The main purpose of this study was to investigate the modulations in H-reflex and V-wave responses (spinal loop properties) induced by prolonged locomotion activities. The second purpose was to compare the development of central fatigue between continuous and intermittent running modes. Eleven males randomly performed two 90-min running exercises either continuously (CONT, first ventilatory threshold) or intermittently (INT, 150 s at a velocity 20% higher than during CONT / 30 s of recovery). Neuromuscular tests of the plantar flexors (including M-wave and H-reflex at rest as well as M-wave and V-wave during MVC) were performed before and 5 and 30 min after the running exercises. During MVC, the torque significantly decreased (P<0.05) from pre- to 5 and 30 min post-exercise (-11% and -9%, respectively), as did the RMS/M ratio (-11% and -13%, respectively) and the V/M ratio (-19% and -37%, respectively) for the soleus muscle. At rest, the H/M ratio also decreased significantly (P<0.001) from pre- to 5 and 30 min post-exercise (-61% and -55%, respectively). Last, no difference in the alteration of spinal loop properties was noted between CONT and INT. In conclusion, the results regarding H-reflex and V-wave suggest for the first time a modulation in spinal loop properties after prolonged running.