3-Week passive acclimation to extreme environmental heat (100± 3 °C) in dry sauna increases physical and physiological performance among young semi-professional football players.

This manuscript aims to evaluate the influence of a novel passive heat acclimation program among human participants in the physical performance, as well as in several physiological parameters. 36 male football players were acclimated using a dry sauna bath to extreme hot (100 ± 3 °C), performing a total of nine sauna sessions with a weekly frequency of three sessions. The players were randomly into the sauna group (SG; n = 18; age: 20.69 ± 2.09 years) and the control group (CG; n = 18; age: 20.23 ± 1.98 years). All participants performed maximal effort test until exhaustion as well as hamstring flexibility test before and after the acclimation program. Anthropometric, respiratory, circulatory, hematological and physiological variables were evaluated at the beginning and at the end of the survey. Statistical analysis consisted of a Mann-Whitney U test to determine differences between groups at the beginning and at the end of the survey and a Wilcoxon test for paired samples to compare the differences for each group separately. Additionally, size effects of the pre-post acclimation changes were calculated. After the acclimation program SG participants experienced a diminution in body weight (p < 0.01), body mass index (p < 0.01), body fat (p < 0.05) and fat percentage (p < 0.05) decreased. Hamstring flexibility (p < 0.05) and work capacity (p < 0.05) increased. External basal temperature decreased (p < 0.05) as well as post-exercise systolic and diastolic blood pressures (p < 0.05). Finally, maximal oxygen uptake (ml Kg-1 min-1) (p < 0.05), maximal minute ventilation (p < 0.05) and maximal breath frequency (p < 0.05) increased at the end of the intervention. There were no significant changes in the CG in any variable. Favorable adaptations have been observed in this survey, suggesting a beneficial effect of extreme heat acclimation on physical performance. Several of the observed responses seem interesting for sport performance and health promotion as well. However, this is a novel, extreme protocol which requires further research.

Three weeks of passive and intervallic heat at high temperatures (100±2 °C) in a sauna improve acclimation to external heat (42±2 °C) in untrained males.

Currently, the effect of passive heat acclimation on aerobic performance is still controversial. Therefore, this study aimed to observe the effect of passive and intervallic exposure to high temperatures (100 ± 2 °C) in untrained males. Forty healthy untrained men participated in this investigation. They were randomised into a Control Group (CG; n = 18) and an Experimental Group (EG; n = 22). Both groups performed maximum incremental tests until exhaustion in normothermia (GXT1; 22 ± 2 °C), and 48h afterwards, in hyperthermia (GXT2; 42 ± 2 °C). The EG performed 9 sessions of intervallic exposure to heat (100 ± 2 °C) over 3 weeks. Subsequently, both groups performed two maximal incremental trials in normothermia (GXT3; 22 ± 2 °C) and 48h later, in hyperthermia (GXT4; 42 ± 2 °C). In each test, the maximal ergospirometric parameters and the aerobic (VT1), anaerobic (VT2) and recovery ventilatory thresholds were recorded. The Wilcoxon Test was used for intra-group comparisons and the Mann-Whitney U for inter-group comparisons. There were improvements in absolute VO2max (p = 0.049), W (p = 0.005) and O2pulse (p = 0.006) in hyperthermia. In VT1 there was an increase in W (p = 0.046), in VO2 in absolute (p = 0.025) and relative (p = 0.013) values, O2pulse (p = 0.006) and VE (p = 0.028) in hyperthermia. While W increased in hyperthermia (p = 0.022) at VT2. The results suggest that passive and intervallic acclimation at high temperatures improves performance in hyperthermia. This protocol could be implemented in athletes when they have to compete in hot environments.

Effects of exposure to high temperatures on serum, urine and sweat concentrations of iron and copper.

The objective of this research was to determine the acute effect of a maximum test until exhaustion in normothermia and hyperthermia, and after repeated exposure to heat at high temperatures on the homeostasis of Fe and Cu. The sample was composed of twenty-nine male university students. The participants were divided into a control group (CG) and an experimental group (EG). All of them underwent an incremental test until exhaustion in normothermia and hyperthermia before and after the repeated exposure of EG to heat at high temperatures, consisting of 9 heat acclimatisation sessions in the sauna. Samples of urine and blood were taken before and after each test. Additionally, sweat samples were collected in the hyperthermia test. The samples were frozen at -80 °C for further analysis by ICP-MS. None of the metal concentrations in serum were affected by hyperthermia or exposure to heat. Urinary Fe increased in CG in the hyperthermia test before Heat exposure at High Temperature (HEHT)(p < 0.05) and in both groups after HEHT (p < 0.05). In EG there was an increase in the urinary excretion of Cu after HEHT (p < 0.01) in both trials. Fe suffered a decrease in sweat in EG after exposure to heat (p < 0.05). The concentrations of Fe and Cu in serum were not affected by acute exercise and exposure to high temperatures. However, there was a decrease in excretion of Fe in sweat due to HEHT, and an increase in urinary excretion in both. Therefore, we think that in conditions of high temperatures for long periods of time, attention should be paid to the body levels of these metals.

Effect of exposure to high temperatures in the excretion of cadmium and lead.

OBJECTIVE: This study aims to observe the effect on urine and sweat excretion levels of cadmium (Cd) and lead (Pb) in healthy men in a maximum incremental test until exhaustion and repeated exposure to heat. METHODS: twenty-nine adult men divided into control group (CG; n = 14) and experimental group (EG; n = 15) performing two maximum tests until exhaustion in normothermia (22 °C) and hyperthermia (42 °C). EG experienced 9 sessions of heat exposure at high temperatures (100 °C) (HEHT). After the nine sessions, the initial tests were repeated in both groups. Urine samples were collected before and after each test. After the hyperthermia tests, sweat samples were gathered. RESULTS: Urinary Cd increased after initial tests in GC and in hyperthermia in EG (p < 0.05). Urinary excretion of Pb rose after HEHT (p < 0.05). Pb in sweat was higher in EG than in CG after HEHT (p < 0.05). CONCLUSION: Heat exercise and constant exposure to heat can be a valid method to increase the excretion of toxic metals.

Influence of a high-temperature programme on serum, urinary and sweat levels of selenium and zinc.

INTRODUCTION: The effect of hyperthermia on the antioxidant system in the human organism is well known. AIM: The objective of this study was to observe the effects of heat on the concentration of Se and Zn, elements related to antioxidant systems. METHODS: Twenty-nine subjects voluntarily participated in this study. They were divided into a control group (CG; n = 14) and an experimental group (EG; n = 15). All of them underwent two incremental tests until exhaustion in normothermia (22 °C, 20-40%RH) and hyperthermia (42 °C, 20-40%RH). EG experienced nine sessions of repeated heat exposure at high temperatures (100 °C, 20%RH) for three weeks (HEHT). After the intervention, the initial measurements were repeated. Urine and blood samples were collected before and after each test. Additionally, sweat samples were collected after tests in hyperthermia. RESULTS: There were no significant changes in serum. An increase in the elimination of Zn and Se in EG was observed in urine after HEHT (p < .05). The elimination of Zn by sweating decreased after HEHT in EG (p < .05). CONCLUSIONS: Exposure to heat at high temperatures increases the urinary excretion of Se and Zn.

Serum, erythrocyte and urinary concentrations of iron, copper, selenium and zinc do not change during an incremental test to exhaustion in either normothermic or hyperthermic conditions.

AIM: The aim of this study was to evaluate the effect of the performance of an incremental exercise test until exhaustion in normothermic and hyperthermic conditions on serum, erythrocyte and urine concentrations of Iron (Fe), Copper (Cu), Selenium (Se) and Zinc (Zn). METHODS: Nineteen adult males (age: 22.58 ±â€¯1.06 years) performed two maximum incremental exercise tests on a cycloergometer in normothermia (22 ±â€¯2 °C) and hyperthermia (42±2 °C) separated by 48 h. Urine, serum and erythrocyte samples were collected before and after each test. RESULTS: Serum Se (p < 0.01) and Cu (p < 0.05) levels were altered after each test, but the significance disappeared with the correction for haematocrit. The rest of the values did not undergo alterations in either condition. CONCLUSIONS: It seems that a higher stimulus is necessary to obtain changes in these minerals. The study reveals the need to correct serum concentrations concerning possible changes in these volumes after an acute effort.

Effect of heat exposure and physical exercise until exhaustion in normothermic and hyperthermic conditions on serum, sweat and urinary concentrations of magnesium and phosphorus.

AIM: The aim of this survey was to ascertain the difference in the levels of Magnesium (Mg) and Phosphorus (P) after an exercise test in normothermia and hyperthermia before and after heat acclimation in comparison to their respective pre-test values. METHODS: Twenty-nine male university students were divided into an Experimental Group (EG) (n = 15) and a Control Group (CG) (n = 14). All of them voluntarily participated in this investigation. Both groups performed an incremental test until exhaustion on a cycloergometer in normothermia (22 °C) and hyperthermia (42 °C). EG underwent 9 sessions of heat acclimation (100 °C) in a sauna (Harvia C105S Logix Combi Control; 3-15 W; Finland). Once the experimental period was completed, all initial measurements were carried out again under identical conditions. Urine and blood samples were obtained before and after each trial. Sweat samples were collected at the end of every test performed in hyperthermia. The samples were frozen at -80 °C until further analysis by ICP-MS. RESULTS: Lower seric Mg levels were observed in both groups at the end of pre-acclimation tests. After acclimation, only EG experimented a decrease of Mg in serum after testing (p < .01). The urinary excretion was unaffected in the pre-acclimated period, but EG experimented an increase in Mg after trials in the post-acclimation evaluation (p < .01). Mg sweat loss decreased significantly after heat acclimation (p < .05). P did not undergo changes, except in its urinary excretion, which was elevated after the normothermia trial in the post-acclimation period (p < .05). CONCLUSIONS: It seems that exercise in hyperthermia altered Mg status but not P homeostasis. Additionally, heat acclimation reduces Mg losses in sweat while increasing its loss in urine. Thus, Mg supplementation should be considered in unacclimated and acclimated subjects if physical exercise is going to be performed in hyperthermic conditions.

Influence of a physical exercise until exhaustion in normothermic and hyperthermic conditions on serum, erythrocyte and urinary concentrations of magnesium and phosphorus.

AIM: The aim of this study was to evaluate the effect of the performance of a maximal exercise test until exhaustion in normothermic and hyperthermic conditions on body concentrations of magnesium (Mg) and phosphorus (P). METHODS: 19 adult males (age: 22.58 ±â€¯1.05 years) performed two maximum incremental exercise tests on a cycloergometer separated by 48 h. The first was performed in normothermia (22 ±â€¯2 °C) and the second in hyperthermic conditions induced with a sauna (42 ±â€¯2 °C). Blood and urine samples were taken before and after each test. RESULTS: The tests in hyperthermia did not produce ergospirometric alterations or a noticeable cardiovascular drift. Serum Mg concentrations underwent a reduction after the stress test in hyperthermia (p > 0.05) but not in normothermia. Nevertheless, urinary and erythrocyte concentrations of Mg, and urinary, erythrocyte and serum concentrations of P did not undergo alterations in either conditions. CONCLUSIONS: It seems that exercise in hyperthermic conditions induces a tissue redistribution of Mg in the body, a fact which was not observed in normothermic conditions.

Qualification and quantification of seventeen natural steroids in plasma by GC-Q-MS and GC-IT-MS/MS.

Studying the plasma steroid profile offers information about the possible existence of endocrinological alterations. This study describes the development and validation of gas chromatographic-mass spectrometric and gas tandem mass spectrometric methods for the simultaneous identification of 17 steroid hormones in human plasma using five different solvents. The n-hexane/ethyl acetate solvent mixture, in a proportion of 70/30 (v/v) provided the best results. The extracts were derivatized with N-methyl-N-trimethylsilyl-trifluoroacetamide. The obtained limits of detection were below 1 ng/mL in the majority of the studied steroids and the limits of quantification were below 5 ng/mL; the method obtained good linearity, reproducibility, repeatability, accuracy and recoveries above 95% in most cases.

Variations in urine excretion of steroid hormones after an acute session and after a 4-week programme of strength training.

Performing strength exercise, whether acutely or in a training programme, leads to alterations at the hypothalamic-pituitary-testicular and hypothalamic-pituitary-adrenal axes. One way to evaluate these changes is by analysis of the excretion of steroid hormones in the urine. The present study determined the variations in the urine profile of glucuroconjugated steroids after a single session of strength exercise and after a 4-week programme of strength training. The subjects were a group (n = 20) of non-sportsman male university students who worked out 3 days a week [Monday (M), Wednesday (W) and Friday (F)], performing the exercises at 70-75% of one repetition maximum strength (1-RM). Four urine samples were collected per subject: (A) before and (B) after a standard session prior to initiating the training programme, and (C) before and (D) after the same standard session at the end of the study, and they were assayed by gas chromatography coupled to mass spectrometry. The concentrations of the different hormones were determined relatively to the urine creatinine level (ng steroid/mg creatinine) to correct for diuresis. After the exercise sessions, both before and after the training programme, there was a fall in the urine excretion of androgens and estrogens, but no statistically significant changes in the excretion of tetrahydrocortisol (THF) and tetrahydrocortisone (THE). The anabolic/catabolic hormones ratio also decreased after the acute session, although only androstenodione + dehydroepiandrosterone (DHEA)/THE + THF ratio had a significant decrease (P < 0.05). After the training programme, there was a significant (P < 0.01) improvement in the strength of the muscle groups studied, and an increased urinary excretion of all the androgens with respect to the initial state of repose, with the difference being significant in the case of epitestosterone (Epit) (P < 0.05). The androsterone (A) + etiocholanolone (E)/THE + THF ratio increased significantly (P < 0.05) concerning the initial state. We therefore conclude that subjects suffer variations of the urine profile with regard to the steroid hormones before and after the acute strength sessions and after the training period. The alteration after the training programme seems to be due to the subjects' hypothalamic-hypophysis-testicular and hypothalamic-pituitary-adrenal axes adaptations, which enable them to increase physical strength.

Determination of natural corticosteroids in urine samples from sportsmen.

A method for the determination of natural corticosteroids (cortisone, cortisol, 5beta-dihydrocortisone, 5beta-dihydrocortisol, tetrahydrocortisone and tetrahydrocortisol) found in the urine of sportsmen, was developed using a capillary gas chromatography-mass spectrometry ion trap system. 17alpha-Methyltestosterone was used as an internal standard. The different corticosteroids were determined from the peak area ratios of the [M]; [M-90] and [M-90-90] fragment ions of their methoxime-trimethylsiyl derivatives. Sensitivity (15 ppb), specificity, accuracy (96%) and reproducibility (RSD=4-10%) of the method were demonstrated to be satisfactory for measuring the urinary concentrations of the selected natural corticosteroids.

Evaluation of the influence of physical activity on the plasma concentrations of several trace metals.

Our study was carried out with the aim of evaluating the influence that the degree of physical activity may have on plasma concentrations of essential and toxic elements. Copper and zinc, elements of known importance in basic cellular processes, have been analysed as essential, and cadmium and lead as toxic for the body in abnormal doses. The study was performed on a total population of 50 healthy individuals, 34 of them professional sportsmen and the rest who undertook moderate physical activity (control group), all of them living in a polluted environment (Madrid, Spain). Sampling was conducted at the beginning of the season (October). Electro-analytical techniques of proved reliability and accuracy were used for the determination of the metals. The results were related to data obtained using graphite furnace atomic absorption spectrophotometry and by use of biological reference materials. We found significantly higher zinc plasma concentrations in the sportsmen involved in anaerobic-type training (judo, fencing) compared to those undertaking aerobic activities (endurance, cycling) (P < 0.05). The values in both cases were higher than those found in the control group. Our study showed an increase of plasma copper concentrations in professional sportsmen, especially in those performing anaerobic activities, compared to those subjects undertaking moderate activity (control group) (P < 0.05). In summary, our results showed that there were no deficiencies of copper and zinc in the athletes studied at the beginning of the season. The levels were higher than those of the control population. As for the toxic metals, cadmium and lead, we observed lower levels in the athletes than in the control group (cadmium P < 0.005, lead P < 0.05). These results may indicate the existence of possible elimination systems for these metals in athletes, when they are training in a polluted environment.