This clinical trial(prospective, pilot study) is to learn about the effect of whole-body vibration on hip girdle muscles in healthy children as a primary study aiming for a new clinical intervention protocol to prevent hip dislocation in patients with severe cerebral palsy.

Design: Prospective, pilot study Setting: hospital rehabilitation department Intervention: Participants will be asked to walk and jump with a surface electromyography(EMG) attached to their hip girdle muscles. After the participants are positioned(standing) on the platform of whole-body vibration device, the study practitioner will record the sEMG values from the hip girdle muscles during the vibration applied. The mean values of repeating the same process with different vibrations applications and the values before vibration will be compared by using the SPSS using the paired "t-test" or Wilcoxon signed rank test for comparison between before and after vibration in the same group.

Inclusion Criteria:

• Healthy children (5 to 15 years old)

Exclusion Criteria:

• Children with cerebral palsy, muscle paralysis, developmental or congenital hip joint abnormalities
• Children who underwent hip joint surgery