Clinical Effects of Regular Dry Sauna Bathing: A Systematic Review

Table 4

Repeated sauna and athletes.

Study characteristics			Study sample		Intervention		Comparators		Health effects	Adverse side effects
Author & year	Level of evidence	Design	Pop/country		Sauna type	Duration	Comparator/; controls	Outcome; measures	Positive/negative/negligible	None/mild/; moderate/; severe
2015; Stanley et al. [61]	III	Single-group,; interrupted time series study	Elite Athletes–; Males/; Australia	7	Finnish	10 days	No control group	Plasma volume changes (calculated from Hb readings); hydration status (using urine SG by digital refractometer); ergometer exercise performance measures; HRV	Positive,; postexercise sauna bathing increased plasma volume after 4 days of intervention ()	Mild –; comments of “hot and very uncomfortable, but tolerable” per thermal comfort survey conducted every 5 min during sauna sessions
2012; Zinchuk and Zhadzko [62]	III	Single-group interventional study	Male Elite Athletes/; Belarus	16	Finnish	5 months	No control group	Axillary temp; venous blood gas analysis; lipid peroxidation and free radical processes by UV and fluorescence analysis of plasma and RBCs; antioxidant estimation by α-tocopherol fluorescence analysis of plasma and RBC catalase activity; nitric oxide metabolism by spectrophotometric methods, plasma nitrate and nitrite levels	Positive, increased axillary body temp 2.6°C () after first sauna and 1.9°C () after course of sauna; increased pH by 0.8% (), decreased base excess by 20.3% (), increased venous O2 by 53.3% (), increased Hb concentration in blood by 5.2% (), right shift of oxy-Hb dissociation curve (decreased affinity – favours release of O2 to tissues) after 1st sauna; similar changes after final sauna (–)	None

RH = relative humidity; Hb = haemoglobin; SG = specific gravity; HRV = heart rate variability; temp = temperature; O₂ = oxygen; ROS = reactive oxygenated species; RBCs = red blood cells or erythrocytes.