Running is challenging if you have weak knees. Weak knees can involve something as simple as weakness in the muscles that support your knee or could be due to a prior injury to the joint, according to the National Institute of Arthritis and Musculoskeletal and Skin Diseases. See a physician before you begin your running program, and start slowly. Also add in regular resistance training sessions to strengthen the leg muscles that support your knee.
Walk Before You Run
If you are new to running or exercise in general, start with a walking program. Begin with walking every other day for as little as 10 minutes at a time. Walking uses the muscles in your lower body just like running but in a low-impact fashion. Increase the frequency of your sessions gradually until you are walking five to seven days per week. Build your duration to 30 to 60 minutes per session at a moderate to vigorous pace.
Alternate Walking and Running
Once you start running you will only be running three times per week. You also will be running short intervals with walking in between to get your body used to running. The first week run/walk every other day. Warm up for five minutes with a brisk walk and then alternate 15 seconds of running with 45 seconds of walking for 30 minutes. Every one to two weeks increase your run time by five seconds and decrease walk time by five seconds. You can do walk-only workouts on the other days of the week. Over time you will build until you can run 30 or more minutes per session. With weak knees you may want to only run every other day to give your joints a rest from high-impact activity.
Don't Skip Resistance Training
Some runners choose to avoid resistance training, thinking either they want to avoid "bulky" muscles or that their legs get enough of a workout from running. However, resistance training will build additional strength in your leg muscles to support your knees and improve your running. Perform resistance exercises two to three times per week on non-consecutive days. Do one to three sets of eight to 12 repetitions for each exercise you perform. Stick with exercises such as squats, step-ups or lunges instead of machines.
Weak knees does not necessarily mean joint pain or deterioration. If your knees cause you pain during or after a run, see a doctor to determine if there is something going on within the joint itself. Even though this training plan is slow and gradual, slow it down even further if you need to. In your resistance training exercises, start with just your body weight and focus on proper form and technique. Stretch your legs after every workout to maintain range of motion through your hips and knees.