Purpose: The purpose of this study will be to examine the feasibility and acceptability of a 6-week high intensity interval training (HIIT) program in patients with knee OA symptoms ranging from mild to severe. A secondary purpose will be to evaluated changes in whole body metabolism induced by 6-weeks of HIIT.

Participants: Fifteen patients (age 40-70 yrs; BMI 20-35 kg/m²) with symptomatic knee OA

Procedures (methods): All participants will be assigned to the single-arm of the study in which all participants will receive 6 weeks of HIIT, delivered twice per week. Outcomes will be assessed at baseline and 6 weeks. The primary outcome will evaluate tolerability, feasibility, acceptability, compliance, and adherence to the HIIT program. Secondary outcomes will include whole body metabolism markers, inflammation, and a set of physical function including knee osteoarthritis symptomatic burden and pain, cardiorespiratory fitness, isometric knee extensor and flexor strength (factors associated with physical function and symptomatic knee OA progression), and body composition.

Inclusion Criteria:

• Must exhibit symptomatic knee OA (WOMAC > 31), radiographic evidence of tibiofemoral OA (2-4 Kellgren-Lawrence scale)
• Age 40-70 years
• Body mass index 20-35 kg/m²
• Cleared by study physician from 12 lead EKG and medical history review

Exclusion Criteria:

• Individuals diagnosed with a cardiovascular condition restricting exercise Individuals currently meeting Department of Health and Human Services Guidelines for Physical Activity (meeting >150 minutes of exercise per week)
• Individuals currently doing HIIT
• Individuals currently participating in physical therapy for knee OA
• Individuals currently participating in another OA intervention study
• Received a corticosteroid or hyaluronic acid injection involved in the knee in the previous 3 weeks or scheduled for during the intervention
• Diagnosis of gout in the knee
• Diagnosis of Rheumatoid arthritis
• Diagnosis of Fibromyalgia
• Other systemic rheumatic disease
• Severe dementia or other memory loss
• Active diagnosis of psychosis or uncontrolled substance abuse disorder
• Hospitalization for a stroke, heart attack, or heart failure, or had surgery for blocked arteries in the past 6 months
• Diabetics (medications include exogenous insulin)
• Total joint replacement knee surgery, other knee surgery, meniscus tear, or ACL tear in the past 12 months
• On a waiting list for total joint replacement
• Severely impaired hearing or speech
• Pregnant or planning to become pregnant in the next 8 weeks
• Inability to speak English
• Serious or terminal illness as indicated by referral to hospice or palliative care
• Nursing home residence
• Inability to ride a stationary bike
• Any other health problems that would prohibit safe participation in the study.