Effect of exercise on serum sex hormones in men: a 12-month randomized clinical trial

Advances in the treatment of functional male hypogonadism

INTRODUCTION

Functional hypogonadism is frequently found in obese men, particularly those with metabolic complications. Several possible therapeutic approaches could be considered.

AREAS COVERED

An extensive search on Medline, Embase, and Cochrane databases was performed to retrieve the available studies assessing the change of testosterone (T) and sexual function upon dieting or physical activity programs, as well as glucagon-like peptide 1 analogues. The role of lifestyle interventions associated with T replacement therapy (TRT) was also evaluated. The expert opinion provided here has been corroborated by meta-analyzing the results of the retrieved studies.

EXPERT OPINION

Current evidence supports the beneficial role of lifestyle modifications in increasing T and improving sexual function as a function of weight loss. While dieting programs are associated with greater effects in younger populations, physical exercise has major effects in older ones. Among the dieting programs, a very low-calorie ketogenic diet shows the best results; aerobic or endurance physical exercise perform similarly. The advantages of functional hypogonadism in lifestyle modifications are empowered by the association with TRT. Therefore, TRT may be a valuable complementary strategy to increase muscle mass and facilitate physical exercise while improving sexual symptoms, thus favoring the motivation and compliance for lifestyle interventions.

Lifelong exercise training promotes the remodelling of the immune system and prostate signalome in a rat model of prostate carcinogenesis

This work aimed to understand how lifelong exercise training promotes the remodelling of the immune system and prostate signalome in a rat model of PCa. Fifty-five male Wistar rats were divided into four groups: control sedentary, control exercised, induced PCa sedentary and induced PCa exercised. Exercised animals were trained in a treadmill for 53 weeks. Pca induction consisted on the sequential administration of flutamide, N-methyl-N-nitrosourea and testosterone propionate implants. Serum concentrations of C-reactive protein (CRP) and tumor necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK) were not different among groups. Peripheral levels of γδ T cells were higher in Pca exercised group than in the PCa sedentary group (p < 0.05). Exercise training also induced Oestrogen Receptor (ESR1) upregulation and Mitogen-activated Protein Kinase 13 (MAPK13) downregulation, changed the content of the phosphorylated (at Ser-104) form of this receptor (coded by the gene ESR1) and seemed to increase Erα phosphorylation and activity in exercised PCa rats when compared with sedentary PCa rats. Our data highlight the exercise-induced remodelling of peripheral lymphocyte subpopulations and lymphocyte infiltration in prostate tissue. Moreover, exercise training promotes the remodelling prostate signalome in this rat model of prostate carcinogenesis.

Effect of exercise on the hypothalamic-pituitary-gonadal axis in a rat model of Alzheimer's disease

Hypothalamic-pituitary-gonadal (HPG) axis dysregulation was suggested to play a crucial role in Alzheimer's disease (AD). This study investigated the effects of exercise on HPG hormones in an AD rat model, as a possible mechanism underlying the favorable effect of exercise on AD. Forty male Wistar albino rats 2-3 months old were subdivided randomly into two groups (n = 20 each): AD group (injected intraperitoneally with aluminum chloride (70 mg/kg/day) for 6 weeks) and Control group. Each group was subdivided into exercised or non-exercised group (n = 10 each). Exercised groups were subjected to a swimming protocol (60 min/day, 5 days/week, 4 weeks). Serum HPG hormones, hippocampal β-amyloid levels and Morris water-maze cognition were assessed. Results demonstrated higher levels of β-amyloid, gonadotropin releasing hormone (GnRH), luteinizing hormone (LH) and follicle stimulating hormone (FSH) together with lower testosterone levels and cognitive impairment in the AD rats compared to controls. Β-amyloid levels negatively correlated with testosterone levels and positively correlated with GnRH, LH and FSH among the AD rats. Higher testosterone and lower GnRH, LH, FSH and β-amyloid levels, as well as cognitive improvement, were observed in the exercised compared to non-exercised AD rats, suggesting a modulatory role of exercise training on AD-associated HPG axis dysregulation.

Circulating testosterone and dehydroepiandrosterone are associated with individual motor unit features in untrained and highly active older men

Long-term exercise training has been considered as an effective strategy to counteract age-related hormonal declines and minimise muscle atrophy. However, human data relating circulating hormone levels with motor nerve function are scant. The aims of the study were to explore associations between circulating sex hormone levels and motor unit (MU) characteristics in older men, including masters athletes competing in endurance and power events. Forty-three older men (mean ± SD age: 69.9 ± 4.6 years) were studied based on competitive status. The serum concentrations of dehydroepiandrosterone (DHEA), total testosterone (T) and estradiol were quantified using liquid chromatography mass spectrometry. Intramuscular electromyographic signals were recorded from vastus lateralis (VL) during 25% of maximum voluntary isometric contractions and processed to extract MU firing rate (FR), and motor unit potential (MUP) features. After adjusting for athletic status, MU FR was positively associated with DHEA levels (p = 0.019). Higher testosterone and estradiol were associated with lower MUP complexity; these relationships remained significant after adjusting for athletic status (p = 0.006 and p = 0.019, respectively). Circulating DHEA was positively associated with MU firing rate in these older men. Higher testosterone levels were associated with reduced MUP complexity, indicating reduced electrophysiological temporal dispersion, which is related to decreased differences in conduction times along axonal branches and/or MU fibres. Although evident in males only, this work highlights the potential of hormone administration as a therapeutic interventional strategy specifically targeting human motor units in older age.

Prefrontal cortex hemodynamic response to acute high intensity intermittent exercise during executive function processing

We investigated prefrontal cortex (PFC) hemodynamic response, through functional near infrared spectroscopy (fNIRS) during executive function (EF) processing in response to acute high intensity intermittent exercise (HIIE) in young adults. We also assessed the associated sex differences in the cognitive scores and related PFC hemodynamic functions in response to HIIE. 49 young healthy adult participants (32 women, 17 men) were randomly assigned to either control or HIIE intervention groups. HIIE group participants performed 4 × 4 minutes of HIIE on cycle ergometer with 3 minutes of active recovery between the bouts; control group relaxed for the time equivalent to intervention. fNIRS data was collected during the performance of the EF tests including Color Word Stroop Test (CWST) and Trail Making Test (TMT) in pre and post sessions in both the groups. Results indicated a significant change in the hemodynamic response in the form of increased oxygenated and decreased deoxygenated hemoglobin in the PFC areas specific to the EF tasks, with improved CWST and TMT scores in response to HIIE intervention. PFC activation was different in men and women in response to HIIE, however similar scores of task performance were observed in men and women during the performance of executive functions in response to HIIE. The study concludes that an acute HIIE session improves executive function which is associated with an increase activation of PFC. Sex differences exist in the activation of PFC in response to HIIE during EF processing. Our study adds to the current evidence regarding exercise and cognition.

Genome-wide association studies of 27 accelerometry-derived physical activity measurements identified novel loci and genetic mechanisms

Physical inactivity (PA) is an important risk factor for a wide range of diseases. Previous genome-wide association studies (GWAS), based on self-reported data or a small number of phenotypes derived from accelerometry, have identified a limited number of genetic loci associated with habitual PA and provided evidence for involvement of central nervous system in mediating genetic effects. In this study, we derived 27 PA phenotypes from wrist accelerometry data obtained from 88,411 UK Biobank study participants. Single-variant association analysis based on mixed-effects models and transcriptome-wide association studies (TWAS) together identified 5 novel loci that were not detected by previous studies of PA, sleep duration and self-reported chronotype. For both novel and previously known loci, we discovered associations with novel phenotypes including active-to-sedentary transition probability, light-intensity PA, activity during different times of the day and proxy phenotypes to sleep and circadian patterns. Follow-up studies including TWAS, colocalization, tissue-specific heritability enrichment, gene-set enrichment and genetic correlation analyses indicated the role of the blood and immune system in modulating the genetic effects and a secondary role of the digestive and endocrine systems. Our findings provided important insights into the genetic architecture of PA and its underlying mechanisms.

The impact of hypotestosteronemia on cardiometabolic effects of atorvastatin in men with hypercholesterolemia: a pilot study

BACKGROUND

Hypothyroidism, hyperprolactinemia, macroprolactinemia and low vitamin D status were found to impair pleiotropic effects of hypolipidemic agents. The aim of the current study was to investigate whether cardiometabolic effects of atorvastatin in men are determined by endogenous testosterone.

METHODS

We studied three groups of men matched for age, BMI, plasma lipids and blood pressure: 19 untreated subjects with low testosterone levels (group A), 19 normotestosteronemic men receiving testosterone preparations (group B) and 21 untreated men with testosterone levels within the reference range (group C). Because of coexistent hypercholesterolemia, all subjects were managed with atorvastatin (40 mg daily) for 6 months. Glucose homeostasis markers, plasma lipids, as well as circulating levels of testosterone, uric acid, high-sensitivity C-reactive protein (hsCRP), fibrinogen, homocysteine and 25-hydroxyvitamin D were determined at the beginning and at the end of the study.

RESULTS

At baseline, group A was more insulin-resistant and was characterized by higher levels of hsCRP, fibrinogen and homocysteine, and lower levels of 25-hydroxyvitamin D than the remaining groups of patients. Despite reducing total and low-density lipoprotein cholesterol and hsCRP levels in all treatment groups, this effect was stronger in groups B and C than in group A. In groups B and C, atorvastatin use was also associated with a decrease in uric acid, fibrinogen and homocysteine concentrations and with an increase in 25-hydroxyvitamin D levels. In group A, but not in the remaining groups, the drug decreased insulin sensitivity.

CONCLUSION

The obtained results suggest that untreated hypotestosteronemia may attenuate cardiometabolic effects of atorvastatin in men.

Effects of Exercise Training on Resting Testosterone Concentrations in Insufficiently Active Men: A Systematic Review and Meta-Analysis

ABSTRACT

Potter, NJ, Tomkinson, GR, Dufner, TJ, Walch, TJ, Roemmich, JN, Wilson, PB, and Fitzgerald, JS. Effects of exercise training on resting testosterone concentrations in insufficiently active men: a systematic review and meta-analysis. J Strength Cond Res 35(12): 3521-3528, 2021-The anabolic hormone testosterone plays a pivotal role in the healthy aging of men and tends to decline with age. The aims of this systematic review and meta-analysis were 2-fold: (a) to evaluate the effect of exercise training on resting total testosterone concentration in insufficiently active, apparently healthy men and (b) to determine whether the effects of exercise training differed by training mode, age, body mass status, or testosterone measure. Electronic databases (MEDLINE, Scopus, CINAHL, and SPORTDiscus) were systematically searched (up to and including October 22, 2020) for peer-reviewed randomized controlled trials (RCTs) meeting the following criteria: population (insufficiently active, apparently healthy men aged ≥18 years), intervention (exercise training [any modality at intensity of ≥4 metabolic equivalents] lasting a minimum of 4 weeks), control (insufficiently active men), and outcome (resting total testosterone concentration). Intervention effects, weighted by the inverse of the pooled variance, were calculated relative to the control group as standardized mean differences (SMDs). Eleven RCTs, representing 421 insufficiently active, apparently healthy men aged 19-75 years across 16 intervention groups who participated in aerobic, resistance, or combined training lasting a median of 12 weeks, were included in the analysis. Overall, exercise training had a negligible effect on resting total testosterone concentration (mean SMD [95% CI]: 0.00 [-0.20 to 0.20]). Subgroup analyses indicated that the effect of exercise training was not significantly affected by training mode, age, body mass status, or testosterone measure. Exercise training does not seem to affect resting total or free testosterone concentration in insufficiently active, eugonadal men.

Physical activity in relation to circulating hormone concentrations in 117,100 men in UK Biobank

PURPOSE

Physical activity may reduce the risk of some types of cancer in men. Biological mechanisms may involve changes in hormone concentrations; however, this relationship is not well established. Therefore, we aimed to investigate the associations of physical activity with circulating insulin-like growth factor-I (IGF-I), sex hormone-binding globulin (SHBG, which modifies sex hormone activity), and total and free testosterone concentrations, and the extent these associations might be mediated by body mass index (BMI).

METHODS

Circulating concentrations of these hormones and anthropometric measurements and self-reported physical activity data were available for 117,100 healthy male UK Biobank participants at recruitment. Objectively measured accelerometer physical activity levels were also collected on average 5.7 years after recruitment in 28,000 men. Geometric means of hormone concentrations were estimated using multivariable-adjusted analysis of variance, with and without adjustment for BMI.

RESULTS

The associations between physical activity and hormones were modest and similar for objectively measured (accelerometer) and self-reported physical activity. Compared to men with the lowest objectively measured physical activity, men with high physical activity levels had 14% and 8% higher concentrations of SHBG and total testosterone, respectively, and these differences were attenuated to 6% and 3% following adjustment for BMI.

CONCLUSION

Our results suggest that the associations of physical activity with the hormones investigated are, at most, modest; and following adjustment for BMI, the small associations with SHBG and total testosterone were largely attenuated. Therefore, it is unlikely that changes in these circulating hormones explain the associations of physical activity with risk of cancer either independently or via BMI.

Exercise effects on DNA methylation in EVL, CDKN2A (p14, ARF), and ESR1 in colon tissue from healthy men and women

Physical activity reduces risk of colon cancer persons by 20-30%. Aberrant methylation patterns are common epigenetic alterations in colorectal adenomas and cancers, and play a role in cancer initiation and progression. Alterations have been identified in normal colon tissue potentially representing a "field cancerization" process, where the normal colon is primed for carcinogenesis. Here, we investigate methylation patterns in three genes -Ena/VASP-like (EVL), (CDKN2A (p14, ARF)), and Estrogen Receptor-1 (ESR1)-in normal colon tissue collected at baseline and 12-months from 202 sedentary men and women, 40-75 years, enrolled in a randomized controlled trial testing an exercise intervention vs. control (http://clinicaltrials.gov/show/NCT00668161). Participants were randomized to moderate-to-vigorous intensity exercise, 60 minutes/day, 6 days/week for 12 months, or usual lifestyle. Sigmoid colon biopsies were obtained at baseline and 12-months, DNA extracted, and bisulphite converted. Droplet digital methylation-specific PCR was performed for EVL, p14ARF, and ESR1. Generalized estimating equations modification of linear regression were used to model relationships between intervention effects and candidate gene methylation levels, adjusting for possible confounders.There were no statistically significant differences between methylation patterns at 12-months between exercisers and controls. ESR1 methylation patterns differed by sex: women -10.58% (exercisers) +11.10% (controls); men +5.54% (exercisers), -8.16% (controls); (P=0.05), adjusting for BMI and age. There were no statistically significant changes in methylation patterns in any gene stratified by change in VO₂max, or by minutes/week of exercise.While no statistically significant differences were found in gene methylation patterns comparing exercises vs. controls, 12-month exercise effects on ESR1 methylation differed by sex, warranting further study.

Why exercise has a crucial role in cancer prevention, risk reduction and improved outcomes

INTRODUCTION

Exercise is one of several factors known to lower the risk of developing cancer, as well as improve outcomes in patients already diagnosed. People who exercise after cancer have lower rates of cancer complications, treatment toxicities, relapse and improved survival. This review highlights the supportive data and biochemical processes, which explain these potential benefits.

SOURCES OF DATA

PubMed, Embase, Medline and Cochrane libraries were searched for papers which addressed the effects of exercise and physical activity on cancer for this review. The search terms used were physical activity, exercise and cancer up to February 2021. We also referred to the background research required for international exercise intervention study involving men with prostate cancer (INTERVAL-GAP4) and scrutinized references within the robust papers published on this subject to ensure we did not miss any clinically studies. One hundred and eighty eight papers were included.

AREAS OF AGREEMENT

Exercise programmes mitigate many of the complications and risks associated with cancer, particularly thromboembolism, fatigue, weight gain, arthralgia, cognitive impairment and depression.

AREAS OF CONTROVERSY

Molecular and biomarker changes, resulting from exercise, suggest that exercise elicits beneficial changes in insulin-related pathways, down-regulates inflammation and serum oestrogen levels, and enhances oxidative, immune and cellular repair pathways. Nonetheless, the evidence remains preliminary.

GROWING POINTS

The timing, intensity and challenges of prehabilitation, adjunct and rehabilitation exercise programmes are being increasingly understood but their implementation remains sporadic.

AREAS FOR DEVELOPING RESEARCH

More robust clinical trial data are needed to substantiate a causal effect of exercise on overall and cancer-specific survival. These studies are ongoing. Research evaluating the most cost-efficient ways of incorporating prehabilitation, adjunct and rehabilitation programmes into routine practice would be helpful to funding bodies and health care strategists.

Potential Physiological and Cellular Mechanisms of Exercise That Decrease the Risk of Severe Complications and Mortality Following SARS-CoV-2 Infection

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has unmasked mankind's vulnerability to biological threats. Although higher age is a major risk factor for disease severity in COVID-19, several predisposing risk factors for mortality are related to low cardiorespiratory and metabolic fitness, including obesity, cardiovascular disease, diabetes, and hypertension. Reaching physical activity (PA) guideline goals contribute to protect against numerous immune and inflammatory disorders, in addition to multi-morbidities and mortality. Elevated levels of cardiorespiratory fitness, being non-obese, and regular PA improves immunological function, mitigating sustained low-grade systemic inflammation and age-related deterioration of the immune system, or immunosenescence. Regular PA and being non-obese also improve the antibody response to vaccination. In this review, we highlight potential physiological, cellular, and molecular mechanisms that are affected by regular PA, increase the host antiviral defense, and may determine the course and outcome of COVID-19. Not only are the immune system and regular PA in relation to COVID-19 discussed, but also the cardiovascular, respiratory, renal, and hormonal systems, as well as skeletal muscle, epigenetics, and mitochondrial function.

Association of Physical Activity with the Risk of Hepatocellular Carcinoma in Patients with Chronic Hepatitis B

Simple Summary

Although viral replication in patients with a chronic hepatitis B (CHB) infection is effectively suppressed by potent antiviral therapy such as entecavir or tenofovir, the risk of hepatocellular carcinoma (HCC) development in CHB patients cannot be totally eliminated. Thus, control of modifiable risk factors for HCC development such as lifestyle modification is important to minimize the HCC risk. In this study, we analyzed a nationwide population-based cohort to evaluate whether there is a significant association between physical activity and development of HCC in CHB patients treated with entecavir or tenofovir. Results in this study suggest that physical activity was significantly associated with a lower risk of HCC development in CHB patients treated with potent antiviral therapy. Increasing physical activity can have beneficial outcomes on HCC development in CHB patients treated with entecavir or tenofovir.

Abstract

Background and Aims: In the general population, previous studies reported that physical activity was associated with risk of hepatocellular carcinoma (HCC) development. However, it is unclear whether physical activity is associated with risk of HCC development in patients with chronic hepatitis B (CHB). We aimed to elucidate the association between physical activity and risk of HCC development in CHB patients. Methods: This nationwide cohort study involved treatment-naive patients with CHB (n = 9727) who started treatment with entecavir or tenofovir and answered self-reported questionnaires between January 2012 and December 2017, using data from the Korean National Health Insurance Service database. The primary endpoint was development of HCC. Multivariable Cox regression and competing risk analyses were used. Results: During a median follow-up of 3.1 years, cumulative HCC incidence rates were 8.3%. There was an inverse association between physical activity and the risk of HCC (p < 0.001). Patients with 1000–1500 metabolic equivalent task (MET)-min/week, compared to those without physical activity, showed a significantly lower risk of HCC in both patients without cirrhosis (adjusted hazard ratio [aHR] 0.66, p = 0.02) and patients with cirrhosis (aHR 0.61, p = 0.02). In patients who were younger (<60), male, without diabetes, and with high BMI, amounts of physical activity of 1000–1500 MET-min/week showed an inverse association with the risk of HCC (aHR 0.65, 0.63, 0.65, and 0.64, respectively, all p < 0.05). Conclusion: Physical activity was significantly associated with a low risk of HCC in CHB patients treated with entecavir or tenofovir.

Exercise-induced gene expression changes in skeletal muscle of old mice

Exercise is believed to be beneficial for skeletal muscle functions across all ages. Regimented exercise is often prescribed as an effective treatment/prophylaxis for age-related loss of muscle mass and function, known as sarcopenia, and plays an important role in the maintenance of mobility and functional independence in the elderly. However, response to exercise declines with aging, resulting in limited gain of muscle strength and endurance. These changes likely reflect age-dependent alterations in transcriptional response underlying the muscular adaptation to exercise. The exact changes in gene expression accompanying exercise, however, are largely unknown, and elucidating them is of a great clinical interest for understanding and optimizing the exercise-based therapies for sarcopenia. In order to characterize the exercise-induced transcriptomic changes in aged muscle, a paired-end RNA sequencing was performed on rRNA-depleted total RNA extracted from the gastrocnemius muscles of 24 months-old mice after 8 weeks of regimented exercise (exercise group) or no formal exercise program (sedentary group). Differential gene expression analysis of aged skeletal muscle revealed upregulations in the group of genes involved in neurotransmission and neuroexcitation, as well as equally notable absence of anabolic gene upregulations in the exercise group. In particular, genes encoding the transporters and receptor components of glutaminergic transmission were significantly upregulated in exercised muscles, as exemplified by Gria 1, Gria 2 and Grin2c encoding glutamate receptor 1, 2 and 2C respectively, Grin1 and Grin2b encoding N-methyl-d-aspartate receptors (NMDARs), Nptx1 responsible for glutaminergic receptor clustering, and Slc1a2 and Slc17a7 regulating synaptic uptake of glutamate. These changes were accompanied by an increase in the post-synaptic density of NMDARs and acetylcholine receptors (AChRs), as well as their innervation at neuromuscular junctions (NMJs). These results suggest that neural responses predominate the adaptive response of aged skeletal muscle to exercise, and indicate a possibility that glutaminergic transmission at NMJs may be present and responsible for synaptic protection and neural remodeling accompanying the exercise-induced functional enhancement in aged skeletal muscle. In addition, the absence of upregulations in the anabolic pathways highlights them as the area of potential pharmacological targeting for optimizing exercise-led sarcopenia therapy.

Testosterone and Dihydrotestosterone Changes in Male and Female Athletes Relative to Training Status

PURPOSE

To establish if training volume was associated with androgen baselines and androgen responsiveness to acute exercise.

METHODS

During a "high-volume" training phase, 28 cyclists (14 men and 14 women) undertook oxygen-uptake and maximal-work-capacity testing. Two days later, they completed a repeat-sprint protocol, which was repeated 3 weeks later during a "low-volume" phase. Blood and saliva samples were collected before and after (+5 and +60 min) the repeat-sprint protocol. Blood was assayed for total testosterone (TT), free testosterone (FT), and dihydrotestosterone (DHT) and saliva, for testosterone and DHT.

RESULTS

Pretrial TT, FT, and DHT concentration was greater for males (P < .001, large effect size differences), and in both genders TT, DHT, and saliva for DHT was higher during high-volume loading (moderate to large effect size). Area-under-the-curve analysis revealed larger TT, FT, and DHT responses to the repeat-sprint protocol among females, and high-volume training was linked to larger TT, DHT, and saliva for DHT responses (moderate to large effect size). Baseline TT and FT correlated with oxygen uptake and work capacity in both genders (P < .05).

CONCLUSION

DHT showed no acute performance correlation but was responsive to volume of training, particularly in females. This work informs on timelines and relationships of androgenic biomarkers in males and females across different training loads, adding to the complexity that should be considered in interpretation thereof. The authors speculate that testosterone may impact acute performance via behavioral mechanisms of motivation and attention; DHT, via training volume-induced androgenic promotion, may facilitate long-term adaptive changes, especially for females.

Enhanced small neutral but not branched chain amino acid transport after epigenetic sodium coupled neutral amino acid transporter-2 (SNAT2) cDNA expression in myoblasts

BACKGROUND

Skeletal muscle mass and function are partly maintained by the supply of amino acids, altered amino acid transport is an important cause of frailty that can lead to decreased independence with increasing age and slow trauma recovery. The system-A sodium coupled neutral amino acid transporter (SNAT)-2 coded by gene family SLC38A2 generates a 506 amino acid 56 kDa protein that is an important transporter of amino acids in skeletal muscle. Ageing is associated with a decrease in expression of SNAT2 transporters.

METHODS

In this study, we used the C2C12 cell line, using myoblast cells and cells differentiated into myotubes. We investigated if the expression of SNAT2 DNA would enhance intracellular amino acid levels and increase their availability for protein synthesis.

RESULTS

In control myoblasts and myotubes, we found significantly decreased expression of SNAT2 (6.5× decrease, n = 4 per group, P < 0.05) in myotubes than found in myoblasts. After transfection with a SNAT2-eGFP cDNA plasmid, C2C12 myoblasts significantly increased perinuclear punctate SNAT2-eGFP expression that persisted and was more cytoplasmic after differentiation into myotubes. Interestingly, transfected cells were significantly more responsive to the hormone 5α-dihydrotestosterone (DHT, 4.5 nM, by 1.6×, n = 3 per group, P < 0.04). Starvation significantly enhanced the amino acid C¹⁴ -MeAIB transport (1.7×, n = 3 per group, P < 0.05) indicating increased function of SNAT2. Inhibiting SNAT2 with high concentrations of MeAIB (3.3 or 5 mM) significantly reduced C¹⁴ -Isoleucine transport by L-type amino acid transporter (LAT2, 52.8% and 77%, respectively, n = 3 per group, P < 0.05). However, there was no increase in the LAT2 transport of C¹⁴ -isoleucine detectable in SNAT2-eGFP transfected cells after DHT (4.5 nM) exposure. This indicated that small amino acid availability was not rate limiting to LAT2 function in myoblasts.

CONCLUSIONS

Overall, these data show that transfection of SNAT2-eGFP expression enhanced its function following starvation and treatment with physiological levels of DHT. Enhanced SNAT2 expression in muscle cells offers a viable epigenetic target in pathological conditions associated with altered amino acid transport.

Regular aerobic exercise improves sexual function assessed by the Aging Males' Symptoms questionnaire in adult men

The leading cause of aging-induced male-specific disorders such as physical, mental and/or sexual symptoms is testosterone deficiency. Although aerobic exercise is suggested to improves circulating testosterone levels, physical fitness, depressive symptoms, and sexual function, the effect of regular aerobic exercise on aging-induced disorders has not yet been clarified. Here we performed cross-sectional and interventional studies to identify the effect of aerobic exercise on aging-induced disorders assessed by the Aging Males' Symptoms questionnaire (AMS). In study 1, the relationship between aerobic exercise capacity (i.e. peak oxygen consumption) and AMS scores were cross-sectionally examined in 169 adult men. In study 2, the effect of a 12-week regular aerobic exercise on AMS scores was longitudinally investigated in 18 adult men. In study 1, the AMS-total, AMS-somatic, AMS-psychological, and AMS-sexual scores were significantly correlated to aerobic exercise capacity even after considering age and testosterone levels. In study 2, 12-week aerobic exercise training significantly improved AMS-sexual and tended to improve AMS-total scores. Additionally, an increase in vigorous physical activity was correlated to improve in the AMS-sexual score. These results suggest that regular aerobic exercise is an effective strategy to improve aging-induced disorders in men.

Optimizing Skeletal Muscle Anabolic Response to Resistance Training in Aging

Loss of muscle mass and strength with aging, also termed sarcopenia, results in a loss of mobility and independence. Exercise, particularly resistance training, has proven to be beneficial in counteracting the aging-associated loss of skeletal muscle mass and function. However, the anabolic response to exercise in old age is not as robust, with blunted improvements in muscle size, strength, and function in comparison to younger individuals. This review provides an overview of several physiological changes which may contribute to age-related loss of muscle mass and decreased anabolism in response to resistance training in the elderly. Additionally, the following supplemental therapies with potential to synergize with resistance training to increase muscle mass are discussed: nutrition, creatine, anti-inflammatory drugs, testosterone, and growth hormone (GH). Although these interventions hold some promise, further research is necessary to optimize the response to exercise in elderly patients.

No relationship between the digit ratios (2D:4D) and salivary testosterone change: Study on men under an acute exercise

The digit ratio (2D:4D) is said to be a potential marker of exposure to prenatal sex steroids. Some studies suggest that the 2D:4D is also linked with the testosterone response to challenging situations due to organizational effect of prenatal hormonal milieu on adult endocrine functioning. However, up to date, there were only four studies (conducted on small samples) that examined the 2D:4D and the testosterone response to a challenging situation (i.e. physical exertion or aggressive context). Here, we examined the relationship between the 2D:4D and the testosterone change under an acute exercise among 97 men. We found that the digit ratios (the right 2D:4D, the left 2D:4D, and the right minus left 2D:4D) were neither predictors of pre-exercise testosterone, nor the change in testosterone level after a cycling task. Our results add a contradictory to previous studies evidence in a discussion on the links of the 2D:4D and the testosterone change.

The therapeutic potential of exercise for neuropsychiatric diseases: A review

Exercise is known to have a myriad of health benefits. There is much to be learned from the effects of exercise and its potential for prevention, attenuation and treatment of multiple neuropsychiatric diseases and behavioral disorders. Furthermore, recent data and research on exercise benefits with respect to major health crises, such as, that of opioid and general substance use disorders, make it very important to better understand and review the mechanisms of exercise and how it could be utilized for effective treatments or adjunct treatments for these diseases. In addition, mechanisms, epigenetics and sex differences are examined and discussed in terms of future research implications.

Testosterone therapy induces molecular programming augmenting physiological adaptations to resistance exercise in older men

BACKGROUND

The andropause is associated with declines in serum testosterone (T), loss of muscle mass (sarcopenia), and frailty. Two major interventions purported to offset sarcopenia are anabolic steroid therapies and resistance exercise training (RET). Nonetheless, the efficacy and physiological and molecular impacts of T therapy adjuvant to short-term RET remain poorly defined.

METHODS

Eighteen non-hypogonadal healthy older men, 65-75 years, were assigned in a random double-blinded fashion to receive, biweekly, either placebo (P, saline, n = 9) or T (Sustanon 250 mg, n = 9) injections over 6 week whole-body RET (three sets of 8-10 repetitions at 80% one-repetition maximum). Subjects underwent dual-energy X-ray absorptiometry, ultrasound of vastus lateralis (VL) muscle architecture, and knee extensor isometric muscle force tests; VL muscle biopsies were taken to quantify myogenic/anabolic gene expression, anabolic signalling, muscle protein synthesis (D₂ O), and breakdown (extrapolated).

RESULTS

Testosterone adjuvant to RET augmented total fat-free mass (P=0.007), legs fat-free mass (P=0.02), and appendicular fat-free mass (P=0.001) gains while decreasing total fat mass (P=0.02). Augmentations in VL muscle thickness, fascicle length, and quadriceps cross-section area with RET occured to a greater extent in T (P < 0.05). Sum strength (P=0.0009) and maximal voluntary contract (e.g. knee extension at 70°) (P=0.002) increased significantly more in the T group. Mechanistically, both muscle protein synthesis rates (T: 2.13 ± 0.21%·day^-1 vs. P: 1.34 ± 0.13%·day^-1 , P=0.0009) and absolute breakdown rates (T: 140.2 ± 15.8 g·day^-1 vs. P: 90.2 ± 11.7 g·day^-1 , P=0.02) were elevated with T therapy, which led to higher net turnover and protein accretion in the T group (T: 8.3 ± 1.4 g·day^-1 vs. P: 1.9 ± 1.2 g·day^-1 , P=0.004). Increases in ribosomal biogenesis (RNA:DNA ratio); mRNA expression relating to T metabolism (androgen receptor: 1.4-fold; Srd5a1: 1.6-fold; AKR1C3: 2.1-fold; and HSD17β3: two-fold); insulin-like growth factor (IGF)-1 signalling [IGF-1Ea (3.5-fold) and IGF-1Ec (three-fold)] and myogenic regulatory factors; and the activity of anabolic signalling (e.g. mTOR, AKT, and RPS6; P < 0.05) were all up-regulated with T therapy. Only T up-regulated mitochondrial citrate synthase activity (P=0.03) and transcription factor A (1.41 ± 0.2-fold, P=0.0002), in addition to peroxisome proliferator-activated receptor-γ co-activator 1-α mRNA (1.19 ± 0.21-fold, P=0.037).

CONCLUSIONS

Administration of T adjuvant to RET enhanced skeletal muscle mass and performance, while up-regulating myogenic gene programming, myocellular translational efficiency and capacity, collectively resulting in higher protein turnover, and net protein accretion. T coupled with RET is an effective short-term intervention to improve muscle mass/function in older non-hypogonadal men.

The complex and bidirectional interaction between sex hormones and exercise performance in team sports with emphasis on soccer

A constant topic reported in the lay press is the effect of sex hormones on athletic performance and their abuse by athletes in their effort to enhance their performance or to either boost or sidestep their hard, protracted, and demanding training regimens. However, an issue that it is almost never mentioned is that the athletic training itself affects the endogenous production of androgens and estrogens, while also being affected by them. Among sports, soccer is a particularly demanding activity, soccer players needing to possess high levels of endurance, strength, and both aerobic and anaerobic capacity, with the very great physiological, metabolic, physical, and psychological exertion required of the players being both influenced by sex steroids and, reciprocally, affecting sex steroid levels. This review focuses on the currently available knowledge regarding the complex relationship between athletic training and competition and sex steroid hormone adaptation to the demands of the exercise effort. In the first part of the review, we will examine the effects of endogenous testosterone, estrogen, and adrenal androgens on athletic performance both during training and in competition. In the second part, we will explore the reciprocal effects of exercise on the endogenous sex hormones while briefly discussing the recent data on anabolic androgenic steroid abuse.

Higher circulating androgens and higher physical activity levels are associated with less central adiposity and lower risk of cardiovascular death in older men

OBJECTIVE

Low endogenous sex hormones and low physical activity (PA) levels have been associated with CVD risk. Whether these interact to influence CVD outcomes remains unclear. We assessed whether sex hormone concentrations and PA were additively associated with lower central adiposity and CVD risk.

PATIENTS

3351 community-dwelling men, mean age 77 years.

MEASUREMENTS

Baseline testosterone (T), dihydrotestosterone (DHT) and oestradiol (E2) were assayed. Levels of PA were ascertained by questionnaire. Men were stratified using median splits into high hormone + high PA (H/H), high hormone + low PA (H/L); low hormone + high PA (L/H) and low hormone + low PA (L/L) groups.

RESULTS

A total of 865 CVD events and 499 CVD deaths occurred during 10-year mean follow-up. Men with higher T, DHT or SHBG and higher PA had the lowest BMI, waist circumference and risk of metabolic syndrome. Men with higher T had the lowest risk of incident CVD events, irrespective of PA level. Men with higher T or DHT and higher PA had the lowest risk of dying from CVD (eg, hazard ratios for T/PA H/H 0.76 P = 0.031; H/L 0.85 P = 0.222; L/H 0.80 P = 0.075; L/L 1.00).

CONCLUSION

Higher circulating androgens and higher PA were associated with less central adiposity at baseline and fewer CVD deaths during follow-up. These findings are consistent with a potential additive effect of androgens and PA on cardiometabolic outcomes in older men.

Energy balance and gastrointestinal cancer: risk, interventions, outcomes and mechanisms

Obesity increases the risk of multiple gastrointestinal cancers and worsens disease outcomes. Conversely, strong inverse associations have emerged between physical activity and colon cancer and possibly other gastrointestinal malignancies. The effect of weight loss interventions - such as modifications of diet and/or physical activity or bariatric surgery - remains unclear in patients who are obese and have gastrointestinal cancer, although large clinical trials are underway. Human intervention studies have already shed light on potential mechanisms underlying the energy balance-cancer relationship, with preclinical models supporting emerging pathway effects. Central to interventions that reduce obesity or increase physical activity are pluripotent cancer-preventive effects (including reduced systemic and adipose tissue inflammation and angiogenesis, altered adipokine levels and improved insulin resistance) that directly interface with the hallmarks of cancer. Other mechanisms, such as DNA repair, oxidative stress and telomere length, immune function, effects on cancer stem cells and the microbiome, could also contribute to energy balance effects on gastrointestinal cancers. Although some mechanisms are well understood (for instance, systemic effects on inflammation and insulin signalling), other areas remain unclear. The current state of knowledge supports the need to better integrate mechanistic approaches with preclinical and human studies to develop effective, personalized diet and exercise interventions to reduce the burden of obesity on gastrointestinal cancer.

Intense Exercise for Survival among Men with Metastatic Castrate-Resistant Prostate Cancer (INTERVAL-GAP4): a multicentre, randomised, controlled phase III study protocol

INTRODUCTION

Preliminary evidence supports the beneficial role of physical activity on prostate cancer outcomes. This phase III randomised controlled trial (RCT) is designed to determine if supervised high-intensity aerobic and resistance exercise increases overall survival (OS) in patients with metastatic castrate-resistant prostate cancer (mCRPC).

METHODS AND ANALYSIS

Participants (n=866) must have histologically documented metastatic prostate cancer with evidence of progressive disease on androgen deprivation therapy (defined as mCRPC). Patients can be treatment-naïve for mCRPC or on first-line androgen receptor-targeted therapy for mCRPC (ie, abiraterone or enzalutamide) without evidence of progression at enrolment, and with no prior chemotherapy for mCRPC. Patients will receive psychosocial support and will be randomly assigned (1:1) to either supervised exercise (high-intensity aerobic and resistance training) or self-directed exercise (provision of guidelines), stratified by treatment status and site. Exercise prescriptions will be tailored to each participant's fitness and morbidities. The primary endpoint is OS. Secondary endpoints include time to disease progression, occurrence of a skeletal-related event or progression of pain, and degree of pain, opiate use, physical and emotional quality of life, and changes in metabolic biomarkers. An assessment of whether immune function, inflammation, dysregulation of insulin and energy metabolism, and androgen biomarkers are associated with OS will be performed, and whether they mediate the primary association between exercise and OS will also be investigated. This study will also establish a biobank for future biomarker discovery or validation.

ETHICS AND DISSEMINATION

Validation of exercise as medicine and its mechanisms of action will create evidence to change clinical practice. Accordingly, outcomes of this RCT will be published in international, peer-reviewed journals, and presented at national and international conferences. Ethics approval was first obtained at Edith Cowan University (ID: 13236 NEWTON), with a further 10 investigator sites since receiving ethics approval, prior to activation.

TRIAL REGISTRATION NUMBER

NCT02730338.

Physical Activity and Pancreatic Cancer Risk among Urban Chinese: Results from Two Prospective Cohort Studies

Background: Associations between physical activity and pancreatic cancer risk are unclear.Methods: In two prospective cohort studies, the Shanghai Women's Health Study and Shanghai Men's Health Study, physical activity and other information were collected at the baseline interview of 72,451 women and 60,037 men. Participants were followed up through annual linkage with a cancer registry in combination with in-person interviews taking place every 2 to 4 years.Results: We identified 225 female and 159 male cases during a median follow up of 16.1 and 10.3 years, respectively. Adult exercise participation was significantly associated with a decreased pancreatic cancer risk in men [hazard ratio (HR), 95% confidence interval (CI): 0.71 (0.50-1.00)]. Meeting the recommended minimum exercise threshold to achieve health benefits of 150 min/week of moderate-intensity or 75 min/week of vigorous-intensity exercise was associated with further decreased pancreatic cancer risk [HR (95% CI): 0.59 (0.40-0.87)]. We also observed an inverse association between adolescent physical activity and pancreatic cancer risk in men [HR (95% CI): 0.54 (0.33-0.90)]. Exercise throughout one's lifetime was associated with a 68% decrease in pancreatic cancer risk [HR (95% CI): 0.32 (0.16-0.66)]. No significant association was found in women. Adult non-exercise daily activity and occupational activity were not associated with pancreatic cancer risk in either men or women.Conclusions: Adult exercise and adolescent physical activity were significantly associated with a decreased pancreatic cancer risk in men but not in women.Impact: These findings underscore the importance of investigating the possible modification by sex on the exercise and pancreatic cancer risk association. Cancer Epidemiol Biomarkers Prev; 27(4); 479-87. ©2018 AACR.

Circulating sex hormones in relation to anthropometric, sociodemographic and behavioural factors in an international dataset of 12,300 men

INTRODUCTION

Sex hormones have been implicated in the etiology of a number of diseases. To better understand disease etiology and the mechanisms of disease-risk factor associations, this analysis aimed to investigate the associations of anthropometric, sociodemographic and behavioural factors with a range of circulating sex hormones and sex hormone-binding globulin.

METHODS

Statistical analyses of individual participant data from 12,330 male controls aged 25-85 years from 25 studies involved in the Endogenous Hormones Nutritional Biomarkers and Prostate Cancer Collaborative Group. Analysis of variance was used to estimate geometric means adjusted for study and relevant covariates.

RESULTS

Older age was associated with higher concentrations of sex hormone-binding globulin and dihydrotestosterone and lower concentrations of dehydroepiandrosterone sulfate, free testosterone, androstenedione, androstanediol glucuronide and free estradiol. Higher body mass index was associated with higher concentrations of free estradiol, androstanediol glucuronide, estradiol and estrone and lower concentrations of dihydrotestosterone, testosterone, sex hormone-binding globulin, free testosterone, androstenedione and dehydroepiandrosterone sulfate. Taller height was associated with lower concentrations of androstenedione, testosterone, free testosterone and sex hormone-binding globulin and higher concentrations of androstanediol glucuronide. Current smoking was associated with higher concentrations of androstenedione, sex hormone-binding globulin and testosterone. Alcohol consumption was associated with higher concentrations of dehydroepiandrosterone sulfate, androstenedione and androstanediol glucuronide. East Asians had lower concentrations of androstanediol glucuronide and African Americans had higher concentrations of estrogens. Education and marital status were modestly associated with a small number of hormones.

CONCLUSION

Circulating sex hormones in men are strongly associated with age and body mass index, and to a lesser extent with smoking status and alcohol consumption.

Enhanced Coupling Within Gonadotropic and Adrenocorticotropic Axes by Moderate Exercise in Healthy Men

CONTEXT

Exercise elicits incompletely defined adaptations of metabolic and endocrine milieu, including the gonadotropic and corticotropic axes.

OBJECTIVE

To quantify the impact of acute exercise on coordinate luteinizing hormone (LH) and testosterone (T) and adrenocorticotropic hormone (ACTH) and cortisol secretion in healthy men in relation to age.

PARTICIPANTS AND DESIGN

Prospectively randomized, within-subject crossover study in 23 men aged 19 to 77 years old. Subjects underwent rest and 30 minutes of mixed exercise at 65% of maximal aerobic capacity with 10-minute blood sampling between 7:00 am and 1:00 pm, 2 weeks apart.

MAIN OUTCOME MEASURES

Incremental changes in LH, T, ACTH, and cortisol concentrations, the feedforward and feedback strength between exercise and rest, quantified by approximate entropy (ApEn), and bihormonal synchrony, quantitated by cross-ApEn.

RESULTS

Mean hourly exercise-minus-rest LH and ACTH increments increased from -0.055 ± 0.187 to 0.755 ± 0.245 IU/L (P = 0.003) and from 2.9 ± 2.2 to 71.2 ± 16.1 ng/L (P < 0.0001), respectively, during exercise. T and cortisol increments increased concurrently from -9.6 ± 16.7 to 47.6 ± 17.1 ng/dL (P < 0.0001) and 0.45 ± 0.76 to 7.27 ± 0.64 µg/dL (P < 0.0001), respectively. During exercise, feedforward and feedback LH-T and ACTH-cortisol cross-ApEn decreased markedly quantifying enhanced hormonal coupling.

CONCLUSIONS

Acute moderate mixed exercise in healthy men rapidly enhances feedforward LH-T and ACTH-cortisol coordination and reciprocal feedback within the gonadotropic and corticotropic axes. In principle, enhancement of both LH-T and ACTH-cortisol secretory synchrony by exercise could reflect augmented coupling between brain-testicular and brain-adrenal neural outflow.

Impact of physical activity and exercise on male reproductive potential: a new assessment questionnaire

Male athletes in general are subjected to the same causes of infertility as the general population, but sports practice itself may be possibly an additional infertility factor or, at least an aggravating factor for a previously existing fertility condition; on the contrary, being physically active has been hypothesized to favor hormonal and seminological processes and could be beneficial for fertility. In this relationship, the different inherent parameters of physical activity-exercise (training volume, intensity, objective, organization and frequency) are of paramount importance. Therefore, this review discusses both the negative and positive impact of physical exercise on the male reproductive potential. Clear knowledge is lacking on this topic as incongruences exist due to the fact that studies lack standardization in assessment tools or research protocols. So that future studies can reveal more information regarding exercising male fertility, we introduce a unique questionnaire developed with the intent to help standardize future studies on male fertility and exercise.

Dihydrotestosterone: Biochemistry, Physiology, and Clinical Implications of Elevated Blood Levels

Benefits associated with lowered serum DHT levels after 5α-reductase inhibitor (5AR-I) therapy in men have contributed to a misconception that circulating DHT levels are an important stimulus for androgenic action in target tissues (e.g., prostate). Yet evidence from clinical studies indicates that intracellular concentrations of androgens (particularly in androgen-sensitive tissues) are essentially independent of circulating levels. To assess the clinical significance of modest elevations in serum DHT and the DHT/testosterone (T) ratio observed in response to common T replacement therapy, a comprehensive review of the published literature was performed to identify relevant data. Although the primary focus of this review is about DHT in men, we also provide a brief overview of DHT in women. The available published data are limited by the lack of large, well-controlled studies of long duration that are sufficiently powered to expose subtle safety signals. Nonetheless, the preponderance of available clinical data indicates that modest elevations in circulating levels of DHT in response to androgen therapy should not be of concern in clinical practice. Elevated DHT has not been associated with increased risk of prostate disease (e.g., cancer or benign hyperplasia) nor does it appear to have any systemic effects on cardiovascular disease safety parameters (including increased risk of polycythemia) beyond those commonly observed with available T preparations. Well-controlled, long-term studies of transdermal DHT preparations have failed to identify safety signals unique to markedly elevated circulating DHT concentrations or signals materially different from T.

Exercise-induced biochemical changes and their potential influence on cancer: a scientific review

AIM

To review and discuss the available international literature regarding the indirect and direct biochemical mechanisms that occur after exercise, which could positively, or negatively, influence oncogenic pathways.

METHODS

The PubMed, MEDLINE, Embase and Cochrane libraries were searched for papers up to July 2016 addressing biochemical changes after exercise with a particular reference to cancer. The three authors independently assessed their appropriateness for inclusion in this review based on their scientific quality and relevance.

RESULTS

168 papers were selected and categorised into indirect and direct biochemical pathways. The indirect effects included changes in vitamin D, weight reduction, sunlight exposure and improved mood. The direct effects included insulin-like growth factor, epigenetic effects on gene expression and DNA repair, vasoactive intestinal peptide, oxidative stress and antioxidant pathways, heat shock proteins, testosterone, irisin, immunity, chronic inflammation and prostaglandins, energy metabolism and insulin resistance.

SUMMARY

Exercise is one of several lifestyle factors known to lower the risk of developing cancer and is associated with lower relapse rates and better survival. This review highlights the numerous biochemical processes, which explain these potential anticancer benefits.

The impact of duration on effectiveness of exercise, the implication for periodization of training and goal setting for individuals who are overfat, a meta-analysis

Given the assumption that all methods of exercise, e.g., endurance (ET), resistance (RT), or combination of both (E+R), can induce a beneficial effect size (ES) for changes in body composition and health status of individuals who are overfat. Thus the aim and purpose of this study is to evaluate the current body of knowledge to address the question as to the impact that the duration of exercise has on its relative effectiveness for inducing health and body compositional changes in individuals who are overfat to assist with developing periodized exercise protocols and establishing short and long term goals. A tiered meta-analysis of 92-studies and 200-exercise groupings were used for establishing pooled ES within and between groupings based on the increments of 4-week of duration and study designs of ≤8, 9-16, 17-23, 24-36, and ≥36 weeks. Analysis based on random-effect of response indicates a continuum of effectiveness within and between ET, RT and E+R based on duration. Where beneficial effectiveness is not indicated for any measures until after 8-weeks of continuous training with progressive effectiveness being noted in changes to cardiorespiratory fitness, inflammatory cytokines, and alteration of metabolic status from 12-weeks through 32-weeks of continuous training. Results indicate a greater ES for RT and E+R versus ET early in intervention that equalizes with longer durations. Supporting the use of RT and E+R within a periodized program. And secondarily, goals should be established first on performance gains and second body composition or health status modifications for the individual who is overfat.

Relationship Between Aerobic Fitness, the Serum IGF-1 Profiles of Healthy Young Adult African American Males, and Growth of Prostate Cancer Cells

The growth of prostate tumors is mediated by the bioavailability of androgens and insulin-like growth factors. This study tested the hypothesis that healthy young adult African American men exhibiting low aerobic capacity (fitness) have serum insulin-like growth Factor-1 (IGF-1) and testosterone levels that promote growth of prostate cancer cells. A cross-sectional data research design was used to study groups of 18- to 26-year-old healthy men exhibiting low and moderate aerobic fitness, based on their peak oxygen consumption (VO_2peak). The individual serum levels of IGF-1, IGF-1 binding protein-3 (IGFBP-3), and testosterone were measured. In vitro growth of androgen-dependent LNCaP prostate tumor cells was measured after incubation in culture medium fortified with each subject's serum. Aerobic capacity was significantly greater in the moderate-fitness group than in the low-fitness group without an intergroup difference in body mass index. The serum IGF-1 concentration was significantly higher in the low-fitness group in the absence of an intergroup difference in serum testosterone. The serum IGFBP-3 concentration was significantly lower in the low-fitness group. Prostate tumor cell growth was significantly greater in the cultures incubated in media containing the sera of the low-fitness group than in the sera of the moderate-fitness group. These findings suggest that moderate aerobic fitness in young adults may decrease the circulating levels of free IGF-1 and lower the potential to support growth of prostate cancer cells.

Cross-sectional association between physical activity and serum testosterone levels in US men: results from NHANES 1999-2004

Testosterone levels and physical activity each play important roles in men's health, but the relationship between the two remains unclear. We evaluated the cross-sectional association between self-reported total physical activity and serum testosterone levels in 738 men (mean age 42.4 years, range 20-≥85 years) who participated in National Health and Nutrition Examination Survey 1999-2004. We compared geometric mean testosterone concentrations measured by radioimmunoassay (RIA) and calculated the odds ratio (OR) of having low or low normal testosterone (≤3.46 ng/mL) across tertiles of total physical activity in all men, and men stratified by age (20-49, ≥50 years), and obesity status (BMI < 30, ≥30 kg/m(2) ). The geometric mean testosterone concentration was 5.31 ng/mL; 18.6% of the men had low or low normal serum testosterone levels. Physical activity tertiles were not associated with testosterone levels overall, or when stratified by age or obesity status. Similarly, there was no association between physical activity tertiles and the odds of low or low normal testosterone, overall or by age. However, among non-obese men, those in the highest physical activity tertile were significantly less likely to have low or low normal testosterone than those in the lowest tertile (OR 0.50; 95% CI = 0.26-0.95); there was no association among obese men. Greater physical activity was not associated with testosterone levels, but may be associated with a reduced odds of low or low normal testosterone in non-obese men, but not in obese men.

Physical activity and its relation to cancer risk: updating the evidence

Scientific evidence for the primary prevention of cancer caused by physical activity of regular moderate-intensity or greater is rapidly accumulating in this field. About 300 epidemiologic studies on the association between physical activity and cancer risk have been conducted worldwide. The objectives of this paper were three-fold: (i) to describe briefly the components of physical activity and its quantification; (ii) to summarize the most important conclusions available from comprehensive reports, and reviews of the epidemiologic individual and intervention studies on a role physical activity in cancer prevention; (iii) to present proposed biological mechanisms accounting for effects of activity on cancer risk. The evidence of causal linked physical activity and cancer risk is found to be strong for colon cancer - convincing; weaker for postmenopausal breast and endometrium cancers - probable; and limited suggestive for premenopausal breast, lung, prostate, ovary, gastric and pancreatic cancers. The average risk reductions were reported to be 20-30%. The protective effects of physical activity on cancer risk are hypothesized to be through multiple interrelated pathways: decrease in adiposity, decrease in sexual and metabolic hormones, changes in biomarkers and insulin resistance, improvement of immune function, and reduction of inflammation. As there are several gaps in the literature for associations between activity and cancer risk, additional studies are needed. Future research should include studies dealing with limitations in precise estimates of physical activity and of a lack of consensus on what defines sedentary behavior of individuals and those linked with the proposed biomarkers to cancer risk and controlled exercise intervention trials.

Effect of different seasonal strength training protocols on circulating androgen levels and performance parameters in professional soccer players

OBJECTIVE

To examine the effects of three seasonal training programs, largely different in strength volume, on androgen levels and performance parameters in soccer players.

DESIGN

Sixty-seven soccer players, members of three different professional teams, participated in the study. Strength intensity of the training programs were assessed as high (for Team-A, n=23), moderate (for Team-B, n=22), and low (for Team-C, n=22). Blood samples were analyzed for total-testosterone, free-testosterone, and the metabolic product of activate testosterone 3a-androstendiol glucuronade (3a-Diol-G). Players were tested for maximal oxygen consumption (VO2max), squad-jump (SJ), countermovement-jump (CMJ), 10 m and 20 m sprint performance prior at the beginning of the pre-season period, at the middle (mid-point), and at the end of the competition period (end-point).

RESULTS

All performance parameters increased significantly until mid-point in all teams (p<0.001). However, performance was further increased only in Team-A only for jumping and sprinting ability between end-point vs mid-point (p<0.001). An effect of the training program of Team-A on TT levels was evident exhibiting significant differences between at all point-measurements (baseline/mid-point:p=0.024, baseline/end-point:p<0.001, mid/end-point:p=0.008), while a marginally significant effect (p=0.051) was detected within Team-B and a non-significant effect in Team-C. Similar results were obtained for 3a-Diol-G in Team-A (p=0.001) where significant differences were found between end-point to both baseline (p=0.001) and mid-point (p=0.038). No differences were detectable for FT. A borderline significant negative correlation was observed between 3a-Diol-G and VO2max in Team-B at mid-point. No other correlations were evident between performance and hormonal parameters.

CONCLUSION

Our findings suggest that the volume of strength training combined with intensive soccer training caused an elevation of circulating TT and 3a-Diol-G levels in parallel to the induction of performance capacity. It is our opinion that the elevation of endogenous androgens as a result of the volume of strength training indicates that the only method to improve athletic performance is hard training. There are no substitutes or shortcuts. If the organism needs more androgens it will produce them endogenously.

Distinctive features of steroid hormone metabolism in female patients with androgenic alopecia

Goal of the study. To study the role of metabolic disorders related to steroid hormones for the genesis of androgenic alopecia in women. Materials and methods. The authors disclose the results of a study of blood serum and saliva concentrations of steroid hormones in 87 female patients suffering from androgenic alopecia and 30 healthy women. Results. A regular menstrual cycle in most of the patients with androgenic alopecia (87.8%) and low (10.3%) rate of the polycystic ovary syndrome confirm the low prevalence of clinical manifestations related to endocrine disorders in female patients with alopecia. An increased level of dihydrotestosterone was revealed in 44.8% of the female patients with androgenic alopecia while total and free blood serum testosterone levels were increased only in 11.5% and 12.6% of the patients, respectively. These data may serve as an indirect indication at the increased activity of 5-alpha-reductase promoting conversion of testosterone into dihydrotestosterone. The authors confirmed the information value of the free testosterone saliva level for assessing the hormonal background in the patients under examination. Conclusion. Based on the study results, it is recommended to determine the concentration of dihydrotestosterone, free androgen index and free testosterone saliva level as a part of examinations of women suffering from androgynous alopecia to evaluate their hormonal background.

Dihydrotestosterone is elevated following sprint exercise in healthy young men

Dihydrotestosterone (DHT) exerts both functional and signaling effects extending beyond the effects of testosterone in rodent skeletal muscle. As a primer for investigating the role of DHT in human skeletal muscle function, this study aimed to determine whether circulating DHT is acutely elevated in men following a bout of repeat sprint exercise and to establish the importance of training status and sprint performance to this response. Fourteen healthy active young men (V̇o2max61.0 ± 8.1 ml·kg body mass−1·min−1) performed a bout of repeat sprint cycle exercise at a target workload based on an incremental work-rate maximum (10 × 30 s at 150% Wmaxwith 90-s recovery). Venous blood samples were collected preexercise and 5 and 60 min after exercise. Five minutes after exercise, there were significant elevations in total testosterone (TT; P < 0.001), free testosterone (FT; P < 0.001), and DHT ( P = 0.004), which returned to baseline after 1 h. Changes in DHT with exercise (5 min postexercise − preexercise) correlated significantly with changes in TT ( r = 0.870; P < 0.001) and FT ( r = 0.914; P < 0.001). Sprinting cadence correlated with changes in FT ( r = 0.697; P = 0.006), DHT ( r = 0.625; P = 0.017), and TT ( r = 0.603; P = 0.022), and habitual training volume correlated with the change in TT ( r = 0.569, P = 0.034). In conclusion, our data demonstrate that DHT is acutely elevated following sprint cycle exercise and that this response is influenced by cycling cadence. The importance of DHT in the context of exercise training and sports performance remains to be determined.

Intracrine and myotrophic roles of 5α-reductase and androgens: a review

Historically, the circulation was thought to be the primary source of androgens influencing skeletal muscle. However, a growing body of research indicates that skeletal muscle expresses several androgen-synthesizing enzymes, including 5α-reductase. The intramuscular expression of these enzymes suggests that skeletal muscle is capable of synthesizing bioactive androgens, which could induce myotrophic effects via intracrine action.

PURPOSE

The aim of this brief review is to discuss recent research related to the intracrine and myotrophic roles of androgens, with particular focus on 5α-reductase as a myotrophic mediator.

METHODS

Included in the review are 17 reviews and 58 original studies that were identified by a systematic review from MEDLINE and deemed particularly relevant to our purpose. Results are summarized to provide an overview of 5α-reductase as a mediator of the myotrophic effects of androgens. In particular, discussions are included regarding androgen biosynthesis and androgen signaling within skeletal muscle, the effects of exercise on intramuscular androgen biosynthesis, and clinical applications of androgens and of a new class of myotrophic agonists termed selective androgen receptor modulator.

RESULTS

The ability of several peripheral tissues to synthesize bioactive androgens is well documented in the literature. Herein, we summarize newer studies that demonstrate that 1) skeletal muscle has the capability to synthesize both testosterone and dihydrotestosterone from dehydroepiandrosterone, which is present in abundance within the circulation, and 2) that exercise increases the expression of certain androgen-biosynthesizing enzymes within muscle.

CONCLUSIONS

Intramuscularly synthesized androgens have the potential to influence skeletal muscle via intracrine action; however, their exact role in skeletal muscle development and maintenance requires further elucidation.