Source document: http://www.horsetalk.co.nz/2016/06/16/evidence-temporary-cardiac-fatigue-endurance-horses/#axzz4Bl8GS2xJ
Source document: https://aerc.org/static/upload/Research_Heart_1012.pdf
Source document: https://perseveranceendurancehorses.wordpress.com/2011/09/01/7-characteristics-of-a-great-endurance-horse-september-2011/