Everything You Need to Know About Exercising After a Knee Replacement

The stationary bike is a great exercise equipment after a knee replacement.
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Knee replacement surgery can feel like the end of your fitness routine. And while your workout will certainly change — especially while you're doing physical therapy — you can still hit the gym as long as you get clearance from your doctor.

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But where to start? The best gym exercises for knee replacement rehabilitation are those that improve range of motion and strength. A stationary bike is a great cardio option as it improves mobility and lower-body strength without placing too much impact on your knee.

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Before getting started, make sure you know the best and the worst exercises after a knee replacement.

Tip

The gym offers many options to help strengthen your legs after a knee replacement. Stick to machines like the stationary bike and leg press, while avoiding activities like jumping or running, which can put too much stress on your new joint.

Knee Replacement Overview

Knee replacement surgery, also known as knee arthroplasty, is a good choice for those people who have severe pain due to osteoarthritis, says the Mayo Clinic. These people have difficulty doing things like walking, climbing stairs and standing up out of a chair.

This procedure involves removing the damaged bone and cartilage from your kneecap, shinbone and thigh bone and replacing it with an artificial joint that is made of special metal alloys, as well as polymers and high-grade plastics.

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The surgery has an excellent recovery rate, with more than 90 percent of patients saying they have a big reduction in pain and improved ability to do activities, reports the American Academy of Orthopaedic Surgeons (AAOS).

You may be surprised to find out that you may start moving and exercising your new knee the day after surgery, says the AAOS. Once you're released from the hospital, listen to your physical therapist or doctor as they can help you choose the best exercise machine for knee rehabilitation.

If you do your prescribed exercises, you can expect to resume your normal activities within three to six weeks and be able to drive four to six weeks after surgery.

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Best Post-Knee Replacement Exercises

Your range of motion after knee replacement will be limited. But your doctor will require you to be able to bend your knee to a 90-degree angle and straighten it before you're discharged, so you won't be starting from nothing.

Your physical therapist will teach you exercises to do at home that will help you get more movement in the joint and help decrease the pain, but there are some simple exercises you can do in addition that can help you progress more quickly.

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Start With Early Exercises

Early exercise focus on flexing the joint and coordinating the supportive muscles. Slowly bending your knee while lying in a bed or siting in a chair gets the joint used to movement. Hold the bend for a few seconds and make the entire movement fluid.

Progress to Functional Exercises

Practice walking and climbing stairs with the help of a walker or crutches. It's helpful to have someone with you in the early stages in case you fall. Support your weight evenly and use the walker or crutches until you're no longer putting weight on them.

At this stage, you can switch to using a single crutch or cane on the opposite side from the replaced knee, but stand up straight and try not to favor the new knee. Once you are no longer putting weight on the crutch or cane, you can begin walking unassisted.

Graduate to Advanced Exercises

Once you're able to walk short distances unassisted, it's important to regain the strength in your leg muscles with resistance exercises. You can do the early rehab exercises with light ankle weights or resistance bands, and you can ride a stationary bike at varying degrees of resistance to strengthen your muscles and work on your range of motion at the same time.

Keep Doing Maintenance Exercises

After your doctor gives you the all-clear to exercise, consider taking yoga or tai chi classes. Both are recommended by the Arthritis Foundation as effective range-of-motion exercises, and both focus on slow, controlled movements and single-leg balance — all important components of post-op recovery.

Yoga poses have variations to accommodate injuries or varying skill levels, and tai chi has been shown to reduce pain and impairment in people with knee problems. When starting yoga immediately after surgery, opt for upper-body chair yoga, then gradually transition to restorative or Yin yoga. They're slower and gentler on your joints and incorporate lots of props to support your joints.

Once you're cleared by your doctor, you're free to do any form of yoga — with modifications — that doesn't cause pain. But it's important to learn from a professional, as injury can result from improper form.

Tip

There are plenty of other activities you can do after a knee replacement, including swimming, golfing, driving, light hiking, dancing and Pilates. Start slowly, listen to your body and stop any activity that causes pain or discomfort.

Best Gym Machines to Use After Knee Replacement

The best exercise machine for knee rehabilitation after surgery will increase range of motion and improve strength. The AAOS recommends exercising for 20 to 30 minutes, two to three times a day, and walking for 30 minutes to regain your strength and mobility after surgery.

Stationary Bike

The stationary bike is a great post-knee-replacement exercise machine as it improves range of motion, flexibility and blood flow. The AAOS says to raise the seat of the bike so the bottom of your foot just touches the pedal.

You will pedal backward at first, doing partial revolutions, and then progress to full revolutions. Once you can pedal backward easily, you can start pedaling forward.

Start adding resistance four to six weeks post-surgery. Aim for 10 to 15 minutes twice a day and build your way up to 20 to 30 minutes, three to four times a week, on the bike.

Leg Press

The leg press after knee replacements is another exercise machine that will help you regain strength and function. The University of Wisconsin recommends the supine leg press with minimal weight (20 to 40 pounds), progressing to more weight as tolerated.

This machine helps strengthen your entire lower leg, which is an important part of recovery. When you are at home, you can replicate this machine with mini squats.

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Treadmill

Walking is one of the best exercises you can do after surgery. The AAOS recommends initially using a walker and progressing gradually to a cane at two to three weeks after surgery. You can stop using a cane once you can walk without a limp.

Once you can move around without a cane, the treadmill is a good post-knee-replacement exercise machine. Keep the incline level and the speed slower initially, progressing it as your strength and endurance improve. Do not run on the treadmill, as this puts too much stress on your new knee.

Warning

You may have some pain or swelling after exercise, but it shouldn’t last longer than 24 hours. Ice your knee and elevate it after your exercise routine to help decrease pain and inflammation. Talk to your doctor about any concerns you may have.

Exercises to Avoid After Knee Replacement

Stairs are a great exercise, but avoid the stair stepper machine immediately after knee replacement surgery as you may injure yourself until you build up your strength and coordination. The AAOS suggests finding a flight of stairs and using the handrail to go up the stairs with your good knee, and down the stairs on your recovering knee to build up strength and mobility.

The Mayo Clinic states that excessive activity can wear out your artificial knee and cause the replacement to become loose and painful. Therefore, it's safer to avoid high-impact activities, such as running and jumping. Lifting more than 50 pounds can overload your knee joint, so stick to lighter weights.

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