Ratings of perceived exertion throughout an ultramarathon during carbohydrate ingestion

Ratings of perceived exertion (RPE) and their relation to selected physiological mediators during endurance exercise have been limited to laboratory settings. The present study characterized the pattern of change in perceptual responses and examined the relation between RPE and selected physiological variables during a long competitive sporting event, i.e., an ultramarathon race (68 km). A single-group design was employed in which all of the 28 subjects provided their perceptual ratings (11.9 ± 0.2) and heart rate (HR) (138 ± 3) periodically (every 5 km) throughout the ultramarathon, and selected physiological responses were measured before, once during (32 km), and immediately after the race. Runners drank approximately 1,000 ml of carbohydrate beverage each hour (60 gm carbohydrate hr. ^-1) and ate 2 or 3 carbohydrate gel packs per hour (25 gm each ^-1). RPE increased significantly throughout the course of the ultramarathon. No significant correlations were found between RPE and HR at any time throughout the ultramarathon. RPE averaged 10.4 ± 0.4 at the beginning of the race (6.4 km) and 15.4 ± 0.4 at the conclusion of the race. Subjects maintained 76.9 ± 1.1% of maximal heart rate; however, there was a tendency for heart rate to drop significantly after 32 km. Significant time main effects were found for serum glucose, insulin, and cortisol throughout the race. However, no significant correlations were found between RPE and any of these physiological mediators. These data indicate that during an ultramarathon race there is a progressive increase in RPE without an accompanying increase in HR or decrease in blood glucose. Therefore, during competitive self-paced exercise the perceptual responses may be mediated through other neurological and physiological mechanisms.