All outcome measures were evaluated at baseline and within one week after the intervention period. The incidences of falls were recorded over a one-year followup period after the end of the intervention by reviewing the nursing notes in the elderly center. Only falls that required medical attention were recorded. These data could still be obtained from the medical records even if a participant did not complete the full training protocol due to a change in residence, refusal to participate, or deteriorating health. The fall data could not be obtained if the participant passed away before the end of the one-year follow-up period. The primary outcome, functional mobility, was assessed using the Timed Up and Go Test.23 For secondary outcomes, functional balance was assessed by the Berg Balance Scale.24 Functional lower limb muscle strength was measured using the five-timessit-to-stand test.25 Endurance was assessed using the 6-minute walk test.26 Balance confidence was measured using the Activities-specific Balance Confidence Scale.27 The risk of falling was assessed using the short form of the Physiological Profile Assessment, which includes the following five components: edge contrast sensitivity, proprioception, knee extension strength, and reaction time.28
Statistical analysis Statistical analysis was conducted using SPSS software (version 20.0; IBM, Armonk, NY) with the
Clinical Rehabilitation 00(0) level of significance at P ≤ 0.05. Between-group differences in baseline characteristics were evaluated by one-way ANOVA for continuous data and Pearson’s chi-square test for categorical data. Group × time interactions were evaluated using mixed-design, multivariate analysis of variance. Intention-to-treat analysis was conducted, in which the last observation carried forward method was used to substitute the missing data for the participants who were lost to follow-up (i.e. dropouts). Previous studies evaluating WBV effects among elderly individuals reported effect sizes (Cohen’s d) of 0.43–0.64 (medium–large) on its effect on mobility.12,13,29 Therefore, to conduct an analysis of variance, with an alpha of 0.05 (two tailed), power of 0.9, and an effect size of f = 0.25 (medium effect size), and considering an attrition rate of 20%, the estimated sample size required for our trial was 72 participants, with 24 participants per group.
Results Characteristics of the study group Participants were enrolled into the trial from June 2012 through October 2014, with the final data collection completed in December 2015. Overall, 73 institutionalized elderly individuals were enrolled into the study (40 women; mean age 82.3 ± 7.3 years) and allocated to the three experimental groups: WBV + exercise, exercise only, and control. Of these, 62 participants completed all assessments (Figure 1). Relevant demographic characteristics and baseline measurements for our study group are summarized in Table 1, with no between-group differences identified.
Effect of WBV and exercise on physical functioning No significant main effect of time nor time × group interactions were identified for the primary outcome (Timed Up and Go Test; P ≥ 0.260; Table 2). For secondary outcomes, a significant main effect of time was identified for the five-times-sit-to-stand test; the Berg Balance Scale total score; the Physiological Profile Assessment total score, and reaction time and
Lam et al.
Figure 1. Consort flow diagram. In total, 73 participants were randomly allocated to one of the three groups: whole-body vibration + exercise group (n = 25), exercise group (n = 24), or control group (n = 24). Fall data were collected to the end of the one-year post-training follow-up period.
5
*We were able to complete the follow-up on the incidence of falls requiring medical attention even if a participant did not complete the full training protocol due to a change in residence, refusal to participate, or deteriorating health because the data could be obtained from the medical records. Fall data could not be obtained from participants who passed away before the end of the follow-up period. This explains why the number of individuals who participated in the posttest assessment was different from that whose fall data were collected.
6
Clinical Rehabilitation 00(0)
Table 1. Participants’ demographics. Whole-body vibration + exercise group (n = 25)a Sex (men/women) Age (years) Walking aid (none/cane/quadripod/ frame/rollator, n) Fall in previous one year (yes/no, n)d Outcomes measures Timed Up and Go Test (seconds) Five-times-sit-to-stand test (seconds) Berg Balance Scale (0–56) PPA total score PPA edge contrast sensitivity PPA proprioception PPA knee extension PPA reaction time PPA sway 6-minute walk test (m) Balance confidence (0–100) Comorbid conditions Total number of comorbid conditions Hypertension (n) Diabetes (n) Dementia (n) History of stroke (n) High cholesterol (n) Depression (n) Heart disease (n)
12/13 84.0 ± 6.7 10/3/3/6/3 5/20
Exercise group (n = 24)b 10/14 82.4 ± 7.6 8/3/4/6/3 3/21
Control group (n = 24)c
P
11/13 80.3 ± 7.3 5/4/3/12/0
0.903 0.204 0.427
3/21
0.697
43.6 ± 37.3 30.3 ± 17.9 35.9 ± 14.2 4.39 ± 1.98 −1.44 ± 0.75 −0.48 ± 1.30 −1.13 ± 0.44 −1.86 ± 1.90 −2.20 ± 1.28 136.6 ± 96.3 39.2 ± 29.0
49.6 ± 30.5 35.8 ± 16.1 31.7 ± 14.1 4.52 ± 1.21 −1.57 ± 0.76 −0.09 ± 1.15 −1.26 ± 0.41 −1.36 ± 1.66 −2.75 ± 0.81 127.8 ± 104.1 35.9 ± 24.8
45.3 ± 34.4 27.1 ± 10.4 31.0 ± 15.5 4.07 ± 1.57 −1.40 ± 0.60 −0.03 ± 0.98 −1.14 ± 0.44 −1.35 ± 1.86 −2.36 ± 1.19 120.4 ± 87.4 31.9 ± 26.3
0.824 0.147 0.455 0.645 0.698 0.347 0.516 0.550 0.241 0.840 0.674
4.0 ± 1.9 21 10 6 9 5 1 5
3.5 ± 1.6 19 10 5 11 3 1 7
3.9 ± 1.5 19 14 10 7 3 0 4
0.478 0.883 0.368 0.227 0.485 0.697 0.604 0.555
PPA: Physiological Profile Assessment. Data are presented as mean ± standard deviation otherwise specified. aFor Timed Up and Go Test and all PPA-related measures, only 24 participants were included in the analysis. bFor all PPA-related measures, only 22 participants were included in the analysis. cFor Timed Up and Go Timed, five-times-sit-to-stand test, all PPA-related measures, and balance confidence, only 23 participants were included in the analysis. dOnly falls requiring medical attention were recorded.
sway score; and the Activities-specific Balance Confidence score (P ≤ 0.045). However, a significant time × group interaction was only identified for the five-times-sit-to-stand test (P = 0.048), with post hoc analysis identifying an improvement for the exercise group (pretest: 35.8 ± 16.1 seconds; posttest: 29.0 ± 9.8 seconds) compared to a decline in performance for the control group (pretest: 27.1 ± 10.4 seconds; posttest: 28.7 ± 12.3 seconds; P = 0.030). The post hoc analysis of the interaction effect also demonstrated that the WBV + exercise group (pretest: 39.2 ±
29.0; posttest: 48.4 ± 30.6) showed significantly more improvement in Activities-specific Balance Confidence compared with the exercise group (pretest: 35.9 ± 24.8; posttest: 38.2 ± 26.5; P = 0.033).
Adherence and safety The attendance rate showed no significant difference among the three groups (WBV + exercise group: 77.1%, exercise group: 67.5%, and control group: 74.5%; P = 0.546). In total, 14 participants
41.5 ± 35.9 27.3 ± 12.9 39.5 ± 12.5 3.86 ± 1.91 −1.37 ± 0.82 −0.26 ± 1.16 −1.02 ± 0.52 −1.49 ± 2.09 −1.81 ± 1.37 150.7 ± 100.5 48.4 ± 30.6 3
30.3 ± 17.9 35.9 ± 14.2 4.39 ± 1.98 −1.44 ± 0.75 −0.48 ± 1.30 −1.13 ± 0.44 −1.86 ± 1.90 −2.20 ± 1.28 136.6 ± 96.3 39.2 ± 29.0
Post
43.6 ± 37.3
Pre
−0.09 ± 1.15 −1.26 ± 0.41 −1.36 ± 1.66 −2.75 ± 0.81 127.8 ± 104.1 35.9 ± 24.8
31.7 ± 14.1 4.52 ± 1.21 −1.57 ± 0.76
35.8 ± 16.1
49.6 ± 30.5
Pre
−0.10 ± 0.59 −1.24 ± 0.39 −1.24 ± 1.27 −2.50 ± 0.82 128.6 ± 101.9 34.8 ± 25.7 5
34.6 ± 12.9 4.34 ± 1.19 −1.57 ± 0.85
29.0 ± 9.8
47.7 ± 32.6
Post
Exercise group (n = 24)b
−0.03 ± 0.98 −1.14 ± 0.44 −1.35 ± 1.86 −2.36 ± 1.19 120.4 ± 87.4 31.9 ± 26.3
31.0 ± 15.5 4.08 ± 1.57 −1.40 ± 0.60
27.1 ± 10.4
45.3 ± 34.4
Pre
−0.03 ± 0.68 −1.15 ± 0.43 −0.96 ± 1.40 −2.31 ± 1.06 116.1 ± 92.2 38.2 ± 26.5 4
32.1 ± 15.1 3.75 ± 1.27 −1.23 ± 0.73
28.7 ± 12.3
43.8 ± 31.5
Post
Control group (n = 24)c
0.045*
0.26
0.624 0.176 0.026* 0.011* 0.605 0.007*
research-article2017
CRE0010.1177/0269215517733525Clinical RehabilitationLam et al.
CLINICAL REHABILITATION
Original Article
Effects of whole-body vibration on balance and mobility in institutionalized older adults: a randomized controlled trial
Clinical Rehabilitation 1–11 © The Author(s) 2017 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav https://doi.org/10.1177/0269215517733525 DOI: 10.1177/0269215517733525 journals.sagepub.com/home/cre
Freddy MH Lam1, Philip FL Chan2, LR Liao3, Jean Woo4, Elsie Hui4, Charles WK Lai2, Timothy CY Kwok5 and Marco YC Pang1
Abstract Objective: To investigate whether a comprehensive exercise program was effective in improving physical function among institutionalized older adults and whether adding whole-body vibration to the program conferred additional therapeutic benefits. Design: A single-blinded randomized controlled trial was conducted. Setting: This study was carried out in residential care units. Participants: In total, 73 older adults (40 women, mean age: 82.3 ± 7.3 years) were enrolled into this study. Interventions: Participants were randomly allocated to one of the three groups: strength and balance program combined with whole-body vibration, strength and balance program without whole-body vibration, and social and recreational activities consisting of upper limb exercises only. All participants completed three training sessions per week for eight weeks. Outcome measures: Assessment of mobility, balance, lower limb strength, walking endurance, and self-perceived balance confidence were conducted at baseline and immediately after the eight-week intervention. Incidences of falls requiring medical attention were recorded for one year after the end of the training period. Results: A significant time × group interaction was found for lower limb strength (five-times-sit-tostand test; P = 0.048), with the exercise-only group showing improvement (pretest: 35.8 ± 16.1 seconds; posttest: 29.0 ± 9.8 seconds), compared with a decline in strength among controls (pretest: 27.1 ± 10.4 seconds; posttest: 28.7 ± 12.3 seconds; P = 0.030). The exercise with whole-body vibration group had a
1Department
of Rehabilitation Sciences, The Hong Kong Polytechnic University, Kowloon, Hong Kong 2Physiotherapy Department, Shatin Hospital, Shatin, Hong Kong 3Department of Rehabilitation, Jiangsu Provincial Yixing Jiuru Rehabilitation Hospital, Yixing, China 4Medical and Geriatric Unit, Shatin Hospital, Shatin, Hong Kong
5Department
of Medicine and Therapeutics, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong
Corresponding author: Freddy MH Lam, Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong. Email: [email protected]
2
Clinical Rehabilitation 00(0)
significantly better outcome in balance confidence (pretest: 39.2 ± 29.0; posttest: 48.4 ± 30.6) than the exercise-only group (pretest: 35.9 ± 24.8; posttest: 38.2 ± 26.5; P = 0.033). Conclusion: The exercise program was effective in improving lower limb strength among institutionalized older adults but adding whole-body vibration did not enhance its effect. Whole-body vibration may improve balance confidence without enhancing actual balance performance. Keywords Exercise, aging, balance, mobility, whole-body vibration Received: 21 April 2017; accepted: 31 August 2017
Introduction Falls can have negative consequences on the psychological (i.e. fear of falling)1 and physical (i.e. fragility fractures)2 status of an individual. Therefore, developing effective interventions to modify the risk of falls among older adults is an important aim in geriatric medicine and rehabilitation. Exercise training is identified as an effective intervention to improve physical function and reduce falls among older adults.3 The exercise program, however, has to be sufficiently challenging to induce significant improvement in balance and mobility function if it is to reduce the risk of falls.3 Whole-body vibration (WBV) could be an effective intervention to increase the intensity of training. Vibration was found to activate the muscle spindles, thereby inducing reflex muscle activation (i.e. tonic vibration reflex) and potentially result in muscle strength benefits.4 WBV can hence potentially augment the strengthening benefits of exercise.5–8 The vibration platform also provides an unstable surface for exercise to further challenge balance control. Therefore, WBV could be effective to improve neuromotor function such as balance and gait.9 However, current evidence regarding the use of WBV training alone to improve balance and mobility in older adults remains largely inconclusive.10,11 Due to concerns about potential harmful effects of long-term exposure to vibrations, WBV treatment is typically limited to a short training duration (45°; absence of knee flexion contracture; ability to stand with support >1 minute; and provision of informed consent by the participant or his or her caregiver. Participants were excluded based on the following criteria: peripheral vascular disease; symptomatic vestibular disorder; contraindications to exercise, such as unstable angina; serious illnesses that would preclude participation, such as cancer; and previous lower limb fracture which required metal implant fixation.
Intervention Participants were randomly allocated to one of the three following groups: WBV + exercise group, exercise group, or control group. The allocation was completed by an off-site researcher who was not involved in other aspects of the trial, using an online randomization program with a ratio of 1:1:1. All three groups participated in three training sessions per week for a period of eight weeks. This intervention volume was based on previously published research reporting a positive effect of similar training
3 dosage on mobility function among communitydwelling older adults.17 The exercise group and the WBV + exercise group participated in a comprehensive exercise program that consisted of a warmup phase, followed by a combination of mobility, strengthening and balance training exercises, and a cool-down phase. Each training session was typically 1-hour long. The exercise protocol was designed according to the ability of the participants. For the WBV + exercise group, the following exercises were performed while receiving WBV: dynamic semi-squats; heel raise; and single-leg standing, on both right and left lower limbs. The purpose of these exercises was to provide multidirectional vibration input to the lower limbs in order to augment activation of the major lower limb muscle groups.5,18 Vertical WBV was delivered using the Fitvibe medical WBV system (GymnaUniphy NV, Bilzen, Belgium). Exposure to vibration was provided in 1-minute bouts, with a 1- to 2-minute rest period between bouts, for a total exposure to WBV of about 4 minutes per training session. Prior to each vibration bout, the duration had been preset using the automated function of the vibration device. The vibration would stop automatically when the predefined time was reached. The total duration of exposure (4 minutes per session) was selected based on previous studies which demonstrated that a brief period of WBV (1–15 minutes) was sufficient to induce positive effects on balance and mobility function17,19 and exercise tolerance of older adults. A frequency of 30 Hz (weeks 1–4) and 40 Hz (weeks 5–8), with a vertical displacement of 0.9 mm, was used. These parameters of WBV have commonly been used in previous research which evaluated the therapeutic benefits of WBV in older adults.19 Previous studies also reported that these WBV parameters significantly increased lower limb muscle activity in both younger and older adults.8,20–22 As measured by calibrated accelerometers (Dytran 7523A5; Dytran Instruments, Inc., Chatsworth, CA), the actual WBV delivered by the platform was at a peak acceleration of 3.40 units of Earth’s gravity (g) in the 30-Hz condition and at 4.7g in the 40-Hz condition. The exercise group performed the identical exercise program both in terms of the type of exercise and number of repetitions, but no WBV was imposed.
4 The control group engaged in social and recreational activities that only involved the upper limbs. The detailed training protocol for each group is provided in Supplemental Table 1. All sessions were supervised by a physiotherapist and a nursing home worker.
Outcome measures Two blinded assessors performed outcome assessments at baseline and at the end of the eight-week intervention. Exercise instructors were informed to not divulge participants’ group allocation to assessors. Study participants and exercise instructors were not blinded to group assignment. Relevant demographic information was obtained from the nursing home records, including sex, age, medications, important medical history, and fall history. All outcome measures were evaluated at baseline and within one week after the intervention period. The incidences of falls were recorded over a one-year followup period after the end of the intervention by reviewing the nursing notes in the elderly center. Only falls that required medical attention were recorded. These data could still be obtained from the medical records even if a participant did not complete the full training protocol due to a change in residence, refusal to participate, or deteriorating health. The fall data could not be obtained if the participant passed away before the end of the one-year follow-up period. The primary outcome, functional mobility, was assessed using the Timed Up and Go Test.23 For secondary outcomes, functional balance was assessed by the Berg Balance Scale.24 Functional lower limb muscle strength was measured using the five-timessit-to-stand test.25 Endurance was assessed using the 6-minute walk test.26 Balance confidence was measured using the Activities-specific Balance Confidence Scale.27 The risk of falling was assessed using the short form of the Physiological Profile Assessment, which includes the following five components: edge contrast sensitivity, proprioception, knee extension strength, and reaction time.28
Statistical analysis Statistical analysis was conducted using SPSS software (version 20.0; IBM, Armonk, NY) with the
Clinical Rehabilitation 00(0) level of significance at P ≤ 0.05. Between-group differences in baseline characteristics were evaluated by one-way ANOVA for continuous data and Pearson’s chi-square test for categorical data. Group × time interactions were evaluated using mixed-design, multivariate analysis of variance. Intention-to-treat analysis was conducted, in which the last observation carried forward method was used to substitute the missing data for the participants who were lost to follow-up (i.e. dropouts). Previous studies evaluating WBV effects among elderly individuals reported effect sizes (Cohen’s d) of 0.43–0.64 (medium–large) on its effect on mobility.12,13,29 Therefore, to conduct an analysis of variance, with an alpha of 0.05 (two tailed), power of 0.9, and an effect size of f = 0.25 (medium effect size), and considering an attrition rate of 20%, the estimated sample size required for our trial was 72 participants, with 24 participants per group.
Results Characteristics of the study group Participants were enrolled into the trial from June 2012 through October 2014, with the final data collection completed in December 2015. Overall, 73 institutionalized elderly individuals were enrolled into the study (40 women; mean age 82.3 ± 7.3 years) and allocated to the three experimental groups: WBV + exercise, exercise only, and control. Of these, 62 participants completed all assessments (Figure 1). Relevant demographic characteristics and baseline measurements for our study group are summarized in Table 1, with no between-group differences identified.
Effect of WBV and exercise on physical functioning No significant main effect of time nor time × group interactions were identified for the primary outcome (Timed Up and Go Test; P ≥ 0.260; Table 2). For secondary outcomes, a significant main effect of time was identified for the five-times-sit-to-stand test; the Berg Balance Scale total score; the Physiological Profile Assessment total score, and reaction time and
Lam et al.
Figure 1. Consort flow diagram. In total, 73 participants were randomly allocated to one of the three groups: whole-body vibration + exercise group (n = 25), exercise group (n = 24), or control group (n = 24). Fall data were collected to the end of the one-year post-training follow-up period.
5
*We were able to complete the follow-up on the incidence of falls requiring medical attention even if a participant did not complete the full training protocol due to a change in residence, refusal to participate, or deteriorating health because the data could be obtained from the medical records. Fall data could not be obtained from participants who passed away before the end of the follow-up period. This explains why the number of individuals who participated in the posttest assessment was different from that whose fall data were collected.
6
Clinical Rehabilitation 00(0)
Table 1. Participants’ demographics. Whole-body vibration + exercise group (n = 25)a Sex (men/women) Age (years) Walking aid (none/cane/quadripod/ frame/rollator, n) Fall in previous one year (yes/no, n)d Outcomes measures Timed Up and Go Test (seconds) Five-times-sit-to-stand test (seconds) Berg Balance Scale (0–56) PPA total score PPA edge contrast sensitivity PPA proprioception PPA knee extension PPA reaction time PPA sway 6-minute walk test (m) Balance confidence (0–100) Comorbid conditions Total number of comorbid conditions Hypertension (n) Diabetes (n) Dementia (n) History of stroke (n) High cholesterol (n) Depression (n) Heart disease (n)
12/13 84.0 ± 6.7 10/3/3/6/3 5/20
Exercise group (n = 24)b 10/14 82.4 ± 7.6 8/3/4/6/3 3/21
Control group (n = 24)c
P
11/13 80.3 ± 7.3 5/4/3/12/0
0.903 0.204 0.427
3/21
0.697
43.6 ± 37.3 30.3 ± 17.9 35.9 ± 14.2 4.39 ± 1.98 −1.44 ± 0.75 −0.48 ± 1.30 −1.13 ± 0.44 −1.86 ± 1.90 −2.20 ± 1.28 136.6 ± 96.3 39.2 ± 29.0
49.6 ± 30.5 35.8 ± 16.1 31.7 ± 14.1 4.52 ± 1.21 −1.57 ± 0.76 −0.09 ± 1.15 −1.26 ± 0.41 −1.36 ± 1.66 −2.75 ± 0.81 127.8 ± 104.1 35.9 ± 24.8
45.3 ± 34.4 27.1 ± 10.4 31.0 ± 15.5 4.07 ± 1.57 −1.40 ± 0.60 −0.03 ± 0.98 −1.14 ± 0.44 −1.35 ± 1.86 −2.36 ± 1.19 120.4 ± 87.4 31.9 ± 26.3
0.824 0.147 0.455 0.645 0.698 0.347 0.516 0.550 0.241 0.840 0.674
4.0 ± 1.9 21 10 6 9 5 1 5
3.5 ± 1.6 19 10 5 11 3 1 7
3.9 ± 1.5 19 14 10 7 3 0 4
0.478 0.883 0.368 0.227 0.485 0.697 0.604 0.555
PPA: Physiological Profile Assessment. Data are presented as mean ± standard deviation otherwise specified. aFor Timed Up and Go Test and all PPA-related measures, only 24 participants were included in the analysis. bFor all PPA-related measures, only 22 participants were included in the analysis. cFor Timed Up and Go Timed, five-times-sit-to-stand test, all PPA-related measures, and balance confidence, only 23 participants were included in the analysis. dOnly falls requiring medical attention were recorded.
sway score; and the Activities-specific Balance Confidence score (P ≤ 0.045). However, a significant time × group interaction was only identified for the five-times-sit-to-stand test (P = 0.048), with post hoc analysis identifying an improvement for the exercise group (pretest: 35.8 ± 16.1 seconds; posttest: 29.0 ± 9.8 seconds) compared to a decline in performance for the control group (pretest: 27.1 ± 10.4 seconds; posttest: 28.7 ± 12.3 seconds; P = 0.030). The post hoc analysis of the interaction effect also demonstrated that the WBV + exercise group (pretest: 39.2 ±
29.0; posttest: 48.4 ± 30.6) showed significantly more improvement in Activities-specific Balance Confidence compared with the exercise group (pretest: 35.9 ± 24.8; posttest: 38.2 ± 26.5; P = 0.033).
Adherence and safety The attendance rate showed no significant difference among the three groups (WBV + exercise group: 77.1%, exercise group: 67.5%, and control group: 74.5%; P = 0.546). In total, 14 participants
41.5 ± 35.9 27.3 ± 12.9 39.5 ± 12.5 3.86 ± 1.91 −1.37 ± 0.82 −0.26 ± 1.16 −1.02 ± 0.52 −1.49 ± 2.09 −1.81 ± 1.37 150.7 ± 100.5 48.4 ± 30.6 3
30.3 ± 17.9 35.9 ± 14.2 4.39 ± 1.98 −1.44 ± 0.75 −0.48 ± 1.30 −1.13 ± 0.44 −1.86 ± 1.90 −2.20 ± 1.28 136.6 ± 96.3 39.2 ± 29.0
Post
43.6 ± 37.3
Pre
−0.09 ± 1.15 −1.26 ± 0.41 −1.36 ± 1.66 −2.75 ± 0.81 127.8 ± 104.1 35.9 ± 24.8
31.7 ± 14.1 4.52 ± 1.21 −1.57 ± 0.76
35.8 ± 16.1
49.6 ± 30.5
Pre
−0.10 ± 0.59 −1.24 ± 0.39 −1.24 ± 1.27 −2.50 ± 0.82 128.6 ± 101.9 34.8 ± 25.7 5
34.6 ± 12.9 4.34 ± 1.19 −1.57 ± 0.85
29.0 ± 9.8
47.7 ± 32.6
Post
Exercise group (n = 24)b
−0.03 ± 0.98 −1.14 ± 0.44 −1.35 ± 1.86 −2.36 ± 1.19 120.4 ± 87.4 31.9 ± 26.3
31.0 ± 15.5 4.08 ± 1.57 −1.40 ± 0.60
27.1 ± 10.4
45.3 ± 34.4
Pre
−0.03 ± 0.68 −1.15 ± 0.43 −0.96 ± 1.40 −2.31 ± 1.06 116.1 ± 92.2 38.2 ± 26.5 4
32.1 ± 15.1 3.75 ± 1.27 −1.23 ± 0.73
28.7 ± 12.3
43.8 ± 31.5
Post
Control group (n = 24)c
0.045*
0.26
0.624 0.176 0.026* 0.011* 0.605 0.007*
