Impact of acute exercise intensity on pulsatile growth hormone release in men

Abstract

To investigate the effects of exercise intensity on growth hormone (GH) release, 10 male subjects were tested on 6 randomly ordered occasions [1 control condition (C), 5 exercise conditions (Ex)]. Serum GH concentrations were measured in samples obtained at 10-min intervals between 0700 and 0900 (baseline) and 0900 and 1300 (exercise+ recovery). Integrated GH concentrations (IGHC) were calculated by trapezoidal reconstruction. During Ex subjects exercised for 30 min (0900-0930) at one of the following intensities [normalized to the lactate threshold (LT)]: 25 and 75% of the difference between LT and rest (0.25LT and 0.75LT, respectively), at LT, and at 25 and 75% of the difference between LT and peak (1.25LT and 1.75LT, respectively). No differences were observed among conditions for baseline IGHC. Exercise+recovery IGHC (mean +/- SE: C = 250 +/- 60; 0.25LT = 203 +/- 69; 0.75LT = 448 +/- 125; LT = 452 +/- 119; 1.25LT = 512 +/- 121; 1.75LT = 713 +/- 115 microg x l(-1) x min(-1)) increased linearly with increasing exercise intensity (P < 0.05). Deconvolution analysis revealed that increasing exercise intensity resulted in a linear increase in the mass of GH secreted per pulse and GH production rate [production rate increased from 16. 5 +/- 4.5 (C) to 32.1 +/- 5.2 microg x distribution volume(-1) x min(-1) (1.75LT), P < 0.05], with no changes in GH pulse frequency or half-life of elimination. We conclude that the GH secretory response to exercise is related to exercise intensity in a linear dose-response pattern in young men.

Exercise-induced GH secretion in the assessment of GH deficiency in adult individuals

“…Interestingly, peak GH levels found in control individuals in this study were comparable to earlier studies with similar exercise intensity (7,10). Of note, a linear dose-relationship between exercise intensity and GH secretory response has been suggested in young healthy men (9). Previous reports indicate that an aerobic exercise duration of at least 20-30 min is required to provoke a relevant GH secretion, whereas a shorter exercise duration may result in comparably high or even higher GH levels if exercise is performed above the aerobic threshold (7,8,10,17).…”

“…Moreover, the time point of GH measurement during or after exercise may strongly affect results. We (7) and others (8)(9)(10) have reported GH to reach peak values between 30 and 45 min after start of exercise in adult individuals.…”

“…Secondly, the studies differed considerably regarding the applied exercise protocols. Since the duration and intensity of exercise strongly affect GH secretion (8,9), this is likely to have influenced diagnostic values. Interestingly, peak GH levels found in control individuals in this study were comparable to earlier studies with similar exercise intensity (7,10).…”

The order effect of combined endurance and strength loadings on force and hormone responses: effects of prolonged training

“…T, TSH, GH) and catabolic (e.g. cortisol) hormone concentrations (Pritzlaff et al 1999, Hackney et al 2012, while prolonged and physically demanding endurance performance (e.g. a marathon run) may in its final phases lead to decreases in testosterone and simultaneous increases in cortisol concentrations (Kuoppasalmi et al 1980).…”

Hormônio do crescimento e exercício físico: considerações atuais

“…Entre 40 e 60 min de atividade, a concentração basal ou de repouso do GH, que é de 1-2 µg/L, pode aumentar em diversas vezes, sendo a amplitude deste aumento dependente da intensidade em que o exercício físico for realizado (Felsing, Brasel, Cooper, 1992). Embora em alguns estudos a concentração do GH tenha variado entre 5-25 µg/L na intensidade leve a moderada (25% a 75% VO 2máx ) (Pritzlaff et al, 1999;Marcell et al, 1999;Pritzlaff et al, 2002) Marcell et al, 1999;Zaccaria et al, 1999;Weltman et al, 2006. Intensidade Liberação aumenta de acordo com a intensidade Bonifazi et al, 1998;Ehrnborg et al, 2003;Kanaley et al, 1997;Pritzlaff et al, 1999;Wideman et al, 1999.…”