Long Distance Running and Knee Osteoarthritis: A ProspectiveStudy
Chakravarty E, Hubert H, Lingala V, Zatarain E, Fries J
Osteoarthritis (OA) is the most common form of arthritis and contributes substantially to disability among older adults. The relationship of physical activity to the development and progression of OA of the knee has been examined in the past with mixed results. Participation in sports and the performing arts at the elite level has been associated with increased risks of OA of lower-extremity joints, especially in contact sports; however, there is less consensus about the role of habitual recreational noncontact exercise. Data suggest that long-distance running may not be associated with increased progression of knee OA in the absence of knee injury, obesity, proprioceptive deficit, or poor muscle tone.

Gluteal Muscle Activation During Common Therapeutic Exercises
DiStefano L, Blackburn J, Marshall S, Padua D
Gluteal muscle weakness has been associated with several lower extremity injuries, including patellofemoral pain syndrome, iliotibial band friction syndrome, anterior cruciate ligament (ACL) sprains, and chronic ankle instability. Weakness of the gluteus medius and maximus may contribute to lower extremity injury by influencing joint-loading patterns and lower extremity control. An example of poor lower extremity control is dynamic knee valgus, which results fromcoupled hip internal rotation and adduction.As the gluteal muscles resist these possibly injurious motions, improving gluteal muscle strength and activation may be a critical aspect of rehabilitation and injury prevention programs