This study examines the effectiveness of two modes of exercise on inhibitory control in adults with Down Syndrome (DS). Thirteen participants attended four sessions: a baseline assessment, an Assisted Cycling Therapy (ACT) session, a Resistance Training (RT) session, and a session of No Training (NT). In the baseline assessment, 1-repetition max (1RM) measurements and voluntary pedal rate measurements were taken. In the resistance training session, the leg press, chest press, seated row, leg curl, shoulder press, and latissimus pulldown were performed. In the cycling intervention, the participant completed 30 minutes of cycling. The Erikson Flanker task was administered prior to each session (i.e., pretest) and after the intervention (i.e., post-test). The results were somewhat consistent with the hypothesis that inhibition time improved more following RT and ACT than NT. there was also a significant difference between ACT and NT. Additionally, it was hypothesized that all measures would improve following each acute exercise intervention, but the most significant improvements were seen following ACT. In conclusion, an acute session of ACT demonstrated a significant trend towards improvements in inhibitory control in adults with DS which we interpreted using a model of neural changes.