In addition, an assesment will be made of the effects of the (combination of) breathing techniques and cold exposure on pain perception. In previous studies, trained subjects experienced substantially less flu-like symptoms during endotoxemia. This could be due to the attenuated immune response in these subjects, but also through other effects induced by the breathing techniques and/or cold exposure. To investigate this, quantitative sensory testing (QST) is used, an objective technique to measure pain thresholds.