K Frick

Effects of Continuous Versus Intermittent Exercise, Obesity, and Gender on Growth Hormone Secretion

CONTEXT Obesity attenuates spontaneous GH secretion and the GH response to exercise. Obese individuals often have low fitness levels, limiting their ability to complete a typical 30-min bout of continuous exercise. An alternative regimen in obese subjects may be shorter bouts of exercise interspersed throughout the day. OBJECTIVE The objective of the study was to examine whether intermittent and continuous exercise interventions evoke similar patterns of 24-h GH secretion and whether responses are attenuated in obese subjects or affected by gender. DESIGN This was a repeated-measures design in which each subject served as their own control. SETTING This study was conducted at the University of Virginia General Clinical Research Center. SUBJECTS Subjects were healthy nonobese (n = 15) and obese (n = 14) young adults. INTERVENTIONS Subjects were studied over 24 h at the General Clinical Research Center on three occasions: control, one 30-min bout of exercise, and three 10-min bouts of exercise. MAIN OUTCOME MEASURES Twenty-four hour GH secretion was measured. RESULTS Compared with unstimulated 24-h GH secretion, both intermittent and continuous exercise, at constant exercise intensity, resulted in severalfold elevation of 24-h integrated serum GH concentrations in young adults. Basal and pulsatile modes of GH secretion were attenuated both at rest and during exercise in obese subjects. CONCLUSIONS The present data suggest that continuous and intermittent exercise training should be comparably effective in increasing 24-h GH secretion.

Effect of fractionized vs continuous, single-session exercise on blood pressure in adults

Exercise training-induced reduction in blood pressure (BP) 1 may be in part due to the BP lowering effects of acute exercise (postexercise hypotension, PEH). 2 PEH has been reported to be ~7-14 mm Hg, can occur within 5 min after exercise, and may persist for up to 22 h. 2,3 .