Knee osteoarthritis骨关节炎 (OA) accounts for more disability in the elderly than any other disease. Running, although it has proven cardiovascular心血管的 and other health benefits, can increase stresses on the joints² of the leg. In a study published in the December 2009 issue of PM&R: The journal of injury, function and rehabilitation³复原, researchers compared the effects on knee, hip⁴ and ankle joint¹ motions of running barefoot versus⁵ running in modern running shoes. They concluded that running shoes exerted more stress on these joints compared to running barefoot or walking in high-heeled shoes. Sixty-eight healthy young adult runners (37 women), who run in typical, currently available running shoes, were selected from the general population. None had any history of musculoskeletal肌与骨骼的 injury and each ran at least 15 miles per week. A running shoe, selected for its neutral中立的，中性的 classification and design characteristics typical of most running footwear鞋类, was provided to all runners. Using a treadmill踏车，跑步机 and a motion analysis system, each subject was observed running barefoot and with shoes. Data were collected at each runner's comfortable running pace after a warm-up period.

The researchers observed increased joint torques彩色项毛圈 at the hip, knee and ankle with running shoes compared with running barefoot. Disproportionately large increases were observed in the hip internal rotation⁷ torque and in the knee flexion and knee varus torques. An average 54% increase in the hip internal rotation torque, a 36% increase in knee flexion torque, and a 38% increase in knee varus内翻足，弓形腿 torque were measured when running in running shoes compared with barefoot.

These findings confirm that while the typical construction of modern-day running shoes provides good support and protection of the foot itself, one negative effect is the increased stress on each of the 3 lower extremity⁸ joints. These increases are likely caused in large part by an elevated heel and increased material under the medial arch足弓，拱门, both characteristic of today's running shoes.

Writing in the article, lead author D. Casey Kerrigan, MD, JKM Technologies LLC, Charlottesville, VA, and co-investigators state, "Remarkably⁹, the effect of running shoes on knee joint torques during running (36%-38% increase) that the authors observed here is even greater than the effect that was reported earlier of high-heeled shoes during walking (20%-26% increase). Considering that lower extremity joint loading is of a significantly greater magnitude during running than is experienced during walking, the current findings indeed represent substantial biomechanical生物力学 changes." Dr. Kerrigan concludes, "Reducing joint torques with footwear completely to that of barefoot running, while providing meaningful footwear functions, especially compliance¹⁰, should be the goal of new footwear designs."