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

• Published in: The journal of clinical endocrinology and metabolism 2008-12, Vol.93 (12), p.4711-4720
• Main Authors: Weltman, Arthur, Weltman, Judy Y., Watson Winfield, Dee Dee, Frick, Kirsten, Patrie, James, Kok, Petra, Keenan, Daniel M., Gaesser, Glenn A., Veldhuis, Johannes D.
• Format: Article
• Language: English
• Subjects: Adult; Anaerobic Threshold - physiology; Biological and medical sciences; Body Composition - physiology; Body Mass Index; Data Interpretation, Statistical; Endocrinopathies; Exercise - physiology; Feeding. Feeding behavior; Female; Fundamental and applied biological sciences. Psychology; Half-Life; Human Growth Hormone - blood; Humans; Lactic Acid - blood; Male; Medical sciences; Obesity - blood; Obesity - metabolism; Original; Physical Fitness - physiology; Rest - physiology; Sex Characteristics; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Vertebrates: endocrinology; Young Adult
• ISSN: 0021-972X; 1945-7197
• DOI: 10.1210/jc.2008-0998

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. Although the response is attenuated in obese adults, one 30-min vs three 10-min bouts of exercise are equally effective for augmenting 24-h spontaneous GH secretion.