Purpose: The purpose of this study was to examine the effect of carbohydrate supplementation on differentiated and undifferentiated ratings of perceived exertion (RPE) during prolonged intermittent exercise and recovery. Methods: Twelve male subjects cycled for 2.0 h at 64% Wmax and 73% VO2peak with 3-min rest intervals interspersed every 10 min (2.6 h of total exercise time, including rest intervals) with placebo (P) or carbohydrate (C) beverages. RPE was assessed during the last minute of each 10-min exercise interval and then every 30 s during the 3-min recovery period. Results: The pattern of change in RPE over time was significantly different between C and P ingestion (P < 0.05), with attenuated RPE responses found for both overall body (O) and legs (L). A significant main effect was found for recovery RPE-O between C and P ingestion (P < 0.05), with attenuated RPE responses found in the later part of the 2-h run. C relative to P ingestion was associated with higher respiratory exchange ratios and plasma levels of glucose and with lower levels of plasma cortisol. Conclusions: These data indicate that carbohydrate supplementation attenuates perceived exertion during prolonged intermittent exercise and recovery.
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