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The effect of exhaustion exercise on thyroid hormones and testosterone levels of elite athletes receiving oral zinc
Abstract
The present study aims to investigate how exhaustion exercise affects thyroid hormones and testosterone levels in elite athletes who are supplemented with oral zinc sulfate for 4 weeks.
The study included 10 male wrestlers, who had been licensed wrestlers for at least 6 years. Mean age of the wrestlers who volunteered in the study was 18.70 +/- 2.4 years. All subjects were supplemented with oral zinc sulfate (3 mg/kg/day) for 4 weeks in addition to their normal diet. Thyroid hormone and testosterone levels of all subjects were determined as resting and exhaustion before and after zinc supplementation.
Resting TT3, TT4, FT3, FT4 and TSH levels of subjects were higher than the parameters measured after exhaustion exercise before zinc supplementation (p<0.05). Both resting and exhaustion TT3, TT4 and FT3 values after 4-week zinc supplementation were found significantly higher than both of the parameters (resting and exhaustion) measured before zinc supplementation (p<0.05). Resting total testosterone and free testosterone levels before zinc supplementation were significantly higher than exhaustion levels before zinc supplementation (p<0.05). Both resting and exhaustion total and free testosterone levels following 4-week zinc supplementation were found significantly higher than the levels (both resting and exhaustion) measured before zinc supplementation (p<0.05).
Findings of our study demonstrate that exhaustion exercise led to a significant inhibition of both thyroid hormones and testosterone concentrations, but that 4-week zinc supplementation prevented this inhibition in wrestlers. In conclusion, physiological doses of zinc administration may benefit performance.
... The mechanisms for the role of micronutrients in synthesis of sex hormones and IGF-1 include the involvement in steroidogenesis, via the involvement of prostaglandins, on the precursors of sex hormones, for vitamins D, E, the carotenoids, zinc and selenium, as well the effects of vitamin C [38][39][40][41][42][43][44][45][46][47][48][49][50]52,60,64,65,68,69,71,[79][80][81][82][83][84][85][86], and effects on transporter proteins. Zinc is also an inhibitor of two enzymes, aromatase and 5α-reductase, that are involved in testosterone metabolism [60]. ...
... The primary outcomes were changes or differences in sex hormone concentrations, including: androgens (androstenediol, androstenedione, dihydrotestosterone and testosterone), oestrogens (E2, estradiol, estriol, and estrone), DHEAS, SHBG, and IGF-1 (see Supplementary Table S1, A). Relevant micronutrients were those with known or potential relevance to sex hormone or IGF-1 metabolism and physiology, as well as sarcopenia, and included any one, or combination, of vitamin A [48,69]; vitamin C [76]; vitamin D [38][39][40][41][42][43][44][45][46][47]; vitamin E [48,50]; carotenoids [69]; or the minerals zinc [64,65], magnesium [54], selenium, potassium [76,77], iron/ferritin [78] and copper [79]. ...
... Despite the biochemical, physiological and mechanistic roles of micronutrients for hormone synthesis in older age our review found a paucity of trials and little direct evidence of significant effects of micronutrient supplementation [38][39][40][41][42][43][44][45][46][47][48][49][50]52,60,64,65,68,69,71,[79][80][81][82][83][84][85][86]. Since the age-related decline in sex-hormones and IGF-1 not only increases the risk of sarcopenia, but also a number of conditions of aging, including falls, osteoporosis, fractures, cardiovascular disease and all-cause mortality, this is unfortunate [5][6][7][8][9][10][11][12][13][14][15][16]. ...
Observational research suggests that micronutrients may be protective for sarcopenia, a key health issue during ageing, potentially via effects on hormone synthesis and metabolism. We aimed to carry out a systematic review of RCTs investigating effects of increasing dietary or supplemental micronutrient intake on sex hormones and IGF-1 in individuals aged 45 years or older. We searched MEDLINE, EMBASE and Cochrane databases for RCTs reporting the effects of different micronutrients (vitamins A, C, D, or E; carotenoids; iron; copper; zinc; magnesium; selenium; and potassium) on sex hormones or IGF-1. Of the 26 RCTs identified, nine examined effects of vitamin D, nine of multi-nutrients, four of carotenoids, two of selenium, one of zinc, and one of vitamin E. For IGF-1 increasing vitamin D (MD: −0.53 nmol/L, 95% CI: −1.58, 0.52), multi-nutrients (MD: 0.60 nmol/L, 95% CI −1.12 to 2.33) and carotenoids (MD −1.32 nmol/L; 95% CI −2.76 to 0.11) had no significant effect on circulating concentrations. No significant effects on sex hormones of other micronutrients were found, but data were very limited. All trials had significant methodological limitations making effects of micronutrient supplementation on sex hormones unclear. Further high quality RCTs with physiological doses of micronutrients in people with low baseline intakes or circulating concentrations, using robust methodology, are required to assess effects of supplementation adequately.
... The mechanisms for the role of micronutrients in synthesis of sex hormones and IGF-1 include the involvement in steroidogenesis, via the involvement of prostaglandins, on the precursors of sex hormones, for vitamins D, E, the carotenoids, zinc and selenium, as well the effects of vitamin C [38][39][40][41][42][43][44][45][46][47][48][49][50]52,60,64,65,68,69,71,[79][80][81][82][83][84][85][86], and effects on transporter proteins. Zinc is also an inhibitor of two enzymes, aromatase and 5α-reductase, that are involved in testosterone metabolism [60]. ...
... The primary outcomes were changes or differences in sex hormone concentrations, including: androgens (androstenediol, androstenedione, dihydrotestosterone and testosterone), oestrogens (E2, estradiol, estriol, and estrone), DHEAS, SHBG, and IGF-1 (see Supplementary Table S1, A). Relevant micronutrients were those with known or potential relevance to sex hormone or IGF-1 metabolism and physiology, as well as sarcopenia, and included any one, or combination, of vitamin A [48,69]; vitamin C [76]; vitamin D [38][39][40][41][42][43][44][45][46][47]; vitamin E [48,50]; carotenoids [69]; or the minerals zinc [64,65], magnesium [54], selenium, potassium [76,77], iron/ferritin [78] and copper [79]. Where studies included groups of individuals with varying age ranges, they were included if the mean age was greater than 45 years, or more than 75% of individuals were older than 45 years (in both treatment arms). ...
... Despite the biochemical, physiological and mechanistic roles of micronutrients for hormone synthesis in older age our review found a paucity of trials and little direct evidence of significant effects of micronutrient supplementation [38][39][40][41][42][43][44][45][46][47][48][49][50]52,60,64,65,68,69,71,[79][80][81][82][83][84][85][86]. Since the age-related decline in sex-hormones and IGF-1 not only increases the risk of sarcopenia, but also a number of conditions of aging, including falls, osteoporosis, fractures, cardiovascular disease and all-cause mortality, this is unfortunate [5][6][7][8][9][10][11][12][13][14][15][16]. ...
Observational research suggests that micronutrients may be protective for sarcopenia, a key health issue during ageing, potentially via effects on hormone synthesis and metabolism. We aimed to carry out a systematic review of RCTs investigating effects of increasing dietary or supplemental micronutrient intake on sex hormones and IGF-1 in individuals aged 45 years or older. We searched MEDLINE, EMBASE and Cochrane databases for RCTs reporting the effects of different micronutrients (vitamins A, C, D, or E; carotenoids; iron; copper; zinc; magnesium; selenium; and potassium) on sex hormones or IGF-1. Of the 26 RCTs identified, nine examined effects of vitamin D, nine of multi-nutrients, four of carotenoids, two of selenium, one of zinc, and one of vitamin E. For IGF-1 increasing vitamin D (MD: −0.53 nmol/L, 95% CI: −1.58, 0.52), multi-nutrients (MD: 0.60 nmol/L, 95% CI −1.12 to 2.33) and carotenoids (MD −1.32 nmol/L; 95% CI −2.76 to 0.11) had no significant effect on circulating concentrations. No significant effects on sex hormones of other micronutrients were found, but data were very limited. All trials had significant methodological limitations making effects of micronutrient supplementation on sex hormones unclear. Further high quality RCTs with physiological doses of micronutrients in people with low baseline intakes or circulating concentrations, using robust methodology, are required to assess effects of supplementation adequately.
... Bosco et al. [15] reported that short-term strenuous exercise increased total and free testosterone levels by 12% and 13%, respectively. But Kilic et al. [16] reported that exhaustive exercise decreased thyroid hormone and testosterone concentrations in elite athletes. ...
... In fact, results of studies examining the relation between exercise and testosterone illustrates that there is no agreement on this topic. In other words, there are contradictions about the cause and effect of physical exercise and the amount of testosterone in different researches [7,16,[20][21][22]. Besides the studies reporting that free and total testosterone levels did not change with exercise [23][24][25], there are also those noting that free and total testosterone levels significantly decreased with exercise [26][27][28]. ...
... Exercise increased total testosterone levels in the Zn group than Se group, and also free testosterone levels in Zn group than other groups. Kilic et al. [16] showed that 4-week zinc supplementation increased resting levels of both thyroid hormones and testosterone concentrations, and exhaustion exercise led to a significant inhibition of those hormones, [39] reported mentioned results about sedentary males in response to fatiguing bicycle exercise. Kilic concluded that "administration of a physiologic dose of zinc can be beneficial to performance." ...
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.
... It was indicated that zinc deficiency affects thyroid hormone metabolism adversely [22]. Zinc supplementation led to an increase in rested and post-exhausting exercise thyroid hormone levels of the elite wrestlers [23]. In that study, the chronic effect of doing exercise on TSH increased significantly with zinc supplementation in parallel with the findings in literature. ...
... It is discovered that there are contradictory findings regarding post-exercise T4 values. Zinc supplementation led to increase in rested and post-exhausting exercise thyroid hormone levels of the elite wrestlers [23]. In another study, it was reported that zinc supplementation had no effect on thyroid hormone levels of cyclists. ...
This study aims at examining the effects of zinc and CoQ10 supplementation applied with 8 w trainings on the thyroid hormone metabolism. The study was conducted on 60 voluntary male football players whose average of age is 20.60 ± 3.15 y and average of weight is 66.20 ± 4.74 kg. The participants were divided equally into 4 groups. The groups were constituted in the following way: 1st group: group which is supplied with zinc (Z), 2nd group: group which is supplied with coenzyme Q10 (Q), 3rd group: control group which does only physical exercises (C) and 4th Group: Group which is supplied with zinc and coenzyme Q10 (ZQ). At the first week of the study, TSH, T3 and T4 levels of the participants were measured from the samples which were drawn from the participants at Pre-exercise resting period (PreRP), post-exercise pre-test fatigue (PreTF), and pre-exercise post-test rested (PostTR) and post-exercise posttest fatigue (PostTF) after 8 w supplementation period. As a consequence, it was discovered that 8 w trainings led to increases in both rested and post-exercise fatigue TSH levels of only the group supplied with zinc (p<0.05). Considering T3 values, it was discovered that statistically significant differences between the PreTF values and PreTR and PostTR values of the control group and the PreTF values were found to be lower than these two measurements (p<0.05). When CoQ10 supplementation was applied with exercises, differences were observed between the PostTF and PostTR T3 values (p<0.05). As zinc and CoQ10 supplementation were given, post 8 w training T3 values decreased when compared to the pre 8 w training values (p<0.05). Regarding T4 values, it was discovered that PostTF values were lower than the PreTR values of only the group supplied with zinc. The result of this being that, the zinc and CoQ10 supplementation applied with 8 w football trainings were found to be effective on the thyroid hormone metabolism. It is believed that antioxidant supplementation may make significant contributions to the thyroid metabolism functions.
... These hormones are secreted from the thyroid gland which is located in the front of the neck and wrapped around the windpipe (trachea) [47]. It plays a major role in the regulation of general metabolism, growth, and tissue differentiation as well as gene expression [48]. It also acts in fatty acid oxidation and thermoregulation [49]. ...
Physical activity induces many changes in the human body by increasing energy metabolism and resting energy expenditure and hormones play a major role in these changes. Hormones are chemical messengers that stimulate biochemical reactions that trigger cell activity and functions. Hormones are secreted from the glands of the endocrine system and communication between the endocrine system and nervous system regulates both internal and external changes and maintains homeostasis. Hormones are classified into lipid, amino acid, and peptide-derived hormones and they play major roles in the human body. Lipid-derived hormones perform many important functions i.e., muscle growth, neuromuscular adaptation, protein metabolism, carbohydrate metabolism, gluconeogenesis, fat oxidation, salt and water homeostasis, etc. Amino acid-derived hormones also perform many important functions like vasoconstriction, thermoregulation, tissue differentiation, fight or flight response, maintaining circadian rhythm and sleep-wake cycle, etc. Peptide-derived hormones play a major role in body fluid homeostasis, regulating appetite, gluconeogenesis, glucose production, and lipid metabolism, maintaining circadian rhythm, maintaining energy balance, reducing weight gain, delaying gastric emptying, etc. Physical activity regulates hormone levels in the body to provide major benefits and enhance the health status of healthy individuals. This review will provide a brief description of all lipid, amino acid, and peptide-derived hormones that perform many important functions and how their functions are influenced by physical activity.
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... Although existing scientific literature has linked Zn status to several factors including (I) anabolic adaptations of relevant hormones such as testosterone [8], (II) antioxidant response to combat exercise-induced oxidative stress [9], (III) muscle growth, (IV) tissue regeneration and synthesis, and (V) energy production and proper functioning of the immune system [10,11], the real impact of Zn homeostasis and its mobilization to other tissues during exercise remains unclear and requires further investigation [12]. In this regard, a decrease in serum Zn levels has been reported after aerobic exercise regardless of participant Zn status, type of exercise or blood collection time [12]; whereas moderate to vigorous exercise has been shown to promote an increase in plasma Zn levels immediately after exercise [13,14]. ...
... In the study conducted by Galbo et al on 8 men, the thyroid responses to exercises with gradually increasing workloads (47%, 77%, and 100% of MaxVO2) and to exercise up to prolonged fatigue were examined. As a result, significant increases in TSH levels were observed (P <0.001), but no significant difference was found in T3 and T4 levels [15]. In the study by Kilic et al., in which they examined the effects of exhausting cycling exercise performed on 10 sedentary men on thyroid and testosterone hormones, they reported significant decreases in total T3, total T4 and free T3 levels after exercise (p <0.01). ...
Background and Study Aim. Thyroid hormone responses to acute maximal aerobic exercise is still unclear, so the aim of the study is to investigate the effect of acute maximal aerobic exercise resulting in fatigue on blood thyroid levels in men and women.
Material and Methods. The study included 8 male and 7 female subjects who did not actively exercise. Both group participants were students in the Kastamonu University in the period of study. The heights, weights, resting hearth rates and 5 cc. venous blood samples of subjects were taken before the exercise. The subjects warmed up for ten minutes before they had 20 m shuttle run. The purpose of this test was to tire the subjects to the exhaustion. The heart rate were measured at the end of the test in order to determine the exhaustion levels of the participants. The 5 cc. venous blood samples were taken again just after the exhaustion exercise. Statistical analysis was carried out using Statistical Package for the Social Sciences (SPSS) 23 program (SPSS Inc. Chicago. II. USA). P value was set at p0.05). There was significant change in TSH values in all group. They increased following the exercise compared to pre-exercise values. Moreover, total T3 decreased in all group. No other significant difference was found in free T3 and free T4 variables.
Conclusions. In conclusion, thyroid responses to exercise emerge in a very complex way, which makes it difficult to reach a clear conclusion about its effects. The reason why the results are so contradictory is that the duration and intensity of the exercise, age, not being able to control the diet, and the timing of collection of blood samples after exercise.
... Testosterone concentrations might be inhibited by exhaustive trainings, which were supposed to promote the secretion of testosterone. To find a way to eliminate this phenomenon, Kilic et al. (2006) investigated the effects of oral zinc supplementation on testosterone levels of elite athletes and concluded that 3 mg/kg/day supplementation suppressed the inhibition of testosterone concentrations caused by the exhausting exercise sessions. ...
Adolescence is a crucial period for growth and sports training during this period, besides its positive effects, may have negative effects on growth. The aim of the present study was to evaluate the effect of an 8-month intensive training on selected hormones in young male wrestlers. Forty-five subjects (13.94±0.57) volunteered as the training group (TG) and a control group (CG) of 35 non-athlete subjects (13.93±0.51) was assigned. TG attended to an 8-month wrestling training program for 5 days a week 90 minutes per day. CG did not receive any exercise sessions. Homogeneity of data was tested by using Kolmogorov-Smirnov test (p>.05) and independent samples t-test was used to analyse the significance of the differences between pre and post-tests. Change in luteinising hormone levels was significant (p<.01) but no significant difference was observed in the other hormone levels (p>.05) or BMI (p>.05). In conclusion, long-term intensive training caused alterations in LH hormone responses in young wrestlers.
... The response of thyroid hormones to exercise varies (Figure 9). With a few exceptions (271)(272)(273), most studies investigating thyroid hormones during or in a short-time interval after training found elevated concentrations of TSH, T4 and/or T3 (46,(274)(275)(276). After resting or in prolonged training programs with repeated heavy strain, however, the majority of studies described reduced concentrations of TSH, T4, and T3 (186,187,(277)(278)(279)(280)(281). ...
The discovery of the negative feedback of thyroid hormones on pituitary thyroid- stimulating hormone (TSH) secretion, a classical endocrine feedback control system, has shaped diagnosis and treatment of thyroid disease for the last decades. Based on this concept, a unique diagnostic category of subclinical thyroid disorders was introduced, being defined exclusively by an abnormal TSH response in the presence of thyroid hormone concentrations within the reference range. Although this approach was able to deliver a conceptually straightforward disease definition problems surfaced in clinical practice as neither the diagnostic reference range nor the appropriate threshold for initiating substitution treatment are universally agreed upon for subclinical thyroid disorders. The situation is further aggravated by the so-called syndrome T, which comprises a substantial but heterogeneous group of L-T4 treated patients with hypothyroidism with reduced quality of life despite “normal” TSH values.
A limited understanding of the physiological relationships between TSH and thyroid hormones may be a main reason for clinical difficulties in dealing with the causes of syndrome T and tailoring substitution therapy for hypothyroid patients with subclinical thyroid disorders.
Feedback regulation has recently been shown to be much more complex than previously assumed. The concept of homeostatic control has also been extended to include the lesser known but equally important allostatic thyroid regulation. The latter aims at adaptive homeostasis or stability through changing setpoints and modulating structural parameters of feedback control, as may be appropriate to adapt to a vast array of conditions spanning from fetal life, ageing, pregnancy, exercise, starvation, obesity, psychiatric disorders to the severe non-thyroidal illness syndrome.
A better understanding of homeostatic and allostatic mechanisms, which govern the behaviour of pituitary-thyroid feedback control, is on the horizon. This promises to improve the diagnostic utility of laboratory methods, laying the foundation for personalised methods to optimise dosage and modality of substitution therapy. The emerging new world of thyroid physiology is reflected on the side of clinical medicine in a new, relational paradigm for diagnosis and treatment.
Considerable progress has been made in this respect in the following key areas:
• the significance of complementary information processing structures within the feedback loop, in particular ultrashort feedback of TSH on its own secretion and the action of a TSH-T3 shunt unburdening the thyroid from T4 synthesis in imminent thyroid failure,
• the unravelling of spatio-temporal dynamics of hormone concentrations ranging from ultradian to circannual rhythms and including hysteresis effects,
• the emergence of “non-canonical” mechanisms of thyroid hormone signalling beyond transcriptional control of gene expression,
• the physiological actions of thyronine metabolites, which have been previously regarded as biologically inactive, such as thyronamines and iodothyroacetates,
• the characterisation of distinct patterns in the adaptive processes to stress and strain and their conclusive explanation through reactions to type 1 and type 2 allostatic load.
This collective volume contains the contributions to the Research Topic “Homeostasis and Allostasis of Thyroid Function”, which was originally published by the journal Frontiers in Endocrinology. Authored by an international team of experts from three continents, the book provides a comprehensive overview on thyroid control from recent research in basic, computational and clinical thyroidology. Many aspects addressed here can be expected to stimulate future research. A more comprehensive view and better integration of in-vitro, in-silico and in-vivo investigations will be invaluable in paving the way to this new world of thyroidology.
... They argue that zinc and selenium supplementation do not create any change in rested values at the end of 4 weeks. The [6] has examined the effect of 4-week zinc supplementation on the thyroid and testosterone levels in wrestlers. At the end of the study, it has been determined 4-week zinc supplementation (3 mg/kg/day) generates significant increases in rested total and free testosterone levels. ...
The purpose of this study, it has been aimed to examine the effects of zinc supplementation applied with weight trainings on the testosterone levels in sedentary individuals and athletes. Materials and Methods. As methods of work it was selected 40 male, 20 sedentary male and 20 male who do physical exercises regularly, participated in the study. The participants are divided equally into 4 groups. The groups are constituted in that way: 1st Group: Control Group (S), 2nd Group: Sedentary Group which is supplied with Zinc (Z), 3rd Group: Training Group which is supplied with Zinc (ZT) and 4th Group: Athletes’ Group who performs the weight training (T). The total testosterone and free testosterone values of the participants were measured from the blood samples which were drawn from the participants at the beginning and at the end of the 6-week training period. Results. Like results, has been asserted that the total and free testosterone values of the groups which are supplied with Zinc and perform weight training have increased depending on training and supplementation. Conclusion. In conclusion consequently it has been determined that 6-week zinc supplementation and weight training increase the testosterone levels. Accordingly, it may be said that this implementation contributes to the performance
... The response of thyroid hormones to exercise varies (Figure 9). With a few exceptions (271)(272)(273), most studies investigating thyroid hormones during or in a short-time interval after training found elevated concentrations of TSH, T4 and/or T3 (46, [274][275][276]. After resting or in prolonged training programs with repeated heavy strain, however, the majority of studies described reduced concentrations of TSH, T4, and T3 (186,187,(277)(278)(279)(280)(281). ...
The hypothalamus–pituitary–thyroid feedback control is a dynamic, adaptive system. In situations of illness and deprivation of energy representing type 1 allostasis, the stress response operates to alter both its set point and peripheral transfer parameters. In contrast, type 2 allostatic load, typically effective in psychosocial stress, pregnancy, metabolic syndrome, and adaptation to cold, produces a nearly opposite phenotype of predictive plasticity. The non-thyroidal illness syndrome (NTIS) or thyroid allostasis in critical illness, tumors, uremia, and starvation (TACITUS), commonly observed in hospitalized patients, displays a historically well-studied pattern of allostatic thyroid response. This is characterized by decreased total and free thyroid hormone concentrations and varying levels of thyroid-stimulating hormone (TSH) ranging from decreased (in severe cases) to normal or even elevated (mainly in the recovery phase) TSH concentrations. An acute versus chronic stage (wasting syndrome) of TACITUS can be discerned. The two types differ in molecular mechanisms and prognosis. The acute adaptation of thyroid hormone metabolism to critical illness may prove beneficial to the organism, whereas the far more complex molecular alterations associated with chronic illness frequently lead to allostatic overload. The latter is associated with poor outcome, independently of the underlying disease. Adaptive responses of thyroid homeostasis extend to alterations in thyroid hormone concentrations during fetal life, periods of weight gain or loss, thermoregulation, physical exercise, and psychiatric diseases. The various forms of thyroid allostasis pose serious problems in differential diagnosis of thyroid disease. This review article provides an overview of physiological mechanisms as well as major diagnostic and therapeutic implications of thyroid allostasis under a variety of developmental and straining conditions.
... Zinc supplementation periodically elevated serum zinc levels in oneweek periods over the course of 4 weeks in both groups, in comparison to resting zinc levels. Zinc support to both athletes and exercised experimental animals was shown to result in increased serum zinc levels (Kilic et al., 2006; Kara et al., 2010; Baltaci et al., 2013). Thus, increased serum zinc levels resulting from zinc supplementation may be considered an expected result and lend support to the results of the researchers cited above. ...
The present study aims to examine the effect of different doses of zinc administration on serum element metabolism and fatigue. The study registered 20 female elite athletes. The subjects were divided into two groups in equal numbers. Group supplemented with 220 mg/day zinc sulfate. Group supplemented with 440 mg/day zinc sulfate. Athletes who were already engaged in their daily training routines were put to a 20-m shuttle run test to create fatigue before and after supplementation. Blood samples were collected from the subjects for a total of 7 times, before and after zinc supplementation and during rest and after exercise within one-week intervals over the course of the 4-week supplementation. The blood samples collected as such were analyzed to determine serum magnesium, phosphorus and calcium, zinc, iron, copper, and selenium, and plasma lactate. Both exercise and zinc supplementations significantly elevated magnesium, calcium, and iron levels for 4 weeks. Pre-supplementation exercise elevated plasma lactate levels, while zinc supplementation led to a fall in plasma lactate. The results of the present study indicate that zinc-supplementation for 4 weeks may have a positive impact on athletic performance by delaying fatigue.
... Testosterone concentrations might be inhibited by exhaustive trainings, which were supposed to promote the secretion of testosterone. To find a way to eliminate this phenomenon, Kilic et al. (2006) investigated the effects of oral zinc supplementation on testosterone levels of elite athletes and concluded that 3 mg/kg/day supplementation suppressed the inhibition of testosterone concentrations caused by the exhausting exercise sessions. ...
Adolescence is a crucial period for growth and sports training during this period, besides its positive effects, may have negative effects on growth. The aim of the present study was to evaluate the effect of an 8-month intensive training on selected hormones in young male wrestlers. Forty-five subjects (13.94±0.57) volunteered as the training group (TG) and a control group (CG) of 35 non-athlete subjects (13.93±0.51) was assigned. TG attended to an 8-month wrestling training program for 5 days a week 90 minutes per day. CG did not receive any exercise sessions. Homogeneity of data was tested by using Kolmogorov-Smirnov test (p>.05) and independent samples t-test was used to analyse the significance of the differences between pre and post-tests. Change in luteinising hormone levels was significant (p<.01) but no significant difference was observed in the other hormone levels (p>.05) or BMI (p>.05). In conclusion, long-term intensive training caused alterations in LH hormone responses in young wrestlers.
... Marques et al. studied the effect of Zn supplementation on TSH and thyroid hormones in competitive athletes and found no effects on serum TSH, T3, or T4 levels [88]. Other investigations have analyzed the influence of Zn supplementation on thyroid hormones and TSH variations after exercise to exhaustion in elite athletes, finding that resting T3, T4, and TSH levels were higher than levels after exhaustion exercise [89]. On the other hand, the potential relation between Mn, Zn, and TSH has been analyzed in pediatric patients with obesity before and after dietetic treatment, and changes in serum TEs levels were not associated with changes in TSH [90]. ...
This study analyzes the relationship between hormonal changes induced by exercise and variations in trace elements associated with oxidative stress during incremental exercise. Nineteen well-trained endurance athletes performed a cycle ergometer test: after a warm-up of 10 min at 2.0 W kg(-1), workload increased by 0.5 W kg(-1) every 10 min until exhaustion. The analysis was controlled for prior diet and activity patterns, levels of exercise training, and time of day (circadian rhythms). Whole blood lactate concentration and plasma concentrations of ions (Zn, Se, Mn, and Co), insulin, glucagon, aldosterone, thyroid stimulating hormone (TSH), calcitonin, and parathyroid hormone (PTH) were measured at rest; at the end of each stage; and 3, 5, and 7 min post-exercise. The statistical analysis involved paired non-parametric tests and correlation coefficients. No significant differences were found in Mn or Co levels as a function of exercise intensity. Zn and Se levels at the end of the exercise protocol and over the recovery time were significantly different to baseline. Further, Zn levels were significantly correlated with aldosterone, calcitonin, and PTH levels, while Se levels were associated with aldosterone, calcitonin, and TSH levels. Our results indicate several different patterns of association between acute changes in hormone concentrations and variations in trace element concentrations related to oxidative stress during submaximal exercise.
... Other studies on zinc deficiency's role in decreased testosterone levels have echoed similar findings (Prasad 1985, Prasad 1988. Research has also shown adequate zinc levels prevent decreases in testosterone levels during exhaustive exercise ( Kilic et al 2006). ...
It seems that testosterone levels in men are slowly becoming extinct, along with the Caspian Tiger, deep squats, Z Cavariccis, and Chess King clothing stores. In the 1940's, the average male had 700mg/dl, compared to roughly 400mg/dl for the modern day male. Studies have shown men's testosterone levels are dropping each decade (Travison 2006). In one particular study, 1500 men aged 45-79 had their testosterone levels tested. The first group of 45-79 year olds was tested in the late 1980's, the second group tested in the mid 1990's and the last group of 45-79 year olds was tested between 2002 and 2004. The researchers found a drop in the same age subject groups from decade to decade. The researchers concluded that men aged 45-79 in the 1980's had higher testosterone than 45-79 year olds in the 1990s. And those men aged 45-79 in the 1990's had higher testosterone levels than men aged 45-79 in 2003-2004. What was once believed to be a natural testosterone decline with age has now been shown to be a general decline in testosterone levels among men with each passing decade. Now we are facing the male version of menopause: andropause. Low testosterone in men has been associated with various chronic health problems. A study out of the University of Florida has shown that men with high blood pressure, diabetes, high cholesterol and even asthma are more likely to have low testosterone (Mulligan et al 2006). Low testosterone has also been linked to prostate cancer and increased risk of heart attack. What can we do about this general decline in men's testosterone levels? From pharmaceutical testosterone to the herbs and supplements that cover the pages of men's fitness and health magazines, there seems to be a cure at every corner. Finding out what works and what doesn't can not only save lots of money, but also save the quality of one's health.
... The results demonstrated that exhaustive exercise led to significant inhibition of both thyroid hormones and testosterone concentrations but that 4-week zinc supplementation prevented this inhibition in wrestlers. The authors concluded that physiological doses of zinc administration may benefit performance (98). Another study, however, examined plasma zinc concentrations and markers of immune function in 10 male runners following a moderate increase in training over 4 weeks and found no benefit in zinc concentration, differential leukocyte counts, lymphocyte subpopulations, or lymphocyte proliferation. ...
Athletes engaged in heavy endurance training often seek additional nutritional strategies to help maximize performance. Specific
nutritional supplements exist to combat certain factors that limit performance beginning with a sound everyday diet. Research
has further demonstrated that safe, effective, legal supplements are in fact available for today’s endurance athletes. Several
of these supplements are marketed not only to aid performance but also to combat the immunosuppressive effects of intense
endurance training. It is imperative for each athlete to research the legality of certain supplements for their specific sport
or event. Once the legality has been established, it is often up to each individual athlete to decipher the ethics involved
with ingesting nutritional supplements with the sole intent of improving performance.
Key wordsExercise–Nutrition–Endurance–Supplements–Ergogenics
... Studies in human male athletes have shown that concentrations of TES in plasma were lower in long distance runners, master class runners, elite amateur cyclists, and wrestlers (Duclos et al., 1996;Slowinska-Lisowska & Majda, 2002;Hackney et al., 2003;Kilic et al., 2006) than in non-athletes. Based on the racing schedules of horses competing year-round, a similar effect of training with the stress of competition may also contribute to the lower plasma concentrations of TES in RIM. ...
Soma, L. R., Uboh, C. E., You, Y., Guan, F., McDonnell, S. Plasma concentrations of testosterone and nandrolone in racing and nonracing intact male horses. J. vet. Pharmacol. Therap. 35, 132–138.
Pennsylvania (PA) State Racing Commissions regulate the endogenous androgenic steroid, testosterone (TES), in racing intact males (RIM) by quantification of TES in post-race samples. Post-race plasma samples (2209) collected between March 2008 and November 2010 were analyzed for TES, nandrolone (NAN), and other anabolic steroids (ABS). Of the 2209 plasma samples, 2098 had quantifiable TES ≥25 pg/mL. Plasma (mean ± SD) concentrations of TES and NAN in RIM were 329.2 ± 266.4 and 96.0 ± 67.8 pg/mL, respectively. Only 64.6% of RIM had quantifiable concentration of NAN, and there was no relationship between TES and NAN. Plasma TES concentrations were significantly (P < 0.0001) higher during the months of April, May, June, July, and August. A significantly higher (P < 0.006) plasma TES was observed in Thoroughbred (TB) (347.6 ± 288.5 pg/mL) vs. that in Standardbred (STB) (315.4 ± 247.7 pg/mL). Plasma concentrations of TES from breeding stallions (BS) were 601.6 ± 356.5 pg/mL. Statistically significant (P < 0.0001) lower plasma concentrations of the two steroids were observed in RIM horses. Based on quantile distribution of TES in the RIM and BS populations, 99.5% were at or below 1546.1 and 1778.0 pg/mL, respectively. Based on this population of RIM, the suggested upper threshold plasma concentration of endogenous TES in horses competing in PA should remain at 2000 pg/mL.
... Zinc supplementation in adults with hypozincemia appeared to have a favorable effect on thyroid hormone levels, particularly total T3 [5]. In elite wrestlers, thyroid hormone levels increased after zinc supplementation, both at resting and after exhaustion exercise [35]. ...
Intense physical activity is associated with biological adaptations involving hormones and trace elements. Zinc supplementation may affect plasma copper concentration, thyroid-stimulating hormone (TSH), thyroid hormones, insulin, and glucose homeostasis, but data in athletes are scarce. The aim of this study was to evaluate in competitive athletes (cyclists, n = 7, 32 ± 8 years) the effect of zinc supplementation (22 mg/day as zinc gluconate) during 30 days, and discontinuation using placebo (maltodextrin) during the following 30 days, on plasma zinc and copper concentrations, serum thyroid hormones, insulin and glucose levels, and HOMA2-IR. Compared to baseline, plasma zinc and Zn:Cu plasma ratio increased, but plasma copper decreased after zinc supplementation (day 30) and discontinuation (day 60) (p < 0.05). Zn supplementation and discontinuation had no effect on TSH, T3, and T4. Fasting serum insulin and HOMA2-IR increased (27% and 47%, respectively) on day 60 compared to baseline (p = 0.03), suggesting a delayed effect of zinc supplementation. Moreover, plasma zinc was positively associated with serum insulin (r = 0.87, p = 0.009) and HOMA2-IR (r = 0.81, p = 0.03) after zinc supplementation (day 30), indicating that supplemental zinc may impair glucose utilization in cyclists.
... poor, such as uraemia/haemodialysis (Antoniou et al., 1977; Mahajan et al., 1982), growth retardation (GhavamiMaibodi et al., 1983), sickle-cell anaemia (Prasad et al., 1981) or infertility (Netter et al., 1981; Favier, 1992), it was shown that administration of the trace element caused a reversal of previously lowered testosterone concentrations. Kilic et al. (2006) reported that supplementation of zinc reversed reduced serum testosterone levels caused by exhaustion exercise. In summary, it can be concluded that even if zinc supplementation may reverse lowered testosterone levels and restore disturbed testosterone metabolism in cases of mild or severe zinc deficiency, it is not capable of further i ...
To investigate whether the administration of the zinc-containing nutritional supplement ZMA causes an increase of serum testosterone levels, which is an often claimed effect in advertising for such products; to monitor the urinary excretion of testosterone and selected steroid hormone metabolites to detect potential changes in the excretion patterns of ZMA users.
Fourteen healthy, regularly exercising men aged 22-33 years with a baseline zinc intake between 11.9 and 23.2 mg day(-1) prior to the study.
Supplementation of ZMA significantly increased serum zinc (P=0.031) and urinary zinc excretion (P=0.035). Urinary pH (P=0.011) and urine flow (P=0.045) were also elevated in the subjects using ZMA. No significant changes in serum total and serum free testosterone were observed in response to ZMA use. Also, the urinary excretion pattern of testosterone metabolites was not significantly altered in ZMA users.
The present data suggest that the use of ZMA has no significant effects regarding serum testosterone levels and the metabolism of testosterone in subjects who consume a zinc-sufficient diet.
Introdução: Corredores de meia idade frequentemente fazem o uso de suplementos para melhorar o desempenho e garantir a saúde. Nesse contexto, a suplementação de zinco é relacionada ao aumento dos níveis de testosterona, embora a literatura sobre o assunto traga resultados inconclusivos. Objetivo: Investigar o efeito da suplementação de zinco em curto prazo nos níveis de testosterona livre e parâmetros antropométricos em corredores do sexo masculino de meia idade. Métodos: Foram selecionados 10 corredores de longa distância. O protocolo foi dividido em três etapas: avaliação inicial, suplementação e avaliação final. As avaliações foram compostas por recordatório alimentar, medidas antropométricas, consumo máximo de oxigênio e uma amostra de saliva para medir a concentração de testosterona livre. Todos os corredores ingeriram uma cápsula contendo 50 mg/dia de Zinco Quelado (1x ao dia por 15 dias). Resultados: A amostra foi composta por corredores de meia-idade (55,5 ± 4,8 anos) com boa aptidão cardiorrespiratória (46,9 ± 4,8 ml.kg-1.min-1) e valores de IMC indicativos de sobrepeso (25,6 ± 2,1 kg/m2). O nível de testosterona mostrou-se adequado (74,2 ± 46,5 pg/ml). Entretanto, seis corredores apresentaram valores abaixo do limiar diagnóstico (70 pg/ml). Conclusão: Nosso estudo não observou diferença nas concentrações de testosterona livre após 15 dias de suplementação de zinco. Observamos um consumo calórico menor que o gasto energético, baixo consumo de carboidratos, proteínas, ferro e potássio, além de maior ingesta de sódio e colesterol. Palavras-chave: Nutrição no esporte; zinco; testosterona; atletismo.
Introduction: Zinc (Zn) deficiency has been described not only on general human health but also within the sports context −as negatively affecting performance–. Thus, Zn status assessment is of great interest for athletes, especially in order to correct deficiency states of this mineral.
Objective: The overall objective of this work was to assess Zn status in professional handball players during the competitive period (through plasma levels, dietary intake and gene expression of the Zn transporters), as well as to determine the effect of Zn supplementation.
Methods: A total of twenty-two participants were recruited, −twelve belonged to the Control Group (CG) and ten male handball players comprised the experimental group (ATH-G)−, being monitored over a 2-month period with 2 evaluation moments: baseline (i.e., initial conditions) and follow-up (i.e., after 8 weeks of training and competition). Zn intake, plasma Zn levels, and gene expression of Zn transporters were obtained.
Results: Plasma Zn levels were higher in ATH-G than in CG at the end of Zn intervention (p ≤0.010). Moreover, differences in the gene expression profile of Zn transporters were observed in ATH-G −with the down-regulation of several Zn transporters−, compared to the CG at baseline (p ≤0.05). Likewise, Zn intervention modified the expression of Zn transporters in ATH-G at 8 weeks (all, p ≤0.001) −ZnT2, ZnT5, ZIP3, ZIP5, ZIP11, ZIP13 and ZIP14 transporters being up-regulated−.
Conclusion: Handball players seemed to have different nutritional needs for Zn, with differences in the gene expression of Zn transporters compared to controls. Zn intervention, in our athletes, modified the expression of Zn transporters, so we could deduce that Zn transporters up-regulation may have increased to mobilise Zn at the cellular level at 8 weeks of Zn intervention.
Objective:
To investigate the relation between serum zinc concentration and several factors, including serum testosterone concentration and the score of questionnaires on sexual function in patients with sexual problems.
Methods:
This study comprised 720 men (age, 46.3 [21-83] years) with some kind of sexual problem. Age, scores of the Sexual Health Inventory for Men and the Erection Hardness Score, and endocrinologic data including serum concentrations of testosterone, prostate-specific antigen, and zinc were included in this study. After serum zinc concentration of the men was classified into 5 groups (<70, 70≤ <80, 80≤ <90, 90≤ <100, ≤100 μg/dl), the relation of each parameter with serum zinc concentration was assessed for a trend analysis. Finally, the relation between serum concentrations of zinc and testosterone as well sexual function evaluated by the scores of the questionnaires was investigated.
Results:
Only serum testosterone concentration (ptrend = 0.028) and serum cortisol concentration (ptrend = 0.003) showed a statistically significant relation to serum zinc concentration by trend analysis. Interestingly, trend analysis between serum concentrations of testosterone and zinc still showed a significant association after adjustment for serum cortisol concentration (ptrend = 0.032). However, no significant association was found in the relation between serum zinc concentration and the scores of the questionnaires after adjustment for serum concentrations of testosterone and cortisol.
Conclusion:
We clearly showed that after adjustment for serum cortisol concentration by trend analysis, serum testosterone concentration decreased as serum zinc concentration decreased, although sexual symptoms were not associated with this decrease.
Introduction
As men age, progressive testosterone deficiency syndrome becomes an increasingly common problem. However, the decreased testosterone levels are not only the result of advanced age.
Areas covered
PubMed search of published data on testosterone, nutritional deficiency, stress, sleep and obesity. Many factors impact the male HPG axis (the hypothalamic-pituitary-adrenal), including body weight, calorific and nutritional value of a diet, the amount and quality of sleep, as well as the level of stress. In the case of persons of healthy weight, a below-average calorific value of a diet may decrease the levels of testosterone in men. On the other hand, the same caloric deficiency in obese persons may result in a neutral or positive impact on testosterone levels.
Expert opinion
Many factors, including external, environmental and internal factors, influence testosterone levels. Undoubtedly, nutritional deficiency, and particularly of such nutrients as zinc, magnesium, vitamin D, together with low polyphenols intake, affects the HPG axis. The levels of mental and oxidative stress can also adversely impact the axis. Hence, a diagnosis of the cause of disturbance in testosterone levels depends on many factors and requires a broad range of research, as well as a change of patients’ lifestyle.
Background
The aim of this study was to investigate the effects of different exercise loads (short, medium and long swimming distances) on the thyroid hormone (THs) levels and serum lipid profiles of male professional swimmers.
Materials and methods
The participants in this study were 20 healthy male professional swimmers aged 18–22 years, who all competed at an elite level. The THs levels [thyroid-stimulating hormone (TSH), triiodothyronine (T3) and thyroxine (T4)] and serum lipid profile were also obtained.
Results
It was determined that the TSH and T4 values increased after exercise (p < 0.05). When compared to the pretest values, the increase in the TSH and T4 values following the L400 tests was statistically significant (p < 0.001 and p < 0.05). It was also determined that the changes in the cholesterol, high-density lipoprotein (HDL) and total glucose (TG) values were significant after exercise (p < 0.001). There was no significant difference between the groups in terms of the low-density lipoprotein (LDL) values (p = 0.07). According to the results, the cholesterol counts for the M200 and L400 groups were lower than the pretest counts (p < 0.001). When compared to the pretest values, the decrease in the HDL counts for the M200 and L400 groups was higher than the pretest HDL counts (p < 0.001 and p < 0.05, respectively). Further, the triglycerides counts for the M200 and L400 groups were higher than the pretest counts (p < 0.001).
Conclusions
Different exercise loads can have a positive impact on the physical health of swimmers via their lipid profiles and THs. Additionally, swimming exercise could be considered an efficient protective strategy against metabolic disorders, as it serves to balance the serum lipid levels.
Purpose: This study was aimed to assess selenium and zinc status in female collegiate athletes and their relationship with dietary intake. Methods: Female collegiate athletic groups of judo and aerobics, and healthy sedentary collegiate females were recruited for this study and their serum selenium and zinc contents were measured by the neutron activation analysis (NAA) method. In addition, the dietary intake of subjects was measured using the two days 24-hour recall method. Results: Serum selenium in judo athletes was 10.7 µg/dl, which was significantly lower than that of aerobic athletes (12.2 µg/dl), but not different from that of the sedentary group (11.4 µg/dl). Additionally, serum zinc levels were 96.1 µg/dl and 90.2 µg/dl in aerobic and judo athletes, respectively, which did not differ significantly. Moreover, dietary selenium and zinc intake of the athletic groups did not differ significantly from that of the sedentary female group. Overall, 33.3% of the serum selenium concentration variation was explained by the intake of vitamin E, selenium and saturated fatty acids, while 14.7% of the serum zinc level variation was explained by the intake of saturated fatty acids. The strongest dietary indicator for serum selenium and zinc levels was saturated fatty acids intake. Conclusion: Judo athletes appear to have lower selenium status than aerobic athletes, suggesting different body selenium status according to sport type. To maintain body selenium and zinc levels, the dietary intake of saturated fatty acids should be decreased.
La tiroides es una glándula situada en el cuello, encargada de producir dos hormonas que
son esenciales para el metabolismo y el crecimiento de las personas: la triyodotironina
(T3) y la tiroxina (T4). La producción en exceso o la falta de estas hormonas provoca
hipertiroidismo en el primer caso e hipotiriodismo en el segundo. Ambas disfunciones
de la tiroides se tratan con fármacos. En este trabajo de revisión se mostrarán los efectos
del ejercicio físico en las personas que sufren bien de hipertiroidismo o de hipotiroidismo,
siendo un complemento al tratamiento médico.
The aim is to determine the effect of 6-week zinc supplement and weight lifting exercise on the thyroid hormone levels. Study participants were 40 males, age between 18-22 years; 20 sedentaries and 20 individuals who do physical exercises. Subjects were divided equally into 4 groups. Which is: The sedentary group (S) control group,Sedentary group which is supplied withonly zinc (Z+S),Training Group which is supplied with zinc (Z+T) and Athletes Group that train regularly (T). Zinc supplement was given 3mg/kg/day/6 weeks as oral. At the beginning of the study and after 6-week training, the blood samples were drawn from the participants before and after the treatments; and TSH, FT3 and FT4 levels of the participants were determined. It was identified that thyroid values of groups which were supplied with zinc decreased owing to the training and zinc supplement. Consequently, it is thought 6-week zinc supplement and exercise can contribute to the athletes’ performance by changing thyroid values positively. © 2017, Association of Physiologists and Pharmacologists of India. All rights reserved.
Introduction: The purpose of this study was to investigate how exhaustion exercise affects testosterone levels and plasma lactates in road cyclists supplemented with oral zinc and selenium for 4 weeks. Materials and Methods: Twenty-four male road cyclists volunteers, were selected from the Tehran Traffic team, and based on BMI were divided into three groups; the selenium, zinc, and controls. The status of zinc and selenium in subjects was assessed at baseline. After 4 weeks of supplementation free, total testosterone, and lactate levels of all subjects were determined before and after exercise. Data was analyzed according to repeated measures ANOVA, and the Bonfferoni post hoc test, with a significance level of P<0.05. Results: Resting total, free testosterone, and lactate levels did not differ significantly between groups, and were increased by exercise (P>0.05). Total testosterone levels in the Zn group were higher than in the Se group after exercise (P<0.05). 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 three groups after exercise (P>0.05). Conclusion: According to this study, 4-week selenium and zinc supplementation had no significant effect on testosterone or lactate levels of subjects who had a zinc and selenium sufficient diet. Zinc supplementation increased levels of total testosterone in contrast with selenium group, and also increased free testosterone versus the other groups, whereas there was no change in the levels of lactate in the three groups post-test.
This study was conducted to examine the effects of a three-month football training program on some trace elements in the serum in male kids aged between eight and twelve years. The study registered eight boys whose mean age was 10.25 ± 0.75 years, mean height was 138.63 ± 3.28 cm and mean weight was 32.13 ± 2.72 kg. The subjects were regularly trained in the accompaniment of coaches for three months (four to five days a week). Blood samples of 5 ml each were taken into plain tubes from the subjects twice, once at the beginning of the study and the other at the end of the three-month training sessions, after 12 h of nocturnal fasting. Serum cobalt (Co), cadmium (Cd), nickel (Ni), molybdenum (Mo), manganese (Mn), aluminum (Al), copper (Cu), zinc (Zn) and iron (Fe) levels were measured using an atomic absorption spectrophotometer. The results were expressed in mg/L. Cadmium, molybdenum, copper and zinc (p<0.05) values were measured after the study and were found significantly lower than those before the study. Results of this study demonstrate that three-month football training significantly reduced cadmium, molybdenum, copper and zinc values in eight to 12-year-old boys. The decrease in zinc levels in particular may be critical for the athletes health and performance.
The aim of the present study was to elucidate whether the recovery from muscle injury is impaired in marginal zinc deficiency. C57BL/6 male mice were fed a marginally zinc-deficient diet (MZD: 8 mg Zn/kg diet), a zinc-adequate diet (ZA: zinc 35 mg Zn/kg diet), and a zinc-high diet (ZH: 190 mg Zn/kg diet) for 4 weeks. Muscle injury was induced in the gastrocnemius muscles using cardiotoxin. The gastrocnemius muscles of these mice were harvested at 3, 5, 7, 10, 14, and 20 days after injury. We evaluated the regeneration of the skeletal muscle with hematoxylin and eosin staining and developmental myosin heavy-chain (dMHC: implicated in regeneration) immunostaining. The rate of dMHC-positive cells was significantly low in MZD mice compared with ZA mice at 3 days after cardiotoxin injection. The peak dMHC expression was found at 3 days after injection in ZA mice, 5 days in ZH mice, and 7 days in MZD mice. These results suggest that recovery from muscle injury might be partly impaired and delayed in MZD mice. Therefore, we strongly suggest the appropriate zinc intake to prevent the impairment of skeletal muscle regeneration.
Zinc is crucial for proper thyroid hormone metabolism; zinc deficiency may result in decreased thyroid hormone levels and resting metabolic rate (RMR). The purpose of this investigation was to assess the effects of zinc supplementation on plasma zinc, serum ferritin, plasma total triiodothyronine (T(3)) and thyroxine (T(4)), serum free T(3) and T(4), and thyroid-stimulating hormone concentrations, and RMR in zinc-deficient, physically active women.
Two zinc-deficient female college students (ZD1 and ZD2) were supplemented with 26.4 mg/day of zinc (as zinc gluconate), and the above parameters were analyzed at 0, 2 and 4 months.
Zinc deficiency was clinically corrected in both subjects, while serum ferritin concentration declined to classify both subjects as borderline iron deficient (ZD1 = 15.3 and ZD2 = 15.3 ng/ml at 4 months). At 4 months, total T(3) concentrations increased in ZD1, while all thyroid hormone concentrations increased in ZD2. RMR increased in both subjects by 4 months.
Zinc supplementation appeared to be directly responsible for the increase in plasma zinc and decline in serum ferritin concentrations in both subjects. Zinc supplementation appeared to have a favorable effect on thyroid hormone levels, particularly total T(3), and RMR.
This study was carried out in order to determine the effect of acute maximal aerobic exercise on the copper and zinc levels in blood. The study was participated by 16 healthy male university students with an average age of 19.44+/-1.63. There were 5 cc blood samples taken from the participants before and after they had been subjected to aerobic loading process (20 m shuttle run). The copper and zinc levels in the blood samples were determined by the use of Anodic Stripping Voltammetry (ASV) technique. The data obtained were evaluated by simple t test and SPSS software. The results revealed the fact that the blood Zn levels of the participants increased and Cu levels decreased with statistical significant extent (p<0.01) after maximal aerobic loading. There found no correlation between the maximal aerobic power levels (Max VO2) of the participants and their resting copper and zinc blood levels. However blood zinc and Max VO2 levels of the participants were positively correlated after maximal aerobic loading. The participants were fed on a zinc and copper free diet six week prior to the program. They were also asked not to use copper and zinc containing vitamins during this period.
The aim of this study was to determine how exercise affects thyroid hormones and testosterone levels in sedentary men receiving oral zinc for 4 weeks.
The study included 10 volunteers (mean age, 19.47+/-1.7 years) who did not exercise. All subjects received supplements of oral zinc sulfate (3 mg/kg/day) for 4 weeks and their normal diets. The thyroid hormone and testosterone levels of all subjects were determined at rest and after bicycle exercise before and after zinc supplementation.
TT3, TT4, FT3, and total and free testosterone levels decreased after exercise compared to resting levels before supplementation (p<0.01). Both the resting and fatigue hormone values were higher after 4 weeks of supplementation than the resting and fatigue values before supplementation (p<0.05).
The results indicate that exercise decreases thyroid hormones and testosterone in sedentary men; however, zinc supplementation prevents this decrease. Administration of a physiologic dose of zinc can be beneficial to performance.
The following study was undertaken to study the effects of multiple stressors on the pituitary-testicular axis in men. We examined the endocrine responses of 16 healthy young men participating in a mountain training exercise. Blood was drawn at 1830 m just before ascent (t = 0 h), after an overnight rest at 3050 m (t = 24 h), and immediately after a descent from 3050 m in adverse conditions (t = 48 h). Plasma E2 increased significantly through the study periods (medians: 74, 104, 164 pmol/l at t = 0, 24, 48 h) while 17 alpha-hydroxyprogesterone progressively decreased. Testosterone and the bioactive LH to immunoreactive LH ratio decreased only at 48 h. There were no changes observed for plasma cortisol, prolactin or thyroxine. The observed rise in E2 may be due to one or more stressors associated with altitude, including hypoxia and increased solar radiation. This data suggests a role for E2 in the secondary testosterone decrease.
The effects of resistance exercise on the nocturnal responses of cortisol (CO), testosterone (TEST), human growth hormone (hGH), and thyroid hormones (T3, T4) were examined in eight trained weight lifters. Each subject completed two trials using a counterbalanced design: a control, no exercise trial (CON) and a heavy resistance exercise session of three sets of six exercises to exhaustion (RE). The exercise session took place between 1900 and 2000 hours. Blood was sampled prior to and at 20-min intervals after RE. For both trials blood was sampled at hourly intervals from 2100 hours until 0700 hours. The hGH and CO concentrations were increased up to 40-min post-exercise (P < 0.05), but returned to resting levels 1 h post-exercise. Nocturnal hGH concentration was not affected by RE (P > 0.26) and peaked at 0200 hours and declined until 0700 hours. Similarly, the CO responses were similar between the trails (P > 0.14). This CO concentrations declined from 2200 hours until 0100 hours, then increased steadily until 0700 hours. The TEST concentrations during both trials rose steadily from 2200 hours until 0700 hours; however, the rise in TEST from 0500-0700 hours during RE was greater than during the CON trails (P = 0.059). The T3 concentrations were unchanged by exercise and were similar at all times between trails. The T4 concentrations were elevated for 20 min after RE; however nocturnal T4 concentrations were lower after RE than during CON. These results would suggest that hGH and CO may have limited nocturnal reactivity to resistance exercise. However, the nocturnal alterations of TEST and T4 after resistance exercise, although small, may have implications for muscle anabolism.
Sports nutritionists generally think an athlete's increased mineral requirements can be satisfied by a greater but well-balanced caloric intake. This study supports that concept, demonstrating that 12 male runners who consumed an unrestricted, isocaloric diet maintained normal plasma mineral levels without using mineral supplements during a 500-km (312-mile) road race. None of the nine minerals tested (calcium, phosphorus, sodium, potassium, chloride, magnesium, iron, copper, and zinc) showed tendencies to become persistently reduced over the 20-day period.
Background:
Physical activity has been reported to affect endocrine function in elderly men.
Objective:
To establish an association between regular moderate physical activity and endogenous anabolic hormone levels in healthy aging men.
Participants:
Twenty four middle-aged (57.4+/-4.7 years) and 24 elderly (68.3+/-2.6 years) physically active men who in the past 10 years had been regularly bicycling during leisure time were compared with 24 middle-aged (57.9+/-4.0 years) and 24 elderly (67.2+/-1.7 years) sedentary men. Groups did not differ for body composition.
Measurements:
Serum dehydroepiandrosterone sulfate (DHEAS), insulin-like growth factor-I (IGF-1), free testosterone (FT), and thyroid hormone levels were assessed.
Results:
In general, elderly men had lower IGF-1 (P<0.001), DHEAS (P=0.013), and triodothyronine levels (P<0.001) than their middle-aged counterparts. Independently of age, however, physically active men had on average higher IGF-1 (P=0.031), DHEAS (P=0.001), and triodothyronine serum levels (P<0.001) than sedentary men. FT and thyroid stimulating hormone (TSH) serum concentrations did not differ across age groups, but physically active men had lower TSH values than sedentary men (P=0.021).
Conclusions:
Our results suggest that, in aging men, regular moderate physical activity is associated with higher levels of IGF-1 and DHEAS levels and with thyroid function alterations.
Serum zinc was determined using atomic absorption spectrophotometry in 160 training athletes (57 females) in the morning at rest. In 23.3% of the male and 43% of the female athletes, serum Zn was lower than the limit accepted for the normal range (75 microgram/dl or 11.5 mumol/l). The average serum Zn (96.7 +/- 12.6 microgram/dl) and the range of the values found in a control group of 15 young adult males did not differ from the accepted values in the literature. In 22 randomly selected male athletes, serum Zn fractions were determined using polyethylene glycol precipitation at pH 7.1; 22.2% of total Zn was bóund to alpha2-macroglobulin, the ratio being very close to 1 atom of metal per molecule of globulin. The possible reasons that may influence the serum Zn level in athletes are discussed with regard to the present knowledge in both exercise physiology and metabolism of zinc in man.
Non-glucoregulatory hormones (T4, T3, rT3, TSH and testosterone) were studied by radioimmunoassay in juvenile-type diabetics in moderate control and in ketosis due to insulin withdrawal and in age matched “normals” during a mild prolonged exercise test.
The basal serum hormone levels revealed the following findings: Serum testosterone was markedly lower in diabetics than in normals (177 ± 24 resp. 618 ± 52 ng/dl). This is in contrast to other studies, but it may reflect decreased testicular function due to an early, clinically not apparent atherosclerotic disease. Serum T3 was significantly lower in diabetics than in normals (110 ± 16 resp. 145 ± 19), suggesting an early “low T3-syndrome” in juvenile-type diabetics. However, increased serum rT3 levels were not observed, and serum T4 and TSH were normal.
Mild prolonged exercise had no major effects on these nonglucoregulatory hormones. In juvenile-type diabetics the degree of metabolic control had no influence on the response of the mentioned hormones. However, an increased cortisol/testosterone ratio in ketotic diabetics in the basal state with a further increase during exercise was demonstrated, indicating an aggravation of the catabolic state in these patients during exercise.
Eight men were studied during graded (47, 77 and 100% of maximal oxygen uptake) and prolonged (76%) exhaustive treadmill running. Plasma catecholamine levels increased progressively with intensity and duration of exercise. Serum concentrations of thyroid-stimulating hormone (TSH) increased with increasing work loads and were 107 (58--243)% (P less than 0.001) above resting values after maximal work. Thyroxine, triiodothyronine and luteinizing hormone in serum never changed significantly. While a small increase in testosterone concentrations (13 [1--24]%) after maximal exercise probably could be explained by changes in plasma volume, a definite increase (31 [14--56]%) occurred after 40 min of prolonged exercise. During continued exercise testosterone concentrations then gradually declined. Testicular stimulation by the increased catecholamine concentrations possible contributed to the rise in testosterone concentrations, but no evidence was found for a direct catecholamine induced increase in the activity of the thyroid gland. The exercise induced increase in TSH levels possibly explians the increased thyroid hormone secretion rate, which previously has been found in individuals participating in physical training programs.
Thyroid hormones are involved in copper and zinc distribution in rat tissues. We examined the influence of thyroparathyroidectomy (TPTY) and of a replacement therapy by T4 on Cu and Zn organ distribution. MT levels were also measured both in basal conditions and after induction by cadmium. The results confirm that a lack of T4 modified Cu and Zn in serum and tissues. In serum, TPTY increased Cu (+15%) and ceruloplasmin (+18%), and decreased Zn (-18%). In tissues, Cu was altered in liver (+13%), kidney (-24%), heart (-16%) duodenum (-18%), and Zn in liver (+25%) and kidney (-10%). The soluble fractions (100,000 g supernatant) were mainly affected in liver and kidney, and the subcellular fractions in heart and duodenum. MT levels were modified in basal conditions only in liver (+57%) and kidney (-36%). T4 administration partially prevented the effect of TPTY on both elements and MT concentrations. Therefore, no evidence is provided for a direct role of T4 in the metabolism of MT in a way comparable to the effects of glucocorticoids. However, MT could mediate the consequences of TPTY on metal distribution in certain organs, such as liver and kidney.
Semistarvation over a ten-day period resulted in a weight loss of 30% in male Wistar rats, which had continuous access to a running wheel. The animals increased their activity up to 20 km per day. Controls fed ad lib increased activity only slightly (up to 2.3 km on day ten). Groups of semistarved and ad lib-fed sedentary rats were studied as controls. The circadian pattern of corticosterone (B), triiodothyronine (T3), luteinizing hormone (LH) and testosterone (T) was studied. Corticosterone was synergistically increased by semistarvation and exercise. The reduction of triiodothyronine by semistarvation was significantly greater in the running wheel group. Both luteinizing hormone and testosterone were significantly decreased by semistarvation. Hyperactivity did not result in additional suppression of LH and testosterone.
In Down syndrome there is a high incidence of overt or subclinical hypothyroidism as well as some immunological defects, early thymic involution associated to low serum zinc levels. Zinc supplementation to the diet has been reported to transiently improve thymic function; moreover thymic function has been shown to be in relation with the pituitary-thyroid axis. The aim of this study was to evaluate if, in Down patients, zinc therapy could improve also thyroid function, by determining serum levels of total and free thyroid hormones and basal TSH levels. In 52 patients studied, we found a high incidence of subclinical hypothyroidism (30%); in 17 patients treated with zinc sulphate we showed a reduction of FT3. More significantly, we detected 9 patients with low zinc levels in which zinc supplementation improved thyroid function, thus reducing the incidence of subclinical hypothyroidism.
Serum zinc was measured four times (October, January, March and May) in six young male athletes during a nine-month sporting season in relation to eleven other parameters. A significant decrease in serum zinc was observed after five months of intensive training (all values remaining in the normal range). This cannot be explained by changes in dietary habits, plasma protein concentrations, hormonal changes nor by the existence of minor infectious or inflammatory pathologies. The dietary intakes seemed adequate. These results support the hypothesis that zinc status may be slightly altered in the high-level athlete.
The effects of thyroparathyroidectomy (TPTY) and of replacement therapy using thyroxin (T4) and calcitonin (CT) on the tissue distribution of elements were studied in the rat under semichronic conditions. The elements Na, K, Ca, Mg, Fe, S, P, Rb, Sr, Mn, Cu, and Zn were determined in whole blood, plasma, brain, liver, heart, kidney, skeletal muscle, and bone. TPTY modified concentrations of all elements tested but only small changes were observed for K, Mg, S, and P. The mineral bone composition was slightly modified, 28 d after TPTY, whereas plasma was the most altered. The consequences of TPTY were corrected fairly well by T4 for Na, Cu, Zn, Fe, and S, and by CT for K, P, Rb but with less efficiency for Ca. This study revealed that hormones of the thyroid gland, mainly T4, play an important role in the plasma and tissue balance of elements. It is suggested that T4 participates in tissue fixation of Cu, Zn, and Fe and that CT influences phosphoremia and cellular Ca binding.
The influence of 11 days at moderate altitude (2,000 m) combined with exercise on plasma concentration of testosterone, FSH (follicle-stimulating hormone), LH (luteinizing hormone), cortisol, aldosterone, and renin activity was studied in ten healthy subjects. Within 48 h of arrival at moderate altitude a significant increase in testosterone was found whereas FSH had decreased significantly and LH showed a tendency to decrease. Cortisol increased significantly at the beginning and reached a maximum at the end of altitude exposure. The plasma aldosterone level rose continuously and on the last day of altitude was significantly elevated. Plasma renin activity showed a tendency to decrease. On return to low land all measured parameters returned to base line values within 2 days.
The findings of increases in plasma levels of aldosterone and testosterone (and serum T3 and T4, as reported by others) are in contrast to the previously found decrease of urinary excretion of all these hormones. This appears to be a distinct dissociation of serum levels of adrenal (and thyroid) hormones from their urinary excretion.
The observed increase in plasma aldosterone is probably mediated through ACTH and the rise in plasma potassium, since plasma renin activity showed an opposite trend. The rise in plasma testosterone is probably of adrenal origin since plasma gonadotropins declined simultaneously.
The increase of plasma levels of glucocorticoids, mineralocorticoids, and androgens after an ascent from 600 m to 2,000 m above sea level is compatible with an ACTH-mediated stimulation of the entire adrenal cortex and/or a diminished elimination of adrenal steroids: The concomitant fall of FSH, LH, and plasma renin would then be a consequence of a direct negative feedback inhibition of these hormones.
The athletes in this study were eager for nutritional knowledge and advice and were motivated to change their eating habits because they believed that such a change would be to their advantage in competition.
“There is no area of nutrition where faddism, misconceptions and ignorance are more obvious than in athletics” (1). Often coaches, trainers, and even team physicians dispense misleading nutrition information. Professional
Responses of serum hormones and factors measured with the SAN-test (feelings of well-being, activation, mood) to a submaximal work load in 83 health athletes were expressed in per cent of the values expected individually according to the respective circadian rhythm [5,6,7]. In the most subjects a significant increase of serum HGH and a significant decrease of serum T (= testosterone) was found under the work load. Within 45 min after the completion of the work the level of HGH returned to the expected one, according to the circadian rhythm, while the level of T did not. Some other minor hormonal responses were observed. No significant differences were shown between the actual values of factors measured with the SAN-test and the respective values expected according to the circadian rhythm.
The effects of marginal (MZD) and severe (SZD) zinc-deficient diets on testicular function and development were studied in rats maintained on dietary treatment for 6 weeks after weaning. SZD produced variable degrees of histological changes as compared with pair-fed controls, including a significant decrease in the diameter of seminiferous tubules (p < .05) with variable degree of maturation arrest in different stages of spermatogenesis. No significant histological changes were obtained in testes of MZD rats. MZD rats-exhibited significant decreases in serum levels of testosterone (62.6%, p < .001) and progesterone (18.2%, p < .05) with no changes in that of FSH or LH. SZD rats showed marked decreases in serum levels of testosterone (17.8-fold, p < .001) and progesterone (28.8%, p < .001), whereas FSH showed an increase (34.4%, p < .05) as compared with respective controls. In vitro acute stimulation by hCG on testicular tissue preparation obtained from MZD rats resulted in much less androgen production (sum of androstenedione, testosterone, and androstanediol) (72.4%, p < .001) as compared with controls. Testicular androgen contents (sum of androstenedione, testosterone, and androstanediol) decreased significantly in MZD and SZD rats, with the latter showing the greatest decrease. SZD rats were asospermic, whereas MZD rats exhibited marked decrease in sperm counts (by 22.9%, p < .05) as compared with respective controls. The results reflect a direct action of zinc deficiency on testicular steroidogenesis and strongly support the idea that hypogonadism of zinc deficiency results mainly from changes in testicular steroidogenesis or indirectly from Leydig cell failure.
Previous studies concerning the effects of swimming on various endocrine gland functions have been performed. Our study was thus designed to analyze the effects of chronic exercise (swimming) on the resting metabolic rates (RMR) of adult rats. Most of the protocols used a water temperature of 33 C. It is our contention that such a protocol is not exclusively an exercise stress, but also a hypothermic stress. The protocol of our study was designed in a way that hypothermic stress was not part of the exercise stress. Male rats were swam in 36 C water for 3 hours a day, 5 days a week for 4 months. RMR of the animals were determined 24 h after the next to last swim session. Plasma hormone levels and epididymal sperm concentrations were determined in animals sacrificed 24 h after the last swim period. Exercising animals had a RMR 16% greater than that of control animals (p < 0.02), yet total and free thyroxine and total and free triiodothyronine were not significantly elevated. Neither plasma testosterone nor epididymal sperm counts were significantly reduced in the exercising animals. It appears that chronic exercise produces an elevation in RMR which is unrelated to thyroid gland activity and does not suppress the hypothalamic-pituitary-gonadal axis.
The aim of the study was to investigate how zinc deficiency and supplementation effect some hematologic parameters of rats performing swimming exercise. Forty adult male Spraque-Dawley rats were divided into 4 groups, zinc deficient swimming group (Group 1, n=10, zinc supplemented swimming group (Group 2, n=10), swimming control group (Group 3, n=10), and control group (Group 4, n=10). Blood samples were taken by decapitation and analyzed for the determination of erythrocyte, hemoglobin level, hematocrit, leukocyte, lymphocyte, platelet count and plasma zinc level at the end of the 4 week experiment. Erythrocyte count of group 1 was the lowest whereas erythrocyte count in group 3 was significantly lower than that in group 2 and 4 (p<0.05). Hemoglobin level of group 1 was significantly lower than that of groups 2 and 4 (p<0.05). Hematocrit was significantly lower in both group 1 and group 3 than both groups 2 and 4 (p<0.05). Lymphocyte count in group 2 was significantly higher than in all other groups (p<0.05). Platelet counts in group 2 was significantly lower than in all other groups (p<0.05). Our findings suggest that zinc deficiency effects the hematologic parameters mentioned negatively whereas zinc supplementation has a positive influence.