Purpose: The purpose of this study was to investigate the lumbar erector spinea and rectus abdominis activations, according to the different gait velocities in young healthy adults. Methods: We recruited 6 young male and 10 young female (mean age=21.43 years; range 19~23) in this study. We used a wireless surface electromyogram (Telemyo 2400T G2, Noraxon, USA) and a treadmill unit for the experiment. EMG activity from the lumbar erector spinea, and rectus abdominis of the dominant side was record with surface electrodes. On different day, all subjects gaited on 2.7 km/h, 4.5 km/h, and 6.3 km/h of speed in random order. They gaited at the same velocity, three times, on the treadmill unit. To reduce fatigue, sufficient rests were given between the measurements. Results: As the gait speed increased, lumbar erector spinea and rectus abdominis activations were significantly increased (p<0.05). Conclusion: In the current study, we found lumbar erector spinea and rectus abdominis activations were changed, according to the gait velocity. We suggested that rehabilitation intervention should be focused on the exercise velocity for the patients with problem of the trunk control.