Exercises for Knee Arthritis
The Most Important Thing to Understand Upfront
If you have knee osteoarthritis and you are looking for the single most effective long-term treatment available, it is not a pill, an injection, or a surgery. It is exercise. Specifically, progressive strengthening of the muscles that support and move your knee.
This is not a dismissal of other treatments. Injections, medications, and procedures all have a legitimate role in managing knee osteoarthritis at the right time and for the right patient. But they are most effective when they are used as tools to help you participate more fully in the active work that actually changes your trajectory. A cortisone injection that reduces pain enough for you to commit to a strengthening program is being used well. A cortisone injection that replaces a strengthening program is not.
The evidence on this point is not subtle. Every major clinical guideline for knee osteoarthritis, including those from the American College of Rheumatology, the Osteoarthritis Research Society International (OARSI), and the American Academy of Orthopaedic Surgeons, lists exercise as a first-line treatment. Not a nice addition to first-line treatment. Understanding why this is true, and what exercises actually matter, is what this article is about.
Active Versus Passive: Why the Distinction Matters
In musculoskeletal medicine, treatments are often categorized as active or passive. This distinction is simple but important.
A passive treatment is something done to you. Heat packs, ice, ultrasound therapy, electrical stimulation, massage, traction, and most injection-based treatments are passive. You show up, something is applied or administered, and you are not required to do any work. Passive treatments can play a useful role, particularly in managing acute pain flares or creating a window of reduced pain that allows you to exercise. But they do not build strength, they do not improve joint stability, and they do not change the underlying mechanical environment of the knee. When the treatment stops, the benefit typically stops with it.
An active treatment is something you do. Exercise, strength training, walking programs, and neuromuscular training are active. They require your participation and effort. And because they require that effort, they produce adaptations that persist long after the treatment session ends: stronger muscles, better movement patterns, improved balance and proprioception, reduced load on the arthritic joint surfaces, and a nervous system that has been recalibrated to interpret movement as safe rather than threatening.
A 2013 Cochrane systematic review examining land-based exercise for knee osteoarthritis, which pooled data from over 40 randomized controlled trials, found that exercise produced clinically meaningful reductions in pain and improvements in physical function compared to no exercise or minimal intervention. Crucially, these benefits were maintained at follow-up periods extending beyond the active treatment phase, something passive treatments rarely demonstrate. The things you do for your knee will always matter more than the things done to it.
Will Exercise Make My Arthritis Worse?
This is the fear that stops more people from exercising than almost anything else. If my knee is already worn down, will loading it with exercise accelerate the damage? The answer, based on a substantial and consistent body of research, is no. Appropriate exercise does not worsen knee osteoarthritis. In fact, the evidence suggests it is protective.
Cartilage, despite having no direct blood supply, is not static tissue. It responds to mechanical loading. Appropriate, graduated loading stimulates the chondrocytes that maintain cartilage health, improves the distribution of synovial fluid that nourishes cartilage, and helps maintain the structural integrity of the tissue that remains. A knee that is protected from loading does not preserve its cartilage. It loses it faster.
A frequently cited study by Roos and Dahlberg published in Arthritis and Rheumatism in 2005 randomized patients with knee osteoarthritis to either an exercise program or a control group and used MRI to track cartilage changes over time. The exercise group showed significantly better cartilage quality at follow-up compared to controls, providing direct imaging evidence that exercise protects rather than degrades articular cartilage.
The question of running and high-impact activity is one that comes up often, and the evidence here is also reassuring. Multiple large epidemiological studies have consistently failed to find higher rates of knee osteoarthritis in recreational runners compared to sedentary individuals. A widely referenced 2017 systematic review published in the Journal of Orthopaedic and Sports Physical Therapy found that recreational running was associated with a lower prevalence of hip and knee osteoarthritis compared to sedentary controls, while competitive running at very high volumes was associated with higher rates. The takeaway is that moderate, progressive loading is protective. It is extreme, high-volume loading in the setting of pre-existing joint vulnerability, combined with insufficient recovery, that carries risk. The fear of exercising an arthritic knee is understandable but it is not supported by evidence. The far greater risk is doing nothing.
Why Muscle Strength Is the Central Target
The muscles surrounding the knee, particularly the quadriceps at the front of the thigh, the hamstrings at the back, and the hip abductors and external rotators of the outer hip and buttock, are the primary shock absorbers and stabilizers of the knee joint. Every step you take, every stair you climb, every time you sit down or stand up, these muscles are working to control the forces that pass through the knee. When these muscles are strong, they absorb a significant portion of the load that would otherwise pass directly through the cartilage and bone of the joint.
The relationship between quadriceps strength and knee osteoarthritis outcomes has been extensively studied. A landmark study by Slemenda and colleagues published in Annals of Internal Medicine in 1997 found that quadriceps weakness was present before the onset of symptomatic knee osteoarthritis, suggesting it is not merely a consequence of pain and disuse but a contributing factor in the development of symptoms. Subsequent research has reinforced this finding. This is why strengthening is not just one option among many for knee osteoarthritis. It is the mechanistic foundation of non-surgical treatment. Everything else is supporting that goal.
The Exercises That Matter Most
The following exercises represent the core of an evidence-based strengthening program for knee osteoarthritis. They are organized from least to most demanding, allowing you to start where your pain and strength permit and progress over time. The goal is gradual, consistent progression, not perfection from the first session.
Before starting any new exercise program, discuss it with your physician or physical therapist, particularly if your pain is severe, you have had recent knee surgery, or you have other health conditions that affect your ability to exercise.
Straight Leg Raises
This is typically the starting point for patients who find weight-bearing exercises too painful to begin with. It strengthens the quadriceps without placing any load through the knee joint itself.
Lie flat on your back. Bend one knee so that foot is flat on the floor. Keep the other leg straight and tighten the thigh muscles of that straight leg. Lift the straight leg to approximately the height of the bent knee, hold briefly, then lower slowly. Perform 3 sets of 15 repetitions on each side.
As this becomes easy, add a light ankle weight to increase the challenge.
Quad Sets
Another starting exercise that activates the quadriceps without joint loading. Sit or lie with your leg straight. Press the back of your knee down toward the floor by tightening your thigh muscles, as if you are trying to flatten the knee against the surface beneath it. Hold for 5 to 10 seconds, then relax. Perform 3 sets of 15 repetitions.
This exercise is deceptively simple but builds the foundational quad activation that more demanding exercises require.
Short Arc Quads
Lie on your back with a rolled towel or small pillow placed under your knee so it is bent to approximately 30 to 40 degrees. Keeping the thigh still, straighten the knee fully and hold for a few seconds before slowly lowering. This works the quadriceps through a limited range of motion that most patients with knee arthritis can tolerate comfortably. Perform 3 sets of 15 repetitions.
Clamshells
This exercise targets the hip abductors and external rotators, particularly the gluteus medius, which plays a critical role in controlling the alignment of the knee during weight-bearing activities. Weakness in these muscles causes the knee to cave inward with walking and stairs, concentrating load on the inner compartment of the knee where arthritis is most common.
Lie on your side with your hips and knees bent to approximately 45 degrees, feet stacked. Keeping your feet together, rotate the top knee upward toward the ceiling as far as you can without rolling your pelvis backward. Lower slowly. Perform 3 sets of 15 repetitions on each side. Add a resistance band above the knees as strength improves.
Glute Bridges
Lie on your back with knees bent and feet flat on the floor. Press through your heels to lift your hips off the floor until your body forms a straight line from shoulders to knees. Squeeze your glutes at the top, hold briefly, then lower slowly. Perform 3 sets of 15 repetitions.
Glute bridges strengthen the gluteus maximus, hamstrings, and core simultaneously. Strong glutes reduce the compensatory load the knee absorbs when the hip extensors are weak, which is extremely common in people with knee pain who have reduced their activity level.
Seated Knee Extensions
Sit in a chair with your feet flat on the floor. Slowly straighten one knee until the leg is extended, hold for a few seconds, then lower slowly. Perform 3 sets of 15 repetitions on each side. A light ankle weight can be added as strength improves.
This is a simple and accessible exercise that directly targets the quadriceps and can be performed anywhere without equipment.
Chair Squats and Box Squats
This is one of the most functional and accessible strengthening exercises available, and it is directly relevant to one of the most common difficulties patients with knee arthritis report: getting up and down from a chair or toilet without pain.
Start by standing in front of a sturdy chair with your feet shoulder-width apart. Slowly lower yourself down until you are sitting, then drive through your heels to stand back up. Focus on lowering yourself in a controlled way rather than dropping into the seat. The lowering phase is just as important as the standing phase for building strength. Perform 3 sets of 10 to 15 repetitions.
To make this easier, start with a higher surface or use your hands lightly on the armrests for assistance, then gradually reduce that assistance as strength improves. To make it harder, hold a weighted backpack against your chest, grip a household item such as a full water jug or a bag of groceries, or, if you are training in a gym, hold a dumbbell or kettlebell at your chest. The goal over time is to progressively increase the load so the muscles continue to be challenged as they get stronger.
Step-Ups and Stair Climbing
Stand in front of a single step, a sturdy low platform, or the bottom stair of a staircase. Step up with one foot, drive through that heel to bring your body up, then step back down slowly and with control. The lowering phase is at least as important as the lifting phase and should not be rushed. Perform 3 sets of 10 repetitions on each side.
For stair climbing as an exercise, walk up and down a flight of stairs for repeated sets, focusing on pushing through the heel of the leading foot rather than using momentum. Start with whatever number of flights feels manageable and build from there.
To progress at home, wear a loaded backpack or carry household items such as water jugs or bags of groceries while performing step-ups or climbing stairs. At the gym, hold dumbbells or a kettlebell at your sides or a barbell across your upper back. Adding load progressively over weeks and months is what drives continued strength gains and keeps the exercise effective as your fitness improves.
Lunges
Lunges train the quadriceps, hamstrings, and glutes simultaneously and add a balance and stability challenge that translates well to real-world movements like walking, climbing stairs, and changing direction.
Stand with feet hip-width apart. Step one foot forward and lower your back knee toward the floor, keeping your front shin as vertical as possible and your front knee tracking over your second toe. Push through the heel of the front foot to return to standing. Perform 3 sets of 10 repetitions on each side.
If balance is a challenge, perform lunges next to a wall or countertop and use a light touch for stability. Stationary lunges, where you stay in the split stance position rather than stepping in and out, are a good starting point for patients who find the stepping motion difficult to control.
To progress at home, wear a loaded backpack or hold household items such as water jugs or canned goods in each hand. At the gym, hold dumbbells at your sides, a kettlebell at your chest, or, as strength develops, a barbell across your upper back. The same principle applies here as with every other exercise in this program: adding load gradually over time is what makes the muscles continue to adapt and grow stronger.
How to Progress Your Program
Starting with the easier exercises in this list and progressing gradually is far more sustainable than attempting the hardest exercises immediately and triggering a pain flare that sets you back for weeks.
A few principles worth keeping in mind:
Some discomfort during exercise is acceptable and normal. Mild to moderate pain during or immediately after exercise, up to about a 3 or 4 out of 10, is generally acceptable and should not deter you. Research supports what is sometimes called the two-hour rule: if pain has returned to its baseline level within two hours of finishing exercise, the session was appropriate. Pain that is significantly worse during the exercise, pain that persists beyond two hours, or swelling that develops after a session are signals to reduce intensity and progress more gradually.
Consistency matters far more than intensity. A 2012 systematic review published in Osteoarthritis and Cartilage found that exercise programs sustained over longer periods produced greater and more durable benefits than shorter programs, regardless of the specific exercises used. Three to four sessions per week of moderate effort, sustained over months, will produce better results than sporadic high-effort sessions followed by periods of rest.
Adding resistance progressively is what drives continued strength gains. Once an exercise becomes easy at a given resistance level, increasing the load, whether through added weight, a stronger resistance band, or a more challenging variation, is what keeps the stimulus effective. Research on resistance training for knee osteoarthritis consistently shows that higher-intensity programs produce greater strength gains and pain reduction than low-intensity programs, provided they are progressed gradually and tolerated well.
Where Injections and Procedures Fit In
None of the above is an argument against injections or procedures for knee osteoarthritis. They have a genuine and important role. A well-timed corticosteroid injection for an acute inflammatory flare, or a PRP injection in an appropriate candidate, can meaningfully reduce pain and improve function. That improved function creates a window to exercise more effectively and with less suffering.
The key word is window. The benefit of any injection is most durable when it is used to enable active rehabilitation rather than to replace it. Patients who receive a pain-reducing injection and then return to a sedentary lifestyle will find the benefit fades relatively quickly. Patients who use that window to build strength consistently tend to maintain their improvement long after the injection effect has worn off. Think of it this way: the injection can open the door. Exercise is what you do once you walk through it.
The Takeaway
Knee osteoarthritis is not a reason to stop moving. It is a reason to move more thoughtfully and more consistently than before.
The muscles around your knee are the most powerful tools you have for managing this condition. They absorb load, stabilize the joint, reduce pain, and protect the cartilage that remains. No passive treatment, however well-designed, can replicate what strong, well-trained muscles do for a knee every single day. What is done to your knee has a role. But what you do for your knee is what changes your outcome.
Start where you are. Progress gradually. Be consistent. And give it time, because the adaptations that matter most take weeks to months to develop, not days.
Questions to Ask Your Doctor or Physical Therapist
Which of these exercises are most appropriate for my current level of pain and strength?
Are there any exercises I should avoid given my specific pattern of arthritis?
How much pain during exercise is acceptable, and when should I back off?
Should I see a physical therapist to get started with a supervised program?
How does my walking and general activity level factor into my overall treatment plan?
At what point would an injection make sense to help me exercise more effectively?
This article is for educational purposes only and does not replace a conversation with your physician or physical therapist. Exercise recommendations should be individualized based on your specific condition, fitness level, and any other health considerations. References to published studies reflect the general findings of those works as understood at the time of writing and should be independently verified before clinical application. If you have questions about starting an exercise program with knee osteoarthritis, please schedule a consultation.