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Modulation of Bone’s Sensitivity to Low-Intensity Vibrations by Acceleration Magnitude, Vibration Duration, and Number of Bouts

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journal contribution
posted on 22.01.2016, 00:00 by S. Judex, T. Koh, L. Xie
Variables defining vibration-based biomechanical treatments were tested by their ability to affect the musculoskeleton in the growing mouse. Duration of a vibration bout, but not variations in vibration intensity or number of vibration bouts per day, was identified as modulator of trabecular bone formation rates. INTRODUCTION: Low-intensity vibrations (LIV) may enhance musculoskeletal properties, but little is known regarding the role that individual LIV variables play. We determined whether acceleration magnitude and/or the number and duration of daily loading bouts may modulate LIV efficacy. METHODS: LIV was applied to 8-week-old mice at either 0.3 g or 0.6 g for three weeks; the number of daily bouts was one, two, or four, and the duration of a single bout was 15, 30, or 60 min. A frequency of 45 Hz was used throughout. RESULTS: LIV induced tibial cortical surface strains in 4-month-old mice of approximately 10 με at 0.3 g and 30 με at 0.6 g. In trabecular bone of the proximal tibial metaphysis, all single daily bout signal combinations with the exception of a single 15 min daily bout at 0.3 g (i.e., single bouts of 30 and 60 min at 0.3 g and 15 and 30 min at 0.6 g) produced greater bone formation rates (BFR/BS) than in controls. Across all signal combinations, 30 and 60 min bouts were significantly more effective than 15 min bouts in raising BFR/BS above control levels. Increasing the number of daily bouts or partitioning a single daily bout into several shorter bouts did not potentiate efficacy and in some instances led to BFR/BS that was not significantly different from those in controls. Bone chemical and muscle properties were similar across all groups. CONCLUSIONS: These data may provide a basis towards optimization of LIV efficacy and indicate that in the growing mouse skeleton, increasing bout duration from 15 to 30 or 60 min positively influences BFR/BS.

Funding

Funding by the US Army Medical Research and Material Command (DAMD 17-03-1-0777), the Department of Defense (DoD W81XWH-14-1-0281), and the National Institutes of Health (NBIB EB01435101A) was greatly appreciated.

History

Publisher Statement

Post print version of article may differ from published version. The final publication is available at springerlink.com; DOI: 10.1007/s00198-014-3018-5.

Publisher

Springer Verlag

issn

0937-941X

Issue date

13/01/2014