Changes in Core Temperature During an Elite Female Rugby Sevens Tournament

Purpose: To characterize player core temperature (Tc) across a World Rugby Women's Sevens Series tournament day (WRWSS) and determine the efficacy of commonly employed cold-water-immersion (CWI) protocols. Methods: Tc was measured in 12 elite female rugby sevens athletes across 3 games (G1-3) from day 1 of the Sydney WRWSS tournament. Symptoms of exertional heat illness, perceptual scales, CWI details, playing minutes, external-load data (measured by global positioning systems), and wet-bulb globe temperature (range 18.5 degrees C-20.1 degrees C) were also collected. Linear mixed models and magnitude-based inferences were used to assess differences in Tc between periods (G1-3 and warm-ups [WU]). Results: Average Tc was very likely lower (effect size; +/- 90% confidence limit -0.33; +/- 0.18) in GI than in G2. Peak Tc was very likely (0.71; +/- 0.28) associated with increased playing time. CWI did not remove the accumulated Tc due to WU and match-play activity (similar to 1 degrees C-2 degrees C rise in Tc still present compared with Tc at WU onset for players >= 6-min match play). Conclusions: Elite WRWSS athletes experienced high Tc during WU (Tc peak 37.9-39.0 degrees C) and matches (Tc peak 37.9-39.8 degrees C), a magnitude known to reduce intermittent high-intensity physical performance (>= 39 degrees C). The CWI protocol resulted in players (>= 6-min match play) with similar to 1 degrees C to 2 degrees C raised Tc compared with Tc at WU onset.