Komiya M1, Urabe Y1, Sasadai J1, Maeda N1
1Hiroshima University, Graduate School of Biomedical and Health Sciences, Department of Sports Rehabilitation, Hiroshima, Japan
Background: Whole-body-vibration (WBV) has become popular therapy in the field of rehabilitation and muscle training. WBV has benefits in improvement of jump performance, balance ability, and flexibility of muscle. We showed that improvement of jump performance after WBV varied according to the choice of 25 Hz or 40 Hz vibration frequencies (Komiya et al., 2016). To our knowledge, a comparison of the acute effects of 25 Hz and 40 Hz vibration frequencies on improvement of balance ability after WBV has not been performed.
Purpose: We measured ankle dorsiflexion angle and postural stability after landing in twenty participants to confirm exercise effects of two different WBV frequencies.
Methods: Twenty healthy men (22.7 ± 1.6 years; 172.4 ± 5.7 cm; 65.2 ± 7.2 kg) participated. Three conditions (0 Hz, 25 Hz, 40 Hz) were designed in this study, and participants performed the exercise in all conditions. The subjects were assigned random to by measurement order. The subjects were placed in the prone position on the plate, with a knee flexion angle at approximately 50° of the non-dominant leg (defined as the support leg when kicking a ball) keeping on the WBV machine named SONIX (Sonic World, Korea), and participants performed 5 sets of 30-second. Ankle dorsiflexion angle and postural stability after landing were measured at pre- and post-WBV. Ankle dorsiflexion angle was measured using an ankle joint exercise device (Maruzen Industrial, Japan). Dynamic postural stability index (DPSI), anterior-posterior stability index (APSI), medial-lateral stability index (MLSI) and vertical stability index (VSI) were used as measurements of postural stability after landing. Each stability index was calculated based on a value of the ground reaction force provided by a single-leg jump tasks, with landing in the anterior direction. A two-way ANOVA [condition × time] with repeated measurements was performed for each measurement parameter and paired t-test was performed follow-up analyses to compare pre- and post-WBV.
Results: Ankle dorsiflexion angle, DPSI, APSI, and VSI all demonstrated significantly different condition × time interactions (p 0.05). Follow-up analyses revealed significant increasing for pre- and post-WBV of ankle dorsiflexion angle. Furthermore, DPSI and APSI at 25 Hz and 40 Hz shown significant decreasing for pre- and post-WBV except VSI, which was significant only at 25 Hz (p 0.05).
Conclusion(s): In the present study, ankle dorsiflexion angle increased 11.0% at 25 Hz and 11.4% at 40 Hz, and DPSI decreased 5.4% at 25 Hz and 2.7% at 40 Hz after vibration stimulation. Previous studies indicated that improvement of range of motion for ankle, knee, and hip joints is one of the important factors in improvement of DPSI. Therefore, this study suggests that improvement of ankle dorsiflexion angle in 25 Hz and 40 Hz lead to improvement of DPSI and APSI. However, improvement of VSI occurred only at 25 Hz. Further investigation of muscle activity is necessary to achieve the best effects of WBV in rehabilitation and muscle training.
Implications: This research could be useful for the choice of appropriate frequency to achieve the best effects of WBV for rehabilitation and muscle training.
Keywords: Whole-body-vibration, Ankle joint angle, Postural stability after landing
Funding acknowledgements: We have no funding acknowledgement in this study
Purpose: We measured ankle dorsiflexion angle and postural stability after landing in twenty participants to confirm exercise effects of two different WBV frequencies.
Methods: Twenty healthy men (22.7 ± 1.6 years; 172.4 ± 5.7 cm; 65.2 ± 7.2 kg) participated. Three conditions (0 Hz, 25 Hz, 40 Hz) were designed in this study, and participants performed the exercise in all conditions. The subjects were assigned random to by measurement order. The subjects were placed in the prone position on the plate, with a knee flexion angle at approximately 50° of the non-dominant leg (defined as the support leg when kicking a ball) keeping on the WBV machine named SONIX (Sonic World, Korea), and participants performed 5 sets of 30-second. Ankle dorsiflexion angle and postural stability after landing were measured at pre- and post-WBV. Ankle dorsiflexion angle was measured using an ankle joint exercise device (Maruzen Industrial, Japan). Dynamic postural stability index (DPSI), anterior-posterior stability index (APSI), medial-lateral stability index (MLSI) and vertical stability index (VSI) were used as measurements of postural stability after landing. Each stability index was calculated based on a value of the ground reaction force provided by a single-leg jump tasks, with landing in the anterior direction. A two-way ANOVA [condition × time] with repeated measurements was performed for each measurement parameter and paired t-test was performed follow-up analyses to compare pre- and post-WBV.
Results: Ankle dorsiflexion angle, DPSI, APSI, and VSI all demonstrated significantly different condition × time interactions (p 0.05). Follow-up analyses revealed significant increasing for pre- and post-WBV of ankle dorsiflexion angle. Furthermore, DPSI and APSI at 25 Hz and 40 Hz shown significant decreasing for pre- and post-WBV except VSI, which was significant only at 25 Hz (p 0.05).
Conclusion(s): In the present study, ankle dorsiflexion angle increased 11.0% at 25 Hz and 11.4% at 40 Hz, and DPSI decreased 5.4% at 25 Hz and 2.7% at 40 Hz after vibration stimulation. Previous studies indicated that improvement of range of motion for ankle, knee, and hip joints is one of the important factors in improvement of DPSI. Therefore, this study suggests that improvement of ankle dorsiflexion angle in 25 Hz and 40 Hz lead to improvement of DPSI and APSI. However, improvement of VSI occurred only at 25 Hz. Further investigation of muscle activity is necessary to achieve the best effects of WBV in rehabilitation and muscle training.
Implications: This research could be useful for the choice of appropriate frequency to achieve the best effects of WBV for rehabilitation and muscle training.
Keywords: Whole-body-vibration, Ankle joint angle, Postural stability after landing
Funding acknowledgements: We have no funding acknowledgement in this study
Topic: Sport & sports injuries; Primary health care
Ethics approval required: Yes
Institution: Hiroshima University
Ethics committee: Hiroshima University Committee on Ethics in Clinical Research
Ethics number: C-195
All authors, affiliations and abstracts have been published as submitted.
