Ask a PT Response: "Running on a hard surface such as a sidewalk definitely results in more impact on your hips and knees compared to utilizing an elliptical. Just curious if you have onset of pain with running on a treadmill as well? Without knowing anything about you such as age, strength, flexibility, weight, past medical history, etc it is hard to answer this question. Often times, for my patients who would like to participate in running I would work on strengthening not only the muscles at the knee but the hip and core as well. Strong hip and core muscles can help absorb some of the forces which translate from the ankle to the knees. I would also have my patients work on achieving increase flexibility at various regions if there is an issue. Running mechanics are also analyzed so as to help maximize performance and minimize injury. Training in the pool is another option as well. I hope this helps and thanks for using CyberPT."