Exploring the Impact of Including Total-body Vibration in Physical Therapy Intervention on Activation of the Key Muscles of Gait in Young Children with Developmental Disabilities

Background & Purpose: To determine if adding total-body vibration (Hypervibe) to physical therapy interventions would increase the activation of key ambulatory muscles [the rectus femoris (RF), semitendinosus (ST), and medial gastrocnemius (MG)] to improve participation in gait-oriented tasks in pediatric patients with developmental disabilities. ¹

Case Description: This case series followed six children between 20 months and 6 years old with varying levels of physical challenge. Three children were diagnosed with cerebral palsy (GMFCS levels I (P05), II (P03), and V (P06)), one with Tuba1A (P04), one with mutation of the CACNA1A gene (P02), and one with SMC1A (P01). All six participants had goals related to gait. The six participants were tested pre-intervention using the Modified Ashworth (MA), surface EMG (sEMG), and Gross Motor Function Measure-88 (GMFM-88).2,3,4,5 Muscle activation of bilateral RF, ST, and MG muscles was measured with sEMG during ambulation. The MA assessed spasticity in these muscles. Two GMFM-88 dimensions were assessed based on each participants’ level of function and goals. Participants completed a 12-week intervention that included an activity on the Hypervibe as well as gait related activities.6,7 At 12 weeks, participants were re-tested using the MA, sEMG, and GMFM-88.

Outcomes: P01 demonstrated a 2% and 5% increase in GMFM-88 dimensions A and B. P02 demonstrated a 12.8% increase in dimension D. P03 demonstrated a 23.1% and 36.1% increase in dimensions D and E. P04 demonstrated a 2.6% and 1.4% increase in dimensions D and E. P05 demonstrated a 7.8% and 13.9% increase in dimensions D and E. P06 demonstrated a 2.6% increase in dimension D. No changes were noted in MA. Muscle activation (calculated as the root mean square value) increased in five to six target muscles in all participants (range of group means: 36.5%-59.9%, median: 43.6%) after receiving the intervention. Additionally, sEMG data showed more physically involved participants demonstrated more muscle activation percent change.

Discussion: The GMFM-88 was utilized due to its ability to detect changes in gross motor function in physically involved children.4,5 All participants demonstrated functional improvements as measured by the GMFM-88, with greater gains noted in participants with less physical involvement. P02, P03 and P05 demonstrated significant improvements while P01, P04 and P06 demonstrated mild improvements in measured dimensions.4,5 Increased muscle activation in the lower extremity at the pathophysiologic level was evident in all participants especially those with more severe motor impairments. Improved muscle activation is a precursor to functional change; and functional change is often harder to elicit in more physically involved children. Findings suggest promise for adding total-body vibration to interventions to prompt meaningful change in function for children with varying physical challenges.