The purpose of this study is to asses the efficacy of a 4 week low-intensity resistance training program with concurrent application of partial blood flow restriction (PBFR) to the exercising limbs to improve quadriceps strength and size, leg muscle power, and mobility in women at risk for developing symptomatic knee osteoarthritis. The primary outcome will be change in isotonic double leg-press 1 repetition maximum (1RM) strength. The investigators will test the following hypotheses. In comparison with low-intensity resistance training without use of PBFR, a four-week low-intensity resistance-training program with PBFR will:

Primary Hypothesis: Increase (a) double leg-press 1RM strength and (b) isokinetic knee extensor strength

Secondary Hypotheses:

1. Increase quadriceps muscle volume assessed by MRI
2. Increase lower limb muscle power on (a) double leg-press at 40% 1RM and (b) a timed stair climb
3. Not adversely effect knee pain or quality of life assessed by the Knee injury and Osteoarthritis Outcome Score (KOOS) questionnaire

Inclusion Criteria:

• Female
• Age 45-65
• BMI greater than or equal to 25 kg/m2, or a history of a knee joint injury or surgery, or knee symptoms (pain, aching, or stiffness) on most of the last 30 days, or knee osteoarthritis

Exclusion Criteria:

• Resistance training at any time in the last 3 months prior to study
• Bilateral knee replacement
• Lower limb amputation
• Lower limb surgery in the last 6 months that affects walking ability or ability to exercise
• Back, hip or knee problems that affect walking ability or ability to exercise
• Unable to walk without a cane or walker
• Inflammatory joint or muscle disease such as rheumatoid or psoriatic arthritis or polymyalgia rheumatica
• Multiple sclerosis
• Known neuropathy
• Self-report of Diabetes
• Currently being treated for cancer or having untreated cancer
• Terminal illness (cannot be cured or adequately treated and there is a reasonable expectation of death in the near future)
• Peripheral Vascular Disease
• History of myocardial infarction or stroke in the last year
• History of deep venous thrombosis
• Chest pain during exercise or at rest
• Use of supplemental oxygen
• Inability to follow protocol (e.g. lack of ability to attend visits or understand instructions)
• Staff concern for subject health (such as history of dizziness/faintness or current restrictions on activity)
• Concurrent study participation (such as the MOST study)
• Unable to attend more than 2 days within any 1 week or unable to attend 4 or more sessions during the study