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Komiya M.1, Urabe Y.1, Maeda N.1
1Graduate School of Biomechanical and Health Sciences, Hiroshima University, Hiroshima, Japan
Background: Whole-body vibration (WBV) has become a popular practice in rehabilitation and training. Improvement in muscle power such as jump height has been demonstrated using WBV in lower frequencies of 25Hz and 30Hz. On the other hand, improved result of sit and reach test has been demonstrated using higher frequencies, of 40Hz and 50Hz. However, very few research studies have examined the effect of different frequencies of WBV for both of jump height and joint mobility in the same group.
Purpose: This study aims to determine whether WBV frequencies of 25Hz and 40 Hz affects single leg squat jump (SLSJ) height and the ankle joint angle of dorsiflexion in the same time.
Methods: Six healthy men (22.7±1.4 years, 174.1±4.0 cm, 64.2±8.3 kg) participated in this study. Measurement items included SLSJ height and ankle joint angle of dorsiflexion in pre- and post-WBV. The WBV at frequencies of 25 Hz and 40 Hz were performed using SONIX (SONIC WORLD, Korea). Participants were positioned on the non-dominant leg (defined as the pivot leg when kicking a ball) and the knee angle was kept at approximately 50° flexion. Participants performed 5 sets of squat posture for 30 seconds with a 30 seconds rest period between sets. MYOTEST (S&C, Japan) was used for measuring SLSJ height. Ankle joint exercise device (Maruzen Industrial, Japan) was used for measuring ankle joint angle of dorsiflexion. Statistical analysis was performed using SPSS ver.20.0 software. Paired t-test was performed to compare SLSJ height and ankle joint angle of dorsiflexion in pre- and post-WBV. The significance level was set at 5 %.
Results: The SLSJ height in pre-WBV of 25 Hz and 40 Hz were 20.2±0.8cm and 20.2±1.4cm and in post-WBV at 25 Hz and 40 Hz were 21.1±0.7 cm and 20.4±1.3 cm respectively. The value of post-WBV at 25 Hz was significantly higher than the respective value of pre-WBV (p 0.05). For frequency range of 25 Hz and 40 Hz, the ankle joint angle of dorsiflexion in pre-WBV were 22.7±1.6° and 22.9±2.3° and in post-WBV, values were 23.9±2.1° and 25.2±2.5° respectively. Values of post-WBV for the two conditions were significantly higher than the respective values of pre-WBV (p 0.05).
Conclusion(s): In this study, SLSJ height in post-WBV was higher than pre-WBV only at the time of 25 Hz. On the other hand, the ankle joint angle of dorsiflexion was significant increase in each frequency. Result of SLSJ height might be influence increasing rate of ankle joint angle of dorsiflexion. However, this study didnt compare the difference effect of 25 Hz and 40 Hz. In addition, this study is only 25 Hz and 40 Hz. Therefore, it is necessary to perform a comparative effect of 25 Hz and 40 Hz and to verify other frequency such as 30 Hz and 50 Hz to achieve the best result.
Implications: This study bears significant help to choose appropriate frequency to achieve the best effect for WBV in rehabilitation and sport training.
Funding acknowledgements: We have no funding acknowledgement in this study.
Topic: Sport & sports injuries
Ethics approval: Subjects participated in this study after signing informed consent form approved by the institutional review board.
All authors, affiliations and abstracts have been published as submitted.
