Whole-Body Vibration and Lower Limb Motor Output

Author Year; Country
Score
Research Design
Sample Size
Methods Outcomes
Bosveld et al. 2015; USA
RCT
PEDro=8
Level 1
N= 25
Population: 25 individuals; chronic SCI; age =49.7 ± 12.5 years; years post injury= >1y
Treatment: Participants were randomized into two groups. Group 1 (n = 13) received whole-body vibration treatment (frequency: 50 Hz, amplitude: 2 mm) comprising of four 45-second bouts with 1-minute rest periods after each bout. Group 2 (n = 12) received sham electrical stimulation. Maximal voluntary isometric quadriceps force was measured with a fixed dynamometer. A modified Five-Time-Sit-To-Stand (FTSTS) test was used to assess functional lower extremity strength. Measures were made at pre-test, immediate post-test, and delayed post-test 20 minutes later.
Outcome Measures: Maximal voluntary isometric quadriceps force, modified Five-Time-Sit-To-Stand (FTSTS) test. 
  1. When comparing the pre-test and immediate post-test data, the difference in mean quadriceps strength between the two groups approached significance (P = 0.10). However, between the pre-test and delayed post-test, there were no significant difference between groups (P = 0.82).
  2. The within-group change for the WBV group was significant with a moderate effect size (P = 0.05; ES = 0.60)
  3. Between the pre-test and immediate post-test, the time from sit to stand between the two groups approached significance (P = 0.10). Between the pre-test and delayed post-test, there was no significant difference between groups (P = 0.32).
Effect Sizes: Forest plot of standardized mean differences (SMD ± 95%C.I.) as calculated from pre- and post-intervention data

Alizadeh-Meghrazi et al. 2015; Canada
Pre-Post
Level 4
N= 10

Population: 10 males; 6 healthy, 4 with chronic SCI; 1 AIS A and 3 AIS C; age= 28.83 ± 7.78y; years post injury > 1y
Treatment: Testing was performed on 2 days, where the participants were randomly allocated to exposure to either the WAVE® or Juvent™ platform each day. All participants were provided with the same shoes to eliminate footwear variability. In the case of the WAVE® platform, all combinations of the following parameters were used: (1) vibration frequencies of 25, 35, and 45 Hz; (2) two vibration amplitude settings and (3) knee angles of 140°, 160°, and 180°. In the case of the Juvent™ platform, all combinations of the following parameters were used: (1) vibration frequencies of 25, 35, and 45 Hz; (2) constant power setting of 28; and (3) knee angles of 140°, 160°, and 180°.
Outcome Measures: EMG
  1. WBV can elicit EMG activity among participants with chronic SCI, if appropriate vibration parameters are employed.
  2. The participants’ knee angle had no significant impact on lower extremity EMG activity.
  3. The vibration frequency had a significant impact on EMG activation in all lower extremity muscles except VL while the amplitude of vibration had a significant impact on EMG activation on the GM and RF muscles only.

Ness & Field-Fote 2009; USA
Pre-Post
N=17

Population: 3 women, 14 men; aged 28-65 years; all participants had a motor-incomplete SCI; C3-T8 lesion level; ≥1 year duration.
Treatment: WBV 3 days/week for 4 weeks with four 45 second bouts of 50 Hz frequency and 2-4mm intensity each session, while standing on a vibration platform and 1 minute seated rest in between.
Outcome Measures: 3-D motion capture system used to measure walking function (walking speed; step length; cadence (steps/min); hip-knee intralimb coordination).
  1. Walking speed significantly increased by mean (SD) 0.062 (0.011) m/s.
  2. Speed continued to improve 1 week post final intervention; only one participant tested.
  3. Cadence, weak side step length, and strong side step length all significantly increased following 12 sessions of WBV.
  4. Increased walking speed was significantly related to increased cadence.

Discussion

A recent report demonstrated the potential benefits of WBV administered for 3 minutes a day for 12 sessions over a 4-week period (Ness & Field-Fote 2009). Following this training period, the authors reported a mean improvement in walking speed of 0.062 m/s, which although statistically significant, was considered a small effect size. Training was also associated with an increase in cadence and hip-knee inter-joint coordination. Although whole-body vibration has been introduced for other neurological disorders such as Parkinson’s disease, this is the first report to demonstrate the potential benefits of whole-body vibration in the SCI population. Another study has since shown the potential benefits of WBV through improvements in muscle force output and sit-to-stand function (Bosveld & Field-Fote 2015).

Another study investigated the physiological effects of whole-body vibration in persons with SCI (Herrero et al. 2010), suggesting possible mechanisms of how WBV could be beneficial for lower limb function (not presented in table due to lack of functional or behavioural results). The authors showed that peak blood flow in the femoral artery increased with higher vibration frequencies (20 or 30 Hz), and that muscle activity increased regardless of frequency. This suggests that incorporating whole-body vibration into rehabilitation programs could benefit persons with SCI by promoting circulation in the legs and increasing muscle activation.

Conclusion

There is Level 1 evidence that WBV improves muscle force output and Sit to Stand test scores (Bosveld & Field-Fote 2015) though neither of these differences was significant.