It has been well known that lack of weight bearing stimulus to bone over time causes bone mineral density loss (BMD).  Typically, early research on disease uses animal models.  In osteoporosis research a question might be, where do they get mice with osteoporosis to test a particular treatment.  The answer is that they simply create them by immobilization.  Once they have osteoporosis, they can then test the benefit of different treatments.

In humans, certain situations have been shown to cause earlier onsets of BMD loss including immobility from spinal cord injury and in extended space flight where weightlessness is maintained for several months.  These forms are called secondary osteoporosis.  During space flight, 1-2% of BMD is lost each month. (1) This level of loss is similar to the yearly loss that occurs with gradual estrogen decline between ages 35 and menopause.

The point of this discussion is that weight bearing stimulus is needed to maintain BMD.  Once osteoporosis is present, increasing weightbearing stress or simulating it can be helpful in restoring BMD.  Daily exercise such as walking in a weight vest or using resistance exercise machines have been shown to improve BMD about 1-2% over time.  While this is helpful it is not enough as a standalone treatment given that in early osteoporosis approximately 25% of BMD has been lost.

Getting back to the mention above about simulating weightbearing stress, this area has been extensively studied.  Weightbearing stress stimulates bone building as it causes activation of cell receptors on osteoblasts, the cell involved in bone generation.  These receptors are called mechanoreceptors meaning that they activate in response to mechanical force.

(2) Different physical modalities can generate this signaling including whole body vibration (WBV), ultrasound, laser therapy and pulsed electromagnetic frequency therapy (PEMF).  Studies with WBV and ultrasound have shown they improve BMD about 2-3% over time.  Laser therapy does somewhat better at 10-15% which is in the range of the most effective osteoporosis drugs called anabolics.

There is strong interest in non-drug interventions for osteoporosis.  A program of nutritional support and PEMF is perhaps the best of the non-drug options.  A PEMF is best supported with the increased exercise as discussed above.  Osteoporosis is a challenging disease to treat and using as many tools as possible ensures the best outcome.

1. Ohshima H. Secondary osteoporosis UPDATE. Bone loss due to bed rest and human space flight study. Clin Calcium. 2010 May;20(5):709-16.

• Thompson WR, Rubin CT, Rubin J. Mechanical regulation of signaling pathways in bone. Gene. 2012 Jul 25;503(2):179-93.