Heat Stress in Tennis: Strategies for Prevention and Recovery

Tennis, a sport known for its grace and precision, has a hidden adversary that challenges the mettle of its players: extreme heat.

Players often find themselves battling not only their opponents but also the relentless sun, leading to an increased risk of heat-related illnesses. This can lead to heat cramps, heat exhaustion, heat stroke, and other issues that will hinder their performance, such as organ failure and muscle fatigue.

Source: Australian Conservation Foundation, Climate change, extreme heat and the Australian Open

Large tournaments such as the Australian and US Open are no stranger to these conditions with temperatures and the prevalence of extreme heat conditions only continuing to soar over time. With temperatures exceeding 104°F and WBGT values surpassing 86°F, heat stress and exhaustion have become common for athletes playing in these tournaments and the fans spectating.

The Problem

Former world No. 1 Andre Agassi once compared playing in the Australian Open to "playing in a giant kiln”, which has been a shared sentiment between several star tennis players. The number of shortened matches and suspensions has also been increasing over the years at different arenas in the Australian Open, Moorabbin and Essendon, which are both located in Melbourne (see visualization).

While the Australian Open might be notorious for its scorching conditions due to it taking place during Australia’s summer months, it is not alone in facing this challenge. At the US Open this year in 2023, players faced extreme heat and humidity so strenuous that the tournament adopted a new policy to partially close arena roofs. Conditions were miserable for players and fans alike, with temperatures consistently above 90°F and humidity topping 50% on September 5th, 2023.

Players have been struggling throughout the tournament with Novak Djokovic even admitting, “I’m drenched in sweat. Just very humid conditions”, in an on court interview. Earlier this year at Wimbledon, even the fans had to get medical aid due to unusually high temperatures that exceeded 89°F.

New Guidelines

The American College of Sports Medicine (ACSM) has established guidelines using the Wet Bulb Globe Temperature (WBGT), which is based on temperature, humidity, wind speed, sun angle and cloud cover.

WBGT is used to determine the risk levels during exercise in the heat—for example, exercising strenuously in conditions over a WBGT of 82.4°F is considered “high risk”, and exercise is suggested to be stopped in conditions over 89.6°F.

The ACSM has categorized these different WBGT values into zones, with Zone 5 being particularly perilous, signifying WBGT values greater than 89.6°F. There was a study conducted by Smith et al (2018) in the Journal of Science and Medicine in Sport, which revealed a stark correlation between WBGT zones and heat-related incidents. It demonstrated a 47% increase in doctor calls, a 41% increase in trainer calls, and an alarming 87% increase in post-match heat-related incident consults as the WBGT zones escalated.

In total, there was a 55% increase in total heat-related incident consults and a 53% increase in total calls for cooling devices. This escalation of calls/consultations per WBGT zone demonstrates the prevalence of heat-related incidents and the need for cooling interventions. These findings help to highlight the urgency of addressing heat stress in tennis and implementing measures to ensure the health and performance of athletes.

Cooling Solutions

Another study in the Journal of Science and Medicine in Sport by Lynch et al (2017) simulated peak conditions from the Australian Open and examined the utility of cooling interventions during simulated tennis match-play. The interventions included iced towels (ICE), an electric fan (FANdry), a fan with moisture applied to the skin (FANwet), and 10°C (or 50°F) water ingestion which was taken as needed (CON).

By the end of set 3, core body temperature was lower in ICE compared to all the other cooling interventions. The one that came closest was FANwet, which prompted a core body temperature of 0.5°C - 1°C (32.9 - 33.8°F) higher than the ICE. ICE also proved to be the most effective by the end of set 4 and set 5, where core body temperature was lowest in ICE compared to all of the other cooling interventions.

The application of ice also resulted in a decreased heart rate, an improved thermal sensation, and reduced perceived exertion. Through this experiment, ice demonstrated its effectiveness in alleviating heat strain and enhancing player comfort during breaks.

This research shows that ice has promising results and is arguably the best option to ease heat exhaustion and the life-threatening health problems that come along with it.

The main problem with the usage of ice is that it is logistically more difficult to handle than fans or water, as it requires more storage and chilling. It also melts easily, and on its own, it is too cold and will burn the skin without a towel or napkin covering it.

The issue with having a towel to prevent freezer burns is that these towels serve as barriers to sweat evaporation, leading to local vasoconstriction (when the muscles around a blood vessel becomes constricted). This can cause high blood pressure and can put someone who is facing hyperthermia, like a tennis player, at high risk of heat stroke.

Cold Therapy Wearables

This is where Eztia's cold therapy wearables come in. The Arctic Patch serves the same benefits as ice without presenting the health concerns that come with traditional ice. The Arctic Patch contains a gel material that efficiently absorbs and radiates heat from the body, helping to regulate body temperature and heat dissipation.

The patches are lightweight and don’t require refrigeration, eliminating the logistical issues associated with ice melting.

They offer the unique ability to provide temperature-regulated cooling without impeding sweat evaporation, and players can wear them throughout the match, unlike unwieldy ice packs. Eztia's cold therapy wearables could serve as an appealing solution for tennis players and other athletes facing heat stress.

And this positive change can be applied to more than just tennis...

Cold therapy wearables can also extend beyond tennis into other sports and major events that face extremely high WBGT levels and temperatures, such as soccer and the FIFA World Cup; cycling and the Tour de France; and the summer Olympics. This could help to ensure athletes’ comfort and reduce heat-related pain and health complications, while also improving their overall performance.

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