Exercise and healthy bones throughout your life
Published in Medicinewise Living
Date published: About this date
Ever wondered if exercise is doing any good for you or your children’s bones?
Good news it is. Exercise helps to build strong bones along with adequate calcium and vitamin D. What’s more, our early years are a critical time for building strong bones.
The greatest amount of bone is built during childhood and adolescence
Once this ‘peak bone mass’ is reached (usually by our mid to late 20’s) we start to lose bone and this continues as we age. The more bone we build early on, the more we can protect ourselves from losing too much down the track.
Not achieving an optimal peak bone mass when we’re younger is as much a concern as losing bone when we’re older.
While other factors such as genetics have a lot to do with this, we can help prevent conditions like osteoporosis later in life by getting enough calcium, vitamin D and exercise in our early years and continuing this throughout adulthood.
Weight-bearing and resistance exercises increase our bone mass
Bones increase in mass and strengthen when they bear weight during exercise, and when some impact or extra strain is placed upon them. To have an effect on bone, exercise needs to be undertaken regularly, be moderate to vigorous in intensity, and ideally include a variety of activities.
Weight-bearing exercises are helpful as they are done on the feet, allowing gravity to exert a force on bone. Activities with a high impact include ball sports like tennis, football and netball, running, jumping, hiking, climbing stairs, aerobics and dancing.
Activities with a lower impact on bone (e.g. leisurely walking), and non-weight bearing exercises like cycling and swimming, are less likely to have an effect, although they’re still good for our health and muscle strength.
Resistance exercises which involve lifting weights with your arms and legs can also increase bone mass. This is because the muscle contractions needed to move a heavy weight place extra strain on the bone attached to those muscles.
We can also help conserve the bone gained earlier in life by exercising
While exercise has a greater effect on bone for children and adolescents, it can also provide some increases in bone mass and help reduce bone loss for adults.
To preserve as much bone as possible, exercise needs to be continued throughout adult life — our bone mass will eventually return to what it was if we stop exercising regularly.
Before undertaking weight-bearing activities (especially high impact) or resistance training, check whether they’re suitable for you with your doctor. Some adults can’t undertake these exercises because of joint problems or certain medical conditions.
Importantly, if you already have osteoporosis or your bones break easily, some weight-bearing and resistance exercises may be more likely to cause you a broken bone (fracture) than to improve your bone mass.
Activities that may cause a fracture in people with fragile bones include trunk flexion (e.g. sit-ups), twisting movements and high-impact or abrupt loading (e.g. when lifting heavy weights).
Continuing exercise into our later years has further benefits
Exercising throughout adulthood can do more than just preserve our bone mass: it can improve our muscle strength, balance and posture. And by doing so, we can help to prevent falls that often lead to fractures of the hip and spine, particularly in older people and those with osteoporosis.
Low-impact muscle strengthening, balance and stability exercises are recommended if you are at risk of fractures from fragile bones or have a tendency for falls. These exercises include Tai Chi, hydrotherapy, gentle weights and walking.
A physiotherapist or exercise physiologist can create an exercise program specific to your needs, abilities and interests.
Get enough calcium and vitamin D to maximise the benefits of exercise
Calcium is essential for building and maintaining healthy bones throughout life. Despite this, the average dietary calcium intake in Australia is well below recommended levels.
Most children, adolescents and adults can get enough calcium by eating 3 serves of dairy food per day: 1 serve = 250mL milk or 200g yoghurt or 40g cheddar cheese.
Children and adolescents may have a poor intake due to substitution of milk with soft drinks, water or fruit juice, the perception that dairy foods on the whole are high in fat, or the family consumes inadequate amounts of calcium-rich foods.
Calcium-rich non-dairy foods (e.g. almonds, beans, tofu, broccoli, tinned salmon) and calcium-fortified foods are options if you don’t eat dairy foods or you’re unable to consume adequate serves each day. The calcium content of fortified foods can vary so check food labels to ensure you meet your daily requirements.
We also need a sufficient amount of vitamin D each day so that our bodies absorb calcium properly.
Most vitamin D is produced in the skin when it’s exposed to sunlight through normal day-to-day outdoor activities. The diet only provides very small amounts of vitamin D through foods such as oily fish (e.g. salmon, mackerel), liver, eggs and some fortified foods.
In summer, short walks of less than 10 minutes around morning or afternoon tea time on most days should provide enough vitamin D if your skin is moderately fair, and you expose your hands, face and arms. Longer periods of exposure may be needed in winter, and all throughout the year for people with darker skin.
But remember, prolonged sun exposure not only increases the risk of skin cancers, it degrades the vitamin D we’ve produced in our skin. So we all need to use sun protection when we’re outdoors for extended periods and avoid unprotected exposure in summer between 10 am and 2 pm (11 am and 3 pm during daylight saving).
More on healthy bones for life
Requirements for exercise, calcium intake and vitamin D for various age groups, as well as the calcium content of dairy products and other foods, are available from Osteoporosis Australia. The Cancer Council also provides information about safe sun exposure and vitamin D.
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