Effect Of Gender On Lipid Mobilization And Lipolytic Hormones During And After Prolonged Submaximal Exercise

Abstract

During prolonged, moderate-intensity exercise, lipid oxidation is a major source of ATP. If present, gender differences in lipolytic hormone concentrations may significantly alter this response. PURPOSE To examine potential gender differences in lipolytic markers and hormones before, during, and after a prolonged, moderate-intensity exercise bout. S276 Vol. 37 No. 5 Supplement METHODS Seven healthy males (age = 25.9 ± 4.9 y, height = 174.4 ± 3.0 cm, mass = 69.9 ± 6.3 kg, body fat = 10.0 ± 2.7%, VO2max = 69.1 ± 6.7 ml·kg-1·min-1) and seven healthy, eumenorrheic females (age = 29.0 ± 4.2 y, height = 166.0 ± 4.2 cm, mass = 54.6 ± 6.5 kg, body fat = 19.3 ± 3.9%, VO2max = 53.1 ± 4.5 ml·kg-1·min-1) participated in this study. All subjects were trained runners familiar with treadmill running. Subjects ran on a motor-driven treadmill for 60 min at 70% VO2max. Blood samples were obtained immediately prior to exercise, 20 and 40 minutes during exercise, and four, 30, and 60 minutes post-exercise; samples were analyzed for lactate, non-esterified fatty acids, glycerol, cortisol, prolactin, growth hormone, epinephrine, norepinephrine, and dopamine. RESULTS The majority of analytes were stimulated or unchanged during the exercise bout; except for non-esterified fatty acids in males, all measurements returned to baseline values within 60 minutes of exercise completion. Prior to exercise, females displayed significantly greater prolactin and dopamine. Four minutes post-exercise, females showed significantly lower epinephrine concentrations than males. No other physiologically or statistically significant gender differences existed. CONCLUSIONS Despite significantly different resting endocrine profiles, males and females appeared to mobilize and utilize lipid substrates similarly during prolonged, moderate-intensity exercise.