Abstract: Objective To study the presentation and changes of trunk flexors and extensors in isokinetic training at different velocities. Methods From March to September, 2018, 27 health volunteers were enrolled. Their peak torques of trunk flexors and extensors at 30°/s, 60°/s, and 90°/s were collected. Results The peak torques of trunk flexors and extensors slightly decreased with the increasing of velocities, but no significant difference was found (F < 2.070, P > 0.05). At 30°/s and 60°/s, the peak torque of extensors was higher than that of flexors (t > 3.138, P < 0.01); at 90°/s, no significant difference was found in the peak torque between flexors and extensors (t = -0.946, P > 0.05). The ratios of the peak torque of flexors to extensors were 0.79∶1 both at 30°/s and 60°/s. The peak torque of flexors decreased in the tenth contraction compared with the second contraction at all the angular velocities, however, it was significantly different only at 30°/s (t = 5.159, P < 0.01); meanwhile, the peak torque of extensors increased with significance only at 60°/s (t = -2.142, P < 0.05). Conclusion At 30°/s and 60°/s, there might be a linear relation between trunk flexors and extensors, and the peak torque ratios of trunk flexors to extensors were approximately the same.

Key words: isokinetic, trunk muscle, spine, peak torque