Deaths occurring during and/or in close proximity to physical restraint have been attributed to positional asphyxia, a conclusion primarily based on opinion and reviews of case studies. This review sought to identify the current scientific evidence available in regard to the aetiology of adverse events or death occurring during or in close proximity to physical restraint. A systematic search of electronic databases (SPORTDiscus, AMED, CINAHL, MEDLINE, PsycINFO) for papers published in English, between 1980 and 2011, using keywords that related to restraint, restraint position and cardiovascular function resulted in 11 experimental papers being found for review. The term positional asphyxia as a mechanism for sudden death is poorly understood. The literature shows that restraint position has the ability to impede life-maintaining physiological functions, but that the imposed impediment is not uniform across all restraint positions/techniques. Further research is required to ascertain the risks posed by struggling during restraint for more prolonged periods of time and in different positions using varied techniques of restraint. This research should seek to and rank known or future risk factors of adverse events occurring during restraint, seeking to understand the interactions and if present the cumulative effect of these risk factors. Finally, future research should focus on populations other than apparently healthy male adults.