To know where we want to go, we need to know who we are and where we come from. This book seeks to situate the reader in terms of the work of the military police in Brazil, using the state of Paraná as a case study, which has a police force that has been in existence for over 160 years. We sought to understand the day-to-day life of the police, working hours, equipment and professional training so that we could analyse the effects of this peculiar activity in the world in terms of possible losses and gains in terms of physical performance, concentration, shooting performance and high-intensity interval training due to some specific aspects such as sleep deprivation during work, night shifts, extra weight in equipment and loaded weapons. It was noted that research in this field is little explored in Brazil and that it is also a fertile field for understanding military police activity and seeking strategies suited to the demands of the activity with a view to more efficient performance in training and preparation for police action.