The aim of this study was to investigate the effect of short-term, moderate intensity and low volume endurance training on gonadal hormone profile in untrained men. Fifteen young, healthy men performed an endurance training of 5-week duration on a cycle ergometer. Before and after the exercise program all participants completed a maximal incremental test. Concentration of testosterone (T), sex hormone-binding globulin (SHBG) and cortisol (C) as well as blood morphology were determined in venous blood samples at rest both before and after the training. The training program resulted in 3.7% improvement of maximal oxygen uptake (V˙O_2max) and 8.2% improvement of power output reached at V˙O_2max (PO_max). This was accompanied by significant increase in T (from 18.84±5.73 nmol·l⁻¹ to 22.03±6.61 nmol·l⁻¹, p = 0.0004) and calculated fT concentration (from 374±116 pmol·l⁻¹ to 470±153 pmol·l⁻¹, p = 0.00005). Moreover, the training caused a significant decrease in SHBG concentration (from 34.45±11.26 nmol·l⁻¹ to 31.95±10.40 nmol·l⁻¹, p = 0.01), whereas no significant changes were found in the cortisol concentration (334±138 nmol·l⁻¹ vs. 367±135 nmol·l⁻¹ for pre- and post-training measures, respectively, p = 0.50) and T/C and fT/C ratios. We have concluded that short-term, moderate intensity and low volume endurance training can significantly increase testosterone concentration in previously untrained men.

The negative relationship between testosterone and inflammatory cytokines has been reported for decades, although the exact mechanisms of their interactions are still not clear. At the same time, little is known about the relation between androgens and acute phase proteins. Therefore, in this investigation, we aimed to study the relationship between androgen status and inflammatory acute phase reactants in a group of men using multi-linear regression analysis. Venous blood samples were taken from 149 men ranging in age from 18 to 77 years. Gonadal androgens [testosterone (T) and free testosterone (fT)], acute phase reactants [C-reactive protein (CRP), ferritin (FER), alpha-1-acid glycoprotein (AAG), and interleukin-6 (IL-6)], cortisol (C), and lipid profile concentrations were determined. It was demonstrated that the markers of T and fT were negatively correlated with all acute phase proteins (CRP, FER, and AAG; p < 0.02) and the blood lipid profile [total cholesterol (TC), low-density lipoprotein (LDL), and triglycerides (TG); p < 0.03]. Multivariate analysis showed that T, fT, and the fT/C ratio were inversely correlated with the CRP, AAG, and FER concentrations independently of age and blood lipids. When adjustment for BMI was made, T, fT, and the fT/C ratio were negatively correlated with the AAG concentrations only. In addition, it was demonstrated that gonadal androgens were positively correlated with physical activity level (p < 0.01). We have concluded that a lowered serum T concentration may promote inflammatory processes independently of adipose tissue and age through a reduced inhibition of inflammatory cytokine synthesis, which leads to enhanced acute phase protein production. Therefore, a low serum T concentration appears to be an independent risk factor in the development of atherosclerosis and cardiovascular diseases. Moreover, the positive correlation between testosterone and physical activity level suggests that exercise training attenuates the age-related decrease in gonadal androgens and, in this way, may reduce the enhancement of systemic low-grade inflammation in aging men.

The effect of prolonged endurance training on the pulmonary V̇o₂on- and off-kinetics in humans, in relation to muscle mitochondria biogenesis, is investigated. Eleven untrained physically active men (means ± SD: age 22.4 ± 1.5 years, V̇o_2peak3,187 ± 479 ml/min) performed endurance cycling training (4 sessions per week) lasting 20 wk. Training shortened τ_pof the pulmonary V̇o₂on-kinetics during moderate-intensity cycling by ∼19% from 28.3 ± 5.2 to 23.0 ± 4.0 s ( P = 0.005). τ_pof the pulmonary V̇o₂off-kinetics decreased by ∼11% from 33.7 ± 7.2 to 30.0 ± 6.6 ( P = 0.02). Training increased (in vastus lateralis muscle) mitochondrial DNA copy number in relation to nuclear DNA (mtDNA/nDNA) (+53%) ( P = 0.014), maximal citrate synthase (CS) activity (+38%), and CS protein content (+38%) ( P = 0.004), whereas maximal cytochrome c oxidase (COX) activity after training tended to be only slightly (+5%) elevated ( P = 0.08). By applying to the experimental data, our computer model of oxidative phosphorylation (OXPHOS) and using metabolic control analysis, we argue that COX activity is a much better measure of OXPHOS intensity than CS activity. According to the model, in the present study a training-induced increase in OXPHOS activity accounted for about 0–10% of the decrease in τ_pof muscle and pulmonary V̇o₂for the on-transient, whereas the remaining 90–100% is caused by an increase in each-step parallel activation of OXPHOS.

New Findings: What is the central question of this study?The main aim of the present study was to determine the effect of prolonged moderate‐intensity endurance training on the endothelial glycocalyx layer integrity in relationship to the training‐induced changes in oxidative stress and antioxidant defence in humans. What is the main finding and its importance?We have shown, for the first time, a protective effect of prolonged moderate‐intensity endurance training on endothelial glycocalyx layer integrity, as judged by significantly lower basal and end‐exercise serum concentrations of glycocalyx damage markers, i.e. syndecan‐1 and heparan sulfate, accompanied by attenuation of oxidative stress and enhancement of antioxidant defence after training in previously untrained healthy young men. In this study, we evaluated the effect of 20 weeks of moderate‐intensity endurance training (ET) on the endothelial glycocalyx layer integrity in relationship to the training‐induced changes in antioxidant defence. Eleven healthy young, untrained men performed an incremental cycling exercise bout until exhaustion before and after 20 weeks of ET. Endurance training consisted of 40 min sessions, mainly of moderate intensity (∼50% of maximal oxygen uptake), performed four times per week. Venous blood samples were taken at rest and at the end of the maximal exercise test. Muscle biopsies from vastus lateralis were taken before and after the training. Endurance training resulted in a significant increase in physical capacity (P < 0.05) as reflected by an increase in power output reached at the lactate threshold and at maximal oxygen uptake. Training led to a decrease (P < 0.05) in basal and end‐exercise concentrations of blood markers of glycocalyx damage (syndecan‐1 and heparan sulfate). The lowering of glycocalyx shedding after the ET was accompanied by an attenuation of oxidative stress, as evidenced by a decrease in the basal plasma concentration of isoprostanes, and by an increase in antioxidant defence, reflected by an enhancement in superoxide dismutase 2 protein content in vastus lateralis (P < 0.05). In contrast, training did not induce a significant increase in basal nitrite/nitrate plasma concentration (P > 0.05). Moderate‐intensity ET exerts a pronounced protective effect on endothelial glycocalyx integrity at rest and during exercise, probably through an improvement of antioxidant defence that may represent the vasoprotective mechanisms highly responsive to moderate‐intensity endurance training.