2.2. Experimental Trials
dehydration, RPE
DEHYDRATION, HEAT
Exercise during the experimental trials took place in an environmental heat chamber (33 °C, 49% RH). Prior to the experimental sessions (4–6 h), participants ingested a core temperature sensor (CorTemp, Palmetto, FL, USA) with water. Participants were encouraged to maintain adequate hydration prior to all testing visits and instructed to consume 500 mL of plain water in the two hours before arriving at the laboratory. Female participants were scheduled to avoid variation in their menstrual cycle, with the second experimental trial scheduled within three days of the first and both scheduled to coincide with the follicular phase, as based on self-reported cycle tracking. Urine specific gravity (USG) was assessed from a urine sample provided upon arrival at the laboratory for all visits via a handheld refractometer (Atago, Bellevue, WA, USA). Water was provided to participants if the urinalysis results indicated mild to moderate dehydration (i.e., USG > 1.020) and USG was re-evaluated before commencing any procedures. Body mass was measured in lightweight running clothing (e.g., shorts, singlet, socks) before participants were fitted with a heart rate monitor (HRM-Run, Garmin, Olathe, KS, USA) and asked to remain seated quietly for 10 min prior to baseline assessments of their heart rate, blood pressure, and core temperature (TParticipants completed 40 min of steady state running in the heat (33 °C, 49% RH) on a motorized treadmill (505 CST, ProForm, Logan, UT, USA) at a heart rate corresponding to 60% of the maximal value observed at VOThe gels were administered with 150 mL of tepid water at 20 min and following 40 min of the steady-state preload. The thermal sensation (TS), thermal comfort (TC), RPE, affect, T