What Type of Cardio Can I Do When Runners Knee Is Flaring Up?

Runners knee, otherwise known as patellofemoral pain syndrome or PFPS, is a generic term used to describe knee pain that occurs when you are doing repetitive, high-impact activities.

It applies to any type of movement that places tension on the patellofemoral (front aspect) of the knee joint. If you have PFPS, there are other ways to achieve a cardio workout without adding to knee pain.

Low-impact cardio is a viable alternative to raise heart rate without adding stress to your knees. Walking on the treadmill or outside at a comfortable pace will provide some cardio advantages with a low impact. Runner's knees often become stiff with long periods of inactivity, so some exercise is beneficial. Elliptical machines provide resistance without impact and work in a gliding effect. Another option is the stationary bike. In addition to lowering impact to the knees, you are also removing weight stressors.

With no impact to any joints in the body, swimming increases cardio activity without pain to the knees. Swimming uses all muscle groups, which provides muscle toning as well as cardiovascular benefits. You get greater resistance in water than air, so muscles have to work harder. The quadriceps -- used frequently in swimming -- become stronger in swimmers, which assists in supporting PFPS knees, according to Dr. Bedi of the University of Michigan MedSport Program.

To achieve a cardio workout from kettlebells, choose lower weights with high repetition rates. By engaging in different lifts and swings, you can achieve solid cardio results without stressing your knees. A key to good kettlebell form is to tighten your abdominal muscles before you begin your swing. Core stability is vital to safety during kettlebell use. If you are unfamiliar with kettlebells, try a class or instructional video before beginning a kettlebell routine.

Cardio boxing is an action-intensive exercise routine. The benefit of cardio boxing is that it gives you a high-energy cardio workout without putting stress on your knees. Advantages include increased endurance, strength, speed and coordination. To begin, take a boxing stance, which means feet apart to shoulder width and your knees slightly bent. Weight is shifted rapidly from left foot to right foot. Add jabs to a heavy bag for increased strength training.

If you decide to engage in cardio exercise with runner's knee, be cautious. Dr. Bedi says not to do any activity that aggravates the injury. Use ice as necessary to decrease the pain and wear a brace if needed. He also suggests strengthening your quadriceps, specifically the vastus medialis muscle, located just above the knee.