This article is more than 5 years old. Information may no longer be current.
Continuous, intermittent exercise increased 24-hour GH secretion
Researchers encourage shorter bouts of exercise interspersed throughout the day.
Click Here to Manage Email Alerts
A single 30-minute and three 10-minute bouts of physical activity increased 24-hour integrated serum growth hormone concentrations in young adults.
These data suggest that both continuous and intermittent exercise may be beneficial in promoting increases in 24-hour GH secretion in obese and nonobese individuals, according to researchers at the University of Virginia and Mayo Clinic in Rochester.
“We originally hypothesized that three 10-minute bouts of exercise would result in a greater 24-hour GH release than the single 30-minute bout of exercise. It may be that just 10 minutes of exercise at a time is not enough to create an additive response because the total response was the same as with a single 30-minute bout of exercise,” said Arthur Weltman, PhD, director of the Exercise Physiology Program at the University of Virginia.
“When sedentary or obese individuals start an exercise program they may have difficulty completing one 30-minute bout of exercise. The ability to spread the bouts of exercise throughout the day allows individuals to complete the exercise with similar benefits and without the sense of discouragement that might occur if the individual cannot complete 30 minutes of continuous exercise,” he told Endocrine Today.
Examining exercise effects
The researchers examined an alternative exercise regimen characterized by shorter bouts of exercise interspersed throughout the day on 24-hour GH secretion. They enrolled 14 obese (n=8 men) and 15 nonobese (n=8 men) young adults aged between 23 and 30 years. Individuals were studied during 24 hours on three occasions: control; one 30-minute bout of exercise; and three 10-minute bouts of exercise. Women were tested in the early follicular phase of their menstrual cycles, according to the study.
“Compared with unstimulated 24-hour GH secretion, both a single 30-minute and three 10-minute bouts of exercise, at constant exercise intensity, resulted in several-fold elevation in 24-hour integrated serum GH concentrations in both nonobese and obese young adults,” the researchers wrote in the Journal of Clinical Endocrinology and Metabolism.
In addition, obese individuals experienced marked attenuation of resting and exercise-stimulated 24-hour GH secretion, which resulted in greater GH pulsatile secretion compared with unstimulated 24-hour GH secretion.
Statistical analysis showed that basal GH secretion was greater in nonobese participants (P<.001) and was greater in woman compared with men (P<.001), according to the study. In both exercise cohorts, basal and pulsatile GH secretion was attenuated when participants were at rest and during exercise for obese participants. The researchers reported no difference in 24-hour GH concentrations between men and women. – by Katie Kalvaitis
J Clin Endocrinol Metab. 2008;93:4711-4720.