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RPE during Prolonged Cycling with and without Carbohydrate Ingestion in Boys and Men

TIMMONS, BRIAN W.; BAR-OR, ODED

Medicine & Science in Sports & Exercise: November 2003 - Volume 35 - Issue 11 - p 1901-1907
doi: 10.1249/01.MSS.0000093752.46408.AF
APPLIED SCIENCES: Psychobiology and Behavioral Strategies

TIMMONS. B. W., and O. BAR-OR. RPE during Prolonged Cycling with and without Carbohydrate Ingestion in Boys and Men. Med. Sci. Sports Exerc., Vol. 35, No. 11, pp. 1901–1907, 2003.

Purpose To examine the effect of prolonged cycling on ratings of perceived exertion (RPE) in boys and men and whether carbohydrate (CHO) ingestion would lower RPE during exercise.

Methods Ten boys (9–10 yr) and 10 men (20–25 yr) cycled for 60 min at ∼70% V̇O2peak on two occasions. In a double-blind, counterbalanced design, a total volume of 24 mL·kg−1 body mass of either a 6% CHO-electrolyte (CT) or flavored water (WT) beverage was consumed intermittently before and during exercise in each trial. Oxygen consumption (V̇O2), ventilation (V̇E), respiratory rate (RR), RPE (Borg’s 6–20 scale), and heart rate (HR) were recorded periodically throughout exercise. Plasma glucose (GLU) was determined before and after exercise.

Results Postexercise GLU was not different between age groups but higher (P < 0.001) during CT (5.6 ± 0.2 mmol·L−1) compared with WT (4.7 ± 0.1 mmol·L−1). CHO ingestion had no effect (P > 0.05) on V̇O2, V̇E, RR, or RPE in either group. RR during exercise was higher (P < 0.01) in boys (39.0 ± 2.2 breaths·min−1) than in men (30.9 ± 1.3 breaths·min−1). HR was slightly higher (P = 0.047) during CT (160 ± 3 beats·min−1) compared with WT (156 ± 4 beats·min−1) and increased less over time (P < 0.01) in boys compared with men. RPE at 5 min of exercise was similar (P > 0.05) between boys (11.8 ± 0.7) and men (12.0 ± 0.7) but increased faster (P < 0.01) over time in boys. The average exercise RPE was higher (P < 0.01) in boys (15.8 ± 0.5) than in men (14.0 ± 0.4).

Conclusions The higher and faster increase in RPE during exercise in boys, compared with men, may reflect a sensitivity to RR that outweighed any effect of CHO ingestion on RPE.

Children’s Exercise and Nutrition Centre, McMaster University, Hamilton, Ontario, CANADA

Address for correspondence: Oded Bar-Or, M.D., Children’s Exercise and Nutrition Centre, Chedoke Hospital, Evel Bldg. (4th floor), Sanatorium Road, Hamilton, Ontario, Canada L8N 3Z5; E-mail: baror@mcmaster.ca.

Submitted for publication November 2002.

Accepted for publication July 2003.

©2003The American College of Sports Medicine