Effect of a reduced-CHO diet on the rate of perceived exertion curve during an incremental test.

The objective of this study was to evaluate the effect of a reduced-carbohydrate (reduced-CHO) diet on the rate of perceived exertion (RPE) curve during an incremental test. Nine physically active men performed a progressive incremental test on a cycle ergometer (25 W · 2 min(-1)) after 72 hr on either a control diet (60% CHO) or a reduced-CHO diet (30% CHO). Lactate and RPE thresholds were identified using the Dmax method (DmaxLa and DmaxRPE, respectively). Power output, heart rate and RPE scores in DmaxLa and DmaxRPE were similar between the diets and were not different from each other, regardless of the diet. Lactate values were consistently higher (p < .05) in the control diet compared with the reduced-CHO diet during power output after the lactate breakpoint; however, they were not accompanied by a proportional increase in RPE scores. These results suggest that DmaxRPE and DmaxLa are not dissociated after a short-period reduced-CHO diet, whereas the lactate values after the lactate threshold are reduced with a reduced-CHO diet, although they are not accompanied by alterations in RPE.