In our first blog of this series, we explored how exercise remodels the heart, one of the body’s major systems and a cornerstone of overall health.
This time, we’re shifting our focus to another essential area, bone and joint health. Whether we’re working with osteoporosis, arthritis, or musculoskeletal injuries, Exercise Physiologists are uniquely equipped to support recovery and function by tailoring movement to the individual. This is especially true in the rehabilitation and return-to-work (RTW) space, where movement is not only therapeutic, it’s essential.
The Physiology of Bone Health
Bones are dynamic structures, constantly being broken down and rebuilt. The process, called bone remodelling, is regulated by two key cell types:
- Osteoclasts, which break down bone tissue
- Osteoblasts, which build new bone
In youth, bone-building outpaces breakdown. But with age, especially post-menopause or with chronic conditions, this balance shifts. Bone mineral density (BMD) begins to decline, increasing the risk of fractures and functional loss.
This decline is accelerated by:
- Inactivity or extended illness
- Certain medications (e.g. corticosteroids, chemotherapy)
- Chronic conditions, including cancer and autoimmune diseases
(We explored these links in our recent blog on cancer and bone health, where the intersection of treatment side effects and skeletal fragility often goes unaddressed).
The Physiology of Joint Health
Joints, particularly synovial joints like the hips, knees and shoulders, are designed for movement. Each time we move, joints:
- Circulate synovial fluid, keeping surfaces lubricated
- Deliver nutrients to cartilage, which has no direct blood supply
- Support range of motion, posture and alignment
- Build the muscles and tissues around them, improving joint stability and reducing pain
Reduced movement leads to stiffness, weakening and often fear-driven inactivity, something we see commonly in clients returning to work post-injury or illness.
Where Bones and Joints Overlap
Although bones and joints are distinct structures, they rely on one another. Strong bones support joint function, while healthy joints allow functional movement that stimulates bone strength.
For example:
- A client recovering from knee surgery may lose bone mass in the leg due to immobility.
- Someone with arthritis may avoid movement, worsening both joint function and BMD.
In short, what’s good for the bones is often good for the joints too, but how we apply that in practice requires nuance.
The Role of Exercise: What Works and Why
This is where Exercise Physiology comes in. We understand how specific types of load influence physiology and we prescribe accordingly.
For Bones:
- Weight-bearing activities stimulate BMD (e.g. walking, dancing, hiking)
- Resistance training provides muscle-driven force on bones (e.g. squats, rows, weighted step-ups)
- High-impact loading triggers osteoblast activity when appropriate (e.g. jumping, skipping)
For Joints:
- Low to moderate load movement keeps joints lubricated and mobile
- Range of motion and control exercises improve function (e.g. controlled mobility drills, balance work)
- Strengthening around joints protects and stabilises (e.g. glute activation for hips/knees)
EPs are trained to prescribe the right movement for the right tissue, at the right intensity and at the right time. Especially important for clients with osteoporosis, arthritis, pain or post-surgical limitations.
Our Advice: A Well Rounded Movement Menu
We encourage our clients to include a variety of movement in their week, just like a balanced meal plan:
- Bone-loading exercises (e.g. resistance training, stair climbs)
- Joint-friendly mobility work (e.g. dynamic warm-ups, Pilates)
- Cardiovascular activity (e.g. walking, cycling, or adapted aerobic movement)
This isn’t just for older adults. Deconditioning happens quickly during injury, illness, or inactivity and we see it in all ages.
Encourage your clients to build bone and joint strength before they “need” it. And if someone is already experiencing changes, post-injury, post-treatment or functionally at risk – refer to an Exercise Physiologist. We’ll take care of the physiology.
Author: Tessa Nielsen
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