Exercise and Osteoarthritis
By Senior Physiotherapist, Michael Phipps
Introduction: Changing the way we think about Osteoarthritis
For many years, osteoarthritis (OA) was described as a “wear and tear” condition with the idea that cartilage gradually breaks down due to aging and injury. We now know this is an oversimplification. Unfortunately, this model has influenced how many people think about OA, often leading to fear of movement and the belief that activity will accelerate joint damage, and that joint surgery (i.e. replacement) is the only treatment available.
Modern research has changed this understanding.
Osteoarthritis is now recognised as a complex, whole-joint condition involving interactions between:
Articular cartilage
Subchondral bone
Synovium (joint lining)
Ligaments
Tendons
Muscles
The nervous system
Rather than being a passive process of mechanical breakdown, OA is a dynamic condition influenced by biological, mechanical, psychological and social factors.
The Australian Knee Osteoarthritis Clinical Care Standard emphasises that the foundations of OA management should include:
Education
Exercise
Weight management (where appropriate)
These interventions form the cornerstone of treatment because they address both the joint and the person living with OA.
What is osteoarthritis?
Osteoarthritis is the most common form of arthritis and commonly affects joints such as the knee, hip and thumb.
While cartilage changes are a feature of OA, the condition involves much more than cartilage.
The joint behaves as a homeostatic biological system:
Cartilage provides a smooth, low-friction surface for movement.
Synovial fluid nourishes cartilage and assists lubrication.
Bone adapts to changes in loading.
Muscles provide force production and joint stability.
The nervous system influences how sensations such as pain are experienced.
Importantly, the amount of structural change seen on scans (such as X-rays) poorly correlates with pain severity and disability.
Why does osteoarthritis develop?
OA develops through a combination of biological and mechanical factors.
Age
Age is one of the strongest risk factors. However, age itself does not guarantee painful OA as many older adults maintain excellent joint function through lifelong physical activity.
Genetics
Genetics influence how joints respond to load. Family history can increase susceptibility through factors affecting:
Joint structure
Collagen composition
Inflammation
Morphological bone characteristics
Previous injury
Joint injury is a major risk factor, particularly in younger adults. With growing participation in competitive sports, and exposure to traumatic injuries, some adults are experiencing OA at younger ages.
Examples of traumatic injuries include:
ACL rupture
ACL reconstruction
Meniscal injury
Fractures involving the joint surface
Post-traumatic OA can occur because injury may alter joint mechanics, biology and loading patterns. However, injury does not mean inevitable disability as optimising rehabilitation, strength and movement after injury can improve long-term joint health.
Metabolic health
OA is influenced by systemic health, and many conditions are linked to factors associated with weight gain, inflammation, biological aging, diet and exercise. This is a growing area of research and may partly explain the increasing prevalence of OA alongside an ageing population. Associations exist with:
Obesity
Reduced physical activity
Smoking
Comorbidities (such as heart disease and type 2 diabetes)
Adipose tissue is not simply stored energy; it acts as an endocrine organ producing inflammatory mediators that may systemically influence health, including joint health.
Pain in osteoarthritis: More than just joint damage
A common misconception is: “My knee hurts because my cartilage is damaged.” However, pain is far more complex than this and is influenced by multiple interacting factors including:
Tissue sensitivity (which is an individual quality)
Muscle strength
Fitness levels
Sleep, stress and mood
Previous experiences
Beliefs about pain and movement
Confidence using the joint
This explains why two people with similar X-ray findings can have completely different experiences. Modern pain science recognises OA pain as a combination of biological, psychological and social factors.
Exercise: first-line treatment for OA
Contemporary consensus supports exercise as a first-line treatment for OA. Exercise provides a range of benefits, including improvements in:
Pain
Physical function
Quality of life
Confidence
Mobility
Strength
Independence
How does exercise improve joint health?
Cartilage is designed to be loaded and requires regular mechanical load and movement to maintain health. Cartilage behaves similarly to a sponge. When a sponge is compressed, fluid is squeezed out. When the pressure is released, fluid is drawn back in. Movement creates cycles of compression and relaxation that allow nutrients and waste products to move through cartilage and synovial fluid.
These cycles of loading expose cartilage cells to mechanical stimuli. Through a process known as mechanotransduction, cells convert these mechanical signals into biological responses that help maintain healthy joint tissues.
Appropriate mechanical loading can promote:
Cartilage maintenance
Bone adaptation
Connective tissue resilience
A lack of loading can also be problematic. Complete rest or prolonged unloading may reduce tissue capacity and contribute to deconditioning. We see this in practice following joint injuries, and illness that leads to bed rest.
Exercise improves the qualities that matter
People with OA often experience reductions in mobility, strength, power and confidence. All exercise can be beneficial especially when it targets physical impairments along with the biological mechanisms associated with OA. For example, reduced quadriceps and lower limb strength are common in knee OA. Resistance training can improve:
Force production
Joint stability
Walking speed
Functional activities such as stairs and getting out of chairs
Preventing falls
Resistance training is particularly effective because it targets strength and power qualities that are often reduced in people with OA.
Exercise reduces fear and builds confidence
It is common for people with OA to develop fear around movement. A common belief being “If it hurts, I must be damaging my knee.” However, avoiding movement can create a cycle of pain and disability.
Pain catastrophic beliefs fear with movement avoiding exercise and activity reduced strength and confidence (deconditioning) disability
Exercise interrupts this cycle by gradually exposing the joint to safe and manageable loads.
How much pain is acceptable during exercise?
A common question is: “Should I stop exercising if my joint hurts?”. Some discomfort during exercise can be normal. A useful guideline:
- Mild to tolerable symptoms during exercise are acceptable, provided they do not progressively worsen
- Symptoms should settle following exercise
- Symptoms should not worsen over the next 24–48 hours
Pain does not always equal damage. The important factor is whether the overall response to exercise is positive. Before you start an exercise program it is important to consult with a physiotherapist.
Why seeing a Physiotherapist matters
When starting an exercise program, just like medicine, the dose matters. A physiotherapist can help determine:
Education about the condition and contributing factors
The right exercises
Starting level
Progression
Frequency
Volume
Load management
This is particularly important because OA affects people differently. A program for a recreational runner, a sedentary older adult and someone recovering from ACL reconstruction will look very different. The goal is to find the right dose of exercise for the individual.
The key messages:
OA is not simply “wear and tear.”
Pain is influenced by many factors, not just imaging findings.
Exercise is a treatment, not something people need to avoid.
The right dose of exercise matters.
A physiotherapist can help tailor that dose.
References
Australian Commission on Safety and Quality in Health Care.
Osteoarthritis of the Knee Clinical Care Standard. Sydney: ACSQHC; 2024.Hunter DJ, Bierma-Zeinstra S.
Osteoarthritis.
Lancet. 2019;393(10182):1745-1759.Bannuru RR, Osani MC, Vaysbrot EE, et al.
OARSI guidelines for the non-surgical management of knee, hip, and polyarticular osteoarthritis.
Osteoarthritis and Cartilage. 2019;27(11):1578-1589.Fransen M, McConnell S, Harmer AR, et al.
Exercise for osteoarthritis of the knee.
Cochrane Database of Systematic Reviews. 2015.Skou ST, Roos EM.
Good Life with osteoarthritis in Denmark (GLA:D): evidence-based education and supervised neuromuscular exercise program.
Clinical Rheumatology. 2017.Khan KM, Scott A.
Mechanotherapy: how physical therapists' prescription of exercise promotes tissue repair.
British Journal of Sports Medicine. 2009;43:247-252.