Changes in sex hormone binding globulin, high density lipoprotein cholesterol and plasma lipids in male cyclists during training and competition

Caballero, M. J.; P, Mena; Maynar, M.

doi:10.1007/bf00376432

Cited by 22 publications

(14 citation statements)

References 21 publications

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“…The results of this study are consistent with our findings. The mechanisms responsible for the increase in serum testosterone levels during exercise are controversial, and may include decreased testosterone clearance, hemoconcentration, increased SHBG, catecholamine, precursor molecule DHEA sulfate, and testosterone production due to stimulation by factors other than LH and the slight decrease in progesterone [30][31][32][33][34][35].…”

Section: Discussionmentioning

confidence: 98%

Effect of Zinc and Selenium Supplementation on Serum Testosterone and Plasma Lactate in Cyclist After an Exhaustive Exercise Bout

Neek

Gaeini

Choobineh

2011

Biol Trace Elem Res

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Zinc and selenium are essential minerals and have roles for more than 300 metabolic reactions in the body. The purpose of this study was to investigate how exhaustive exercise affects testosterone levels and plasma lactate in cyclists who were supplemented with oral zinc and selenium for 4 weeks. For this reason, 32 male road cyclists were selected equally to four groups: PL group, placebo; Zn group, zinc supplement (30 mg/day); Se group, selenium supplement (200 μg/day); and Zn-Se group, zinc-selenium supplement. After treatment, free, total testosterone, and lactate levels of subjects were determined before and after exhaustive exercise. Resting total, free testosterone, and lactate levels did not differ significantly between groups, and were increased by exercise (P > 0.05). Serum total testosterone levels in Zn group were higher than in Se group after exercise (P < 0.05). Serum-free testosterone levels in the Zn group were higher than the other groups (P < 0.05).There was an insignificant difference between levels of lactate in the four groups after exercise (P > 0.05). The results showed that 4-week simultaneous and separately zinc and selenium supplementation had no significant effect on resting testosterone and lactate levels of subjects who consume a zinc and selenium sufficient diet. It might be possible that the effect of zinc supplementation on free testosterone depends on exercise.

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Section: Discussionmentioning

confidence: 98%

Effect of Zinc and Selenium Supplementation on Serum Testosterone and Plasma Lactate in Cyclist After an Exhaustive Exercise Bout

Neek

Gaeini

Choobineh

2011

Biol Trace Elem Res

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“…First, high levels of bioavailable testosterone has been associated with increased risk of prostate cancer (Gann et al, 1996;. Several studies have reported lower levels of free testosterone (Tikkanen et al, 1998;Tymchuk et al, 2001) in athletically trained men relative to untrained men and immediately after exercise (Nindl et al, 2001) as well as increased levels of sex hormone binding globuline (SHBG) immediately after exercise in older men (Zmuda et al, 1996) and after an exercise programme (Caballero et al, 1992;Tymchuk et al, 1998). However, there are also studies showing increasing levels of testosterone with increasing levels of exercise (Zmuda et al, 1996).…”

Section: Epidemiologymentioning

confidence: 99%

Occupational physical activity and risk for prostate cancer in a nationwide cohort study in Sweden

et al. 2002

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We investigated effects of occupational physical activity on relative risk for prostate cancer. From Swedish nationwide censuses in 1960 and 1970, we defined two cohorts of men whose occupational titles allowed classification of physical activity levels at work in 1960 (n=1 348 971) and in 1970 (n=1 377 629). A third cohort included only men whose jobs required a similar level of physical activity in both 1960 and 1970 (n=673 443). The incidence of prostate cancer between 1971 and 1989 was ascertained through record linkage to the Swedish Cancer Register. A total of 43 836, 28 702, and 19 670 prostate cancers, respectively, occurred in the three cohorts. In all three cohorts, the relative risk for prostate cancer increased with decreasing level of occupational physical activity (P50.001), using Poisson regression. Among men with the same physical activity levels in 1960 and 1970, the rate ratio was 1.11 for men with sedentary jobs as compared with those whose jobs had very high/high activity levels after adjustment for age at follow-up, calendar year of follow-up and place of residence (95% CI 1.05 -1.17; P for trend 50.001). There was no association between occupational activity and prostate cancer mortality. Since we had no data on other potential risk factors the observed associations for both incidence and mortality might have been confounded. Further studies are needed to better understand the potential role of physical activity for prostate cancer. Keywords: prostatic neoplasms; occupational physical activity; exercise; cohort studies; risk factors Prostate cancer is the most common cancer among Swedish men (31.5% of all cancer cases in men in 1999 and incidence rate 159 per 100 000) and the incidence rate has been steadily increasing since the 1960s (The Swedish Cancer Registry, 2001). The causes of prostate cancer are not clearly understood and genetic and environmental/life style factors seem to be important (Ross and Schottenfeld, 1996).Epidemiological studies of physical activity and prostate cancer risk have been inconclusive, but suggest a protective effect with higher levels of activity (Friedenreich and Thune, 2001). The theory is biologically plausible since physical activity may affect serum levels of testosterone and insulin-like growth factor I (IGF-I) and regulate the immune system (Chan et al, 1998b;McTiernan et al, 1998;Friedenreich and Thune, 2001). Moreover, physical activity might alter prostate cancer risk indirectly, by influencing body weight . In a prospective study, both cardiorespiratory fitness and self-reported history of sports activities were inversely related to prostate cancer risk (Oliveria et al, 1996).We used the nationwide, Swedish Cancer-Environment Register 60/70, to assess risk for prostate cancer in relation to occupational physical activity. We focused on men employed in 1960, and in 1970, with special attention given to men with the same level of occupational physical activity at these two assessments 10 years apart. The large number of observed prostate cancer case...

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“…Some evidence indicates a role for aerobic physical activity in SHBG production, at least in men. SHBG concentrations have been observed to increase acutely with such exercises as cycle ergometry, and with longer-term endurance training (38)(39)(40)(41), although some reports involving endurance-trained younger men have not confirmed this effect (18,21,37,42). As SHBG concentrations vary inversely with circulating insulin (43), a plausible explanation for greater SHBG values in trained older men could be attenuation of agerelated insulin-resistance.…”

Section: Journal Of Endocrinology (1998) 138mentioning

confidence: 99%

Relationship of chronic endurance exercise to the somatotropic and sex hormone status of older men

Cooper

Taaffe

Guido

et al. 1998

European Journal of Endocrinology

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To investigate putative abrogating effects of habitual endurance exercise on age-related changes in endocrine function and body composition, we compared insulin-like growth factor-I (IGF-I), sex hormonal status and body composition in 15 Masters runners and 15 minimally exercising men (MEM) aged 60-70 years. A higher maximal oxygen uptake (VO 2 max.) in the runners (41.4 Ϯ 1.6 compared with 27.3 Ϯ 1.4 ml/kg/min, P ¼ 0.0001; mean Ϯ S.E.M.) reflected our group allocations. Analysis of body composition and bone mineral density (BMD) by dual energy X-ray absorptiometry showed no group differences in lean tissue mass or in regional or whole body BMD, but MEM were heavier, reflecting greater adiposity. Of nine muscle groups tested, only quadriceps strength differed significantly, being greater in runners (60.3 Ϯ 2.8 compared with 51.1 Ϯ 2.3 kg, P ¼ 0.02). Total IGF-I (129 Ϯ 10 compared with 124 Ϯ 11 ng/ml, P ¼ 0.72) and IGF-binding protein-3 (2854 Ϯ 94 compared with 2623 Ϯ 128 ng/ml, P ¼ 0.16), were similarly depressed compared with young adult norms in both groups. There was no relationship between total or bioavailable IGF-I and any body composition, BMD or muscle strength variable. In the runners, concentrations of total testosterone (19.1 Ϯ 0.8 compared with 15.0 Ϯ 0.9 nmol/l, P ¼ 0.002) and sex hormone binding globulin (SHBG) (124.4 Ϯ 21.6 compared with 67.7 Ϯ 11.6 nmol/l, P ¼ 0.03) were significantly greater, but the free androgen index was significantly lower (20.7 Ϯ 2.7 compared with 31.4 Ϯ 4.1, P ¼ 0.04). Directly measured free testosterone, however, was similar between the runners and MEM (47.9 Ϯ 1.8 compared with 47.1 Ϯ 2.0 nmol/l, P ¼ 0.80). Therefore the group differences in total testosterone and free androgen index were due to their different SHBG concentrations. Although estrone concentration was higher in MEM (85.1 Ϯ 5.2 compared with 108 Ϯ 6.7 pmol/l, P ¼ 0.03), estradiol concentration was similar between groups (73.0 Ϯ 6.3 compared with 81.8 Ϯ 8.0 pmol/l, P ¼ 0.18), indicating that estrogens were not responsible for the increased SHBG in runners. These results indicate that even high levels of regular endurance exercise do not prevent the decline in the somatotropic axis that occurs with aging. Furthermore, the somatic effects of exercise in older men (reduced adiposity and increased regional muscle strength) occurred independently of somatotropic or androgen status. Although habitual exercise does not influence free testosterone concentrations in older men, it appears to enhance the age-associated increase in SHBG synthesis.

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Changes in sex hormone binding globulin, high density lipoprotein cholesterol and plasma lipids in male cyclists during training and competition

Cited by 22 publications

References 21 publications

Effect of Zinc and Selenium Supplementation on Serum Testosterone and Plasma Lactate in Cyclist After an Exhaustive Exercise Bout

Effect of Zinc and Selenium Supplementation on Serum Testosterone and Plasma Lactate in Cyclist After an Exhaustive Exercise Bout

Occupational physical activity and risk for prostate cancer in a nationwide cohort study in Sweden

Relationship of chronic endurance exercise to the somatotropic and sex hormone status of older men

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