Circulating METRNL, Adipocytokines, and Insulin-Resistance Markers After Repeated Whole-Body Cryotherapy in Women of Different Ages

Metabolic risk increases with age and may be accompanied by changes in adipocytokine secretion and insulin sensitivity. The primary exploratory aim of this prospective, uncon-trolled study was to determine whether repeated whole-body cryotherapy (WBC) changes circulating meteorin-like hormone (METRNL) concentrations in women of different ages. Secondary exploratory outcomes included irisin, asprosin, leptin, adiponectin, insulin, fasting blood glucose (FBG), lipid profile, homeostasis model assessment of insulin resistance (HOMA-IR), triglyceride-glucose index (TyG), atherogenic index of plasma (AIP), and the leptin/adiponectin ratio. A total of 48 women were divided into three groups: GR-60 (60-70 years, n = 14), GR-40 (40-50 years, n = 18), and GR-20 (20-30 years, n = 16). Participants underwent 30 WBC sessions, each lasting 3 min at minus 120 °C. Blood samples were collected before the first WBC session, after the 10th, 20th, and 30th sessions, and two weeks after the final session. Repeated WBC did not significantly change circulating METRNL or other adipocytokines in any age group. A preliminary decrease in insulin concentration and HOMA-IR was observed after 20 WBC sessions only in GR-60. These findings suggest that repeated WBC may be associated with favorable changes in selected insulin-resistance markers in older postmenopausal women; however, the absence of a non-WBC control group, small subgroup sizes, and the multiplicity burden preclude causal or therapeutic conclusions. Randomized controlled studies are needed to verify these exploratory observations.