Kenneth Gardner - Fitness club

The loss of bone mass is an important indicator of ageing. Both men and women begin to lose bone density in their 30s, at a rate of one per cent each year. The rate of bone mass loss is much more pronounced in women because of the menopause period.

Bone loss makes us more prone to fractures. Our bone development peaks in our 20s and then declines throughout the rest of our lives because of the imbalance in bone remodelling that is, the replacement of old bone with new bone. Remodelling keeps the skeletal system in peak form.

Physical activity regulates and influences bone remodelling. Physical activity retards and even prevents bone mineral loss which is due to ageing. In fact, physical activity stimulates increased bone mineral content making our bones more resistant to breaking and better able to heal after a fracture.

Jogging and walking

A fitness buff takes a power walk in Emancipation Park, St Andrew. Resistance exercises, such as walking and jogging, strengthen the bones. - Winston Sill/Freelance Photographer

Weight-bearing and resistance exercises such as walking, jogging and weight training are very good for strengthening bones. All things being equal, the greater physical stress and compression that is placed on our bones the stronger and denser they become.

Sixty to 70 per cent of bone is composed of minerals which makes them resistant to compression; the remaining 30 to 40 per cent is protein and this makes the bone resistant to tension. After maturity, the proportion of fluid and organic material gradually decreases with age. Thus, healing becomes more difficult.

Appropriate stress such as physical activity is quite necessary for bone growth and development. Activities that cause constant irritative pressure cause our bones to deteriorate. The intermittent stresses of normal muscle activity, as is experienced during physical activity, encourage bone development. Thus, bones cease to develop when muscular and functional forces are negated by problems such as paralysis.

The following exercises should be quite useful in the improvement of your bone mass:

Shuffle step

1. Stand with your feet together and your hands on your hips.

2. Jump and place your feet to the sides, 18 to 24 inches apart.

3. Jump and return to the starting position.

4. Jump and place your right foot forward and your left foot backward.

5. Jump and place your left foot forward and your right foot backward.

6. Jump and return to the starting position.

7. Repeat the routine.

Side leg hops

1. Stand with your hands on your hips.

2. Hop off your right foot as you lift your left leg straight out to the side.

3. Turn your head to the side as you lift your leg.

4. Do the same on the other side of the body.

5. Repeat, hopping on the right foot and then the left while raising the opposite leg out to the side,

6. Do as many repetitions as you can.

Half squats

1. Use a barbell with weights you can manage comfortably.

2. Place the barbell on your shoulders.

3. Grip the bar with your hands about halfway between your shoulders and the weights.

4. Place your feet shoulder-width apart directly under the bar.

5. Straighten your back, keep your head up and your back erect.

6. Slowly bend your knees until you are in a sitting position with your knees over your toes.

7. Return to an erect position by straightening your knees.

6. Repeat the routine.

Dr Kenneth Gardner is an exercise physiologist at Holiday Hills Research Center; email: yourhealth@gleanerjm.com.