E-edition: #OlympicsInTheHeat

Dear Reader,

Welcome to this special BJSM e-Edition on #OlympicsInTheHeat.

Due to COVID-19, the 2020 Tokyo Olympics have been postponed by one year and will be held from 23 July to 8 August 2021. This delay does not change the period of the year and the Olympics will be held during the Japanese summer, in hot and humid environments, in the world’s largest metropolitan area. Two years to the day before the original 2020 Olympics, temperatures surpassed 41ºC with over 65 heat related deaths recorded in a single week. The International Olympic Committee (IOC) responded to this concern by creating an expert working group who has been adapting some of the schedules, planning various countermeasures for athletes, workers and spectators, and developing various education material. In this context, it appeared that despite the abundant scientific literature regarding training and competing in the heat, the translation of science into practice remains heterogenous between athletes/sports/nations.

Therefore, the current e-Edition aims to provide a summary of the main information to protect athlete health during an #OlympicsInTheHeat. Importantly, this concern goes beyond Tokyo 2020, as Paris (2024) is regularly facing heat waves during the Olympic period and a new world record for the hottest temperature ever recorded on earth was reached this year in California (~200 miles from the site of the Los Angeles 2028 Games).

This e-edition aims to offer the reader an insight into the extent of the problem (i.e. Epidemiology and environmental conditions), how to plan ahead and adapt the athlete calendar (i.e. Traveling to acclimate vs traveling to compete), the standard countermeasures to be implemented on site (Hydration and Cooling) and, in case those preventive measures fail, the evidence-based management of the exertional heat-stroke (Prevention and treatment of EHS). All the manuscripts highlighted in this E-edition are recent (i.e. from 2019 onward) and, most importantly, all sections include brief evidence-based summaries for the busy clinicians and practitioners.


Prof Sebastien Racinais | @ephysiol


Epidemiology and environmental conditions

This introductory section explains how athletes can reach a core temperature above 41ºC when exercising in the heat (Racinais et al 2019). Although most of our knowledge is derived from occupational settings and endurance sports, it also includes special considerations for Football (Nybo et al 2020) and an analysis of 8530 elite beach volleyball matches (Racinais et al 2000) showing the higher risk of playing in the heat when not seasonally acclimated. The editorial from Notley et al (2020) (which features the figure below) confronts the conception of a thermoregulatory difference between men and women as all humans are challenged by acute heat exposure but are able to adapt, irrespective of sex.

While the effect of exercising in the heat are relatively well understood, there is still discussion on how to define “heat” and evaluate the heat stress as it depends on several factor including temperature, humidity, radiation, and air flow. This complexity is explained in the editorial by Grundstein and Vanos (2020), and Thorson et al (2020) present original data challenging the traditional WBGT utilised by most International Federations (IFs).

For another highly recommended summary of this issue, we would recommend you watch this video on the effect of environmental temperature on elite athletes, with Professor Sebastien Racinais.

Similarly, in this Experts in Sport podcast (hosted by Loughborough University), host Martin Foster is joined by Dr Lee Taylor, Reader in Exercise & Environmental Physiology, Ben Stephenson, Research Assistant (Peter Harrison Centre for Disability Sport) and Professor Sebastian Racinais, Head of Research at Aspetar, where they discuss some of the challenges posed by the Tokyo Games.

Traveling to acclimate vs traveling to compete

The most important countermeasure one should adopt before competing in the heat is heat acclimation (Racinais et al 2015). However, although 61% of the elite cyclists responding to a questionnaire had some form of heat exposure prior a world championship in hot ambient conditions, only 38% seem to have a dedicated acclimation plan (Racinais et al 2020).

This section provides brief notes illustrated by a figure (included below) on how to individualise heat-acclimation (Racinais and Ihsan 2020), how to recover from it (Ihsan et al 2020) and how to schedule it (Racinais and Periard 2020).

It also explains the other travel (Janse van Rensburg et al 2020) and environmental (i.e. pollution, Sandford et al 2020) requirements.

Hydration and Cooling

It is strongly recommended to acclimate in advance to avoid a last minute physiological and perceptual load during the tapering period (Racinais and Periard 2020), as evidenced in this figure.

Once on site, the athletes should be focusing on their hydration (Periard et al 2020) and perfecting their race-day cooling (Bongers et al 2020) which should have been piloted beforehand (Taylor et al 2020). Annecdotically, similar cooling techniques can also be used to attenuate personal protective equipment (PPE)-induced heat stress due to COVID-19 (Bongers et al 2020).

In this video, Evan Dunfee (4th Rio 2016 and 3rd Worlds 2019 50 km race walk) and Trent Stellingwerff (Canadian Sports Institute – Pacific), discuss everything from altitude camps, heat adaptation, nutrition, scheduling, to the fine details of putting everything together (cooling, pacing, hydration, nutrition) on race day.

Prevention and treatment of EHS

If despite all the above precautions, an athlete is suffering from exertional heat stroke (EHS), it is important for the IFs to have clear policies and procedures (Mountjoy et al 2020) including adapting the rules, promoting acclimation, having an emergency plan, and providing adequate education and training to the athletes (Parsons et al 2020). As summarised by Hosokawa et al (2020), on-site rapid cooling is the most important treatment and should be facilitated by the implementation of a ‘heat-deck’ by the local organising committee. This section also provides an overview of other issues including heat stress during pregnancy (Ravanelli et al 2019) or gastrointestinal perturbations (Snipe et al 2019).

We hope you have enjoyed this e-Edition. If you want more relevant content, you might enjoy this summary of the issues facing those competing in Tokyo. Get in touch via the usual social media channels if you have any feedback about this e-Edition, and we wish the very best to anyone going to the Games later this year.