[Purpose] The purpose of this study was to investigate the modular control of locomotor tasks and compared the modules before and after a running intervention. [Subjects and Methods] Electromyographic measurements were performed on eight young, healthy males engaged in a 60s run on a treadmill at 2.8 m/s before and immediately after the 600s of running intervention. Electromyographic data for 15 trunk and lower-limb muscles on the right side were recorded. Muscle synergies were extracted from the electromyography signals using non-negative matrix factorization. [Results] Four modules explained the electromyographic activity of all muscles and had the functions of load acceptance (module 1), push-off (module 2), preparation of landing (module 3), and trunk-stabilization activity during the stance phase (module 4). Modules 1, 2, and 3 matched the basic modules reported in previous studies; whereas, module 4 was different before and after the intervention. [Conclusion] Before the intervention, module 4 engaged the trunk muscles and it was activated in the stance phase during running. However, after the intervention, module 4 engaged the muscles around the pelvis and it was activated after landing. This result suggests that the posture control changes from the trunk muscles to the lower-limb muscles after 10 minutes running.