Whole body vibration versus magnetic therapy on bone mineral density in elderly osteoporotic individuals

1. Introduction

Osteoporosis is a chronic systemic skeletal disease which is usually characterized by gradual reduction of bone mineral density (BMD) [1, 2]. Osteoporosis is one of the common causes of morbidity in elderly individuals [3, 4] and dramatically increases with advancing age [5, 6] especially when combined with other risk factors such as menopause, prolonged cortisone therapy, low calcium intake, smoking, alcohol consumption and physical inactivity [5]. Osteoporosis increases risk of repeated fractures and co-morbid complications that may result from otherwise trivial trauma and mild stresses [2, 3, 4] and it places a huge financial burden on health services [5]. Although pharmacological treatments including hormonal therapy, vitamin D and calcium are commonly prescribed as main line treatment [4], non-pharmacological management is a tangible part of the long-term prevention and treatment for osteoporosis [7]. Adequate intake of vital nutrients and minerals in addition to lifestyle changes and an increase in active exercise are emphasized as effective interventions [1, 4, 7, 8, 9, 10, 11, 12, 13]. Another non-pharmacological treatment, magnetic therapy, is a physical therapy modality that is both feasible and safe [14, 15]. Magnetic therapy is recommended as an alternative regimen for treatment of osteoporosis in both animals [16, 17, 18, 19] and humans [4, 20, 21, 22]. Pulsed electromagnetic fields (PEMFs) applied in magnetic therapy can stimulate osteogenesis by increasing osteoblastic activity and decreasing osteoclast formation [23]. Thus, magnetic therapy has the potential to enhance bone cell formation and increase BMD of osteoporotic bones [15]. Magnetic therapy [4, 14, 19] could therefore be an alternative therapy to traditional physical therapy modalities such as increased physical activity or strength building exercises for increasing BMD in older individuals [8, 24, 25, 26].

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Whole body vibration (WBV) is a novel mechanical stimulus, low-impact alternative therapeutic exercise to combat bone loss, increase bone mass and optimize peak bone in older subjects without the associated risks and effort of strenuous exercise [1, 27]. WBV training is a relatively new and promising non-pharmacological method for prevention of BMD decline [1]. WBV is generated in oscillating platforms and transmitted through the feet to the bones and muscles of the whole body [28]. However, the results of clinical trials investigating the impact of WBV on BMD are conflicting [29, 30, 31]. Recently some authors found that 12 months of WBV therapy did not alter BMD [29], but others found that treatment can strengthen weak muscles [30]. Beck and Norling [31] found that WBV for two sessions per week over 8 months increased hip BMD and balance performance more than walking exercise [31].

WBV and magnetic therapy are appealing alternatives to weight bearing exercises such as walking, which can be difficult for elderly individuals due to aging complications such as muscle weakness and a loss of balance [4, 32, 33, 34]. As the aging population grows, so does the need for alternative interventions for the prevention and treatment of osteoporosis. The aim of the study presented here is to evaluate the impact of WBV or magnetic therapy when combined with pharmacological treatment on osteoporosis. The null hypothesis tested here is that no difference in effectiveness in the management of osteoporosis will be observed with WBV or magnetic therapy when combined with pharmacological treatment, compared to pharmacological treatment alone.

Study design: Experimental study was conducted as a blind, randomized clinical trial.

3. Results

Osteoporosis is considered one of the most common and important health problems facing older individuals. It has been demonstrated that multi-component exercise programs based on strength, aerobic and/or weight-bearing training are beneficial to treating and preventing osteoporosis [8, 40]. However, some patients are limited in their ability to practice these exercises due to common complications related to aging such as muscle weakness, advanced osteoarthritis, neurological diseases and balance disturbance. Therefore, the availability of alternative physical therapy modalities with demonstrated effectiveness in treating osteoporosis when used in combination with pharmacological treatment would be tremendously beneficial, particularly for elderly patients [4].

The primary purpose of the study presented here was to evaluate and compare the effect of WBV therapy or magnetic therapy, in combination with pharmacological treatment, on BMD in elderly subjects with osteoporosis. BMD was evaluated in three regions, the lumbar spine, right, and left femoral heads and quantified using a “T-score”. The “T-score” was measured using DEXA, a commonly used radiological method to detect bone mineral density [18] that has been shown to reliably detect changes in BMD in osteoporotic bone [13]. Study results demonstrated a statistically significant improvement of BMD in all three areas after treatment with either WBV or magnetic therapy combined with pharmacological treatment. This improvement is in contrast to pharmacological treatment alone which resulted in no significant improvement in BMD.

Participants in all three treatment groups in this study received the same pharmacological treatment 1000–12000 mg/day of oral calcium supplementation, 10 mg/day or 70 mg/week of alendronate sodium, and 600 IU/day of vitamin D as recommended in literature [36, 37]. The recommendation of supplemental calcium and vitamin D for treatment of osteoporosis is based upon reports of a high prevalence of inadequate intake of these critical vitamins and minerals in elderly osteoporotic patients [41]. Furthermore, the supplementation of vitamin D3 and calcium was proven to have beneficial effects on increasing and maintaining BMD by enhancing the process of osteogenesis [42]. Consequently, the prevention and treatment of osteoporosis requires special attention to both calcium intake, which is a primary factor for bone health, and vitamin D, which improves calcium absorption [36, 37]. Thus, some researchers have proposed that adequate intake of calcium and vitamin D in addition to physical interventions or active exercise can synergistically improve the treatment of osteoporosis [36, 37]. The current study supports this approach, showing an enhanced increase in BMD when physical interventions such as WBV or magnetic therapy are combined with calcium and vitamin D supplementation. Other studies support these findings, reporting that vitamin D supplementation has no extra short-term skeletal benefit over calcium citrate supplementation in women with vitamin D insufficiencies [43]. In another study, investigators showed a reduction in bone loss at the femoral neck with calcium and vitamin D treatment, but results were not statistically significant [44]. While these studies do not conclusively demonstrate an effective increase in BMD based on vitamin D and calcium supplementation alone, a one year intervention study with calcium and vitamin D supplementation did show reduced bone turnover and significantly increased BMD in patients younger than 70 years of age. However, the effect of intervention in this study was positively correlated to physical activity, which emphasizes the importance of physical activity on positive results [45]. This further supports the conclusion of the study presented here, that for a significant positive impact on BMD in osteoporotic patients, calcium and vitamin D supplementation should be combined with physical therapy.

In addition to further supporting the importance of combining pharmacological treatment with physical therapy in combating osteoporosis, the study presented here demonstrates the effectiveness of two alternative modalities of physical therapy other than traditional physical activity and strength-building exercises. In support of the results presented here, previous studies have also reported increases in BMD with magnetic therapy, with one study specifically demonstrating an increase in BMD in older osteoporotic women after treatment [4, 14, 17]. Effects of magnetic therapy on BMD in osteoporotic participants can be explained by many mechanisms [14, 46, 47]. It was shown that magnetic therapy significantly suppressed trabecular bone loss and restored trabecular bone structure in bilateral ovariectomized rats [23]. Magnetic therapy may also stimulate calcification of the fibro-cartilage in the space between bony segments. Magnetic therapy can increase blood supply, which has been considered as a main source of improvement for bone healing, and may also stimulate osteogenesis, increasing osteoblastic activity [20]. In addition to the improvements in effectiveness of treatment, magnetic therapy also provides a non-invasive, easy, and safe method of direct treatment that can be targeted to specific sites in the body. It has even been suggested that magnetic therapy may prevent many older subjects from undergoing surgery [14].

As another alternative to traditional physical therapy, WBV has also been shown to significantly increase bone mineral density in this study as well as others [48, 49]. There is some agreement among researches that WBV therapy may be a suitable therapeutic modality for the prevention and treatment of osteoporosis [38, 50, 51]. It can be considered as a common exercise where individuals stand on an oscillating platform and the motor transmits vertical acceleration to muscle and bone [49]. One direct mechanism by which WBV is hypothesized to produce osteogenic effects is by changing the flow of bone fluid through bone stimulation and mechano-transduction. In addition, WBV may indirectly stimulate bone through activation of skeletal muscle by means of stretch reflex stimulation [52, 53]. WBV training can also produce an endocrine system response, increasing growth hormone and testosterone levels, indirectly affecting bone remodeling [54]. The positive effect of testosterone on BMD was detected in the forearm, the lumbar spine, and the hip in healthy men and women [1]. The WBV training has shown osteogenic effect in both college age individuals [3] and on the femoral neck in post-menopausal women [32]. The high-frequency and high-magnitude WBV has been applied on post-menopausal non-osteoporotic women, and it was found that vibration training improved isometric and dynamic muscle strength and significantly increased BMD of the hip [38].

While many studies support the results presented here, some clinical trials have contradicted these results. In several studies, the authors report non-signifi- cant benefit of WBV on post-menopausal bone measurements [29, 55]. Slatkovska et al. [29] applied WBV at 0.3G and either 90 or 30 Hz in addition to calcium and vitamin D supplementation for 12 months, measuring volumetric BMD (trabecular, cortical, and total) and bone structure (cortical thickness and trabecular thickness) at the distal tibia and distal radius as outcomes. Also measurement by the outcomes in Slatkovska et al.’s work did not show significant improvement with WBV therapy, the outcome measures differed from the current study in which is “T-score” of BMD at lumbar spine, right and left femoral heads are measured. Rubin et al. [55] also did not find significant changes in bone density after using either the WBV or placebo treatment, but the protocol for WBV use differed from the current study. Rubin et al. used a quiet standing posture to receive high-frequency, 30-Hz vibration, low-magnitude, 2.0 m/s 2 peak to peak, acceleration WBV with a relatively short treatment duration (10 minutes per session), compared to the current study which employed longer durations of 55 minute per session. In addition, patients in Rubin et al. [55] study were restricted to post-menopausal women while the current study included both male and female subjects.

To the best of our knowledge, there is no direct clinical trial comparing WBV with magnetic therapy. The results of the current study revealed WBV produces greater increases in BMD in the lumbar spine and right femoral head ( - 0.26 & 0.32, respectively) than magnetic therapy ( - 0.24 & - 0.28). However, magnetic therapy revealed greater increases in BMD in the left femoral head than WBV ( - 0.29 compared to - 0.24). While differences in the magnitude of response were observed, the differences were not statistically significant. Differences in results between the two therapies may be attributed to differences in the physical stimulation applied in each approach. In WBV, the participants are required to stand up-right, thus benefitting from both the direct effects of WBV as a muscular exercise as well as the inherent physical activity of maintaining a standing position throughout the session whereas magnetic therapy is applied in the supine position and patients only benefit from the magnetic therapy itself. While the results presented here suggest there may be differences in effect between the two therapies, it is recommended that more clinical studies are needed to compare the effectiveness of these two recent interventions on larger sample sizes and for longer treatment periods to detect statistically significant differences.

5. Conclusions

Application of either WBV or magnetic therapy in combination with standard pharmacological treatment for osteoporosis increases BMD of the lumbar spine, right, and left femoral heads in elderly osteoporotic individuals. Usage of pharmacological intervention alone is not sufficient to achieve significant increases in BMD over a 4 month period. Thus, it can be concluded that application of either whole body vibration or magnetic therapy in combination with pharmacological treatment is a promising and effective method to treat osteoporosis in older individuals.

6. Recommendations

Further studies are needed to compare effects of WBV with that of magnetic therapy on BMD in older individuals using a larger sample size for a longer time and with long-term follow up.

7. Limitations

Limitations of the current study include a relatively short duration of treatment and evaluation (4 months) with measurements taken only before and after treatment with no long-term follow-up.

Conflict of interest

The authors declare that they have no conflict of interest.