Innate immune cells, such as monocytes and neutrophils, play an essential defensive role in the first line against pathogens. Monocytes and neutrophils are activated even after surgery or a blunt trauma in order to localize and eradicate harmful stimuli and restore the homeostatic state in the body. We have already summarized, immunometabolism plays a key role in the regulation of immune cell functions (Hortová‐Kohoutková et al., 2021). Metabolic switch in activated immune cells is crucial to meeting cells' energetic demands and preserving optimal effector functions. In this proposed project, I will observe metabolic alterations in monocytes and neutrophils in patients undergoing planned orthopedic surgery and in patients admitted to the ICU with blunt trauma. Furthermore, I will study how the metabolic switch affects effector functions of these cells since the relationship between these two has not yet been fully understood. We hypothesize that monocytes and neutrophils switch metabolic pathways after activation to provide intermediate metabolites in order to successfully execute defensive functions. These functions, such as phagocytosis, reactive oxygen species (ROS) production, and cytokine profiling, will be monitored using flow cytometry. Immunophenotyping will be performed on monocytes and neutrophils in stabilized whole blood. Single cell metabolism will be measured using a flow cytometry based method called SCENITH (Single Cell ENergetIc metabolism by profilIng Translation inHibition). The main aim of the proposed project is to unravel metabolic changes of innate immune cells and clarify the interconnection between the metabolic state of innate immune cells and effector functions of these cells. These findings can contribute to the shape of new treatment strategies of inflammatory-related conditions.