Pain sensitization has been associated with pain severity in people with knee osteoarthritis (KOA) and a neuropathic pain component has been identified in up to 30% of KOA patients. In addition, exercise-induced hypoalgesia (EIH), a measure of descending pain control, has previously been found dysfunctional in a subgroup of people with painful KOA and has also been utilized as a predictive factor for pain progression following total knee replacement.

Measures of pain sensitization have been used prognostic to identify responders to treatment but EIH as a prognostic tool for Physiotherapy-guided Evidence-based Exercise Therapy (PEET) has not been investigated. The primary aim of this explorative study is to investigate if EIH assessed pre-PEET was associated with changes in pain, disability and PainDETECT (PDQ) score post-PEET. The secondary aim is to investigate if PEET changes EIH and PDQ score in patients with painful KOA.

Part 2:

Cross-sectional studies indicate, that daily level of activity influence the effectivity of the EIH mechanims, while pain patients (e.g. KOA patients) can have normal of dysfunctional EIH. It has not been investigated if EIH changes after prolonged exercise in healthy subjects. The aim of this secord part of the study, is to investigate if EIH changes after 6-9 weeks of intensive military training in healthy subjects

Inclusion Criteria:

• The American College of Rheumatology for clinical knee osteoarthritis (excluding radiological OA assessment)

Exclusion Criteria:

• Known factors to influence pain and pain sensitization.

Part 2:

Inclusion Criteria

• starting as recruits in Defence Command Denmark

Exclusion Criteria:

• Known factors to influence pain and pain sensitization.

25 patients with knee osteoarthritis scheduled for PEET.

Part 2 40 healthy subjects (age 18-28) signed up as recruits in Defence Command Denmark