Participants and study design
illness, mental illness, LBP
COMPLICATIONS
This study was conducted as a preventive care model research project of the Japan Labor Health and Welfare Organization with the goal of developing measures to prevent LBP in the workplace. The sample constituted 128 individuals (64 per group) based on the sample size obtained using G*power version 3.1.9.7 (Heinrich-Heine-Universität Düsseldorf, Germany) [This was a randomized controlled trial. A short class on preventing LBP was taught by a physical therapist in December 2016 and July 2018. Participants provided written consent to participate after a summary of the research was explained at Companies A (Izumisano city, Osaka prefecture) and B (Amagasaki city, Hyogo prefecture). The inclusion criteria were as follows: age 20–65 years and participation in the short course regardless of the presence of LBP. The exclusion criteria were as follows: diagnosis of specific LBP and ongoing treatment, ongoing treatment for mental illness or other decline in mental health, presence of any illness that limited movement, lack of consent for participation in the study, and pregnancy. The criteria for discontinuation of study participation were as follows: inability to continue exercising due to severe illness complications, difficulty with study participation due to mental health reasons, transfer to a workplace in a different region or retiring, becoming pregnant, withdrawal of consent, and missing questionnaire responses.The intervention was performed in a three-month period between December 2016 and April 2017 at Company A and between July 2018 and November 2018 at Company B. Quick and simple whole-body exercises were recommended before work in each workplace. However, these exercises were not aimed at preventing LBP. Their purpose was unclear, and practicing them was not compulsory. There were 154 and 27 participants in the physical therapist’s short courses at Companies A and B, respectively. Questionnaires were distributed to these 181 individuals, and a total of 165 responses were collected after the exclusion of non-responses and incomplete responses (response rate, 92%). Questionnaire data for those with a history of diagnosis and treatment for specific LBP (5 participants) or poor mental health (5 participants) were removed. The data for the remaining 155 participants were randomly assigned to two groups after adjusting for age and sex. Assignment was performed using a computer-generated random number table by an individual not involved in the evaluation or instruction. Participants as well as researchers responsible for measurement and analysis were blinded to participant assignment. Leaflets were distributed to participants individually in envelopes with their names. A total of 77 participants were assigned to the intervention group (mean age 46 ± 12 years, 71 men, 5 women) and 78 to the control group (mean age, 46 ± 12 years; 70 men and 8 women; BMI, 23.3 ± 3.1 kg/mParticipant flow in this studySD, standard deviationThis study was approved by the ethics committee of Osaka Rosai Hospital (approval no. 27-115) and registered in the UMIN Clinical Trials Registry (UMIN000024117).