Osteoporosis

Bone mineral density is a measurement of bone strength, most commonly measured through the gold standard dual-energy X-ray absorptiometry (DEXA) scan. Osteoporosis is a chronic condition following osteopenia that impacts the integrity of an individual’s bones through microarchitectural deterioration, therefore placing them at an increased fracture risk than a healthy compare.

The World Health Organisation and internationally agreed upon definition has remained relatively unchanged since 1994 with osteopenia being -1 to >-2.5 SD, osteoporosis ≤-2.5 SD and severe osteoporosis ≤-2.5 SD with a previous fracture when compared to a t-score (normal 30yr old bones) through DEXA examination.

Epidemiology

It is estimated that some 924 000 or 3.8% of Australians have some kind of bone loss whether that be osteopenia or osteoporosis. The condition has a higher prevalence amongst females than males at 6.2% and 1.5% respectively and tends to increase with age as 29% of females and 10% of males over 75 years have the disease.

Pathophysiology and causes/risk factors

Our bones are constantly remodelling by removing older cells and laying down and forming new cells. The pathophysiology or reasons behind density reductions involves a series of metabolic dysfunctions including receptor activation at the bone, hormonal activity (or there lack of), that result in natural bone absorption (osteoclast behaviour) occurring faster than the body can lay down new bone (osteoblast activity).

Certain risk factors, both modifiable and non-modifiable are listed below. These tend to increase the activity of bone resorption by impacting the remodelling process.

Treatment and benefits of exercise

Prevention

The latest research summation finds higher volumes of exercise as defined by duration, intensity and frequency are of increased benefit. That is, 60+ minutes per session for 2+ days a week for at least 7 months due to the slow nature of bone turnover. Additionally, they found a combination of exercise domains to be most beneficial inclusive of resistance training, cardiovascular, plyometric, general physical activity, functional training and hobbies such as dancing provided they loaded bones effectively.

Management and reducing the rate of decline:

In postmenopausal women (those most at risk), exercise had a significantly positive effect on BMD through promoting an osteogenic effect. Exercise type remains similar to the above, just tailored to the individual and their DEXA results.

Balance, falls risk and fractures:

Exercise has been repeatedly proven throughout literature to prevent falls. Further, a large summation of evidence utilising medication as an intervention concluded that positive bone mineral density changes were strongly associated with a reduced fracture risk. Hence, if an osteoporotic population reduces their falls risk and strengthens their bones through either exercise, medication, mitigating modifiable risk factors or a combination of the three, their risk of a fracture may also decline.

Assessment and how an Exercise Physiologist can assist

• Provide an in depth assessment of medical history to see the whole picture
• Explain what your scans mean and educate how exercise may help
• Provide an exercise program that takes a graded approach, depicts a clear direction towards your goals and works within your current lifestyle
• Follow up where required to ensure you are moving in a positive direction.

Key take homes

• Bone remodelling is constantly occurring naturally throughout your body
• Maximal bone mineral density is at approximately 30yrs of age
• The importance of loading bones into an elderly age is imperative to reducing fracture risk
• Seeing an Exercise Physiologist can safely tailor and effective exercise program towards your goals accounting for bone density and other comorbidities if present

Photo by Anastase Maragos on Unsplash