Carbohydrate supplementation and perceived exertion during prolonged running

Alan C. Utter, Jie Kang, David C. Nieman, Charles L. Dumke, Steve R. McAnulty, Debra M. Vinci, Lisa S. McAnulty

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


Purpose: The purpose of this study was to investigate the relationship between carbohydrate energy substrate and hormonal regulation on the perception of exertion during prolonged running. Methods: Sixteen experienced marathoners ran on treadmills for 3 h at ∼70% VO2max on two occasions while receiving 1 L·h-1 carbohydrate (C) or placebo (P) beverages. Blood and vastus lateralis muscle biopsy samples were collected before and after exercise. Results: The pattern of change in ratings of perceived exertion (RPE) over time was significantly different between C and P ingestion (P < 0.01) with attenuated RPE responses found in the latter part of the 3 h run. The pattern of change in the respiratory exchange ratio and carbohydrate oxidation rates were significantly greater (P < 0.01) in the C than P condition. Change in muscle glycogen content did not differ between C and P (P = 0.246). C relative to P ingestion was associated with higher plasma levels of glucose, insulin, and lactate and lower levels plasma cortisol. Conclusions: These data indicate that a lower RPE was associated with a higher carbohydrate oxidation, plasma glucose, and insulin levels, and lower plasma cortisol during prolonged running after C supplementation as compared with P feeding despite no differences in muscle glycogen content. These findings support a physiological link between RPE and carbohydrate substrate availability as well as selected hormonal regulation during prolonged running.

Original languageEnglish
Pages (from-to)1036-1041
Number of pages6
JournalMedicine and Science in Sports and Exercise
Issue number6
StatePublished - Jun 2004


  • Carbohydrate ingestion
  • Cortisol
  • Glucose
  • Muscle glycogen


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