Dismounted soldiers often need to perform physical tasks and cognitive tasks concurrently and/or sequentially. Previous research on the effects of concurrent and subsequent physical activity on cognitive performance has focused on physical activities with little complexity and variation, such as treadmill running and cycling. However, physical activities of infantry units often varies in complexity and intensity, especially in urban settings. Methods: In this pilot study, a design was applied by letting soldiers (n = 10) individually run the varied LEAP obstacle course while conducting cognitive tasks (N-back, Mackworth clock detection task, or self-reports) compared to cognitive performance measured during more simple physical activity (i.e., running on flat – obstacle-free terrain), and compared to no physical activity (i.e., sitting). Results: The current pilot study showed that cognitive performance (N-back misses) during physical activity was indeed most affected by the LEAP condition, less by the running condition, and least by the sitting condition, confirming cognitive-energetic theories. Considering a low number of participants that effected the power of our results, the differences between the conditions were statistically significant and the effect sizes were large (r > .85). Self-reported mental effort was only significantly higher in the physically active conditions compared to sitting, also with a large effect size (r >.85). Cognitive performance (N-back misses) subsequent to physical activity were only significantly differed between the physically active conditions and sitting, with large effect sizes, (r’s > .80) confirming arousal theories. The subjective mental effort indicated the same pattern in differences between conditions (Z=2.80, p=0.005). The cognitive Mackworth clock detection task revealed only a significant difference between the LEAP condition and sitting, perhaps indicating that the LEAP condition had a more pronounced positive effect (Z=2.68, p=0.007; r=.85). Conclusions: Though Corona restrictions limited the number of participants, the results seem to indicate that it is wise to avoid concurrent performance of cognitive tasks and intense or complex physical tasks, if possible, when also required to perform cognitively. In addition, sequencing cognitive tasks directly after physical activity could possibly be used to enhance cognitive performance. Military Impact: Sequencing physical activity in a specific order can have a positive impact on cognitive performance in military personnel. The LEAP obstacle environment is able to simulate complex urban terrain, thereby offering the moderation of physical activity to improve cognitive performance. Hence, the LEAP course might also a platform to evaluate the effect of physical activity as Human Augmentation technology.