The Effect of Sex Steroid Hormones on Substrate Oxidation during Prolonged Submaximal Exercise in Women.

Abstract

Skeletal muscle glycogen is an essential constituent to exercise performance [1]. Several factors are known to affect glycogen storage and utilization within skeletal muscle, such as dietary practices, exercise activity, and hormonal status [1]. Most research concerning this last factor has dealt with traditional metabolic hormones (e.g., epinephrine, insulin, and glucagon). However, so-called non-metabolic hormones also have an impact upon muscle glycogen and thus could affect exercise performance [1]. One such category of hormone includes the female sex steroids, estrogens and progesterone. Rodent studies indicate estrogens increase muscle glycogen storage at rest and reduce glycogen utilization during prolonged submaximal exercise, primarily due to the increased oxidation of free-fatty acids as an energy source, which results in a glycogen sparing effect [2]. Human research has been limited in this area, but the findings of several Key words: energy metabolism, menstrual cycle, activity. Abstract:In animals, female sex steroid hormones (SS, estrogens-progesterone) influence the energy substrate that is metabolized. Human research on this issue is controversial. This study examined whether changes in circulating SS hormone levels affected the carbohydrate-lipid metabolism during submaximal prolonged (60 min) exercise. Young, physically active females were studied. Four were classified as anovulatoryoligomenorrheic and four were classified as ovulatory-eumenorrheic. Subject responses were pooled to form one group (nϭ8) and then their responses under low (L) and high (H) pharmaceutically manipulated SS hormone conditions were examined. During exercise, the mean oxygen consumption levels were 1.70Ϯ0.10 l · min Ϫ1for L-SS and 1.75Ϯ0.11 l · min Ϫ1 for H-SS (pϭ 0.07), respectively. The respiratory exchange ratio (RER) responses were significantly different during exercise between the conditions: 0.93Ϯ0.04 for L-SS and 0.90Ϯ0.04 for H-SS (pϽ0.05), respectively. RER responses were utilized to calculate substrate oxidation. Significantly less carbohydrate oxidation was found in the H-SS condition as compared to the L-SS condition (pϽ0.05). Lipid oxidation was also significantly different, but for this measure, the levels of oxidation were greater in the H-SS than in the L-SS condition (pϽ0.05). Finally, total energy expenditure for the 60 min of exercise was not significantly different between the hormonal conditions. Results suggest that sex steroid hormones have an impact upon substrate oxidation in women during exercise. Specifically, high circulating concentrations of the SS hormones result in an enhanced reliance upon the oxidation of lipid as an energy substrate and consequently induce a reduction in carbohydrate oxidation. The mechanism inducing this "metabolism shift" appears due to sex steroid hormones directly and indirectly increasing lipid mobilization and lipolysis.

The effect of hormone replacement therapy and/or exercise on skeletal muscle attenuation in postmenopausal women: a yearlong intervention

“…Oestrogens may modify muscle strength indirectly by its role in promoting lipolysis, which could modify the amount of fat within the muscle (Wenz et al, 1997;Hackney et al, 2000;Campbell & Febbraio, 2001;D'Eon et al, 2002). In the current trial at the whole body level, although there was no significant change in percent body fat, differences between body weight and LBM indicate that both HRT treated groups likely reduced their absolute body fat from 1 to 1AE5 kg.…”

“…In the current trial at the whole body level, although there was no significant change in percent body fat, differences between body weight and LBM indicate that both HRT treated groups likely reduced their absolute body fat from 1 to 1AE5 kg. Hackney et al (2000) recently reported that combined oestradiol and progesterone administration in women during submaximal exercise enhanced the oxidation of lipid as a substrate and reduced carbohydrate utilization. Hackney et al (2000) recently reported that combined oestradiol and progesterone administration in women during submaximal exercise enhanced the oxidation of lipid as a substrate and reduced carbohydrate utilization.…”

Internal exposure to pollutants and body size in Flemish adolescents and adults: Associations and dose–response relationships

“…Cadmium can also activate the estrogen receptor alpha (Stoica et al 2000) and, in view of the stimulation of lipid mobilization and lipolysis known to be induced by sex hormones (Hackney et al 2000), this xeno-estrogenic activity might contribute to the negative association with BMI observed for girls, men and women, whereas the fact that cadmium is associated with lower testosterone levels in boys might explain the absence, after adjustment for concurrent exposures, of a significant negative association in boys. That all observed effects were more pronounced at exposure values below the median than at higher exposures, is certainly compatible with a receptor mediated mechanism (see below).…”

“…In the boys participating in this study , serum concentrations of marker PCBs showed a positive association with serum levels of endogenous sex hormones. The oestrogenic effects of PCBs might, through stimulation of lipid mobilization and lipolysis known to be caused by sex hormones (Hackney et al 2000), explain the strong negative associations with BMI for both male and female adolescents, and also for female adults. For 26 male adults too a negative association was observed between PCB levels and BMI, that was however only significant after correction for concurrent exposures.…”

Avaliação de consumo alimentar, medidas antropométricas e tempo de menopausa de mulheres na pós-menopausa

“…Nos primeiros anos da pós-menopausa há decréscimo da taxa metabólica de repouso (TMR) maior do que na senilidade, provavelmente por conta da diminuição dos hormônios ovarianos. Entre os diversos mecanismos envolvidos destacam-se as mudanças na ação sobre o substrato energético, no repouso e durante o exercício, na regulação do metabolismo de carboidratos e lipídios, e a participação no processo de síntese de proteínas 9 . Há também alterações no consumo, com excesso de ingestão de alimentos energéticos e ingestão elevada de proteínas, associados à deficiência de micronutrientes como as vitaminas A e C, ferro e cálcio 10 .…”