 The loss of accuracy during more intense anaerobic exercise is among others due to factors including the bicarbonate buffer system.The body tries to compensate for the accumulation of lactate and minimize the acidification of the blood by expelling more CO2 through the respiratory system.An RER of 0.7 indicates that fat is the predominant fuel source, a value of 1.0 is indicative of carbohydrate being the predominant fuel source, and a value between 0.7 and 1.0 suggests a mix of both fat and carbohydrate.