Effect sizes (<i>Cohen′s d</i>) calculated by comparing water immersion strategies versus CTRL for each of the heart rate variability index and moment.

Effect sizes <0.2 ‘trivial’; 0.2–0.5 ‘small’; 0.5–0.8 ‘moderate’ and >0.8 ‘large’. CTRL is control (recovery at room temperature), CWI is cold water immersion (recovery in water at 15°C), TWI is temperate water immersion (recovery in water at 28°C), HWI is hot water immersion (recovery in water at 38°C). WI is the response during water immersion, POST-WI is the response after water immersion, POST-REC is the response after 4 hours of recovery. mRR: mean R-R intervals; ln rMSSD: normal logarithm of the square root of the mean of the sum of the squares of differences between adjacent normal R–R intervals; SD1: instantaneous beat-to-beat variability; SD2: continuous beat-to-beat variability. Effect sizes (Cohen′s d) calculated by comparing water immersion strategies versus CTRL for each of the heart rate variability index and moment.