Introduction
decreases in blood oxygen
Face masks have been confirmed as adequate protection against SARS-CoV-2 infectionNumerous studies showed that wearing masks during physical exercise causes non-health relevant decreases in blood oxygen as well as slight increases in blood carbon dioxideTo address the gap of knowledge regarding these questions, we created a partially (two of four modules) double-blinded randomized cross-over design for the present study. The aim of the study was to investigate the influence of three common types of masks worn for protection against SARS-CoV-2 on basic breathing physiology, as well as cardiopulmonary parameters and subjects' perceived physical exertion under different exercise and common workplace conditions in a study group covering a wide range of age and training condition.We hypothesize that (1) face masks alter the breathing patterns (e.g. longer inspiratory and expiratory time or reduced minute ventilation) when compared to the no mask situation under different exercise as well as common workplace conditions. Further we hypothesize, that (2) wearing face masks has a negative effect on objective (cardiopulmonary, blood gas parameters) and subjective (subjects' perceived physical exertion) outcomes under different exercise and common working conditions.