The effects of graded exercise on plasma proenkephalin peptide F and catecholamine responses at sea level

Summary The purpose of this study was to evaluate the effects of graded treadmill exercise on plasma preproenkephalin peptide F immunoreactivity and concomitant catecholamine responses at sea level (elevation, 50 m). Few data exist regarding the sea-level responses of plasma peptide F immunoreactivity to exercise. Thirty-five healthy men performed a graded exercise test on a motor-driven treadmill at the relative exercise intensities of 25, 50, 75, and 100% of maximum oxygen consumption (VO_2max). Significant (P<0.05) increases above rest were observed for plasma peptide F immunoreactivity and norepinephrine at 75 and 100% of the VO_2max and at 5 min into recovery. Significant increases in plasma epinephrine were observed at 75 and 100% of VO_2max. Whole blood lactate significantly increased above resting values at 50, 75, and 100% of the VO_2max and at 5 min into recovery. These data demonstrate that exercise stress increases plasma peptide F immunoreactivity levels at sea level. While the exercise response patterns of peptide F immunoreactivity are similar to catecholamines and blood lactate responses, no bivariate relationships were observed. These data show that sea-level response patterns to graded exercise are similar to those previously observed at moderate altitude (elevation, 2200 m).Human subjects participated in these studies after giving their free and informed voluntary consent. Investigators adhered to AR 70-25 and USAMRDC regulation 70-25 on Use of Volunteers in Research. The views, opinion, and/or findings contained in this report are those of the author(s) and should not be construed as an official Department of the Army position, policy, or decision, unless to designated by other official documentation.