When exercising in the cold, optimizing thermoregulation is essential to maintain performance. However, no study has investigated thermal parameters with wearable-based measurements in a field setting among elite Nordic skiers. Therefore, this study aimed to assess the thermal response and sensation measured at different body parts during exercise in a cold environment in biathletes.; Thirteen Swiss national team biathletes (6 females, 7 males) performed two skiing bouts in the skating technique on two consecutive days (ambient temperature: -3.74 ± 2.32 °C) at 78 ± 4% of maximal heart rate. Heat flux (HF), core (T; core; ) and skin (T; skin; ) temperature were measured with sensors placed on the thigh, back, anterior and lateral thorax. Thermal sensation (TS) was assessed three times for different body parts: in protective winter clothing, in a race suit before (PRE) and after exercise (POST).; HF demonstrated differences (; p; < 0.001) between sensor locations, with the thigh showing the highest heat loss (344 ± 37 kJ/m; 2; ), followed by the back (269 ± 6 kJ/m; 2; ), the lateral thorax (220 ± 47 kJ/m; 2; ), and the anterior thorax (192 ± 37 kJ/m; 2; ). T; core; increased (; p; < 0.001). T; skin; decreased for all body parts (; p; < 0.001). Thigh T; skin; decreased more than for other body parts (; p; < 0.001). From PRE to POST, TS of the hands decreased (; p; < 0.01).; Biathletes skiing in a race suit at moderate intensity experience significant heat loss and a large drop in T; skin; , particularly at the quadriceps muscle. To support the optimal functioning of working muscles, body-part dependent differences in the thermal response should be considered for clothing strategy and for race suit design.
