Athletes, soldiers, and rescue personnel are often required to perform intensive and prolonged physically demanding activities while remaining cognitively focused. The combined effect of physical and cognitive tasks is of great interest, as both efforts share central nervous system reserves. Amid a larger study that is aimed to create an ecologically validated virtual reality (VR) - based experimental protocol to explore the effect of high-load physical and cognitive efforts on young individuals, the present report focuses on comparing new cognitive tasks presented in the context of simulated military missions with physical load to already established cognitive testing battery. Twelve young participants performed a 10 Km loaded march on a treadmill in VR settings with or without additional cognitive tasks (VR-COG). Each experimental day, subjects underwent pre-and post-evaluation, in which cognitive (trail making test - the color trail test CTT version, and SYNWIN battery for multitasking evaluation) and physical tests (time to exhaustion test - TTE) were conducted. In general, strong or moderate correlations were found between VR-COG performances and the cognitive tests. The VR-COG tasks, together with CTT components, were able to successfully predict the effect of the combined physical and cognitive load on the multitasking performance. Multitasking was evaluated by the SYNWIN score. We believe that our protocol allows optimal conditions for measurement of the effect of high-load physical and cognitive efforts for an extended period of time, thus contributing to the motor-cognitive interaction model knowledge base. It is apparent that virtual environments are ideal set ups for studying military activities, as they enable the participants to experience a particular situation within a controlled area.