Abstract
Physiological changes with endurance exercise (EE) and resistance training (RT) are likely influenced by the metabolic and hormonal response to each exercise bout, but may be blunted in obese individuals. To compare acute effects of EE, RT, and a control upon hormonal changes in obese women, sedentary, obese women (n=12) participated in a randomised crossover-design study on 3 occasions. EE consisted of treadmill walking (65% VO2max for 1 h). A total-body RT workout consisted of 3 sets of 10 repetitions, 90 s rest for 8 exercises at 90-100% of 10RM. Blood samples were taken 30 min before exercise (0 min), 30 min post-exercise (120 min), and again at 200, 280, and 520 min to assess changes in growth hormone (GH), cortisol, and insulin throughout the postprandial period. A 20 kcal/kg fat-free mass (FFM) meal was given after post-exercise blood sample. There was a main effect of condition for GH ΔAUC (change in area under the curve), with both RT and EE significantly different from the control (RT = 463.0±138.2; EE = 243.2±131.6; Control = -90.4±157.6 ng/ml * 400 min, P<0.02, Control vs EE, effect size (ES) = 2.3; Control vs RT, ES=3.7; EE vs RT, ES=1.6). There were no condition effects for cortisol or insulin ΔAUC. There were no significant time-by-condition interactions for any variables. In obese women, circulating GH concentration is enhanced in the postprandial state following a single bout of either EE or RT, with the GH response being more robust than cortisol or insulin. As circulating GH has shown to be reduced in obesity, the present observations could be considered beneficial, particularly alongside the absence of enhanced cortisol level after exercise.