Abnormal pain pressure thresholds and temporal summation have been previously used for identifying sub-groups of patients with widespread pain hypersensitivity. Conditioned pain modulation (CPM) is reflective of the endogenous inhibitory capacity of the nociceptive system and dysfunction of CPM is associated with syndromes such as fibromyalgia and temporomandibular joint disorder where central sensitization is a recognised hallmark. Pain sensitization will therefore be operationalized by the presence of decreased PPTs and enhanced temporal summation at local (knee) and remote (arm) sites in addition to dysfunctional CPM. The cut-off point for what is abnormal or sensitized will be determined when control data has been gathered and the spread or variability of 'normal' results is seen. Points will be summed to produce a pain sensitization score where a higher score will represent greater pain sensitization.