Age Science: Bones

It’s time to bone up on your health. Osteoporosis is a disease that erodes bone structure until it collapses, like a bridge whose supports have rusted away. Cells called osteoclasts remove old bone; osteoblasts build and renew bone, forming a structure for minerals like calcium and phosphorus. 

Osteoclasts and Osteoblasts

Osteoporosis affects 1.4 million Canadians, including one in four women. Sex hormones play a role: post-menopausal women initially lose bone mass quickly as estrogen levels fall. The first five to 10 years after menopause, a woman can lose 2 to 5 per cent of bone tissue. In Canada, one man in eight, aged 50-plus, has osteoporosis — and probably doesn’t know it until a bone breaks. The gradual bone loss men experience is mainly due to increased levels of a substance that binds testosterone, keeping it from promoting bone formation.

We normally get shorter with age as spinal disks shrink. For those 60 or older, a difference of six centimetres or more between current height and a person’s historic tallest height can point to the disease. Less than 3.6 centimetres (two finger-breadths) between the ribs and the top of the hip could indicate the presence of fractures in the lower part of the spine, according to Osteoporosis Canada. The group recommends that people over 65 have a bone mineral density test (BMD), which scans the hip and spine using dual energy X-ray absorptiometry (DXA). Other candidates for the procedure are 50-plus people who have had a recent fracture and osteoporosis is suspected.

Finnish researchers studying age-related osteoporosis put older rats (equivalent in human years to 75-year-old men and 80-year-old women) through a treadmill program. After testing the rats’ bones, they concluded even old bones can be strengthened, provided the activity is safe and effective. Weight-bearing exercise that directs force through the length of bones stimulates bone formation. Resistance training that progressively loads bones and strengthens muscles also aids bone building, protecting people who have not developed the disease. From our mid-30s, the process of either resorbing or renewing favours progressive bone loss. If your diet is lacking, your body recruits minerals like calcium and phosphorus from your body’s precious savings bank — your bones.

Whole Body Vibration (WBV) training uses a platform on which you stand, sit or lie to transmit mechanical forces through the body, causing muscles to react to the vibrations — which supposedly exercises them. Now, very low-intensity vibration machines like the Juvent 1000 DMT (Dynamic Motion Therapy) Platform ( hold promise as a preventative treatment for osteoporosis. “There is preliminary data suggesting these machines may have potential benefits for bones,” says Dr. Angela Cheung, director of the osteoporosis program at the University Health Network/Mount Sinai Hospital in Toronto. She is leading a randomized control trial to see if use of the Juvent, already licensed as a medical device by Health Canada, can help decrease bone loss and deterioration of bone structure in post-menopausal women. “We’re hoping that the benefits will be similar in magnitude to calcium and vitamin D supplementation,” she adds, noting that the machines are for sale to patients in Canada for about $2,400, and “our study provides it to our participants for free if they are in the intervention group.”

— Charmaine Gooden