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.

Erythrocyte concentrations of chromium, copper, manganese, molybdenum, selenium and zinc in subjects with different physical training levels.

BACKGROUND: The aim of the present study was to determine changes occurring in the erythrocyte concentrations of chromium (Cr), copper (Cu), manganese (Mn), molybdenum (Mo), selenium (Se) and zinc (Zn) in male subjects with different training levels living in the same region (Spain). METHODS: Thirty sedentary subjects (24.34 ± 3.02 years) formed the control group (CG); 24 moderately trained (4-7 h/week) subjects (23.53 ± 1.85 years) formed the group with a moderate degree of training (MTG) and 22 professional cyclists (23.29 ± 2.73 years), who performed more than 20 h/week of training, formed the high-level training group (HTG). Erythrocyte samples were collected from all subjects in fasting conditions, washed and frozen at - 80 °C until analysis. Erythrocyte analysis of trace elements was performed by inductively coupled plasma mass spectrometry (ICP-MS). RESULTS: The results showed that there was a statistically significant lower erythrocyte concentration of Cu, Mn, Mo and Zn in the MTG and HTG than CG. Se was only significantly lower in HTG than CG. The correlation analysis indicates that this change was correlated with training in the case of Cu, Mn, Se and Zn. All results are expressed in µg/g Hb. CONCLUSIONS: We can conclude that physical training produces a decrease in erythrocyte concentrations of Cu, Mn, Se and Zn, which can cause a decrement in athletes' performance given the importance of these elements. For this reason, erythrocyte monitoring during the season would seem to be advisable to avoid negative effects on performance.

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.

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.

Influence of a 6-month physical training program on serum and urinary concentrations of trace metals in middle distance elite runners.

BACKGROUND: The aim of this survey was to determine the effects of an aerobic physical training program of six months duration on the serum and urinary concentrations of essential trace elements among middle distance runners and untrained, non-sportsmen participants. METHODS: 24 well-trained, middle-distance (1500 and 5000 m), aerobic male runners (AG) were recruited at the beginning of their training season and 26 untrained males formed the control group (CG). All participants were from the same region of Spain, and all of them had been living in this area for at least two years. Serum and urine of samples of Cobalt (Co), Copper (Cu), Manganese (Mn), Molybdenum (Mo), Selenium (Se), Vanadium (V) and Zinc (Zn) were obtained at the beginning of the training season, and six months later, from all participants. All samples were analyzed with inductively coupled plasma mass spectrometry (ICP-MS). RESULTS: Two-way ANOVA showed significant differences relative to group effect in serum concentrations of Co, Cu, Mn, Mo, Se and Zn. Attending to time effect, there were differences in Mn (p = 0.003) and Zn (p = 0.001). The group x time interaction revealed differences only in the case of Mn (p = 0.04). In urine, significant differences between group were obtained in Co, Cu, Mn, Se and V. Time effect showed changes in Co, Cy, Mo and Se. Finally, the group and time interaction revealed significant differences in urinary Cu (p = 0.001), Mn (p = 0.01) and Se (p = 0.001). CONCLUSIONS: A six-month aerobic training program for well-trained athletes induced modifications in the body values of several minerals, a fact which may reflect adaptive responses to physical exercise. The obtained data could be interesting for physicians or coaches in order to consider specific modifications in sportsmen's diets as well as to determine specific nutritional supplementation strategies.

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.

Influence of an exercise until exhaustion in serum and urinary concentrations of toxic minerals among professional athletes, a preliminary approach.

The aim of the present survey was to determine differences in the serum and urinary concentrations of several toxic trace elements (As, Be, Cd, Cs and Pb) between long distance runners and non-sportsmen living in the same area of Extremadura (Spain) in basal conditions as well as after the performance of a maximal effort test until exhaustion. 21 Spanish national long-distance runners were recruited before the start of their training season and 26 untrained students. All of them had similar ages. The effort test consisted in running on a treadmill incrementally in stages, until exhaustion. Serum and urine analysis of trace metals was performed by inductively coupled plasma mass spectrometry (ICP-MS). In the statistics the urine and blood basal concentrations was analyzed first using Student t test. Then the differences between the pre and post-test values were analyzed using Wilcoxon test. The serum concentrations of Be (p < 0.001), Cd (p < 0.01), Cs (p < 0.001) and Pb (p < 0.001) were higher in the athletes than the control groups in basal conditions. In relation to the exercise, the results showed that there were lower serum concentrations of Be, Cd and Pb after the test, but without statistically significance, in both groups. Cs (p < 0.001) concentrations were statistically lower after the exercise tests in both groups, but if the parameters were corrected in relation to hematocrit and hemoglobin concentrations the differences were significant only among the athletes. In urine, the concentrations of Be (p < 0.001) and Cd (p < 0.01) were higher among athletes than among controls, being the opposite case for urinary Pb values. In relation to the exercise-induced effect of the test, the results showed that among controls only Cd values were modified, but if creatinine corrections are applied this difference does not reach statistical significance. However, sportsmen suffered a diminution in Be values, that can be observed only if urine values are corrected. Also, an increase in Cd, both in corrected and normal values, was observed, fact that occurred also in the case of Cs, but only if urinary values are corrected. It can be concluded that an incremental exercise to exhaustion among elite athletes of long distance modalities can produce changes in serum and urinary concentrations of toxic trace elements which may reflect an adaptive mechanism to prevent toxicity, and which could be an interesting outcome for physicians in the treatment and prevention of toxic situations.