I guess we rather take our bones for granted, until there’s a problem, and don’t tend to give much thought to what they do for us. Our skeleton supports our internal organs, protecting them and allowing them to function. Our bones store important minerals and contain bone marrow, which is where our blood cells are made. Many people don’t realise, but bones are living tissue: even after we stop gaining height in our teens, our bones constantly renew themselves to stay strong and function well.
‘Bone density’ relates to bone mineral content – the amount of actual bone that there is within your bones, if you will. After the age of 35 or so, the density of our bones naturally begins to decrease as part of the aging process. Some cancer treatments can noticeably accelerate this loss of bone density.
The higher your bone mineral content, the more dense your bones are. And the denser your bones, the stronger they generally are, and the less likely they are to break.
Impact of cancer treatment on bones
There are strong links between bone health and our hormone systems, and therefore certain cancer-related hormone treatments can have an impact on bone density.
This is particularly the case for breast cancer treatment in women that lowers oestrogen levels, such as chemotherapy that causes early menopause and hormone therapy with a drug called an LHRH analogue (zoladex) or an aromatase inhibitor (such as anastrozole, exemestane or letrozole). Radiotherapy or surgery to the ovaries can also affect bone density.
Similarly, hormone deprivation therapy in men with prostate cancer is known to cause reduced bone density.
People who had acute lymphoblastic leukaemia (ALL) as children are known to have a higher risk of reduced bone density later in life.
Osteoporosis and Osteopenia
Osteoporosis, sometimes called ‘bone thinning’ or ‘brittle bones’, refers to the condition in which bones lose their mineral and bone content at a faster rate than it can be replaced.
Osteopenia is the pre-curser to osteoporosis in which the mineral content of bone tissue is reduced, but less severely than in osteoporosis. The main risk to people who develop osteoporosis is that they are at much greater risk of fracture.
Weight bearing exercise
There’s a great deal of evidence that exercise can noticeably help to restore bone density. Weight bearing exercise – where you transfer your body weight from one foot to another – is particularly helpful. This is because the effect of that weight transfer is to cause jolts to the bones, and these jolts stimulate the bones into repair mode.
This is my best metaphor: Imagine you’re re-filling a coffee or tea caddy, or the pepper mill. If you tap the pot, the jolting causes the content to pack down more densely. That, in essence, is how weight bearing exercise works on your bone density – the jolting as you move stimulates your bone to pack down more tightly.
Examples of weight bearing exercise are
- Walking, and Nordic walking
- Playing racquet sports
- Climbing stairs
- Tai Chi and yoga
Swimming and cycling are excellent forms of exercise, but they are not weight bearing. Weight bearing means you need to be on your feet and moving.
Having strong muscles, or building them, contributes significantly to our bone health, and our ability to move. If you consider how we actually move: our brain tells our muscles to pull and push our bones. The stronger and more flexible our muscles are, the more that they support and move our frame.
Strength training is therefore an essential part of any fitness plan if you’re trying to take care of your bones. Of course, some strength training exercises – such as walking lunges – are also weight bearing and can therefore be doubly useful.
By far, your best bet is to combine aerobic, weight bearing exercise (on your feet, getting out of puff) with strength training (getting strong). Schwartz et al found that doing exactly this during chemotherapy helped preserve bone density in women being treated for breast cancer, and Almstedt et al found the same in women after treatment. It’s the same picture for men too: those taking hormone treatments for prostate cancers have improved their bone mineral density by combining aerobic exercise with strength training.
Exercise if you’ve already got osteoporosis
Do please check with your doctor or cancer nurse specialist if you’re concerned, but frequently people with osteoporosis are advised to exercise, in order to reap the many possible benefits.
If you have osteoporosis already, it’s advisable that you find ways to exercise that don’t increase your risk of falling and breaking bones. Combat sports, skiing or skating are best avoided. Choose low impact exercise, rather than activities that involve running or jumping – Nordic walking is a fantastic alternative to jogging as it gives you a good all-body workout, but with much less stress on your joints than running. Nordic walking poles can help you to feel steadier if you’re worried about falling.
Yoga and Mat Pilates are excellent forms exercise that are both weight bearing and muscle strengthening. If you enjoy them, and have osteoporosis, avoid moves such as deep back bends, especially moves where you bend forwards, as they can put too much strain on the spine.
 Source CRUK
 Exercise Effects… Schwartz Winters-Stone and Gallucci Oncology Nursing Forum vol 34 No3 2007
 Combined aerobic… Almstedt Grote Tarleton Bone Rep Dec 2016
 Lee Leslie & Lau A comprehensive bone-health management approach Curr Oncol Aug 2011