Often the approach to investigating muscular coordination during transitions entailed conducting tests at speeds held constant. This study investigated muscular activity during continuously changing speeds in order to further detail and quantify neuromuscular changes during gait transitions. Twelve healthy adults, 18-41 years of age, were recruited as participants. Informed consent was obtained. Gait transitions were induced by the speed of the treadmill changing with constant acceleration. Reflective markers were placed on anatomical landmarks of the hip, knee,ankle, heel, and 5 th metatarsal joint. Bipolar surface electrodes were positioned on the subjects’skin over the muscular bellies of the gluteus maximus (GM), rectus femoris (RF), vastus lateralis (VL), biceps femoris (BF), tibialis anterior (TA), gastrocnemius (GAS), and soleus (SOL). Electromyographic (EMG) data were collected at 960 Hz. Five transition trials were conducted for both progression modes: walk-to-run (WR) and run-to-walk (RW), and five interval trials were collected for both gaits at constant speeds. Five steps preceding the gait transitions were analyzed. The mean of recorded transition speeds (MTS) was calculated from the prior transition trials. There were five different constant speed trials for walking (WC) and running (RC); the speeds were MTS - 0.6, MTS - 0.3, MTS, MTS + 0.3, and MTS + 0.6 mph. Cross-correlation comparisons and discrete parameters of the EMG activity ensemble curves were examined across trials and conditions. Two factor (condition and trial) repeated measures ANOVA was employed for statistical analysis (á = .05). For the correlation parameters, significant running condition/trial interactions were observed for all muscles. Significant condition/trial interactions were revealed for the discrete parameters concerning activation magnitude (GM, RF, VL, TA, GAS, and SOL)and duration (RF, GAS, and SOL) for both walking and running. EMG activity intensity and duration in some muscles changed with the locomotion speed in a quadratic fashion, which was only observed in transition related trials. These results indicate that neuromuscular changes occurred steps before the observed gait transition and that changing velocity induces gait transition related behavior that cannot be observed with constant velocity in the same range.