In this work, we study the tensile deformation of chicken muscle fibers and the temperature dependence of the tensile deformation of non-twisted nylon 6 lines and twisted nylon 6 (artificial muscles). Both the non-twisted nylon 6 lines and twisted nylon 6 are annealed at different temperatures of 150, 175, 190 and 200 degrees C. The chicken muscle fibers under tensile loading exhibit four deformation stages with the tensile load being a linear function of the elongation in each stage. The largest Young's modulus (the slope of the load versus the elongation curve) occurs at stage III. For the tensile deformation of the annealed non-twisted nylon 6 lines, the tensile load is proportional to the elongation. For the tensile deformation of the twisted nylon 6 (artificial muscles), there exist three stages with the tensile loading being a linear function of the elongation in stages I and III. The Young's modulus calculated from the load-elongation curves decreases with the increase of the testing temperature. For the testing conditions used in this work, the tensile deformation eventually leads to the fracture of both the chicken muscle fibers and the annealed non-twisted nylon 6 lines. The fracture stress of the annealed non-twisted nylon 6 lines decreases with the increase of the testing temperature.