There is evidence to suggest that the balance between SNS and PNS is affected by MPS. This is supported by Perry et al.(1989) who report patients with chronic MPS and with arthritis had decreased parasympathetic activity and increased sympathetic activity, and by Delaney et al.(2002) who found that myofascial trigger point massage therpy decreased heart rate, systolic blood pressure and diastolic blood pressure and increased parasympathetic activity. The later study also found a related self-perceived reduction in muscle tension when compared to the baseline. Regional and/or referred pain are characteristic of MPS, which can lead to anxiety and depression and reduced HRV if not effectively treated