Aching knees don't mean the end of exercise. When you're recovering from a knee injury or dealing with ongoing knee pain, movement can actually help you feel better.
The right cardio workouts can help boost the flow of fluids through your lymphatic system, a vital part of your immune system, says Galina Denzel, a restorative exercise specialist and personal trainer with a special interest in chronic pain. The circulation of both lymphatic fluid and blood speeds healing by shuttling vital nutrients to the site of your injury, then carrying away waste products.
Even if you have a progressive condition like osteoarthritis, research shows gentle, low-impact exercise (like walking) can ease your pain and form a critical component of your treatment plan. In fact, a June 2019 review in Osteoarthritis and Cartilage called the body of evidence on the topic so robust that no further studies are needed to bolster the case.
Activity also helps prevent certain injuries — say, torn ligaments or tendinitis — from lingering, Denzel says. When you first get hurt, damaged tissues cause pain. And while resting immediately after the injury is important, if you avoid movement for too long, your brain can tag the entire area as dangerous, even after it's healed. That's when your pain becomes chronic and far more difficult to treat.
Physical benefits aside, cardio also serves as a stress reliever, says Keli Roberts, a personal trainer based in the Los Angeles area. Even if you need to choose a different exercise than what you'd prefer, such as cycling instead of running, you'll still produce many of the same feel-good chemicals that lead to that famed "runner's high."
Maintaining a mindset of curiosity — wondering what you can do, instead of dwelling on your limitations — can improve the effectiveness of your entire rehab program, Roberts says. Exercise may also prevent the depression that often accompanies injury, according to an April 2018 review in the Cochrane Database of Systematic Reviews.
Plus, when you sweat regularly, you maintain the strength and mobility you need to move through your daily life, according to a June 2014 study in JAMA, and you keep your weight under control, which can ease pressure on your knees, according to a November 2018 study in Arthritis Care & Research.
The U.S. Department of Health and Human Services' Physical Activity Guidelines for Americans recommend adults get 150 to 300 minutes of moderate-intensity aerobic exercise a week.
The Best Cardio Workouts for Sore or Injured Knees
The type of aerobic exercise that works best for you will depend, in part, on the cause of your knee problems. Your physical therapist is the best source of information on what's right for your body and your injury.
But generally speaking, any type of exercise that doesn't exacerbate your symptoms will probably get a green light— and many people do best when they mix it up and try several different movements. Some ideas:
For most knee injuries, lower-impact activities are better than high-impact moves like running and jumping. Cycling is often not only safe, but beneficial.
If you need to have surgery for an injury like an ACL tear, your physical therapist may include time on the bike as part of your rehab to improve your range of motion, says David Reavy, a physical therapist and founder of React Physical Therapy in Chicago.
Cycling can also help many people with patellofemoral pain syndrome or runner's knee, a pain under the kneecap that often occurs when the kneecap moves out of alignment. Weakness or imbalance in the quadriceps muscles contributes to this condition, Reavy says. Cycling can fire up all four of the muscles that make up your quads, returning your knee to the right track.
Here's everything you need to know to start cycling for exercise.
If you have access to an elliptical machine, it's another low-impact choice to consider because your feet never leave the pedals. An elliptical workout delivers both cardio and strengthening benefits while exerting minimal force on achy joints, according to the Arthritis Foundation.
Experiment with adjusting the resistance and incline of the elliptical to make your workouts harder. You can also change your speed at will to amp up your calorie burn or ease off a bit.
Learn how to customize your elliptical workouts for weight loss, endurance and more.
Walking workouts can be totally safe for people with knee pain, as long as you're not limping or altering your natural gait. Like running, you can take a walk just about anywhere with little more than a good pair of sneakers. Incorporating intervals of different walking speeds can keep your walks challenging.
If you have access to a treadmill, setting the incline high makes the workout more challenging and activates the muscles on the backs of your legs, which are often neglected in regular walking or running, Reavy says. Just don't cheat and hold onto the handrails.
This beginner's guide to walking proves small steps really do add up.
You don't need to do formal laps if you don't want to; you can grab a board and kick, use a pool buoy to work on your arm movements or walk or jog through shallow or deep water, Roberts says.
If a knee injury required surgery, you might need to wait a bit to get into the water, but once you're cleared, swimming can be a mentally soothing, low-impact workout to try.
Discover how to start swimming to reach your fitness goals.
Tips for Your Best Cardio Workout With Knee Pain
- No matter which cardio workout you choose, make sure you do a dynamic warm-up beforehand. This activates the muscles around your knee so you take some pressure off the joint, Reavy says.
- If you feel a sharp, stabbing pain mid-workout, stop what you're doing. If your joint is unexpectedly sore or swollen following your workout, you might not be ready for that activity just yet. Try something different, shorter or less intense until you gain back more of your strength and function.
- Talk to a doctor or physical therapist about your use of pain medications. Reavy suggests laying off the pain relievers while you're exercising so you can keep in touch with the signals your body is sending you. If you use them to mask pain and push too hard, you might delay or set back your recovery.
- JAMA: "Effect of Structured Physical Activity on Prevention of Major Mobility Disability in Older Adults"
- Arthritis Care & Research: "Intentional Weight Loss in Overweight and Obese Patients With Knee Osteoarthritis: Is More Better?"
- Osteoarthritis Cartilage: "Do We Need Another Trial on Exercise in Patients With Knee Osteoarthritis?: No New Trials on Exercise in Knee OA."
- Cochrane Database of Systematic Reviews: "Exercise Interventions and Patient Beliefs for People with Hip, Knee or Hip and Knee Osteoarthritis: a Mixed Methods Review"
- HHS: "Physical Activity Guidelines for Americans"
- Arthritis Foundation: "Elliptical Machines Go Easy on Your Joints"
- American Association of Orthopaedic Surgeons: Aerobic Exercise