Suppression of the hypothalamic-pituitary-gonadal axis during intensive training is attenuated by carbohydrate supplementation

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: MON 758-775-Beta Cells, Glucose Control & Complications
Monday, June 17, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board MON-773
Maysa Vieira de Sousa*1 and Maria Elizabeth Rossi da Silva2
1University of Sao Paulo, São Paulo, Brazil, 2University of Sao Paulo
Intensive training seems to have a suppressive effect on the hypothalamic-pituitary gonadal (HPG) axis (1). Lower basal circulating levels of testosterone have been reported in athletes who have performed chronic or acute long distance exercise while luteinizing hormone (LH) has been shown to decrease or remain unchanged (2). However, the cause of the decreased androgen levels is not completely understood but is postulated to be a dysfunction (or perhaps a readjustment) within the HPG axis. Also, it is known that CHO supplementation during exercise attenuates catabolic stress (3). Based on that, the aim of this study was to evaluate the effect of short-term intensive microcycle training (8 days) with CHO supplementation on the HPG axis of elite runners. Twenty-four male runners were randomly assigned to two groups (CHO group and control group). The participants were submitted to an overload training program (days 1 - 8), followed by a high-intensity intermittent running protocol (10 x 800 m) on day 9. The runners received maltodextrin solution (CHO group) or zero energy placebo solution as the control equivalent before, during, and after this protocol. After 8 days of intensive training, total (TT) and free  testosterone (FT) concentrations were higher in the CHO group compared to the control group (TT: 694.0±54.6 ng/dL vs. 610.8±47.9 ng/dL; FT: 552.7±49.2 pmol/L vs. 395.7±36.6 pmol/L; p < 0.05). This was accompanied by increased secretion of LH in the CHO group (4.6±0.6 UL/mL vs. CON: 2.9±0.3 UL/mL, p < 0.05). On day 9, at 80 min post intermittent running (10 x 800 m), TT concentration decreased in both groups compared to baseline values (CHO: 771.7±34.2 and 390.0±35.7 pmol/L, Control: 600.7±60.7 and 341.5±57.9 pmol/L, respectively, p < 0.05). Similar response was observed for FT levels while LH remained increased at 80 min of the recovery period (4.9± 0.7 UL/mL vs. CON: 3.2±0.5 UL/mL, p < 0.05). Cortisol levels were blunted in the CHO group post running (22.4±0.9 vs. CON: 27.6±1.4 pmol/L) and at 80 min of recovery (15.5±1.0 vs. CON: 23.6±1.3 pmol/L, p<0.05).  These data demonstrated that CHO supplementation attenuated the suppression of the hypothalamic-pituitary-gonadal axis during short intensive training microcycle thereby increasing total and free testosterone levels while promoting better anabolic state to elite runners.

(1) Lane AR et al., Eur J Appl Physiol 2010; 108:1125-31(2) Kraemer WJ et al., Br J Sports Med 2008; 42: 116-20(3) de Sousa MV et al., Eur J Appl Physiol 2010; 109:507–516

Nothing to Disclose: MV, MER

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Sources of Research Support: FAPESP Grant 2010- 08030-0