## 1 Introduction
Therefore, PBC is more often used in field work with sports teams, and WBC is more often used in rehabilitation or sports centers [10; 31]. Although these techniques are becoming more and more popular, there are still few studies assessing the range of changes in the skin temperature of the body of players, which is necessary to trigger for the reflex thermoregulatory reactions. The production and accumulation of heat in skeletal muscles during prolonged dynamic exercise leads to the dissipation of heat through the bloodstream and therefore an increase in the temperature of the tissues [32]. For this reason, infrared thermography (IRT) has become one of the quantitative methods of assessing training effects that is increasingly used in sports medicine. IRT is a safe, non-invasive, and low-cost technique that allows for the rapid and non-contact recording of the irradiated infrared energy that is released from the body. Therefore, IRT allows you to carry out multiple, repeatable measurements without exposing the patient to unpleasant feelings [33; 34; 35; 36; 37; 38; 39; 40; 41; 42; 43; 44]. The most important areas of application for infrared thermography in sports are: the detection of injury in sports medicine, exercise-associated thermographic changes, the relationship between skin temperature and muscle activation, the assessment of the symmetry/asymmetry of the temperature distribution of selected areas of the body after physical effort, thermal analysis, and the performance properties of thermal protective clothing [45]. Both static and dynamic thermography are increasingly used to assess the temperature of the skin areas over the selected muscle groups participating in symmetrical or asymmetric exercises [41; 42; 46; 47; 48]. IRT is also a good tool for assessing the body's thermal response to physical stimuli applied to it, including extremely low temperatures [49]. PBC is based on a direct contact between participant and nitrogen. The interaction between the body and cooling agent occurs principally at the skin. The skin temperature may therefore reflect the balance of heat loss and heat produced by metabolically active tissues. Therefore, the main goal of this study was to evaluate the effect of PBC performed immediately after football match as a method of post-exercise regeneration on the skin temperature (Tsk) changes in selected body areas. The following should be mentioned as supplementary objectives: (i) whether and to what extent selected areas of the players' body differ in skin temperature and whether there is symmetry of temperature distribution between the right and left sides of the body before and after the PBC, (ii) in which areas of the body there was the greatest and the smallest decrease in temperature in response to the applied PBC effect, and (iii) whether there are relationships between the thermal response and individual characteristics of the participants, such as blood pressure, BMI value, content of adipose tissue, muscle tissue, and water as well as the post-match blood concentration of the LA, CK, LDH, and AST. Additionally, the dynamics of changes in muscle damage markers during 72 h of post-match regeneration in football players was assessed.