Implementation of a mixed-methods heat acclimation programme in a professional soccer referee before the 2022 FIFA World Cup in Qatar: A case study

Read, Dale ORCID: https://orcid.org/0000-0001-6367-0261, Evans, Daniel, Breivik, Simon, Elliott, Joshua, Gibson, Oliver and Birdsey, Laurence (2024) Implementation of a mixed-methods heat acclimation programme in a professional soccer referee before the 2022 FIFA World Cup in Qatar: A case study. BMJ Open Sport & Exercise Medicine. ISSN 2055-7647 (In Press)

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Abstract

Objectives: This case study reports the real-world practicalities of implementing a mixed-method heat acclimation (HA) programme before the 2022 FIFA World Cup. Methods: One male English soccer referee (age: 44 years; height: 1.82 m; body mass: 76.0 kg) who had officiated professionally for over 17 years and had over 10 years' experience officiating in European and international matches undertook an eleven-session HA programme over 22 days. On days one and 22, a 30-minute fixed-intensity heat tolerance test (9 km.h-1, 2% gradient, 40°C, 40% relative humidity) was performed, and physiological and perceptual responses were measured. A mixed-methods HA approach was used, including environmental chamber isothermic training, post-temperate training saunas and hot water immersion. Results: Compared to the pre-test, peak core temperature reduced by 0.40°C (38.4 vs. 38.0°C; minimal detectable change [MDC] = 0.34°C), peak skin temperature reduced by 0.5°C (36.7 vs. 36.2°C; MDC = 0.28°C) and peak heart rate reduced by 5 b·min-1 (167 vs. 162 b·min-1; MDC = 4 b·min-1) in the post-test. In the post-test, the sweat rate increased by 17% (1.94 vs. 2.27 L.h-1; MDC = 0.42 L.h-1). Peak thermal sensation (7 = “hot”) and the rating of perceived exertion (3 = “moderate”) were unchanged between the tests. However, peak thermal comfort (3 = “slightly uncomfortable” vs. 2 = “uncomfortable”) was rated lower in the post-test. Conclusion: The HA programme elicited positive physiological but indifferent perceptual responses, highlighting that mixed-methods HA can be implemented when a referee still has officiating, travel, and training responsibilities during the HA window.