The influence of exercise on cognitive function is an important topic. This study examines the effects of different interventions on executive functioning, specifically on cognitive planning, which is a sub-category of executive function, in adults with Down syndrome. Research has shown that an acute bout of Assisted Cycle Therapy improved manual motor functioning, cognitive planning, and information processing in adolescents with Down syndrome but there is a lack of research when it comes to resistance training. Fourteen adults with Down syndrome completed acute sessions of Assisted Cycle Therapy, Resistance Training, and No Training. Cognitive planning was measured by the Tower of London test. The results show that cognitive planning can be improved following Assisted Cycle Therapy. An increase in cognitive planning was also present in the No Training group which may be a result of cognitive stimulating games that were played. In conclusion, this study suggests that teachers, therapists, etc. that work with adults with DS, should be sure to include a cognitive component in all activities.