Herrera-Espitia, S. C.; Olaya-Mira, N.; Soto-Cardona, I. C.; Osorio-Vasco, J. Biomechanical Analysis of the Lumbar Area Using Surface Electromyography: Flexion–relaxation Ratio in Maintenance Workers. Rev. Fac. Nac. Salud Pública 2024, 42, e356473.