In this study, we systematically investigate the compression behavior of Expanded Polypropylene (EPP) bead foams using precise experiments in a custom-designed vacuum chamber. The material's response is examined under controlled pressure conditions, including compression tests at both ambient pressure and 4 mbar, at various strain rates. Considering that most foams consist of more than 90% air, our focus is on elucidating the influence of cell gas on mechanical properties, such as compression modulus, plateau stress, plateau slope, and energy absorption. The impact of cell gas on recovery behavior was analyzed by loading–unloading-steps in the vacuum chamber. Notably, the presence of cell gas shows a pronounced effect on the foam's deformation behavior, particularly in the plateau region, significantly affecting its resistance to deformation and energy absorption. The findings offer valuable insights for the development of foam materials and structures/components made of foams, especially in applications where resilience and durability are paramount.