4 Medical Rehabilitation / Rehabilitacja Medyczna (Med Rehabil) 2022, 26 (3): 4-20 DOI: 10.5604/01.3001.0015.8212 eISSN 1896–3250 © AWF Krakow The individual division of this paper was as follows: A – research work project; B – data collection; C – statistical analysis; D – data interpretation; E – manuscript compilation; F – publication search Article received: 06.01.2022; Accepted: 04.04.2022 Cite as: Teległ ów A., Ptaszek B., Podsiadł o S., Mardył a M., Marchewka J., Maciejczyk M. Comparing the Effects of Whole-Body Cryotherapy and Swimming in Cold Water – Winter Swimming on Chosen Morphological and Biochemical Blood Indices and Factors Released by Brown Adipose Tissue. Med Rehabil 2022; 26(3): 4-20. DOI: 10.5604/01.3001.0015.8212 Internet version (original): www.rehmed.pl This article is licensed under the Creative Commons Attribution-ShareAlike 4.0 International License CC BY-SA (http://creativecommons.org/licenses/by-sa/4.0/) Comparing the Effects of Whole-Body Cryotherapy and Swimming in Cold Water – Winter Swimming on Chosen Morphological and Biochemical Blood Indices and Factors Released by Brown Adipose Tissue Porównanie wpływu krioterapii ogólnoustrojowej i pływania w zimnej wodzie – morsowania, na wybrane wskaźniki morfologiczno-biochemiczne krwi oraz czynniki uwalniane przez brunatną tkankę tłuszczową Aneta Teległów 1 (A,B,D,E,F) , Bartłomiej Ptaszek 2 (A,B,D,E,F) , Szymon Podsiadło 3 (C,E) , Mateusz Mardyła 4 (B) , Jakub Marchewka 3 (B) , Marcin Maciejczyk 4 (B) 1 Department of Health Promotion, Institute of Basic Sciences, University of Physical Education in Kraków, Kraków, Poland 2 Institute of Applied Sciences, University of Physical Education in Kraków, Kraków, Poland 3 Institute of Clinical Rehabilitation, Department of Motor Rehabilitation, University of Physical Education in Kraków, Kraków, Poland 4 Institute of Biomedical Sciences, University of Physical Education in Kraków, Kraków, Poland Keywords Cold water swimming, whole-body cryotherapy, blood morphology, blood biochemical indices, brown adipose tissue Abstract Introduction: Introduction: Whole-body cryotherapy and winter swimming are applied to induce physiological, organ-related and systemic defence responses that are beneficial and effective in maintaining or restoring human body homeostasis. Objective: Objective: The aim of the study was to evaluate blood morphological and biochemical indices in men and women exposed to whole-body cryotherapy and winter swimming. Materials and methods: Materials and methods: Fasting blood samples were collected into vacuum tubes from the ulnar vein of all participants (n=70). This was done before beginning and after completing the 20 whole-body cryotherapy sessions (women n=15, men n=15), as well as at the beginning (November) and end of the winter swimming season (April) (women n=15, men n=15), and in the control group (women n=10, men n=10). Blood morphological and biochemical indicators as well as brown adipose tis- sue were determined at the Blood Physiology Department of the Central Research and Development Laboratory – University of Physical Education in Kraków, and at the Department of Analytics and Clinical Biochemistry of the Kraków Unit of Maria Sklodowska-Curie National Research Institute of Oncology. Results: Results: In both sexes included in the study, both whole-body cryotherapy and winter swimming protocols induced changes in selected peripheral blood morphological and biochemical indices, mainly in blood count, proteinogram and chloride con- centrations. The increase in brown adipose tissue-released FGF-21 (fibroblast growth factor-21) under the influence of whole- body cryotherapy occurred in females. In contrast, no statistically significant changes were found for Nrg4. Both whole-body cryotherapy and winter swimming resulted in decreased values of red blood cells, haemoglobin and iron, with sex-dependent variation. Conclusions: Conclusions: Cold in the form of whole-body cryotherapy, similarly to winter bathing, affects changes in blood morphological and biochemical parameters, while the release of FGF21 in brown adipose tissue was noted only after whole-body cryotherapy. Słowa kluczowe krioterapia ogólnoustrojowa, zimowa kąpiel, morfologia krwi, wskaźniki biochemiczne, brunatna tkanka tłuszczowa