Table 7.
Repeated sauna and male fertility.
| Study characteristics | Study sample | Intervention | Comparators | Health effects | Adverse side effects | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| Author & year | Level of evidence | Design | Pop/country | N | Sauna type | Duration | Comparator/controls | Outcome measures | Positive/negative/negligible | None/mild/ moderate/ severe |
| 2013 Garolla et al. [27] |
II | Single-group, longitudinal time-course study | Healthy males/Italy | 10 | Finnish sauna | 3 months | No control group | Before, after intervention, after 3 months, after 6 months' intervention: semen analysis; plasma sex hormone levels (LH, FSH, testosterone, inhibin); sperm parameters; sperm chromatin structure analysis; sperm apoptosis; sperm heat stress gene expression with quantitative real-time PCR analysis: HIF-1α, KDR, FLT1, VEGF, HSP90, HSP70, HSF1, HSF2, HSFY |
NEGATIVE - Post-intervention: lowered sperm count (93 ± 27.0 × 106 vs 223 ± 52.8 × 106, p < 0.001); lowered sperm concentration (31 ± 13.1 × 106/ml vs 89 ± 29.3 × 106/ml, p < 0.001); fewer motile sperm (36.1 ± 3.6% vs 58.0 ± 7.6%, p < 0.01) with no differences noted by 6 months post end of sauna intervention. No significant changes in plasma sex hormones at any timepoints. Abnormal sperm parameters [decrease in normal histone-protamine replacement (p < 0.05), abnormal chromatin condensation (p < 0.05), altered mitochondrial function (p < 0.01)]; up-regulation of heat-stress genes [HIF-1α (p < 0.001), KDR (p < 0.001), FLT1 (p < 0.001), VEGF (p < 0.001)] and up-regulation of heat shock proteins/factors [HSP90 (p < 0.001), HSP70 (p < 0.001), HSF1 (p < 0.001), HSF2 (p < 0.001), HSFY (p < 0.001)] directly after sauna intervention but all changes completely reversed by 6 months post ceasing sauna activity. |
None |
LH = luteinizing hormone; FSH = follicle stimulating hormone; PCR = polymerase chain reaction; HIF-1α = hypoxia-inducible factor I alpha; KDR = kinase insert domain; FLT1 = fms-related tyrosine kinase; VEGF = vascular endothelial growth factor; HSP90 = heat shock protein 90; HSP70 = heat shock protein 70; HSF1 = heat shock factor 1; HSF2 = heat shock factor 2; HSFY = heat shock factor Y.