Effects of carbohydrate supplementation on the RPE-blood lactate relationship.
OBJECTIVE
To examine the effects of carbohydrate (CHO) ingestion on the RPE-blood lactate relationship during incremental and constant-effort exercise.


METHODS
Six male and three female subjects (mean age = 27.2 +/- 8.2 yr, height [ht] = 174.5 +/- 13.5 cm, weight [wt] = 68.9 +/- 12.5 kg, body fat = 18.5 +/- 8.3%), completed two incremental cycling lactate threshold (LT)/(.)VO2peak tests followed by two 45-min production trials. Two hundred and forty milliliters of either carbohydrate or placebo (PL) was ingested before and every 15 min during exercise.


RESULTS
No differences were observed between conditions at LT, 2.5 and 4.0 mM, and peak. Within the CHO condition: V O2 = 25.0, 32.6, 37.5, 47.2 mL x kg x min(-1); power output = 123.3, 170.7, 200.1, 241.7 W; RPE = 12.8, 15.4, 17.2, 19.3; and HR = 137.4, 156.8, 168.7, 187.7 beats x min(-1) at LT, 2.5 mM, 4.0 mM, and peak, respectively. Within PL: V O2 = 24.7, 32.5, 36.8, 45.7 mL x kg x min(-1); power output = 130.0, 175.4, 201.9, 240.0 W; RPE = 12.1, 15.0, 17.0, 19.3; and HR = 134.9, 157.9, 169.6, 187.2 beats x min(-1), respectively. In the CHO condition, blood glucose was higher (P < 0.001), and a trend was observed for lower RPE over time (P = 0.07). During the production trials (RPE of 16) in the CHO condition, higher blood glucose area under the curve (AUC) (PL: 204.1 +/- 79.3 mM; CHO: 220.6 +/- 18.5 mM; P = 0.039) and a trend for greater total work (PL: 448.5 +/- 73.8 kJ; CHO: 470.5 +/- 65.6 kJ; P = 0.089) were observed.


CONCLUSIONS
We conclude that 1) CHO ingestion does not alter the blood lactate-RPE relationship during incremental LT/(.)VO2peak cycling; and 2) carbohydrate supplementation during exercise, eliciting high RPE, may increase work output during training sessions.
Steiner
Jennifer L
JL
Department of Human Services, University of Virginia, Charlottesville, VA 22904, USA.
A Curmaci
Alyssa
A
Patrie
James T
JT
Gaesser
Glenn A
GA
Weltman
Arthur
A
D000328:Adult; D001642:Bicycling; D001786:Blood Glucose; D004040:Dietary Carbohydrates; D019587:Dietary Supplements; D016552:Ergometry; D015444:Exercise; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D006801:Humans; D007537:Isometric Contraction; D019344:Lactic Acid / Q000097:blood*; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000502:physiology; D011446:Prospective Studies
D001786:Blood Glucose; D004040:Dietary Carbohydrates; D019344:Lactic Acid