Article

Low-level accelerations applied in the absence of weight bearing can enhance trabecular bone formation.

Department of Biomedical Engineering, State University of New York at Stony Brook, Stony Brook, NY 11794-2580, USA.
Journal of Orthopaedic Research (Impact Factor: 2.97). 06/2007; 25(6):732-40. DOI: 10.1002/jor.20354
Source: PubMed

ABSTRACT High-frequency whole body vibrations can be osteogenic, but their efficacy appears limited to skeletal segments that are weight bearing and thus subject to the induced load. To determine the anabolic component of this signal, we investigated whether low-level oscillatory displacements, in the absence of weight bearing, are anabolic to skeletal tissue. A loading apparatus, developed to shake specific segments of the murine skeleton without the direct application of deformations to the tissue, was used to subject the left tibia of eight anesthesized adult female C57BL/6J mice to small (0.3 g or 0.6 g) 45 Hz sinusoidal accelerations for 10 min/day, while the right tibia served as an internal control. Video and strain analysis revealed that motions of the apparatus and tibia were well coupled, inducing dynamic cortical deformations of less than three microstrain. After 3 weeks, trabecular metaphyseal bone formation rates and the percentage of mineralizing surfaces (MS/BS) were 88% and 64% greater (p < 0.05) in tibiae accelerated at 0.3 g than in their contralateral controls. At 0.6 g, bone formation rates and mineral apposition rates were 66% and 22% greater (p < 0.05) in accelerated tibiae. Changes in bone morphology were evident only in the epiphysis, where stimulated tibiae displayed significantly greater cortical area (+8%) and thickness (+8%). These results suggest that tiny acceleratory motions--independent of direct loading of the matrix--can influence bone formation and bone morphology. If confirmed by clinical studies, the unique nature of the signal may ultimately facilitate the stimulation of skeletal regions that are prone to osteoporosis even in patients that are suffering from confinement to wheelchairs, bed rest, or space travel.

0 Bookmarks
 · 
91 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Long-duration spaceflight results in muscle atrophy and a loss of bone mineral density. In skeletal muscle tissue, acute exercise and protein (e.g., essential amino acids) stimulate anabolic pathways (e.g., muscle protein synthesis) both independently and synergistically to maintain neutral or positive net muscle protein balance. Protein intake in space is recommended to be 12%-15% of total energy intake (≤1.4 g∙kg-1∙day-1) and spaceflight is associated with reduced energy intake (~20%), which enhances muscle catabolism. Increasing protein intake to 1.5-2.0 g∙kg-1∙day-1 may be beneficial for skeletal muscle tissue and could be accomplished with essential amino acid supplementation. However, increased consumption of sulfur-containing amino acids is associated with increased bone resorption, which creates a dilemma for musculoskeletal countermeasures, whereby optimizing skeletal muscle parameters via essential amino acid supplementation may worsen bone outcomes. To protect both muscle and bone health, future unloading studies should evaluate increased protein intake via non-sulfur containing essential amino acids or leucine in combination with exercise countermeasures and the concomitant influence of reduced energy intake.
    09/2014; 4(3):295-317. DOI:10.3390/life4030295
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study was to examine the effect of whole-body vibration (WBV) on calcaneal quantitative ultrasound (QUS) measurements; which has rarely been examined. We conducted a single-centre, 12-month, randomized controlled trial. 202 postmenopausal women with BMD T score between -1.0 and -2.5, not receiving bone medications, were asked to stand on a 0.3 g WBV platform oscillating at either 90- or 30-Hz for 20 consecutive minutes daily, or to serve as controls. Calcium and vitamin D was provided to all participants. Calcaneal broadband attenuation (BUA), speed of sound, and QUS index were obtained as pre-specified secondary endpoints at baseline and 12 months by using a Hologic Sahara Clinical Bone Sonometer. 12-months of WBV did not improve QUS parameters in any of our analyses. While most of our analyses showed no statistical differences between the WBV groups and the control group, mean calcaneal BUA decreased in the 90-Hz (-0.4 [95 % CI -1.9 to 1.2] dB MHz(-1)) and 30-Hz (-0.7 [95 % CI -2.3 to 0.8] dB MHz(-1)) WBV groups and increased in the control group (1.3 [95 % CI 0.0-2.6] dB MHz(-1)). Decreases in BUA in the 90-, 30-Hz or combined WBV groups were statistically different from the control group in a few of the analyses including all randomized participants, as well as in analyses excluding participants who had missing QUS measurement and those who initiated hormone therapy or were <80 % adherent. Although there are consistent trends, not all analyses reached statistical significance. 0.3 g WBV at 90 or 30 Hz prescribed for 20 min daily for 12 months did not improve any QUS parameters, but instead resulted in a statistically significant, yet small, decrease in calcaneal BUA in postmenopausal women in several analyses. These unexpected findings require further investigation.
    Calcified Tissue International 11/2014; DOI:10.1007/s00223-014-9920-1 · 2.75 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: 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. 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. 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. 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. 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.
    Osteoporosis International 01/2015; 26(4). DOI:10.1007/s00198-014-3018-5 · 4.17 Impact Factor

Full-text (2 Sources)

Download
54 Downloads
Available from
May 21, 2014