Endocrine Abstracts

Growth hormone and ghrelin responses to very intense exercise in humans

KA Stokes¹, D Sykes¹, KL Gilbert¹ & J Frystyk²

¹University of Bath, Bath, United Kingdom , ²Aarhus University Hospital, Aarhus, Denmark.

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Objective

It has been suggested that ghrelin may play a role in regulating the growth hormone (GH) response to exercise. This study was designed to determine whether very intense exercise alters circulating ghrelin concentrations. Design: Following Local Ethics Committee approval, 7 male volunteers were familiarised before completing two trials in a random order. In one trial participants performed a single 30-s sprint on a cycle ergometer, in the other they rested in the laboratory. Blood samples were taken pre-, immediately post-, 10 and 30 min post-exercise, and at equivalent time- points in the rest trial. Hormone data were corrected for changes in plasma volume. Results: Blood lactate concentrations increased approximately 14-fold following exercise, indicating that the exercise was demanding. Serum GH increased following exercise, and was significantly higher than pre-exercise 30 min after the sprint. Serum ghrelin decreased following exercise and was significantly lower than pre-exercise, and the corresponding time-points in the rest trial, 10 and 30 min after the sprint. There were no significant changes in GH, ghrelin or lactate in the rest trial, Table 1.>

Table 1 Mean(SD) serum GH and ghrelin at rest and following exercise (ex)

	Trial	Pre-	Post-	10 min	30 min
GH	Rest	0.6(1.2)	—	1.1(1.7)	2.1(4.5)
(μg.l−1)	Ex	0.7(1.2)	5.9(10.8)	16.0(23.3)	20.0(21.0)*
Ghrelin	Rest	0.62(0.18)	0.61(0.19)	0.63(0.18)	0.61(0.17)
(μg.l−1)	Ex	0.62(0.19)	0.62(0.20)	0.55(0.17)*#	0.49(0.16)*#

*significantly different from pre-exercise, p<0.05

# significantly different from corresponding time-point in rest trial, p<0.01

Conclusion

Circulating ghrelin is suppressed following very intense exercise, indicating that systemic ghrelin is unlikely to be responsible for exercise-induced GH release.

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Endocrine Abstracts (2005) 10 P62