Low-amplitude high frequency vibration down-regulates myostatin and atrogin-1 expression, two components of the atrophy pathway in muscle cells

Utilization of Low-Magnitude High-Frequency Vibration (LMHFV) as an Aid in Treating Peri-Implantitis: Case Presentations

Peri-implantitis is an inflammatory process initiating in the soft tissue and then progressing to the hard tissue surrounding dental implants leading to loss of osseous support and potential loss of the implant if not identified early in the process. This process initiates in the soft tissue, which become inflamed spreading to the underlying bone leading to decreases in bone density with subsequent crestal resorption and thread exposure. In the absence of treatment of the peri-implantitis, the bone loss at the osseous implant interface progresses with inflammatory mediated decrease in the bone density that moves apically, eventually leading to mobility of the implant and its failure. Low-magnitude high-frequency vibration (LMHFV) has been shown to improve bone density, stimulate osteoblastic activity, and arrest progression of peri-implantitis with improvement of the bone or graft around the affected implant with or without surgery as part of the treatment. Two cases are presented using LMHFV to augment treatment.

Primary cilia in satellite cells are the mechanical sensors for muscle hypertrophy

Skeletal muscle atrophy is commonly associated with aging, immobilization, muscle unloading, and congenital myopathies. Generation of mature muscle cells from skeletal muscle satellite cells (SCs) is pivotal in repairing muscle tissue. Exercise therapy promotes muscle hypertrophy and strength. Primary cilium is implicated as the mechanical sensor in some mammalian cells, but its role in skeletal muscle cells remains vague. To determine mechanical sensors for exercise-induced muscle hypertrophy, we established three SC-specific cilium dysfunctional mouse models-Myogenic factor 5 (Myf5)-Arf-like Protein 3 (Arl3)^-/-, Paired box protein Pax-7 (Pax7)-Intraflagellar transport protein 88 homolog (Ift88)^-/-, and Pax7-Arl3^-/--by specifically deleting a ciliary protein ARL3 in MYF5-expressing SCs, or IFT88 in PAX7-expressing SCs, or ARL3 in PAX7-expressing SCs, respectively. We show that the Myf5-Arl3^-/- mice develop grossly the same as WT mice. Intriguingly, mechanical stimulation-induced muscle hypertrophy or myoblast differentiation is abrogated in Myf5-Arl3^-/- and Pax7-Arl3^-/- mice or primary isolated Myf5-Arl3^-/- and Pax7-Ift88^-/- myoblasts, likely due to defective cilia-mediated Hedgehog (Hh) signaling. Collectively, we demonstrate SC cilia serve as mechanical sensors and promote exercise-induced muscle hypertrophy via Hh signaling pathway.

Effects of Focused Vibrations on Human Satellite Cells

Skeletal muscle consists of long plurinucleate and contractile structures, able to regenerate and repair tissue damage by their resident stem cells: satellite cells (SCs). Reduced skeletal muscle regeneration and progressive atrophy are typical features of sarcopenia, which has important health care implications for humans. Sarcopenia treatment is usually based on physical exercise and nutritional plans, possibly associated with rehabilitation programs, such as vibratory stimulation. Vibrations stimulate muscles and can increase postural stability, balance, and walking in aged and sarcopenic patients. However, the possible direct effect of vibration on SCs is still unclear. Here, we show the effects of focused vibrations administered at increasing time intervals on SCs, isolated from young and aged subjects and cultured in vitro. After stimulations, we found in both young and aged subjects a reduced percentage of apoptotic cells, increased cell size and percentage of aligned cells, mitotic events, and activated cells. We also found an increased number of cells only in young samples. Our results highlight for the first time the presence of direct effects of mechanical vibrations on human SCs. These effects seem to be age-dependent, consisting of a proliferative response of cells derived from young subjects vs. a differentiative response of cells from aged subjects.

Possible Mechanisms for the Effects of Sound Vibration on Human Health

This paper presents a narrative review of research literature to “map the landscape” of the mechanisms of the effect of sound vibration on humans including the physiological, neurological, and biochemical. It begins by narrowing music to sound and sound to vibration. The focus is on low frequency sound (up to 250 Hz) including infrasound (1–16 Hz). Types of application are described and include whole body vibration, vibroacoustics, and focal applications of vibration. Literature on mechanisms of response to vibration is categorized into hemodynamic, neurological, and musculoskeletal. Basic mechanisms of hemodynamic effects including stimulation of endothelial cells and vibropercussion; of neurological effects including protein kinases activation, nerve stimulation with a specific look at vibratory analgesia, and oscillatory coherence; of musculoskeletal effects including muscle stretch reflex, bone cell progenitor fate, vibration effects on bone ossification and resorption, and anabolic effects on spine and intervertebral discs. In every category research on clinical applications are described. The conclusion points to the complexity of the field of vibrational medicine and calls for specific comparative research on type of vibration delivery, amount of body or surface being stimulated, effect of specific frequencies and intensities to specific mechanisms, and to greater interdisciplinary cooperation and focus.

Effect of vibration therapy on physical function in critically ill adults (VTICIA trial): protocol for a single-blinded randomised controlled trial

INTRODUCTION

Vibration therapy has been used as an additional approach in passive rehabilitation. Recently, it has been demonstrated to be feasible and safe for critically ill patients, whose muscle weakness and intensive care unit (ICU)-acquired weakness are serious problems. However, the effectiveness of vibration therapy in this population is unclear.

METHODS AND ANALYSIS

This study will enrol 188 adult critically ill patients who require further ICU stay after they can achieve sitting at the edge of the bed or wheelchair. The sample size calculation is based on a 15% improvement of Functional Status Score for the ICU. They will be randomised to vibration therapy coupled with protocolised mobilisation or to protocolised mobilisation alone; outcomes will be compared between the two groups. Therapy will be administered using a low-frequency vibration device (5.6-13 Hz) for 15 min/day from when the patient first achieves a sitting position and onward until discharge from the ICU. Outcome assessments will be blinded to the intervention. Primary outcome will be measured using the Functional Status Score for the ICU during discharge. Secondary outcomes will be identified as follows: delirium, Medical Research Council Score, ICU-acquired weakness, the change of biceps brachii and rectus femoris muscle mass measured by ultrasound, ICU mobility scale and ventilator-free and ICU-free days (number of free days during 28 days after admission). For safety assessment, vital signs will be monitored during the intervention.

ETHICS AND DISSEMINATION

This study has been approved by the Clinical Research Ethics Committee of Tokushima University Hospital. Results will be disseminated through publication in a peer-reviewed journal and presented at conferences.

TRIAL REGISTRATION NUMBER

UMIN000039616.

Local low-intensity vibration improves healing of muscle injury in mice

Recovery from traumatic muscle injuries is typically prolonged and incomplete. Our previous study demonstrated that whole‐body low‐intensity vibration (LIV) enhances healing in a mouse laceration model. We sought to determine whether locally applied LIV (a) improves muscle repair following injury in mice and (b) is directly transduced by cultured muscle cells, via increased IGF‐1 activity. C57BL/6J mice were subjected to laceration of the gastrocnemius muscle and were treated with LIV applied directly to the lower leg for 30 min/day or non‐LIV sham treatment (controls) for 7 or 14 days. LIV was also applied to differentiating myotubes in culture for 30 min/day for 3 or 6 days. Compared with control mice, LIV increased myofiber cross‐sectional area, diameter, and percent area of peripherally nucleated fibers, and decreased percent damaged area after 14 days of treatment. In cultured myotubes, LIV increased fusion and diameter compared with controls after 6 days of treatment. These LIV‐induced effects were associated with increased total Akt on day 7 in injured muscle and on day 3 in myotubes, whereas phosphorylated‐to‐total Akt ratio increased on day 14 in injured muscle and on day 6 in myotubes but were not associated with increased IGF‐1 levels at any time point. These changes were also associated with LIV‐induced suppression of FOXO1 and Atrogin‐1 gene expression at day 7 in injured muscle. These findings demonstrate that muscle cells can directly transduce LIV signals into increased growth and differentiation, and this effect is associated with increased Akt signaling.

Effects of Vibration Training in Interstitial Lung Diseases: A Randomized Controlled Trial

BACKGROUND

Numerous studies have reported positive effects of exercise training in patients with interstitial lung disease (ILD) on physical capacity and quality of life. However, evidence is rare on the effects of specific forms of training and further pathophysiological mechanisms in these patients.

OBJECTIVES

In this multicenter study we aimed to explore the clinical effects of whole-body vibration training (WBVT) in patients with ILD on various outcome measures, including proinflammatory cytokines and myostatin.

METHODS

We randomly assigned 26 patients with different forms of multidisciplinary confirmed fibrotic ILDs either to the WBVT group (n = 11; 55% male, 61 ± 14 years old, forced vital capacity 83.2 ± 29.3% predicted, 6-min walking distance [6MWD] 478 ± 79 m) performing 3 months of a standardized training (3 times per week), or to a control training group (CTG, n = 15; 60% male, 63 ± 9 years old, FVC 74.6 ± 20.5% predicted, 6MWD 455 ± 85 m) performing sham WBV training. Training in the two groups was performed on a GalileoTM vibration plate (6-20 vs. 5 Hz). The functional assessments before and after the intervention period included pulmonary function, 6MWD test, chair rise test, ultrasonographic measurement of quadriceps muscle thickness (cross-sectional area), quality of life questionnaires, and serum samples.

RESULTS

We observed a significant increase in 6MWD (∆Training = 30 m [12-67], p = 0.024) and a decrease of myostatin (∆Training = -465 pg/mL [-713 to -166], p = 0.008) in the WBVT group. In contrast, no significant differences were observed in the CTG.

CONCLUSIONS

The present study demonstrates that WBVT is able to significantly increase 6MWD and decrease myostatin in patients with fibrotic ILDs. Therefore, WBVT seems to be a beneficial and feasible training modality in ILD patients. Clinical Trial Registry: German Clinical Trials Registry (DRKS00012930).

Impaired Fracture Healing in Sarco-Osteoporotic Mice Can Be Rescued by Vibration Treatment Through Myostatin Suppression

Sarcopenia is highly prevalent in fragility fracture patients and is associated with delayed healing. In this study, we investigated the effect of low-magnitude high-frequency vibration (LMHFV) on osteoporotic fracture with sarcopenia and the potential role of myostatin. Osteoporotic fractures created in sarcopenic SAMP8, non-sarcopenic SAMR1 were randomized to control or LMHFV (SAMP8, SAMR1, SAMP8-V, or SAMR1-V) groups. Healing and myostatin expression were evaluated at 2, 4, and 6 weeks post-fracture. In vitro, conditioned-media were collected from myofibers isolated from aged and young SAMP8 or C2C12 myoblasts with or without LMHFV. Osteoblastic MC3T3-E1 under osteogenic differentiation were treated with plain or conditioned-medium (±myostatin propeptide). LMHFV significantly enhanced callus formation was in non-sarcopenic SAMR1 mice; but the enhancement effect was not significant in SAMP8 mice at week 2. Myostatin expressions in callus and biceps femoris of SAMP8 group were significantly higher all groups with significant negative correlation with callus size (R²  = 0.7256; p = 0.0004). Mechanical properties (week 4) and callus remodeling (week 6) were inferior in SAMP8 versus SAMR1 and were significantly enhanced by LMHFV. Alkaline Phosphatase (ALP) and Runx2 expression of MC3T3-E1 was lower in aged myofiber compared with young, but upregulated by LMHFV or myostatin inhibition; also confirmed with C2C12. LMHFV enhanced early callus formation, microarchitecture, callus remodeling and mechanical properties of fracture healing in both SAMP8 and SAMR1; however, more effective in non-sarcopenic SAMR1 mice. Impaired fracture healing in sarcopenic SAMP8 mice is attributed by elevated myostatin expression in callus and muscle, which correlated negatively with callus formation. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:277-287, 2020.

Mechanical oscillations superimposed on the pelvic floor muscles during Kegel exercises reduce urine leakage in women suffering from stress urinary incontinence: A prospective cohort study with a 2-year follow up

INTRODUCTION

New methods of conservative treatment of female stress urinary incontinence are needed. We investigated whether superimposed vibration mechanosignals during Kegel exercises could reduce the amount of urinary leakage after 4 and 6 weeks of training.

MATERIAL AND METHODS

Sixty women with stress urinary incontinence were included in this prospective cohort study. Vibration mechanosignals were superimposed during Kegel exercises using an intravaginal device. Each training session consisted of 15 maximal contractions of pelvic floor muscles for 5 s. The women performed training (5 min/day) at home for 4 (n = 60) and 6 (n = 36) weeks. Urine leakage (g) during stress test with standardized bladder volume, and contraction force without and with superimposed mechanical stimulations were measured at inclusion (T₀ ), and after 4 (T₂ ) and 6 (T₃ ) weeks of training using an intravaginal device. Incontinence Questionnaire-Short Form was recorded at T₀ , and in a sub-cohort of women (n = 36) at 2 years follow up.

RESULTS

Mean urine leakage reduced significantly from 20.5 (± 12.2) g at T₀ to 4.8 (± 6.7) g at T₂ and 1.5 (± 6.7) g at T₃ . After 4 and 6 weeks of training, urinary leakage was ≤ 4 g on stress test in 44 and 49 of the 60 women, respectively. At T₀ , the mean Incontinence Questionnaire-Short Form score was 13 (± 2.4), and at 2 years follow up, the score was 6.3 (± 3.75).

CONCLUSIONS

Superimposed mechanical stimulation with Kegel exercises significantly reduced urinary leakage in women with stress urinary incontinence.

Whole-Body Vibration Mimics the Metabolic Effects of Exercise in Male Leptin Receptor-Deficient Mice

Whole-body vibration (WBV) has gained attention as a potential exercise mimetic, but direct comparisons with the metabolic effects of exercise are scarce. To determine whether WBV recapitulates the metabolic and osteogenic effects of physical activity, we exposed male wild-type (WT) and leptin receptor-deficient (db/db) mice to daily treadmill exercise (TE) or WBV for 3 months. Body weights were analyzed and compared with WT and db/db mice that remained sedentary. Glucose and insulin tolerance testing revealed comparable attenuation of hyperglycemia and insulin resistance in db/db mice following TE or WBV. Both interventions reduced body weight in db/db mice and normalized muscle fiber diameter. TE or WBV also attenuated adipocyte hypertrophy in visceral adipose tissue and reduced hepatic lipid content in db/db mice. Although the effects of leptin receptor deficiency on cortical bone structure were not eliminated by either intervention, exercise and WBV increased circulating levels of osteocalcin in db/db mice. In the context of increased serum osteocalcin, the modest effects of TE and WBV on bone geometry, mineralization, and biomechanics may reflect subtle increases in osteoblast activity in multiple areas of the skeleton. Taken together, these observations indicate that WBV recapitulates the effects of exercise on metabolism in type 2 diabetes.

Whole-body vibration of mice induces progressive degeneration of intervertebral discs associated with increased expression of Il-1β and multiple matrix degrading enzymes

OBJECTIVE

Whole-body vibration (WBV) is a popular fitness trend based on claims of increased muscle mass, weight loss and reduced joint pain. Following its original implementation as a treatment to increase bone mass in patients with osteoporosis, WBV has been incorporated into clinical practice for musculoskeletal disorders, including back pain. However, our recent studies revealed damaging effects of WBV on joint health in a murine model. In this report, we examined potential mechanisms underlying disc degeneration following exposure of mice to WBV.

METHODS

Ten-week-old male mice were exposed to WBV (45 Hz, 0.3 g peak acceleration, 30 min/day, 5 days/week) for 4 weeks, 8 weeks, or 4 weeks WBV followed by 4 weeks recovery. Micro-computed tomography (micro-CT), histological, and gene expression analyses were used to assess the effects of WBV on spinal tissues.

RESULTS

Exposure of mice to 4 or 8 weeks of WBV did not alter total body composition or induce significant changes in vertebral bone density. On the other hand, WBV-induced intervertebral disc (IVD) degeneration, associated with decreased disc height and degenerative changes in the annulus fibrosus (AF) that did not recover within 4 weeks after cessation of WBV. Gene expression analysis showed that WBV for 8 weeks induced expression of Mmp3, Mmp13, and Adamts5 in IVD tissues, changes preceded by increased expression of Il-1β.

CONCLUSIONS

Progressive IVD degeneration induced by WBV was associated with increased expression of Il-1β within the IVD that preceded Mmp and Adamts gene induction. Moreover, WBV-induced IVD degeneration is not reversed following cessation of vibration.

Whole-body vibration to prevent intensive care unit-acquired weakness: safety, feasibility, and metabolic response

Background

Intensive care unit (ICU)-acquired weakness in critically ill patients is a common and significant complication affecting the course of critical illness. Whole-body vibration is known to be effective muscle training and may be an option in diminishing weakness and muscle wasting. Especially, patients who are immobilized and not available for active physiotherapy may benefit. Until now whole-body vibration was not investigated in mechanically ventilated ICU patients. We investigated the safety, feasibility, and metabolic response of whole-body vibration in critically ill patients.

Methods

We investigated 19 mechanically ventilated, immobilized ICU patients. Passive range of motion was performed prior to whole-body vibration therapy held in the supine position for 15 minutes. Continuous monitoring of vital signs, hemodynamics, and energy metabolism, as well as intermittent blood sampling, took place from the start of baseline measurements up to 1 hour post intervention. We performed comparative longitudinal analysis of the phases before, during, and after intervention.

Results

Vital signs and hemodynamic parameters remained stable with only minor changes resulting from the intervention. No application had to be interrupted. We did not observe any adverse event. Whole-body vibration did not significantly and/or clinically change vital signs and hemodynamics. A significant increase in energy expenditure during whole-body vibration could be observed.

Conclusions

In our study the application of whole-body vibration was safe and feasible. The technique leads to increased energy expenditure. This may offer the chance to treat patients in the ICU with whole-body vibration. Further investigations should focus on the efficacy of whole-body vibration in the prevention of ICU-acquired weakness.

Trial registration

Applicability and Safety of Vibration Therapy in Intensive Care Unit (ICU) Patients. ClinicalTrials.gov NCT01286610. Registered 28 January 2011.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-016-1576-y) contains supplementary material, which is available to authorized users.

Distinct Skeletal Muscle Gene Regulation from Active Contraction, Passive Vibration, and Whole Body Heat Stress in Humans

Skeletal muscle exercise regulates several important metabolic genes in humans. We know little about the effects of environmental stress (heat) and mechanical stress (vibration) on skeletal muscle. Passive mechanical stress or systemic heat stress are often used in combination with many active exercise programs. We designed a method to deliver a vibration stress and systemic heat stress to compare the effects with active skeletal muscle contraction. Purpose: The purpose of this study is to examine whether active mechanical stress (muscle contraction), passive mechanical stress (vibration), or systemic whole body heat stress regulates key gene signatures associated with muscle metabolism, hypertrophy/atrophy, and inflammation/repair. Methods: Eleven subjects, six able-bodied and five with chronic spinal cord injury (SCI) participated in the study. The six able-bodied subjects sat in a heat stress chamber for 30 minutes. Five subjects with SCI received a single dose of limb-segment vibration or a dose of repetitive electrically induced muscle contractions. Three hours after the completion of each stress, we performed a muscle biopsy (vastus lateralis or soleus) to analyze mRNA gene expression. Results: We discovered repetitive active muscle contractions up regulated metabolic transcription factors NR4A3 (12.45 fold), PGC-1α (5.46 fold), and ABRA (5.98 fold); and repressed MSTN (0.56 fold). Heat stress repressed PGC-1α (0.74 fold change; p < 0.05); while vibration induced FOXK2 (2.36 fold change; p < 0.05). Vibration similarly caused a down regulation of MSTN (0.74 fold change; p < 0.05), but to a lesser extent than active muscle contraction. Vibration induced FOXK2 (p < 0.05) while heat stress repressed PGC-1α (0.74 fold) and ANKRD1 genes (0.51 fold; p < 0.05). Conclusion: These findings support a distinct gene regulation in response to heat stress, vibration, and muscle contractions. Understanding these responses may assist in developing regenerative rehabilitation interventions to improve muscle cell development, growth, and repair.

Effect of Low-Magnitude, High-Frequency Vibration Treatment on Retardation of Sarcopenia: Senescence-Accelerated Mouse-P8 Model

Sarcopenia-related falls and fall-related injuries in community-dwelling elderly people garnered more and more interest in recent years. Low-magnitude high-frequency vibration (LMHFV) was proven beneficial to musculoskeletal system and recommended for sarcopenia treatment. This study aimed to evaluate the effects of LMHFV on the sarcopenic animals and explore the mechanism of the stimulatory effects. Senescence-accelerated mouse P8 (SAMP8) mice at month 6 were randomized into control (Ctrl) and vibration (Vib) groups and the mice in the Vib group were given LMHFV (0.3 g, 20 min/day, 5 days/week) treatment. At months 0, 1, 2, 3, and 4 post-treatment, muscle mass, structure, and function were assessed. The potential proliferation capacity of the muscle was also evaluated by investigating satellite cells (SCs) pool and serum myostatin expression. At late stage, the mice in the Vib group showed higher muscle strength (month 4, p = 0.028). Generally, contractibility was significantly improved by LMHFV (contraction time [CT], p = 0.000; half-relaxation time [RT50], p = 0.000). Enlarged cross-sectional area of fiber type IIA was observed in the Vib group when compared with Ctrl group (p = 0.000). No significant difference of muscle mass was observed. The promotive effect of LMHFV on myoregeneration was reflected by suppressed SC pool reduction (month 3, p = 0.000; month 4, p = 0.000) and low myostatin expression (p = 0.052). LMHFV significantly improved the structural and functional outcomes of the skeletal muscle, hence retarding the progress of sarcopenia in SAMP8. It would be a good recommendation for prevention of the diseases related to skeletal muscle atrophy.

PKCε as a novel promoter of skeletal muscle differentiation and regeneration

INTRODUCTION

Satellite cells are muscle resident stem cells and are responsible for muscle regeneration. In this study we investigate the involvement of PKCε during muscle stem cell differentiation in vitro and in vivo. Here, we describe the identification of a previously unrecognized role for the PKCε-HMGA1 signaling axis in myoblast differentiation and regeneration processes.

METHODS

PKCε expression was modulated in the C2C12 cell line and primary murine satellite cells in vitro, as well as in an in vivo model of muscle regeneration. Immunohistochemistry and immunofluorescence, RT-PCR and shRNA silencing techniques were used to determine the role of PKCε and HMGA1 in myogenic differentiation.

RESULTS

PKCε expression increases and subsequently re-localizes to the nucleus during skeletal muscle cell differentiation. In the nucleus, PKCε blocks Hmga1 expression to promote Myogenin and Mrf4 accumulation and myoblast formation. Following in vivo muscle injury, PKCε accumulates in regenerating, centrally-nucleated myofibers. Pharmacological inhibition of PKCε impairs the expression of two crucial markers of muscle differentiation, namely MyoD and Myogenin, during injury induced muscle regeneration.

CONCLUSION

This work identifies the PKCε-HMGA1 signaling axis as a positive regulator of skeletal muscle differentiation.

Potential regenerative rehabilitation technology: implications of mechanical stimuli to tissue health

BACKGROUND

Mechanical loads induced through muscle contraction, vibration, or compressive forces are thought to modulate tissue plasticity. With the emergence of regenerative medicine, there is a need to understand the optimal mechanical environment (vibration, load, or muscle force) that promotes cellular health. To our knowledge no mechanical system has been proposed to deliver these isolated mechanical stimuli in human tissue. We present the design, performance, and utilization of a new technology that may be used to study localized mechanical stimuli on human tissues. A servo-controlled vibration and limb loading system were developed and integrated into a single instrument to deliver vibration, compression, or muscle contractile loads to a single limb (tibia) in humans. The accuracy, repeatability, transmissibility, and safety of the mechanical delivery system were evaluated on eight individuals with spinal cord injury (SCI).

FINDINGS

The limb loading system was linear, repeatable, and accurate to less than 5, 1, and 1 percent of full scale, respectively, and transmissibility was excellent. The between session tests on individuals with spinal cord injury (SCI) showed high intra-class correlations (>0.9).

CONCLUSIONS

All tests supported that therapeutic loads can be delivered to a lower limb (tibia) in a safe, accurate, and measureable manner. Future collaborations between engineers and cellular physiologists will be important as research programs strive to determine the optimal mechanical environment for developing cells and tissues in humans.

Musculoskeletal response of dystrophic mice to short term, low intensity, high frequency vibration

OBJECTIVES

We aimed to identify parameters of low-intensity vibration that initiate the greatest osteogenic response in dystrophin-deficient mice and determine vibration safety for diseased muscle in three separate studies.

METHODS

Study1: Mdx mice were randomized into seven vibration treatments and 14 d later, plasma osteocalcin and tibial osteogenic gene expression were compared among treatments. Study2: Three days of vibration was compared to other modalities known to elicit muscle injury in mdx mice. Study3: Dystrophic mice with more severe phenotypes due to altered utrophin were subjected to 7 d vibration to determine if muscle injury was induced. Muscle torque and genes associated with inflammation and myogenesis were assessed in Studies 2-3.

RESULTS

Two sets of parameters (45 Hz 0.6 g and 90 Hz 0.6 g) evoked osteogenic responses. 45 Hz upregulated alkaline phosphatase and tended to upregulate osteoprotegerin without altering RANKL, and 90 Hz simultaneously upregulated osteprotegerin and RANKL. Thus, subsequent muscle studies utilized 45 Hz. Vibration for 3 or 7 d was not injurious to dystrophic muscle as shown by the lack of differences between vibrated and non-vibrated mice in torque and gene expression.

CONCLUSIONS

Results indicate that vibration at 45 Hz and 0.6 g is safe for dystrophic muscle and may be a therapeutic modality to improve musculoskeletal health in DMD.