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Heart Rate Drift is the reduction in the amount of blood the heart pumps with each beat (Stroke Volume) and the resulting rise in [[Heart Rate ]] as the heart attempts to maintain the flow of blood (Cardiac Output). This drift starts happening after about 10 minutes of moderate (50-75% [[VO2max| V̇O<sub>2</sub>max]]) exercise. Heart Rate Drift is also called cardiovascular drift.
=Heart Rate Drift and V̇O<sub>2</sub>max=
Decreases in stroke volume of 10-16% and increases in heart rate of 12-16% are associated with a 9% to 19% reduction in [[VO2max| V̇O<sub>2</sub>max]]<ref name="Ganio-2006"/><ref name="Wingo-2006b"/><ref name="Wingo-2006a"/><ref name="Wingo-2005"/>. Fluid intake<ref name="Ganio-2006"/> or body cooling<ref name="Wingo-2006a"/> will mitigate the reduction in stroke volume and [[VO2max| V̇O<sub>2</sub>max]]. Reducing the exercise load to keep the Heart Rate constant will also mitigate, but not eliminate the reduction in [[VO2max| V̇O<sub>2</sub>max]]<ref name="Wingo-2006b"/>. Heart Rate drift and reduction in [[VO2max| V̇O<sub>2</sub>max]] is greater in hot than cooler conditions<ref name="Lafrenz-2008"/>.
