Published in The Toronto Star, October, 2009.
Photo by Vivian Song
Ginny Cowan is teetering on stability discs.
Her legs are shaking atop inflated exercise discs and she's lurched slightly forward to catch herself from falling backwards.
She looks precarious for a few seconds, but when her trainer throws a six-pound medicine ball towards her, she catches it decisively.
"I call him the torturer," she says.
Every week, for an hour, Cowan, 66, undergoes a strenuous exercise regime that challenges her strength and balance muscles at Osteosolution, an osteoporosis clinic downtown.
The thing is, Cowan is not completely osteoporotic. She has osteopenia – a milder form of bone loss – in her hips. But after watching her mother fracture her wrist and hip because of the debilitating bone disease, Cowan is bent on avoiding the same fate.
"I'm doing my best not to let my condition go any further," she said.
But Cowan knows that, at best, all her hard work will only be able to maintain her bone mineral density – not create new bone mass.
That's because peak bone mass is achieved by the age of 16 for women and 20 in men. And the most rapid period of bone acquisition occurs during puberty.
"Preventing bone loss starts when you're young," said Dr. Ben Deheshi, an orthopedic surgeon at Osteosolution. "If you start a savings plan when you're young, like an RRSP account, you'll have more when you retire. Same goes for building a bone account."
It's a common analogy among osteoporosis experts.
"There's only so much time to put bone in the bone account," added Dr. Sophie Jamal, director of the osteoporosis program at Women's College Hospital and member of Osteoporosis Canada's scientific advisory council.
"Because at the age of 20, the bone bank closes. How much bone you have in the bank account is key."
For parents, that means providing kids with a diet rich in calcium and vitamin D during their optimal bone building years, and encouraging a wide range of exercise, says Margaret Martin, an Ottawa-based physical therapist who designed the MelioGuide, an online resource for all things osteoporosis.
"Exercise needs to be as high impact as possible, like basketball, gymnastics or soccer," Martin said. "And ideally, kids should be doing as many different types of exercises as possible because each sport challenges bones differently."
More than 25 per cent of all the bone built in a boy's lifetime will happen between the ages of 13 and 15, while the same will happen for girls during the ages of 12 and 14.
"In those two years, you will acquire as much bone as you will lose in your entire adult life," she said. "That's why it's important to build as much as you can here."
For girls, the optimal bone-building years can also be defined as the onset of menstruation. The older the girl is before she gets her period, the narrower her window of time for building bone mass. And for many girls with delayed menstruation, the reason can be traced back to eating disorders.
"The marker for puberty in girls is her period," Jamal explained.
"But if she has an eating disorder and doesn't get her period until she's 18, she only has until the age of 20, or two years, to put on bone mass."
Low body weight and malnutrition will delay or stop periods altogether, halting the production of estrogen which plays an essential role in the bone remodelling process.
The only way to gain back any bone mass lost during an eating disorder is if the disorder is caught and treated before the early 20s are entered.
"They can rebuild, but they'll be disadvantaged," Deheshi said.
Other behavioural and lifestyle decisions which can lead to amenorrhea – the absence of menstrual cycles – include excessive or elite-level athletic activity, like marathon running he added.
"That's a big red flag and should be seen by an endocrinologist."
Martin advises both parents and female sports coaches to make a habit of asking girls about their cycles.
"Menstrual cycles are a clear sign of whether or not a girl is at a safe body weight," she said. "It's OK to be slim as long as you have regular periods."
A thin body frame is another red flag for lower bone density, added Jane Aubin, the scientific director for the Institute of Musculoskeletal Health and Arthritis at the Canadian Institutes of Health Research.
"If genetically you have a smaller frame, you're on the lower end of bone mass. These people need to be extra vigilant about getting exercise and maximizing their bone health."
For older adults, strength-training exercises should be at a weight load that tires them out at between 10 to 12 repetitions. Sessions should be about 45 minutes and occur two to three times a week, Martin suggests.
Other lifestyle habits that can cause bone loss include smoking and drinking.
The Canadian Pediatric Society also advises that pregnant, breastfeeding mothers and infants take vitamin D supplements to make up for a nation-wide deficiency. Vitamin D is an essential bone-building block and can increase calcium absorption in the body by up to 80 per cent.
Perhaps the most significant factor in our bone health, says Jamal, is family history.
"Over half of our bone mass is inherited from our parents," she said.
For Cowan, despite her healthy diet and active childhood, she was fighting an uphill battle when it came to her bone health because of her mother.
"I hated him for it then, when my father was always nagging at me to sit up straight," Cowan said. "But bless him for it now."