Circulating opioid peptides during thermal stress.
Level 4 - case-series / case-control
Uncontrolled experimental physiological study in a small cohort
PubMed 2155166 · doi:10.1055/s-2007-1004846
What was done
Researchers measured circulating endogenous opiates (beta-endorphin [beta-EP] and methionine-enkephalin [Met-enk]) and adrenocorticotropic hormone (ACTH) responses to sauna-induced hyperthermia in 8 young, healthy subjects.
What was found
Sauna exposure led to an increase in plasma beta-EP and ACTH levels, but had no significant effect on circulating Met-enk. The abstract reports no numerical values, exact changes, or p-values.
Why it matters
It provides preliminary physiological evidence that acute thermal stress activates specific components of the pituitary-adrenal and opioid neuroendocrine pathways.
Limits
Very small sample size (n = 8), uncontrolled design without a sham or rest comparator, absence of quantitative data in the abstract, and lack of details on subject sex or sauna exposure conditions (temperature and duration).
Cited by
- supports Heat stress increases circulating beta-endorphins.