<p>Completing cognitive training alongside physical activity may be an effective and efficient way to improve cognitive performance. To inform ongoing randomized controlled trials (RCTs) investigating the efficacy of physical and cognitive training, intervention fidelity and participant experience should be considered. This study aimed to provide a comprehensive account of the interventions and participant experiences within a concurrent physical and cognitive training RCT. In total, 107 healthy active young adults were recruited for a 12-week investigator-blinded RCT. Participants were assigned to one of three intervention groups: (1) concurrent physical and cognitive training, (2) separate physical and cognitive training, or (3) physical-only training. Measures of physical and perceived load including power output, cadence, exertion, enjoyment, and task load, were collected in weeks 3, 7, and 10 of the intervention. Cognitive training volume and load were collected for the concurrent and separate groups over the duration of the intervention. Measures of intervention acceptability included withdrawal rates and end-of-intervention participant feedback. Participant attendance at training sessions was high (concurrent: 92 ± 7%; separate: 96 ± 6%; physical-only: 93 ± 7%); with no difference between groups (<i>p</i> = 0.220). There were no differences in physical load between groups; however, compared to the concurrent group, the separate group had a higher cognitive training volume (<i>p</i> = 0.001) and training fitness (<i>p</i> = 0.002). Overall, participants from all groups reported that they enjoyed the physical training and experienced improvements in memory and focus from cognitive training. Concurrent physical and cognitive training appears to be a well-tolerated and time-efficient approach for investigating methods of improving cognitive performance in younger adults.</p>