Two in three Australians over the age of 50 have low bone density. A diagnosis of osteopenia or osteoporosis often raises important questions, particularly around whether exercise is safe and how to move confidently and safely during everyday activities.

The important thing to know is that bone health isn’t fixed. While it’s normal for bone density to change over time, there are practical steps and modifiable factors you can address to support and maintain strong, healthy bones.

Understanding how your bones adapt and respond to movement is a helpful place to start.

What is Bone Mineral Density?

Bone mineral density refers to how strong and dense your bones are. It is typically measured using a DEXA scan. Bone density is classified on a DEXA as:

• Normal bone density (-1.0 or higher)
• Osteopenia – lower than normal bone density (-1.0 to -2.5)
• Osteoporosis – more significant bone loss and increased fracture risk (-2.5 or lower)

Our bones are constantly being renewed through a process called bone remodelling, which involves two main types of cells: cells that break down old bone (osteoclasts) and cells that build new bone (osteoblasts). In healthy bone, these processes are balanced. However, in people with low bone density, bone breakdown occurs faster than bone formation.

This leads to a gradual loss of minerals such as calcium from the bone, reducing bone mass and strength. Over time bones become thinner and less dense, which increases the risk of fractures (even with relatively minor traumas such as a small fall).

Why Bone Health matters

Our bones play an important role in structural support, movement and protection of vital organs. When bone density declines, bone strength is compromised, increasing susceptibility to fractures. Common sites include the hip, spine and wrist.

The consequences of these fractures extend well beyond the initial injury. They are often associated with reduced mobility, loss of independence and a decline in overall quality of life. Many will experience a loss of confidence with movement and increased fear of falling.

A key challenge is that low bone density typically develops gradually and as a result many individuals are unaware of changes in their bone health. Regular monitoring of bone mineral density, particularly for those over the age of 50, can help detect early changes and ensure a proactive management plan can be introduced to reduce the likelihood of future fractures.

How does Bone Mineral Density change over our life span?

Bone mineral density increases throughout early adulthood, reaching its peak in the late 20s to early 30s. From this point, bone mass is gradually lost over time, with the rate of decline accelerating after the age of 50. On average, adults can lose around 1-2% of their bone density per year beyond this age, with a more rapid decline often seen in post-menopausal women due to hormonal changes.

Factors affecting bone density

Bone density is not determined by age alone. It is influenced by a combination of factors including:

• Physical activity levels: bone responds positively to load. Weight-bearing and resistance training stresses our bones to help stimulate further bone formation and improve their capacity over time.
• Nutrition: Adequate intake of key nutrients is essential for bone health. Calcium provides the building blocks for bone, vitamin D helps your body absorb calcium and protein supports the structure and repair of bone tissue. Poor nutrition can limit the body’s ability to maintain strong bones.
• Hormonal health: Hormones regulate the balance between bone breakdown and formation. Estrogen in particular helps protect against bone loss, which is why declines during menopause can accelerate reductions in bone density.
• Medical conditions and medications: certain conditions such as thyroid disorders and medications such as corticosteroids can negatively affect bone density by increasing bone breakdown or reducing bone formation.

Understanding bone health moving forward

Being told you have low bone density can feel uncertain, but it doesn’t mean you need to stop being active or avoid exercise. In many cases it’s an opportunity to better understand how your body responds to load and how to support your bone health over time.

Focusing on modifiable factors such as movement, nutrition and overall healthy lifestyle behaviours can play a meaningful role in maintaining and improving bone strength over time.

In our next blog, we will break down resistance training and why it is one of the most effective ways to support bone health, along with how to approach it safely and effectively.