RANDOMIZED CONTROLLED COMPARATIVE STUDY The immediate effects of traditional Thai massage on heart rate variability and stress-related parameters in patients with back pain associated with myofascial trigger points Vitsarut Buttagat, B.Sc., M.Sc., PhD candidate a,*, Wichai Eungpinichpong, B.Sc., M.Sc., PhD a , Uraiwon Chatchawan, B.Sc., M.PH., PhD a, Samerduen Kharmwan, MD b a Division of Physical Therapy, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen 40002, Thailand b Department of Rehabilitation Medicine, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand Received 29 December 2008 received in revised form 13 June 2009 accepted 16 June 2009 KEYWORDS Massage Traditional Thai massage Myofascial trigger point Back pain Randomized control trial Summary The purpose of this study was to investigate the immediate effects of traditional Thai massage (TTM) on stress-related parameters including heart rate variability (HRV), anxiety, muscle tension, pain intensity, pressure pain threshold, and body flexibility in patients with back pain associated with myofascial trigger points. Thirty-six patients were randomly allocated to receive a 30-min session of either TTM or control (rest on bed) for one session. Results indicated that TTM was associated with significant increases in HRV (increased total power frequency (TPF) and high frequency (HF)), pressure pain threshold (PPT) and body flex- ibility (p 0.05) and significant decreases in self-reported pain intensity, anxiety and muscle tension (p 0.001). For all outcomes, similar changes were not observed in the control group. The adjusted post-test mean values for TPF, HF, PPT and body flexibility were significantly higher in the TTM group when compared with the control group (p 0.01) and the values for pain intensity, anxiety and muscle tension were significantly lower. We conclude that TTM can increase HRV and improve stress-related parameters in this patient population. �� 2009 Elsevier Ltd. All rights reserved. * Corresponding author. Tel./fax: ��66 43 202 085. E-mail address: ball3001_4@hotmail.com (V. Buttagat). 1360-8592/$ - see front matter �� 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.jbmt.2009.06.005 available at www.sciencedirect.com journal homepage: www.elsevier.com/jbmt Journal of Bodywork & Movement Therapies (2011) 15, 15e23

Background Myofascial pain syndrome (MPS) has been defined as musculoskeletal pain arising from one or several hyperirri- table spots within the belly of muscle(s) called myofascial trigger points (MTrPs) (Fricton and Awad, 1989). MPS is associated with many musculoskeletal conditions. A Thai study found that MPS was the primary diagnosis in 36% of 431 patients with musculoskeletal disorders (Chaiamnuay et al., 1998) and a study at a pain clinic reported that MPS was cited as the most common cause of pain occurring in 85% of people with back pain (Fishbain et al., 1986). The pathophysiology of MPS is largely unknown making it difficult to design effective approaches for its treatment, although numerous therapeutic approaches, both pharmo- logical and non-pharmalogical, have been tried with varying success rates. Massage therapy is now one of the most frequently used alternative treatments for back pain (Eisenberg et al., 1998). Traditional Thai massage (TTM) is a form of deep massage with brief sustained pressure on the muscles. Pressure point massage along the body���s hypothesised 10 major energy channels or ������Sen Sib������ is believed to release blocked energy and to increase awareness and vitality. Gentle stretching of the muscles relieves tension, enhances flexibility, and induces a deep state of tranquility (Tapanya, 1993). The report by Chaithavuthi and Muangsiri (2005) suggests that TTM also increases blood circulation, lowers heart rate, reduces pain, improves the depth of breathing and promotes relaxation. However, controlled studies to support the effectiveness of TTM for the treat- ment of different conditions are limited (Chatchawan et al., 2005). There is no published research that objectively assesses the physiological changes involved with the repor- ted relaxation response following TTM, which could be done using methods such as evaluation of heart rate variability. Heart rate variability (HRV) is controlled by the auto- nomic nervous system. Generally, sympathetic nervous system (SNS) activity increases heart rate (decreases HRV) and parasympathetic nervous system (PNS) activity decreases heart rate (increases HRV). Observed HRV is believed to be an indicator of the dynamic interaction and balance between the SNS and the PNS (Terathongkum and Pickler, 2004 Task Force of The European Society of Cardiology and The North American Society of Pacing and Electrophysiology, 1996). 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 therapy (MTPT) 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 (Carney et al., 1995 Stauss, 2003 Terathongkum and Pickler, 2004 Tousignant-Laflamme and Marchand, 2006 Hummel and van Dijk, 2006). Measurement of HRV to investigate autonomic influence on the cardiovascular system can be done using a simple, sensitive and non-invasive technique. This technique is increasingly being used as a powerful predictor of hyper- tension in patients (Terathongkum and Pickler, 2004 Delaney et al., 2002). One of the conventional methods for analyzing HRV is the frequency domain method that uses spectral analysis to quantify the frequency content of the ECG signals. This analysis has been used to determine the total power frequency and power of high and low frequencies, data that can then be used to determine the contribution of the sympathetic and parasympathetic nervous system to the variability in heart rate. It is generally accepted that vagal activity is the major contributor to the high frequency (HF) component of the spectral analysis, thus an increase in HF power (as well as an increase in total power) reflects increased para- sympathetic activity. Interpretation of increased LF power is still unclear and depends to some extent on the unit of measure used. An increase in absolute value of power (ms2) of the LF component may reflect both sympathetic and para- sympathetic activity. The LF/HF ratio is considered to be an index of sympathetic/vagal balance with an increase in the ratio suggesting either an increase in sympathetic cardiac modulation or a decrease in parasympathetic modulation, or both (Task Force of The European Society of Cardiology and The North American Society of Pacing and Electrophysiology, 1996 Terathongkum and Pickler, 2004). HRV analysis has also been used to evaluate changes in sympathovagal tone during various emotional states (such as stress and anxiety) and pain (Carney et al., 1995 Stauss, 2003 Terathongkum and Pickler, 2004 Tousignant- Laflamme and Marchand, 2006 Hummel and van Dijk, 2006). Current literature suggests that the relaxation response, meditation, prayer, yoga and therapeutic touch have each been associated with physiologic changes indi- cating decreased emotional stress and increased para- sympathetic activity, which were measurable by HRV (Terathongkum and Pickler, 2004 Benson et al., 1974). In addition, Diego et al. (2005) reported that massage therapy increased the cardiac vagal index (CVI), vagal tone, gastric motility and decreased tachygastria in a group of preterm neonates when compared with sham massage in a control group. Given the value of HRV as a measure of PNS activity and the lack of evidence about the effect of TTM on the auto- nomic nervous system we investigated the effects of TTM on HRV and other stress-related parameters in patients with back pain associated with MTrPs. Methods Design and setting A randomized control trial was conducted in the Division of Physical Therapy, Faculty of Associated Medical Sciences, Khon Kaen University, Thailand. The study was approved by the ethical committee of Khon Kaen University. 16 V. Buttagat et al.