@unpublished{TUW-229173, author = {Kaniusas, Eugenijus and Varoneckas, Giedrius}, title = {Heart rate variability and voluntary apnea for the assessment of fatigue and fitness}, year = {2014}, note = {invited; talk: International Conference on Wearable and Implantable Body Sensor Networks ({BSN} 2014), Z{\"u}rich, Schweiz; 2014-06-16 -- 2014-06-19} }