Effects of an eight-week whole body vibration on lower extremity muscle tone and function in children with cerebral palsy

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Highlights

  • WBV intervention can control the spasticity and enhance ambulatory performance.

  • WBV intervention can increase AROM in knee joints.

  • Timed up-and-go was significantly correlated with the relaxation index.

  • Timed up-and-go was significantly correlated with six-minute walk test.

  • WBV can potentially be used as a rehabilitation protocol in children with CP.

Abstract

The aim of this study was to evaluate the effect of an eight-week whole body vibration (WBV) on lower extremity spasticity and ambulatory function in children with cerebral palsy with a complete crossover design. Sixteen participants aged 9.2 (2.1) years participated in this study. Half of the participants received a 10-min WBV, 3 times a week for 8 weeks. Then a 4-week washout period followed, after which they received a sham WBV 3 times a week for 8 weeks. The other half received the intervention in a reversed order. The participants were evaluated via variables measuring range-of-motion, muscle tone, and ambulatory function before, immediately after, 1 day after, and 3 days after each intervention. Repeated-measures analyses revealed significant beneficial effects on most variables expect the passive range-of-motion measurement. Significant correlations were found between timed up-and-go and relaxation index, and between timed up-and-go and six-minute walk test. The results suggested that an 8-week WBV intervention normalized muscle tone, improved active joint range and enhanced ambulatory performance in children with cerebral palsy for at least 3 days. These indicated that regular WBV can serve as an alternative, safe, and efficient treatment for these children in both clinical and home settings.

Introduction

Cerebral palsy (CP) is the most common childhood disabilities which affect individual's posture and movement (Koman, Smith, & Shilt, 2004). Compared to the typically developed children, these children have impaired sensation and increased muscle tone therefore they have trouble voluntarily controlling their muscles. About seventy to eighty percent of children with CP demonstrate spastic clinical features (Krigger, 2006). Traditionally spasticity is managed via anti-spastic medication or injection. Several disadvantages are associated with these treatments. First, not all patients achieve satisfactory results, and not all parents are comfortable with long-term medication use or invasive injection. In addition, there are side effects such as general weakness that in turn affect their functional performance. As a result, there is a need for alternative or additional treatment options.

Other than spasticity, poor muscle strength is also an important factor that leads to movement dysfunction in CP (Damiano, Martellotta, Sullivan, Granata, & Abel, 2000). The weak quadriceps in this population inevitability impaired their walking performance (Damiano, Kelly, & Vaughn, 1995). These days whole body vibration (WBV) has become popular in local gym and fitness centers, and it was found to offer fitness and health benefits, including flexibility and muscle strength (Dolny and Reyes, 2008, Kosar et al., 2012; Rittweger, 2010). Recently, it seems to reach satisfactory results in managing spasticity and muscle strength among participants with upper motor neuron syndrome (Ahlborg, Andersson, & Julin, 2006Chan et al., 2012, Ness and Field-Fote, 2009).

Whole body vibration (WBV) is a training method which exposures the whole body of an individual to low frequency, low amplitude mechanical stimuli via a vibrating platform. The vibration stimulate the muscle spindles, sending nerve impulses to initiate muscle contractions according to the tonic vibration reflex (Cardinale & Bosco, 2003). Its effects on enhancing health and fitness in general population have been studied extensively; however, little was done with special groups, for example children with CP. Ruck, Chabot, and Rauch (2010) examined the effects of a 9-min WBV program on children with CP and found their mobility improved (Ruck et al., 2010). In this particular study, the only indicator for mobility was the change in self-selected walking speed (Ruck et al., 2010). Unger, Jelsma, and Stark (2013) investigated the vibration on trunk muscle strengthening and found beneficial effects onto posture and gait. Other than the postural related measurements, there was only one gait parameter, the 1-min walk test, assessed (Unger et al., 2013). Furthermore, the direct effect on spasticity was never evaluated.

Ahlborg et al. (2006) performed a comprehensive survey of spastic, strength, and walking variables after an 8-week WBV or an 8-week resistance training in adult with CP (Ahlborg et al., 2006). They found WBV was more effective in decreasing spasticity of the knee extensors compared to the resistance training. Leg muscle strength increased in both groups. On the other hand, the ambulatory parameters did not change significantly. Although this study demonstrated an extensive investigation on the effects of WBV on CP, there were aspects that can be improved. First, findings of the study were gathered from adults with CP, not children. Children usually demonstrate a better potential in functional improvement, therefore studies with children as subjects are of great needs. Second, this study had no control group. A control group provides true baselines for all testing variables, and this becomes substantially important when dealing with children. Third, when isokinetic strength was measured before ambulatory parameters, the muscle exertion would hinder the effects of WBV on ambulation. Last, the study only measured immediate influences, no lasting effects were evaluated.

Therefore, the aim of this study was to evaluate the immediate and lasting effects of WBV on lower extremity spasticity and ambulatory function in children with CP. It was hypothesized that upon the completion of this 8-week program, the spasticity among these CP children would decrease significantly and their ambulatory function would improve.

Section snippets

Materials and methods

A crossover repeated measures design was employed in this study. Sixteen children with CP were randomly divided into two groups. One group received an 8-week WMV intervention followed by an 8-week control condition, with a 4-week rest in between; the other group began their treatment sequence with the control condition to counterbalance the order effects (Fig. 1). The outcome variables included active and passive range-of-motion (AROM and PROM) of both knees, relaxation index (RI) assessed by

Results

The initial spasticity measurements for MAS and RI were 4.61 (0.95) and 0.59 (0.07), respectively. The initial measurements for TUG and 6MWT were 13.53 (2.30) s and 201.33 (17.51) m, respectively.

Descriptive and inferential statistics for outcome analyses are presented in Table 1. Significant differences were found in change scores between the treatment and control condition for variables including MAS, RI, and 6MWT. Multiple comparisons revealed that differences existed between change scores

Discussion

This study is the first to implement a crossover repeated measures design for measuring the effects of an 8-week WBV protocol on children with CP. The results were consistent with our hypothesis that spasticity (MAS and RI) would reduce, and ambulatory function (TUG and 6MWT) would improve significantly after the WBV intervention. These effects could last up to 3 days after the intervention. These benefits would facilitate children to actively engage in daily activities, exercise trainings and

Conclusion

To sum up, WBV program can be a suitable approach to control spasticity and improve walking function in children with CP, particularly it is non-invasive, easy to apply, relatively safe and requires little efforts. It may also serve as a routine addition or substitute for other anti-spastic agents with future supporting studies. Performed before the rehabilitation session, it serves as a spasticity reducing protocol and gets the individual ready for advanced exercise trainings. Previous studies

Acknowledgments

The authors thank all children, parents, school teachers and staff for their participation and assistance in this study. This study was supported by the Ministry of Science and Technology (103-2221-E-182-048, 103-2410-H-179-002), and the Chang Gung Medical Research Program, Taiwan (CMRPD1D0131).

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