Excess post-exercise oxygen consumption Excess post-exercise oxygen consumption Excess post-exercise oxygen consumption (EPOC, informally called afterburn) is a measurably increased rate of oxygen intake following strenuous activity. In historical contexts the term "oxygen debt" was popularized to explain or perhaps attempt to quantify anaerobic energy expenditure, particularly as regards lactic acid/lactate metabolism; in fact, the term "oxygen debt" is still widely used to this day. However, direct and indirect calorimeter experiments have definitively disproven any association of lactate metabolism as causal to an elevated oxygen uptake. In recovery, oxygen (EPOC) is used in the processes that restore the body to a resting state and
American Oxygen shiver down your spine." Rob Le Donne of "The Guardian" wrote that the single features more "serious" Rihanna than the persona on her previous singles, "it's hard to tell exactly what Rihanna is trying to say – but maybe that’s the point." Further more, he praised the producers Alex da Kid and West and the "layered" production that they have done on the song. However, he thought that "American Oxygen" is not "radio-friendly" unlike Eminem and Rihanna's 2010 single "Love the Way You Lie", which was also produced by Alex da Kid, or Rihanna's songs from her previous album, "Unapologetic",