Limiting the Rise in Core Temperature During a Rugby Sevens Warm-up With an Ice Vest.

PURPOSE:: Determine how a cooling vest worn during a warm-up could influence selected performance [counter movement jump (CMJ)], physical (GPS metrics) and psycho-physiological (body temperature and perceptual) variables.

METHODS:: In a randomized crossover design, twelve elite male World Rugby Sevens Series athletes completed an outdoor (WBGT: 23-27°C) match-specific externally-valid 30 min warm-up wearing a phase change cooling vest (VEST) and without (CONTROL), on separate occasions 7 days apart. CMJ was assessed before and after the warm-up, with GPS indices and heart rate monitored during the warm-ups, whilst core temperature (Tc; ingestible telemetric pill; n = 6) was recorded throughout the experimental period. Measures of thermal sensation (TS) and comfort (TC) were obtained pre- and post-warm-ups, with rating of perceived exertion (RPE) taken post-warm-ups.

RESULTS:: Athletes in VEST had a lower ΔTc [mean (SD) VEST 1.3°C (0.1°C); CONTROL 2.0°C (0.2°C)] from pre-warm-up to post-warm-up [effect size (ES) ± 90% confidence limit; -1.54; ±0.62] and Tc peak [mean (SD) VEST 37.8°C (0.3°C); CONTROL 38.5°C (0.3°C)] at the end of the warm-up (-1.59; ±0.64) compared to CONTROL. Athletes in VEST demonstrated a decrease in ΔTS (-1.59; ±0.72) and ΔTC (-1.63; ±0.73) pre- to post-warm-up, with a lower RPE post warm-up (-1.01; ±0.46), compared to CONTROL. Changes in CMJ and GPS indices were trivial between conditions (ES < 0.2).

CONCLUSIONS:: Wearing the vest prior-to and during a warm-up can elicit favorable alterations in physiological (Tc) and perceptual (TS, TC and RPE) warm-up responses, without compromising the utilized warm-up characteristics or physical performance measures.