The hypothesis of this investigation is to observe if HBO have an anti-inflammatory effect in humans induced by tonic heat stimulation. It has been shown in animal studies with rats that HBO could reduce the paw edema induced by carrageenan as an inflammatory agent. The authors are not aware of similar studies in human subjects investigating this effect of HBO. Aim: To investigate the anti-inflammatory effect of HBO by reducing the hyperalgesia induced by heat stimulation in healthy subjects and promote future research and understanding of the anti-inflammatory processes in humans. The primary endpoint is a reduced area of secondary hyperalgesia after HBO.