Risk Assessment for Work-Related Musculoskeletal Disorders in Thai Traditional Massage Therapists

Abstract

Thai traditional massage (TTM) in spa businesses and hospitals has become popular for relieving muscle strain in Thai people as well as foreigners. Due to inherent risks in expertly performing massages, the massage therapists may become patients themselves. The aim of this study was to assess physiological strain and perceived workload in these health-related professionals. Sixty-one female TTM therapists volunteered to participate in the study. They were divided into three age groups: ≤ 34, 35-44, and ≥ 45 years. A questionnaire was used to assess the perceived discomfort. Actual physical manifestations were assessed by measuring %cardiovascular load (%CVL) and muscle strain (%maximum voluntary contraction, %MVC) of the trapezius and deltoids on both sides during a 50-minute treatment. The impact of the massage therapy on the therapist was assessed by comparing pre- and post-massage maximum voluntary contraction (MVC) test and measuring the shift in median power frequency (ΔMPF) of EMG to assess fatigue during the massage session. Results showed that %MVC was < 15% in all age groups, indicating safe levels of work, with no significant difference in physiological strain among groups. A trend in muscle capacity loss (decreases in MVC after a massage session) was observed. A mild fatigue level (ΔMPF) was found in the 35-44 years age group (P < 0.05). The levels of perceived discomfort and the objective measurement corresponded well in all age groups, supporting the assessment of subjective workload as a tool in risk evaluation. Moreover, this study showed that objective measurement of cardiovascular and muscle strains were possible in TTM setting. The protocol in this work can be a basis for further research to optimize work conditions in TTM and other therapeutic methods, to benefit therapists as well as patients.