Adult Testosterone Levels Research Articles

Negative correlation between metabolic score for insulin resistance index and testosterone in male adults

BackgroundInsulin resistance (IR) is strongly correlated with the decreased deficiency of testosterone levels in males. The metabolic score for insulin resistance (METS-IR) index is regarded as an innovative measure for the assessment on IR. The research aims to explore the correlation between the METS-IR index and the testosterone levels in males.MethodsIn this study, a cross-sectional design was made through the data obtained from the National Health and Nutrition Examination Survey (NHANES) from 2013 to 2020. Besides, the METS-IR index was derived from serum triglyceride levels, fasting plasma glucose, HDL-C and BMI.ResultsA total of 2082 participants were included in the final analysis. After controlling for confounding variables, it was found that METS-IR was independently and negatively correlated with testosterone levels (β = −3.88, 95% CI = −4.49, −3.27, P < 0.001). As shown by the generalized smooth curve fitting, METS-IR had a linear correlation with testosterone levels without threshold or saturation effects, which was consistently observed across all subgroups through stratified analysis (all P > 0.05). As revealed by the analysis on the ROC curve, the area under the curve (AUC) for the METS-IR index (0.732, 95% CI = 0.705, 0.760) was significantly larger than that of homeostatic model assessment of insulin resistance (HOMA-IR), TG/HDL ratio, triglyceride-glucose index (TyG) and body mass index (BMI).ConclusionThe findings suggest a negative relationship between the METS-IR index and the testosterone levels in male adults. Furthermore, the METS-IR index demonstrates superior predictive ability for testosterone deficiency in comparison to HOMA-IR, TG/HDL ratio, TyG and BMI.

Evaluation of the Incidence of Low Testosterone Levels in Young Male Adults with Moderate to Severe Obesity-Single-Centre Study from India.

With the increase in obesity epidemic among Asians, it is necessary to evaluate the impact of obesity on this population. Low testosterone levels are known to be associated with obesity. This is the 1st study from Asia to evaluate incidence and magnitude of hypotestosteronemia in young adults with BMI more than 32.5kg/m2 defined as moderate to severe obesity in Asians. One hundred thirty-four male patients with BMI more than 32.5kg/m2, between 18 and 30years old who visited a single bariatric facility between 2017 and 2020, were evaluated with BMI, total and free testosterone levels and clinical features of gynecomastia, hypogonadism, and thinning of pubic and armpit hair. Statistical analysis was performed using SPSS, Spearman's correlation coefficient, and ANOVA test. 60.4% of patients (84/134) had low testosterone levels (< 300ng/dl) and 23.9% (32/134) had levels between 300 and 400ng/dl. 89.6% patients (120/134 had gynecomastia, 60.4% (81/134) had thinning of pubic and arm pit hair, and 62.7% (84/134) had hypogonadism. Testosterone levels showed a decreasing trend with increasing BMI, but it was not statistically significant. Obesity is one of the important etiologies of hypotestosteronemia and its manifestations in young adults. The actual incidence may be significantly higher than what is reported in the literature. High-quality research is required to address questions of diagnosis and best treatment options.

Neuroplastin Expression in Male Mice Is Essential for Fertility, Mating, and Adult Testosterone Levels.

Male reproduction depends on hormonally driven behaviors and numerous genes for testis development and spermatogenesis. Neuroplastin-deficient (Nptn-/-) male mice cannot sire offspring. By immunohistochemistry, we characterized neuroplastin expression in the testis. Breeding, mating behavior, hormonal regulation, testicular development, and spermatogenesis were analyzed in cell-type specific neuroplastin mutant mice. Leydig, Sertoli, peritubular myoid, and germ cells express Np, but spermatogenesis and sperm number are not affected in Nptn-/- males. Neuroplastin lack from CNS neurons or restricted to spermatogonia or Sertoli cells permitted reproduction. Normal luteinizing hormone (LH) and follicle-stimulating hormone (FSH) blood levels in Nptn-/- males support undisturbed hormonal regulation in the brain. However, Nptn-/- males lack mounting behavior accompanied by low testosterone blood levels. Testosterone rise from juvenile to adult blood levels is absent in Nptn-/- males. LH-receptor stimulation raising intracellular Ca2+ in Leydig cells triggers testosterone production. Reduced Plasma Membrane Ca2+ ATPase 1 (PMCA1) in Nptn-/- Leydig cells suggests that Nptn-/- Leydig cells produce sufficient testosterone for testis and sperm development, but a lack of PMCA-Np complexes prevents the increase from reaching adult blood levels. Behavioral immaturity with low testosterone blood levels underlies infertility of Nptn-/- males, revealing that Np is essential for reproduction.

Pubertal attainment and Leydig cell function following pediatric hematopoietic stem cell transplantation: a three-decade longitudinal assessment.

Impaired testosterone secretion is a frequent sequela following hematopoietic stem cell transplantation (HSCT) in pediatrics, but long-term longitudinal trendlines of clinical and biochemical findings are still scanty. Monocentric, retrospective analysis. Male patients transplanted <18 years between 1992 and 2021, surviving ≥2 years after HSCT and showing, upon enrollment, clinical and biochemical signs consistent with pubertal onset and progression were included. Clinical and biochemical data collected every 6-12 months were recorded. Of 130 patients enrolled, 56% were prepubertal, while 44% were peri-/postpubertal upon HSCT. Overall, 44% showed spontaneous progression into puberty and normal gonadal profile, while the remaining experienced pubertal arrest (1%), isolated increase of FSH (19%), compensated (23%) or overt (13%) hypergonadotropic hypogonadism. Post-pubertal testicular volume (TV) was statistically smaller among patients still pre-pubertal upon HSCT (p 0.049), whereas no differences were recorded in adult testosterone levels. LH and testosterone levels showed a specular trend between 20 and 30 years, as a progressive decrease in sexual steroids was associated with a compensatory increase of the luteinizing hormone. A variable degree of gonadal dysfunction was reported in 85%, 51%, 32% and 0% of patients following total body irradiation- (TBI), busulfan-, cyclophosphamide- and treosulfan-based regimens, respectively. TBI and busulfan cohorts were associated with the lowest probability of gonadal event-free course (p<0.0001), while it achieved 100% following treosulfan. A statistically greater gonadotoxicity was detected after busulfan than treosulfan (p 0.024). Chemo-only regimens were associated with statistically larger TV (p <0.001), higher testosterone (p 0.008) and lower gonadotropin levels (p <0.001) than TBI. Accordingly, the latter was associated with a 2-fold increase in the risk of gonadal failure compared to busulfan (OR 2.34, CI 1.08-8.40), whereas being pre-pubertal upon HSCT was associated with a reduced risk (OR 0.15, CI 0.08-0.30). a) patients pre-pubertal upon HSCT showed a reduced risk of testicular endocrine dysfunction, despite smaller adult TV; b) patients showed downwards trend in testosterone levels after full pubertal attainment, despite a compensatory increase in LH; c) treosulfan was associated to a statistically lower occurrence of hypogonadism than busulfan, with a trend towards larger TV, higher testosterone levels and lower gonadotropins.

Genetic analyses implicate complex links between adult testosterone levels and health and disease

BackgroundTestosterone levels are linked with diverse characteristics of human health, yet, whether these associations reflect correlation or causation remains debated. Here, we provide a broad perspective on the role of genetically determined testosterone on complex diseases in both sexes.MethodsLeveraging genetic and health registry data from the UK Biobank and FinnGen (total N = 625,650), we constructed polygenic scores (PGS) for total testosterone, sex-hormone binding globulin (SHBG) and free testosterone, associating these with 36 endpoints across different disease categories in the FinnGen. These analyses were combined with Mendelian Randomization (MR) and cross-sex PGS analyses to address causality.ResultsWe show testosterone and SHBG levels are intricately tied to metabolic health, but report lack of causality behind most associations, including type 2 diabetes (T2D). Across other disease domains, including 13 behavioral and neurological diseases, we similarly find little evidence for a substantial contribution from normal variation in testosterone levels. We nonetheless find genetically predicted testosterone affects many sex-specific traits, with a pronounced impact on female reproductive health, including causal contribution to PCOS-related traits like hirsutism and post-menopausal bleeding (PMB). We also illustrate how testosterone levels associate with antagonistic effects on stroke risk and reproductive endpoints between the sexes.ConclusionsOverall, these findings provide insight into how genetically determined testosterone correlates with several health parameters in both sexes. Yet the lack of evidence for a causal contribution to most traits beyond sex-specific health underscores the complexity of the mechanisms linking testosterone levels to disease risk and sex differences.

Evaluating and implementing block jackknife resampling Mendelian randomization to mitigate bias induced by overlapping samples.

Participant overlap can induce overfitting bias into Mendelian randomization (MR) and polygenic risk score (PRS) studies. Here, we evaluated a block jackknife resampling framework for genome-wide association studies (GWAS) and PRS construction to mitigate overfitting bias in MR analyses and implemented this study design in a causal inference setting using data from the UK Biobank. We simulated PRS and MR under three scenarios: (1) using weighted SNP estimates from an external GWAS, (2) using weighted SNP estimates from an overlapping GWAS sample and (3) using a block jackknife resampling framework. Based on a P-value threshold to derive genetic instruments for MR studies (P < 5 × 10-8) and a 10% variance in the exposure explained by all SNPs, block-jackknifing PRS did not suffer from overfitting bias (mean R2 = 0.034) compared with the externally weighted PRS (mean R2 = 0.040). In contrast, genetic instruments derived from overlapping samples explained a higher variance (mean R2 = 0.048) compared with the externally derived score. Overfitting became considerably more severe when using a more liberal P-value threshold to construct PRS (e.g. P < 0.05, overlapping sample PRS mean R2 = 0.103, externally weighted PRS mean R2 = 0.086), whereas estimates using jackknife score remained robust to overfitting (mean R2 = 0.084). Using block jackknife resampling MR in an applied analysis, we examined the effects of body mass index on circulating biomarkers which provided comparable estimates to an externally weighted instrument, whereas the overfitted scores typically provided narrower confidence intervals. Furthermore, we extended this framework into sex-stratified, multivariate and bidirectional settings to investigate the effect of childhood body size on adult testosterone levels.

Genetic Associations of Birthweight, Childhood, and Adult BMI on Testosterone Levels: A Mendelian Randomization.

Birthweight, childhood, and adult BMI have been indicated associated with the testosterone levels, but the current studies are plagued by significant heterogeneity, and a consensus about the role of these weight traits in testosterone levels is still debated. This work aims to evaluate the genetic associations of birthweight and childhood and adult body mass index (BMI) on the adult testosterone levels (bioavailable testosterone [BT], sex hormone-binding globulin [SHBG], and total testosterone [TT]) in women and men. Random-effect inverse-variance weighted (IVW) and 7 sensitivity analyses were performed. Data for weight traits were collected from large-scale genome-wide association studies (GWAS) ranging from 39 620 to 434 794 individuals. Summarized data for testosterone levels were obtained from a GWAS up to 230 454 individuals. Higher adult BMI are significantly associated with lower BT (β = -0.13; 95% CI, -0.16 to -0.09) and TT in men (β = -0.25; 95% CI, -0.30 to -0.20). On the contrary, higher adult BMI increased the levels of BT (β = 0.23; 95% CI, 0.23 to 0.20) and TT (β = 0.04; 95% CI, 0.01 to 0.07) in women. Similar genetic associations on testosterone levels with sexual differences were observed for childhood BMI. However, higher birthweight led to lower BT levels in adult men (β = -0.08; 95% CI, -0.12 to -0.03) and women (β = -0.07; 95% CI, -0.13 to -0.02). Our study supports that birthweight, childhood BMI, and adult BMI affect testosterone levels in men and women in adult life. The genetic associations of childhood BMI on testosterone levels are consistent with adult BMI, but not with birthweight.

A Proprietary Herbal Blend Containing Extracts of Punica granatum Fruit Rind and Theobroma cocoa Seeds Increases Serum Testosterone Level in Healthy Young Males: A Randomized, Double-Blind Placebo-Controlled Study

LN18178 is a proprietary herbal blend containing extracts of Punica granatum fruit rind and Theobroma cocoa seeds. The objective of the present study was to evaluate the effect of LN18178 on serum testosterone levels in healthy young adults in a randomized, double-blind, placebo-controlled study. One hundred and twenty male volunteers (age 21-35 years) were randomized into three groups. Each group (n = 40) received a daily dose of either placebo or 200 or 400 mg LN18178 for fifty-six days. An increase in serum testosterone (free and total) was the primary efficacy measure of the study. The secondary measures included dihydrotestosterone (DHT), cortisol, Luteinizing hormone (LH), 17β-Estradiol (E2), hand grip strength, and the mid-upper arm circumferences (MUAC). The vital signs and clinical chemistry parameters in blood and urine were performed to determine product safety. Post-intervention, both doses of LN18178 significantly increased free testosterone (p < 0.0001 vs. baseline; p = 0.0268 and p < 0.0001, respectively vs. placebo). The high dose group showed significant increases in total testosterone (p < 0.0001 vs. baseline; p = 0.0184 vs. placebo) and luteinizing hormone (p < 0.0007 vs. baseline; p = 0.0470 vs. placebo). The changes in other hormones were not significant. At post-trial, the LN18178-400 group showed significant improvements in the hand grip strength and mid-upper arm circumference. The hemato-biochemical parameters, urinalysis, and vital signs of the participants were within the normal range. Together, these observations suggest that LN18178 is a safe and tolerable herbal blend; it increases testosterone level and increases muscle strength and MUAC in young, healthy males. Supplemental data for this article is available online at https://doi.org/10.1080/19390211.2022.2035037 .

Combined hormonal contraceptives are associated with minor changes in composition and diversity in gut microbiota of healthy women

Recent human and animal studies have found associations between gut microbiota composition and serum levels of sex hormones, indicating that they could be an important factor in shaping the microbiota. However, little is known about the effect of regular hormonal fluctuations over the menstrual cycle or CHC-related changes of hormone levels on gut microbiota structure, diversity and dynamics. The aim of this study was to investigate the effect of CHCs on human gut microbiota composition. The effect of CHC pill intake on gut microbiota composition was studied in a group of 7 healthy pre-menopausal women using the CHC pill, compared to the control group of 9 age-matched healthy women that have not used hormonal contraceptives in the six months prior the start of the study. By analyzing the gut microbiota composition in both groups during one menstrual cycle, we found that CHC usage is associated with a minor decrease in gut microbiota diversity and differences in the abundance of several bacterial taxa. These results call for further investigation of the mechanisms underlying hormonal and hormonal contraceptive-related changes of the gut microbiota and the potential implications of these changes for women's health. This article is protected by copyright. All rights reserved.

Stretched penile length and its associations with testosterone and infertility.

BackgroundMale infertility can be associated with secondary sexual characteristics, hypogonadism, and several findings in the examination of external genitalia. We sought to identify if stretched penile length (SPL) is associated with infertility or baseline testosterone.MethodsWe performed a retrospective review of all males age 18–59 presenting to a Men’s health clinic from 2014 to 2017. SPL of patients with infertility were compared to patients with any other complaint. Patients with Peyronie’s disease, prior penile surgery, prostatectomy, on testosterone replacement, clomiphene or β-hCG were excluded from our study. Baseline characteristics were compared between the two groups (infertile vs. other). Linear regression was used to assess the association between infertility and testosterone with SPL after adjusting for patient age, BMI, and race. Scatterplot was used for correlation between testosterone and SPL.ResultsSix hundred and sixty-four men were included in our study (161 infertile, 503 other). The unadjusted mean SPL in the infertile group was 12.3 cm compared to 13.4 cm in the other group (P<0.001). The significance remained when adjusted for age, BMI, testosterone and race (12.4 vs. 13.3, P<0.001). Mean total testosterone in the infertile group was not significantly different than the other group (414 vs. 422, P=0.68). Infertile men were younger than the other group (33.2 vs. 42.1 years, P<0.001). BMI did not significantly differ (28.9 vs. 28.9 kg/m2, P=0.57). There was a weak positive correlation between testosterone and penile size in both the infertile group (r=0.20, P=0.01) and the other group (r=0.24, P<0.001).ConclusionsThough SPL differed amongst our groups, adult testosterone levels did not. If developmental levels of testosterone exposure accounted for some of the differences in SPL between our two groups, these variations did not persist into adulthood. It remains unknown if reduced length is a result of genetic or congenital factors associated with infertility. Further investigation is needed to better understand the association of shorter SPL with male infertility.

Systematic comparison of the male reproductive tract in fetal and adult Wistar rats exposed to DBP and DINP in utero during the masculinisation programming window

This study investigates possible effects of in utero exposure of rats to a low dose (125 mg/kg bw/day) and a high dose (750 mg/kg bw/day) of Diisononyl phthalate (DINP) during the masculinisation programming window (MPW) which is embryonic days 15.5–18.5 (e15.5 - e18.5). Dibutyl phthalate (DBP) was used at a high dose level (750 mg/kg bw/day) as an established positive control substance for anti-androgenic effects on the developing male reproductive tract.We focussed on the MPW and measured a multitude of biological endpoints at various life stages and applied state of the art histopathology staining techniques to refine the characterization of potential changes to the testis, beyond what is currently available with DINP. If DINP can mediate testicular dysgenesis (TDS) disorders, this exposure window would be sufficient to induce androgen impacts and alter male reproductive tract development as shown earlier in this validated experimental model with DBP.Overall, the results of this systematic comparison provide convincing evidence on the differences between the effects occurring with DBP and DINP. In contrast to what was seen with DBP, DINP did not cause cryptorchidism or hypospadias, had no effect on anogenital distance/anogenital index (AGD/AGi) and Leydig cell aggregates on e17.5 and e21.5 did not increase. With DINP no reduction of intratesticular testosterone, no effects on sperm motility and sperm count and no effect on adult testosterone or luteinizing hormone (LH) levels were seen. Our results demonstrate that DINP does not cause the adverse reproductive effects known to occur with DBP, a well-established endocrine disruptor.

Cardiovascular Safety and Efficacy of Testosterone Therapy in Elderly Men With Hypogonadism

Serum testosterone level steadily decreases with ageing [1]. Low testosterone levels in older adults have been associated with increased adverse cardiovascular (CV) events [2-5].

Relationships Between Empathy, Gender, and Testosterone Levels in Older Adults

We focused on the relationship between testosterone levels and empathy in older people and how this relationship changes with age and between genders. Participants comprised 45 younger (30–39 years) and 144 older (50–75 years) individuals who completed an empathy test and whose free testosterone (FT) levels in a blood sample were measured. Results showed that women scored significantly higher in empathy, and that FT levels were negatively correlated with emotional and cognitive empathy. However, women had a stronger emotional empathy relationship with FT, and a cognitive empathy relationship with FT was observed only in men. In addition, the effect of FT levels on empathy showed an age-related decline from middle to late adulthood, and this effect may vary by gender and by both components of empathy.

The 2D:4D ratio, a proxy for prenatal androgen levels, differs in men with and without MS.

To determine whether the 2D:4D ratio (ratio of the second and fourth digit lengths), a proxy for lower prenatal androgen to estrogen ratio, differs in men with and without multiple sclerosis (MS) using a case-control study design. We obtained 2 digital scans of the right hand for men with MS presenting to a scheduled clinic visit at a large MS referral center, and for men without autoimmune or endocrine diseases. All individuals were aged 18 to 65 years, right-handed, and reported no prior digit trauma. We calculated a mean 2D:4D ratio using digital calipers. In participants with MS, we assessed age at first MS symptoms, MS type, and the MS Severity Score; 51 had provided a testosterone level within 10 years of symptom onset. Our primary analysis was a cross-sectional comparison of the 2D:4D ratio between men with and without MS, using a 2-sample t test for independent samples assuming unequal variance. In total, we scanned 137 men with MS and 145 men without MS. A statistically significant association between 2D:4D ratio and MS status was observed in the univariate logistic regression model (p<0.05). These differences were not associated with age or race, which differed between the 2 groups. In participants with MS, the 2D:4D ratio was not correlated with MS type, age at first symptoms, or MS Severity Score (p>0.15 for each), and it was not correlated with adult testosterone levels (r=0.06, p=0.68, n=51). During the prenatal period, low androgens could represent a risk factor for MS.

A quantitative and qualitative review of the effects of testosterone on the function and structure of the human social-emotional brain.

Social and affective research in humans is increasingly using functional and structural neuroimaging techniques to aid the understanding of how hormones, such as testosterone, modulate a wide range of psychological processes. We conducted a meta-analysis of functional magnetic resonance imaging (fMRI) studies of testosterone administration, and of fMRI studies that measured endogenous levels of the hormone, in relation to social and affective stimuli. Furthermore, we conducted a review of structural MRI i.e. voxel based morphometry (VBM) studies which considered brain volume in relation to testosterone levels in adults and in children. In the included testosterone administration fMRI studies, which consisted of female samples only, bilateral amygdala/parahippocampal regions as well as the right caudate were significantly activated by social-affective stimuli in the testosterone condition. In the studies considering endogenous levels of testosterone, stimuli-invoked activations relating to testosterone levels were noted in the bilateral amygdala/parahippocampal regions and the brainstem. When the endogenous testosterone studies were split by sex, the significant activation of the brain stem was seen in the female samples only. Significant stimuli-invoked deactivations relating to endogenous testosterone levels were also seen in the right and left amygdala/parahippocampal regions studies. The findings of the VBM studies were less consistent. In adults larger volumes in the limbic and temporal regions were associated with higher endogenous testosterone. In children, boys showed a positive correlation between testosterone and brain volume in many regions, including the amygdala, as well as global grey matter volume, while girls showed a neutral or negative association between testosterone levels and many brain volumes. In conclusion, amygdalar and parahippocampal regions appear to be key target regions for the acute actions of testosterone in response to social and affective stimuli, while neurodevelopmentally the volumes of a broader network of brain structures are associated with testosterone levels in a sexually dimorphic manner.Electronic supplementary materialThe online version of this article (doi:10.1007/s11011-015-9692-y) contains supplementary material, which is available to authorized users.

Reduced fetal androgen exposure compromises Leydig cell function in adulthood.

Disruption of normal fetal development can influence functioning of organs and cells in adulthood. Circumstantial evidence suggests that subtle reductions in fetal androgen production may be the cause of adult male reproductive disorders due to reduced testosterone production. The mechanisms through which these fetal events affect adult testosterone levels are largely unknown. A recent paper of Kilcoyne et al. provides evidence that fetal reduction in androgen production or signaling results in a reduced Leydig stems cell number after birth and concomitant Leydig cell failure in adulthood. This implies that fetal androgen deficiency can lead to negative programming of adult Leydig cell (ALC) function, which may have implications for general health, aging, and longevity.

Irreversible perinatal imprinting of adult expression of the principal sex-dependent drug-metabolizing enzyme CYP2C11.

We proposed to determine whether, like other sexual dimorphisms, drug metabolism is permanently imprinted by perinatal hormones, resulting in its irreversible sex-dependent expression. We treated newborn male rats with monosodium glutamate (MSG), a total growth hormone (GH) blocker, and, using cultured hepatocytes, examined expression of adult CYP2C11, the predominant cytochrome-P450 expressed only in males, as well as the signal transduction pathway by which episodic GH solely regulates the isoform's expression. In addition, adolescent hypophysectomized (hypox) male rats served as controls in which GH was eliminated after the critical imprinting period. Whereas renaturalization of the masculine episodic GH profile restored normal male-like levels of CYP2C11, as well as CYP2C12, in hepatocytes from hypox rats, the cells derived from the MSG-treated rats were completely unresponsive. Moreover, GH exposure of hepatocytes from hypox rats resulted in normal induction, activation, nuclear translocation, and binding to the CYP2C11 promoter of the signal transducers mediating GH regulation of CYP2C11 expression, which dramatically contrasted with the complete unresponsiveness of the MSG-derived hepatocytes, also associated with hypermethylation of GH-response elements in the CYP2C11 promoter. Lastly, neonatal MSG treatment had no adverse effect on postnatal and adult testosterone levels. The results demonstrate that the sexually dimorphic expression of CYP2C11 is irreversibly imprinted shortly after birth by a hormone other than the customary testosterone, but likely by GH.

A short-term arm-crank exercise program improved testosterone deficiency in adults with chronic spinal cord injury.

To determine the influence of arm-crank exercise in reproductive hormone levels in adults with chronic SCI. Further objectives were to assess the influence of arm-crank exercise on muscle strength and body composition. Seventeen male adults with complete SCI at or below the 5th thoracic level (T5) volunteered for this study. Participants were randomly allocated to the intervention (n = 9) or control group (n = 8) using a concealed method. The participants in the intervention group performed a 12-week arm-crank exercise program, 3 sessions/week, consisting of warming-up (10-15 min) followed by a main part in arm-crank (20-30 min [increasing 2 min and 30 seconds each three weeks]) at a moderate work intensity of 50-65% of heart rate reserve (HRR) (starting at 50% and increasing 5% each three weeks) and by a cooling-down period (5-10 min). Serum follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone and estradiol were determined by ELISA. Muscle strength (handgrip) and body composition (waist circumference [WC]) were assessed. After the completion of the training program, testosterone level was significantly increased (p = 0.0166;d = 1.14). Furthermore, maximal handgrip and WC were significantly improved. Lastly, a significant inverse correlation was found between WC and testosterone (r =- 0.35; p = 0.0377). The arm-crank exercise improved reproductive hormone profile by increasing testosterone levels in adults with chronic SCI. A secondary finding was that it also significantly improved muscle strength and body composition in this group.

Digit ratio (2D:4D) as an indicator of body size, testosterone concentration and number of children in human males

Objectives: The 2nd to 4th digit ratio (2D:4D) is thought to reflect exposure to androgens during foetal development. This study examined the relationship between low (more masculine) and high (more feminine) 2D:4D and body size at different stages of the life course, adult testosterone levels and number of children among males.Methods: Five hundred and fifty-eight men from rural Poland at the Mogielica Human Ecology Study Site participated in this study. Life history data and anthropometric measurements were collected. Salivary morning and evening testosterone levels among 110 men from the same population were measured.Results: Low 2D:4D was related to higher birth weight (p = 0.04), higher birth length (p = 0.01), higher body mass during childhood and adolescence (p = 0.01), higher BMI (borderline significance, p = 0.06), higher number of children among fathers (p = 0.04) and higher testosterone levels during adulthood (p = 0.04).Conclusions: This study shows, for the first time in a single population, that digit ratio is related to sub-adult body size at different stages of the life course, adult testosterone levels and number of children. The observed results suggest that digit ratio might be a valuable predictor of male body size and reproductive characteristics.

Salivary testosterone and immunoglobulin A were increased by resistance training in adults with Down syndrome

This study was designed to assess the influence of resistance training on salivary immunoglobulin A (IgA) levels and hormone profile in sedentary adults with Down syndrome (DS). A total of 40 male adults with DS were recruited for the trial through different community support groups for people with intellectual disabilities. All participants had medical approval for participation in physical activity. Twenty-four adults were randomly assigned to perform resistance training in a circuit with six stations, 3 days per week for 12 weeks. Training intensity was based on functioning in the eight-repetition maximum (8RM) test for each exercise. The control group included 16 age-, gender-, and BMI-matched adults with DS. Salivary IgA, testosterone, and cortisol levels were measured by ELISA. Work task performance was assessed using the repetitive weighted-box-stacking test. Resistance training significantly increased salivary IgA concentration (P=0.0120; d=0.94) and testosterone levels (P=0.0088; d=1.57) in the exercising group. Furthermore, it also improved work task performance. No changes were seen in the controls who had not exercised. In conclusion, a short-term resistance training protocol improved mucosal immunity response as well as salivary testosterone levels in sedentary adults with DS.