Some people use hand-held weights called Heavy Hands and/or ankle weights to walk. Research shows that squeezing the weights in your hands increases your workout and thereby your heart rate. Nonetheless, I have reservations about both.
Physical therapy is the use of exercise and stretching to improve the health and life of a patient. The therapy is tailored to the specific needs of each person. The movements of the therapy are also designed to prevent further injury in the near and distant future.
What about running and your knees–is it bad? An offshoot study of the famous Harvard Paffenberger study of cardiac disease and lifestyle was a study on knees. This study showed that running did not necessarily cause knee problems unless you already had a problem.
Running the stadium steps has been a standard for some school athletes for conditioning, and some coaches prescribe it as a disciplinary penalty. We now know this is punishing to your knees and specifically your kneecaps if not to your spirit. The problems it causes are threefold.