Effects of long‐term whole‐body cold exposures on plasma concentrations of ACTH, beta‐endorphin, cortisol, catecholamines and cytokines in healthy females

Abstract

Objective. Cold therapy is used to relieve pain and inflammatory symptoms. The present study was designed to determine the influence of long‐term regular exposure to acute cold temperature. Two types of exposure were studied: winter swimming in ice‐cold water and whole‐body cryotherapy. The outcome was investigated on humoral factors that may account for pain alleviation related to the exposures. Material and methods. During the course of 12 weeks, 3 times a week, a group of healthy females (n = 10) was exposed to winter swimming (water 0–2°C) for 20 s and another group (n = 10) to whole‐body cryotherapy (air −110°C) for 2 min in a special chamber. Blood specimens were drawn in weeks 1, 2, 4, 8 and 12, on a day when no cold exposure occurred (control specimens) and on a day of cold exposures (cold specimens) before the exposures (0 min), and thereafter at 5 and 35 min. Results. Plasma ACTH and cortisol in weeks 4–12 on time‐points 35 min were significantly lower than in week 1, probably due to habituation, suggesting that neither winter swimming nor whole‐body cryotherapy stimulated the pituitary‐adrenal cortex axis. Plasma epinephrine was unchanged during both experiments, but norepinephrine showed significant 2‐fold to 3‐fold increases each time for 12 weeks after both cold exposures. Plasma IL‐1‐beta, IL‐6 or TNFα did not show any changes after cold exposure. Conclusions. The main finding was the sustained cold‐induced stimulation of norepinephrine, which was remarkably similar between exposures. The frequent increase in norepinephrine might have a role in pain alleviation in whole‐body cryotherapy and winter swimming.