Compared with Marine service members, those motor vehicle operators in both the Army, 2.74 (95% CI 2.60–2.89), and the Air Force, 1.98 (95% CI 1.84–2.14), had a significantly increased adjusted IRR for low back pain. The adjusted IRRs for the less than 20-year and more than 40-year age groups, compared with the 30to 39-year age group, were 1.24 (1.15–1.36) and 1.23 (1.10–1.38), respectively.