The purpose of this study is to develop a negative work exercise regimen as an intervention for posttraumatic osteoarthritis (PTOA). "Negative work" is the force produced by muscles as they lengthen, and regularly occurs with common activities such as lowering an object from a shelf or walking down stairs. In this study, the investigators are examining the effectiveness of negative work exercise over a 12-week period in older, male, Veterans.

Purpose: To develop a negative work exercise regimen as an intervention for posttraumatic osteoarthritis (PTOA). Given that the medical management of chronic PTOA is similar to idiopathic OA, the investigators propose a randomized, clinical trial to pilot negative work exercise in Veterans with knee OA as a proof-of-concept study for a subsequent investigation for people with PTOA.

Research Setting: DC VAMC, Physical Medicine & Rehabilitation Laboratory

Participants: Men between the ages of 50 and 70 years with a history of bilateral knee osteoarthritis will be consecutively recruited from the DC VAMC Rheumatology Service, Geriatrics Service, and Primary Care Medical Service.

Implications/Significance: The use of negative work exercise to enhance the force attenuation properties of muscle is an innovative approach to the treatment of OA and PTOA, and represents a significant departure from previous rehabilitation studies concerning arthritis. Use of a negative work paradigm may prove to be beneficial for older Veterans with OA and active military personnel with PTOA since similar muscle mechanics are involved in the energy absorption at the knee joint during gait. Despite the functional importance of lengthening muscle actions in protecting weight-bearing joints affected by arthritis, the authors are not aware of a study that involves the sole use of a negative work intervention for OA or PTOA. Addressing the aims of this proposal would lay the ground work needed to justify larger clinical trials featuring the negative work paradigm for soldiers with PTOA.

Inclusion Criteria:

• Adult men 50 y.o. 70 years old will be recruited for this proposed study.
• Participant inclusion criteria includes having bilateral knee OA (Kellgren-Lawrence Grade 2 or 3) and sedentary (e.g., have not engaged in 3 exercise sessions per week for 3 consecutive months).
• Gait aides and orthoses will not preclude participation in this study.

Exclusion Criteria:

• Exclusion criteria include uncontrolled cardiovascular disease, non-ambulatory status, neurogenic weakness, knee extensor and flexor manual muscle test < 3 out of 5, lower extremity amputation, and current participation in a supervised exercise program.
• In addition, major surgical procedures within the last six months, unstable joints, endocrine or metabolic disorders that result in excessive fatigue or muscle weakness, or use of medications that may impair exercise tolerance would also preclude participation in this study.