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

Effects of High Temperature Exposure on the Wingate Test Performance in Male University Students

It has been suggested that heat exposure prior to exercise could induce changes in anaerobic exercise. Therefore, the purpose of this study was to observe the effects of high temperature heat exposure prior to an anaerobic test. Twenty-one men (age: 19.76 ± 1.22 years; height: 1.69 ± 0.12 m; weight: 67.89 ± 11.78 kg) voluntarily participated in this investigation. All of them performed two Wingate tests, vertical jump and macronutrient intake control. On the first day, the test was performed under normal environmental conditions. On the second day, it was performed in a similar way, but with previous exposure to heat at high sauna temperatures (15 min; 100 ± 2 °C). There were no differences in the vertical jump and macronutrient intake. However, the results showed an improvement in power (W) (p < 0.05), relative power (W/kg) (p < 0.01) and revolutions per minute (p < 0.05) 10 s after the start of the test. There was also an increase in thigh (p < 0.01) and skin temperature (p < 0.01) with pre-heat exposure. The results obtained suggest that this pre-exercise protocol could improve power in short and intensive actions.

Hematological Adaptations to Post-Exercise Sauna Bathing With No Fluid Intake: A Randomized Cross-Over Study

Purpose: Sauna bathing is recommended to improve the sports training process, yet empirical evidence confirming its effectiveness is still inconclusive. We examined the effects of post-exercise sauna bathing on hematological adaptations and exercise capacity in healthy men. Methods: Thirteen physical education students participated in randomized cross-over study: two, 4-week interventions, with 10-week washout. The interventions involved 3 times per week 60-min stationary cycling either with 30-min of post-exercise sauna bathing (89 ± 3°C, 10 ± 2% RH) or without; no fluid was ingested during both exercise and sauna sessions. Before and after both interventions, participants were tested for total hemoglobin mass (tHb-mass), intravascular volumes, erythropoietin, ferritin, red blood cell parameters with reticulocyte fractions, along with maximal/peak and submaximal variables in a graded exercise test (GXT). Results: Regardless of intervention type, tHb-mass increased (p = .014) whereas ferritin concentration decreased (p = .027); however, changes in tHb-mass were within the range of typical error (<1.8%). Absolute and relative values of maximal power and power at gas exchange threshold, as well as peak oxygen uptake (all p < .010), also increased irrespective of intervention type. Conclusions: The use of post-exercise sauna bathing with fluid intake restrictions does not provide any additional benefits in tested variables over endurance training alone. Thus, further evidence is required before recommendations to utilize this post-exercise conditioning strategy are deemed valid.

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.