The Effect of Training and Epinephrine Infusion on Ratings of Perceived Exertion (RPE)

Seven untrained males (mean age [± SD] = 25.6 ± 3.9 yr, mean ht = 177.0 ± 5.9 cm, mean wt = 65.8 ± 7.4 kg) completed a 6-week exercise program (cycle ergometer). Prior to training, and at the end of each week of training, each subject performed a 20 min constant-power exercise test (absolute power was the same each week). At the end of the six week training program (within a few days), an additional 20 min constant-power test was performed, during which epinephrine was infused at a rate of 100 ng · kg^-1 · min^-1 over the final 10 min of exercise. Training significantly (P < 0.05) reduced end-exercise ratings of perceived exertion (RPE), plasma epinephrine concentration [Epi], plasma norepinephrine concentration [NE], blood lactate concentration [La^-], minute ventilation (V_E), heart rate (HR), and blood glucose concentration [Glc]. Epinephrine infusion failed to increase RPE despite significant (p < 0.05) increases in [Epi], [La^-], V_E and [Glc]. Therefore, the present data indicate that RPE during exercise is not causally related to changes in plasma [Epi]. It also appears that modest changes in plasma [NE], blood [La^-], V_E and blood [Glc] during constant-power cycle ergometry (as observed during Epi infusion) do not impact RPE.

Key words

RPE - exercise - catecholamines