Factors influencing excess postexercise oxygen consumption in trained and untrained women

This study investigated the effects of blood lactate and norepinephrine levels and rectal temperature on excess postexercise oxygen consumption (EPOC) following two different exercise intensities. Six trained and seven untrained women each performed two exercise tests, short-term high-intensity exercise ([HI] approximately 80% maximum oxygen consumption [VO2max]) and long-term low-intensity exercise ([LOW] approximately 65% VO2max) until 300 kcal were expended. Rectal temperature, oxygen consumption (VO2), and lactate and norepinephrine levels were monitored at rest, during exercise, and for 60 minutes into recovery. Exercise times averaged 30.0 +/- 4.5 and 23.7 +/- 0.9 minutes in trained women and 45 +/- 3.6 and 30.0 +/- 0.4 minutes in untrained women for LOW and HI, respectively. Rectal temperature, VO2, and lactate and norepinephrine levels were significantly elevated (P < .05) during HI compared with LOW in both groups. VO2 was elevated throughout recovery following LOW and HI in untrained women only. Additionally, VO2 was elevated until minutes 50 and 40 following LOW and HI, respectively, in trained subjects. Rectal temperature returned to resting levels after 30 minutes of recovery following LOW, but remained significantly elevated throughout minute 50 of recovery following HI in trained women. However, values remained significantly elevated throughout recovery following both exercise bouts in untrained subjects. Norepinephrine levels remained elevated above resting levels throughout recovery following HI and until minute 50 following LOW in trained subjects, whereas levels remained elevated for 5 minutes following LOW and 50 minutes following HI in untrained subjects. Lactate levels remained elevated above baseline values throughout recovery following HI and LOW in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)