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Exercise keeps heart and bones strong

14th October 2009

By Olivia Fens.

The importance of exercise for maintaining strong, healthy bones cannot be underestimated.
Exercise can help to build bones in youth - and it can also help to maintain them in adulthood.

Bones need regular weight-bearing exercise. Exercise stimulates bone, creating bone turnover, growth and strength.

Weight-bearing exercise includes any physical activity where you have to support the weight of your own body. These weight-bearing exercises include:

  • Dancing
  • Running
  • Walking
  • Jogging
  • Aerobics
  • Tennis
  • Squash
  • Football.

While cycling and swimming are excellent activities for overall fitness they do not benefit bone strength as they are not weight-bearing.

President of the Irish Osteoporosis Society, Prof Moira O'Brien, recommends 30 minutes of daily weight-bearing exercise for all age groups, including senior citizens.

This type of daily exercise is incredibly important for children as most peak bone mass building is done during adolescence, Prof O'Brien said.

"The most important age for people to exercise is during the growth period, from eight to 20 years. Sixty per cent of the bone you are going to have throughout your life is laid down at that time," Prof O'Brien said.

"Unfortunately, computers and hand-held games are very popular for people in that age group, and they often choose them over playing outside.

"A study in Canada found that students who did jumping jacks for 10 minutes every day improved their bone density significantly," Prof O'Brien added.

But it's not just children who need to do daily weight-bearing exercises.

Prof O'Brien said even older people need at least 30 minutes of weight-bearing exercise each day. You can even break this exercise up into three to five minute intervals over the course of the day.

"Walking is a weight-bearing exercise, but you need to alter speeds (eg. brisk two minutes, moderate one minute, brisk two minutes, etc). However, you need good balance to do this," Prof O'Brien said.

"Dancing is a great weight-bearing exercise for all age groups. There are also certain exercises that can be done sitting or lying down.

"Walking waist-deep in a swimming pool is good for people with arthritis. Gravity is reduced and the resistance from the water is great for muscles and bones. It can improve strength and endurance and it means there's a lot less stress on the bones. It is modified weight-bearing and it is a great form of exercise which can be combined with weight-bearing exercise."

Exercise awareness
Last year, the UK's National Osteoporosis Society surveyed more than 2,600 people, and found that only 44% of the people questioned could identify walking as being beneficial for bone strength.

Less than a quarter of people thought that dancing could be beneficial to bones, and only 18% recognised that running could help to reduce the risk of osteoporosis. However, in the survey, 46% of participants believed that swimming was beneficial in preventing osteoporosis.

The survey added that knowledge of how to reduce the risk of osteoporosis through exercise was lowest among 18 to 24 year olds. More than half of young people in this age group did not think that exercise played a role in reducing the risk of osteoporosis.

International studies
The IOF reports that a Finnish study of teenage girls found that those who were the most physically active gained 40% more bone mass than the least active girls.

International research also showed that older people benefited from weight-bearing exercise and could actually reduce the risk of a fracture (breaking a bone).

A study in the US and Japan, found that older, postmenopausal women, who used small weights to strengthen their back muscles over a period of two years, were less likely to get vertebral fractures. In fact the back strengthening exercises reduced the chance of getting a fracture by almost threefold.

In the women aged 58 to 75 years, only one in 10 of those who exercised were found to have a vertebral fracture, while almost one-third of the women in the group that had not used the exercise regimen had suffered a fracture.

Women who had not taken part in the back exercise programme were also about twice as likely to have a compression fracture in the spine. This can lead to a hump developing on a person's upper back, a very painful condition which increases the risk of falling.

Don't overdo it
While exercising is important, it is also possible to exercise too much, which can affect hormone levels and worsen bone mass:

  • Women and teenage girls who exercise to an extreme degree with inadequate calories can develop amenorrhea (cessation of menstruation) due to oestrogen deficiency
  • Preoccupation with exercise can be a sign of an eating disorder, such as anorexia or bulimia
  • Both male and female athletes who exercise excessively without adequate caloric intake are at a heightened risk of osteoporosis. Athletes who train hard while trying to keep their weight below a certain level for competitive reasons are at particularly high risk
  • Too much exercise can result in stress fractures or joint damage.

Key things to remember
Exercise is not only essential for building bone strength in young people, it can also play a crucial role in rehabilitation. Exercise can help to rebuild bone in those who have already developed osteoporosis, and it can also provide relief from osteoporosis pain.

Prof O'Brien said that while exercise was crucial to maintaining healthy bones, it was only one of four essential steps to good bone density:

  • The bones need regular weight-bearing exercise - consider brisk walking, jogging or weight training
  • The bones need adequate calories - a healthy diet rich in calcium and vitamin D is essential for healthy bones
  • Bones need normal hormones levels - excessive exercising and stress can affect sex hormone levels, which can lead to an increased risk of osteoporosis
  • Protein - bones need protein (from meat and dairy products). Also excessive fibre (vegetarian and vegan diets) can affect hormone levels.

Additionally, too much alcohol, smoking and too much caffeine can all have detrimental effects on bone density.

Prof O'Brien added that if you have already been diagnosed with low bone density, it is essential to determine and treat the cause/causes.

Prof O'Brien concluded: "You have to commit, making exercise part of your daily routine. The most important thing is that doing exercise is just as effective inside the house as it is outside."

The advice of the Osteoporosis Society is to pick an exercise you enjoy doing, and you're more likely to continue with it. Doing a mix of different exercises is ideal.


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