Effect of carbohydrate ingestion on ratings of perceived exertion during a marathon.
OBJECTIVE
The purpose of this study was to investigate the effects of carbohydrate substrate availability on ratings of perceived exertion (RPE) and hormonal regulation during a competitive marathon.


METHODS
A randomized, double-blind study design was used in which subjects ran the marathon, and every 3.2 km, RPE and heart rate were measured. The marathoners were randomly assigned to receive carbohydrate (C) (N = 48) or placebo (P) (N = 50) beverages at a rate of 1 L x h(-1) during the race.


RESULTS
Heart rate (%(HRMAX) ) was lower in P (82.0% +/- 0.6) than C (84.2% +/- 0.6) (P < 0.01), especially during the final 10 km: (78.7% +/- 1.0) and (84.5% +/- 0.7), respectively (P < 0.001). RPE was not significantly different between P and C throughout the marathon (P = 0.08) or during the final 10 km: (16.8 +/- 0.3) and (16.1 +/- 0.3), respectively (P = 0.06). Postrace plasma glucose (P < 0.001), insulin (P < 0.001), and lactate (P < 0.05) levels were significantly lower in P than C, and postrace cortisol (P < 0.05) significantly higher in P compared with C.


CONCLUSIONS
Marathoners ingesting carbohydrate compared with placebo beverages were able to run at a higher intensity while reporting a nonsignificant difference in RPEs during a competitive race.
Utter
Alan C
AC
Department of Health, Appalachian State University, Boone, NC 28608, USA. utterac@appstate.edu
Kang
Jie
J
Robertson
Robert J
RJ
Nieman
David C
DC
Chaloupka
Edward C
EC
Suminski
Richard R
RR
Piccinni
Cristiana R
CR
D000328:Adult; D000704:Analysis of Variance; D001774:Blood Chemical Analysis; D001786:Blood Glucose / Q000032:analysis; D004040:Dietary Carbohydrates / Q000008:administration & dosage* / Q000378:metabolism; D004311:Double-Blind Method; D004734:Energy Metabolism / Q000502:physiology; D005260:Female; D006339:Heart Rate; D006801:Humans; D019344:Lactic Acid / Q000032:analysis; D008297:Male; D010101:Oxygen Consumption; D010807:Physical Endurance / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology*; D011336:Probability; D012016:Reference Values; D012420:Running / Q000502:physiology*; D012680:Sensitivity and Specificity
D001786:Blood Glucose; D004040:Dietary Carbohydrates; D019344:Lactic Acid