Musculoskeletal discomfort and ergonomic risk in manual versus automatic transmission taxi drivers: a cross-sectional study in eastern Iran

Musculoskeletal disorders (MSDs) are common among taxi drivers in developing countries, largely due to prolonged driving and repetitive movements in heavy traffic. While high MSD rates have been reported in this occupation, direct comparisons of discomfort and ergonomic risk between manual and automatic transmission taxi drivers using validated tools remain limited. This study compared musculoskeletal discomfort and postural risk between manual and automatic transmission taxi drivers in eastern Iran. In this cross-sectional study conducted between January and June 2025, 200 full-time taxi drivers (100 Manual Transmission Vehicles [MTV] and 100 Automatic Transmission Vehicles [ATV]) were recruited via stratified random sampling. Participants completed a demographic/occupational questionnaire and the validated Persian Cornell Musculoskeletal Discomfort Questionnaire (CMDQ). Ergonomic postural risk was evaluated using the Driver Ergonomic Risk Assessment (DERA). Group differences were analyzed using t-tests, Mann–Whitney U tests, chi-square tests, and MANOVA adjusted for age, BMI, and daily driving hours. The groups were comparable in demographic and occupational characteristics ( p > 0.05). Manual transmission drivers reported significantly higher CMDQ scores across all 20 body regions (MANOVA Pillai’s Trace = 0.209, p = 0.001). The largest differences observed in the neck (9.40 vs. 0.65, η 2 = 0.11), lower back (11.7 vs. 2.12, η 2 = 0.07), and knees. Adjusted odds ratios showed substantially higher odds of frequent discomfort (several times/days or daily) in manual versus automatic transmission drivers, ranging from 2.70 (lower back) to 18.71 (upper back). Notably, the odds were 14.73 times higher for the neck (95% CI: 5.83–37.26) and 7.50–15.67 times higher for the knees (all p < 0.001). DERA scores were markedly higher in the manual group (left = 10, right = 14; high risk) than in the automatic group (left = 4, right = 5; low risk). Manual transmission taxi drivers reported substantially greater musculoskeletal discomfort and ergonomic postural risk than automatic transmission drivers. Transitioning urban taxi fleets to automatic vehicles may represent a potential ergonomic intervention to reduce MSD burden in resource-limited settings.