Evidence has shown that knee osteoarthritis causes an increase in base of support and a decrease in stride length and gait velocity which results in an increase in energy expenditure during walking. This increase in energy cost of walking is suggested to result in walking related performance fatigability. However, fatigue is not commonly considered in the clinical settings in term of neither assessment nor management of knee osteoarthritis. One common tool used to evaluate walking relate performance is six minute walk test and the purpose of this study is to determine the reliability of using six minute walk test to determine walking related performance fatigability in persons with knee osteoarthritis.

Inclusion Criteria:

• Age 40-70 years
• Knee OA with history not less than three months.
• Radiological evidences of grade III or less on Kellgren classification.
• Knee pain on VNRS no more than 8/10.

Exclusion Criteria:

• Neuromuscular conditions that may lead to fatigue such as multiple Sclerosis
• Signs of serious pathology (e.g., malignancy, inflammatory disorder, infection).
• History of trauma or fractures in lower extremity.
• Signs of lumbar radiculopathy or myelopathy.
• History of knee surgery or replacement.
• Patients on intra-articular steroid therapy within two months before the commencement of the study.
• Impaired skin sensation and renal function.