Cardiovascular drift (CVD, CVdrift) is the phenomenon where some cardiovascular responses begin a time dependent change, or "drift" after around 5-10 minutes of exercise in a warm or neutral environment (90 Fahrenheit+) without an increase in workload. It is characterised by decreases in mean arterial pressure and stroke volume and a parallel increase in heart rate. It has been shown that a reduction in stroke volume due to dehydration is almost always due to the increase in internal temperature. It is influenced by many factors, most notably the ambient temperature, internal temperature, hydration and the amount of muscle tissue activated during exercise. To promote cooling, blood flow to the skin is increased, resulting in a shift in fluids from blood plasma to the skin tissue. This results in a decrease in pulmonary arterial pressure and reduced stroke volume in the heart. To maintain cardiac output at reduced pressure, the heart rate must be increased.
Effects of cardiovascular drift are mainly focused around a higher RPE (Rate of Perceived Effort); that is, a person will feel like they are expending more energy when they are not. This creates a mental block that can inhibit performance greatly.
Prevention or minimization of cardiovascular drift includes consistently replacing fluids and maintaining electrolyte balance during exercise, acclimatization to the environment in which one is performing, and weight training to supplement cardiovascular efforts.
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