In our latest on the research blog, Performance Specialist Amber Taylor talks us through the hidden opponent that tennis players are now increasingly coming up against: heat. How does heat impact on performance, and what are some of the countermeasures organisations and athletes can take to combat increasingly extreme conditions.
The Overlooked Factor in Tennis Performance
Tennis is widely known for its demanding physical nature, lengthy matches, and mental toughness, but one of the most important and detrimental factors is often overlooked: heat. Approximately 30% of professional tennis tournaments are played in hot conditions (temperatures >28°C, dry or humid). With roughly 1 in 3 matches in the professional calendar played under thermal stress; 3 of the most well-known known Grand Slam tournaments (US open, Australian and French Open) are held in these extreme heat environments, with Wimbledon also having seen some extreme heat in recent years. Players are therefore required to maintain the upper limits of their performance abilities while managing this thermal stress.
Why is heat such a problem in tennis?
The nature of the sport
The unique demand of tennis requires a high level of physical exertion over durations of 90 minutes to 5 hours. During matches, the intermittent nature of the game requires short bursts of high intensity activity (lasting 4-10s) with short recovery between points. The ability to sustain this high intensity throughout is a key determining factor for a player winning or losing a match.
Tennis requires both physical and cognitive skill that are put under stress when play progresses and a player fatigues. High levels of power and endurance are required for optimal execution of groundstrokes, serves and the ability to change direction and accelerate and decelerate quickly. Beyond just the physical component, cognitively, players require the ability to react, respond and make appropriate decisions under the pressures of this fast-paced game. As fatigue sets in, these technical skills (both physical and cognitive) become impaired and overall performance declines.
This combination of high intensity activity, technical skills and long match duration puts greater strain on the body’s ability to regulate core body temperature. Alone, the nature of tennis itself provides a great opportunity for thermal discomfort and heat stress.
The Environment
Interestingly, the courts that matches are played on can impact the temperature players are exposed to. Temperatures can reach 10-20°C higher than surrounding air temperatures due to surface characteristics – asphalt and concrete absorb and retain heat from the sun making hard courts the most physically draining court surface compared to a clay or grass court surface. Clay courts also retain heat from the sun due to the mineral surface characteristics but to less of an extent, while grass courts remain much closer to ambient air temperatures as the sun reflects off the grass rather than storing it and the moisture from the surface itself helps to keep the court cooler. Tournaments played on darker surfaces absorb even more solar radiation, intensifying these heat affects. This explains why for the Australian and US open (played on a dark hard-court surfaces) players are exposed to more severe heat conditions.
Tournament scheduling has also played a huge impact on weather conditions for players. With the Australian and US open played in the summer, temperatures can exceed 43 °C. Much attention is set on the major Grand Slams; however, many lower tier matches are also held in similar extreme environments throughout a professional calendar year but, unlike major tournaments, fewer resources and regulations are available– putter greater thermal strain on players. Tournaments such as the Dubai Tennis Championships, Citi Open regularly expose players to these high temperatures, exacerbated by high humidity levels also. Further, ITF and Challengers tours are also held in hotter regions of the world including Africa, Asia, and South America. During these lower-level tournaments, given the player wins, they play matches consecutively without a day’s break that is given for the majors. Research has shown that even with adequate hydration and recovery following intense exercise in hot conditions, a “carry-over” effect can occur, resulting in reduced performance and an impaired physiological response to heat during later stages of a tournament (Bergeron, 2014). Furthermore, even in the absence of heat stress, consecutive match play in elite tennis has been found to negatively affect hitting accuracy, stroke positioning, and emotional responses (Gescheit et al., 2016). These tournaments are highly important for professionals to increase their ranking and are also a great developmental pathway for lower – ranked professionals to get more match exposure a play against more experienced players. This shows that heat exposure in tennis is not constraint to the most well-known tournaments but is a consistent challenge faced throughout the calendar year.
What happens when we add heat?
When on-court temperatures exceed 28°C, the physiological strain placed on tennis players increases significantly, negatively affecting performance and player safety. Competitive tennis played under heat stress places higher demands on players due to the combined effects of elevated core temperature, dehydration, and cumulative thermal strain throughout tournaments (Périard and Bergeron, 2014). A study comparing match play in hot and cool conditions found that whole-body hyperthermia was magnified in hotter environments, leading to increases in heart rate, perceived exertion, thermal discomfort, and thermal sensation (Périard et al., 2014). Reductions in muscle strength and torque production contributed to physical fatigue and impaired movement efficiency. Players increased the duration between points to minimise the effects of the heat, reducing effective playing time and performance aspects, including shot quality, accuracy, and technical execution. Slower reactions and impaired decision-making were also made apparent. This highlights how excessive heat can directly reduce both the physical and cognitive performance required for elite tennis competition.
The impact of heat on play and performance is also demonstrated through many cases of on court complaints, retirements, and losses due to heat related illness. For example, Emma Radacanu had to retire early from her first round in Wuhan due to dizziness while Jelena Ostapenko reported getting heat stroke. Famous words from Medvedev ‘one player is going to die’ highlights the impact that the 34°C heat had on thermal comfort and the severity on performance.
Heat related illnesses: What are they and why are they so severe?
Heat-related illnesses occur when the body is exposed to excessive or extended periods of heat without enough hydration or cooling. The severity of these illnesses ranges from mild, moderate to severe and can develop through these stages quickly, especially during high intensity exercise under hot conditions. The 3 main types of heat related illnesses are heat cramps, heat exhaustion and heat stroke. Heat exhaustion is the most common heat related illness and includes symptoms such as nausea and vomiting, tachycardia, dizziness, muscle cramps, energy depletion, central fatigue, and syncope (Nichols, 2014). Differentiating between heat exhaustion and heat stroke can be difficult with both conditions involving elevated body temperature. However, in heat exhaustion, core body temperature generally remains below 40°C, whereas heat stroke is defined by a core temperature above 40°C together with neurological impairment, including apathy, confusion, or altered consciousness. Heat stroke is life-threatening and therefore the most serious heat related illness. Sustained heat stroke in the range of 41.6–42°C may result in protein denaturation, cellular injury, and failure of normal physiological mechanisms (Nichols, 2014).
Looking at core body temperatures highlights the severity of the risk of heat related illness. Core body temperatures of professional male and female players have been shown to peak to 38.9-39.1°C (Tippet et al., 2011). More concerning data has been displayed by Julien Periard who reported males to peak at 39.4°C in hot conditions (34°C) compared to 38.7°C when temperatures were moderate (19°C) (Périard et al., 2014).
How have governing bodies responded?
Recent developments in professional tennis regulations are starting to show the growing concern around extreme heat. The Association of Tennis Professionals have recently introduced a new heat regulation policy at the start of 2026 developing the previous set in 2014. This new approach will be allowing a 10-minute cooling break for players when Wet Bulb Global Temperature (WBGT) exceeds 30.1°C, with play suspended entirely if it rises above 32.2°C. WBGT is a measure of the environmental heat stress placed on the body accounting for 4 environmental conditions: humidity, radiant heat, and wind, to provide more realistic measure of overall thermal stress. This therefore considers the fact on court temperature is hotter than ambient temperature outside.
Governing bodies are beginning to respond to players concerns and try to reduce the issue around heat stress. However, these measures do not prevent the drop in performance that still occurs under extreme conditions as the intensity of tennis itself still provides thermal stress on the body that doesn’t prevent core body temperature from reaching dangerous temperatures and has only been implemented for few of the calendar tournaments per year. Also, as we saw earlier players may be more inclined to need these heat policies in tournament where play occurs on consecutive days. As a result, players performance levels are likely to remain poorer if heat training is not implemented.
Jet lag and travel: does this influence heat tolerance?
Professional tennis players frequently travel long distances to compete, often crossing multiple time zones over the course of a season. It is important to consider the effect of jet lag and long-haul travel, on how players respond to heat and their body’s ability to regulate core temperature.
Although direct research has not yet conclusively determined whether jet lag specifically reduces heat tolerance in elite tennis players, there is indirect evidence, by linking jet lag to circadian disruption, sleep loss, and impaired thermoregulation. Research examining sleep and recovery in elite athletes has shown that long-haul travel can reduce total sleep time, decrease sleep efficiency, and negatively affect perceived recovery for up to 48 hours after arrival (Doherty et al., 2023).
Studies also suggest that sleep restriction can increase feelings of fatigue and thermal discomfort, causing athletes to feel hotter and perceive exercise as more demanding, even when core body temperature itself is not dramatically altered. These effects can negatively impact both physical and cognitive performance, including concentration, decision-making, and reaction time during competition (Moore et al., 2013). These are key metrics that are assessed when looking at the quality of tennis performance so it is clear performance would be worse in this case.
Why Heat Acclimation Matters in Tennis.
Heat acclimation involves training in hot environments to elevate core body temperature which in turn causes the body to adapt better to deal with heat. Evidence suggests maintaining a core temperature above 38.5°C, is optimal for promoting physiological adaptation and improving the body’s ability to cope with thermal stress (Gibson, Watt, & Maxwell, 2015). An increase of approximately 1.5°C to resting core body temperate can potentially induce this physiological response too. Through repeated exposure, the body becomes more efficient at regulating core temperature, by enhancing its cooling mechanisms. These adaptations include an earlier onset of sweating, a higher sweat rate, reduced electrolyte loss, and the ability to maintain a lower core temperature at rest and during exercise. Athletes also experience improved thermal comfort, meaning they feel less strain when competing in the heat. Ways to use heat to elevate Tc >38.5°C can be both passive e.g., sauna sessions and post exercise hot water immersion or active e.g., exercising in a heat chamber or wearing a sauna suit. There is not one specific protocol that would induce “optimal” adaptations across all athletes, so protocol selection should be customised to current training status, training availability, tolerance to additional training stress and access to equipment/ hot environments (Pryor et al., 2018).
Benefits for Tennis Players
Ultimately, heat acclimation will enhance performance levels and improve players safety. By improving the body’s ability to cope with heat, players can maintain higher levels of physical output, maintain skill execution, and sustain effective decision-making throughout a match. Additionally, athletes will feel less fatigued and have a lower perceived effort, which will help them to stay at the upper end of their performance capabilities.
The benefits of heat acclimation extend beyond safety. While reducing the risk of heat-related illness is critical and will ensure players won’t need to retire early from matches, the ability to maintain a higher quality performance even as they fatigue provides a noticeable competitive edge. In professional tennis, where matches are often decided by small margins, this advantage can be the winning edge for players.
How to Implement Heat Training?
How can professional tennis players use heat training to improve heat tolerance to enhance thermoregulatory efficiency and reduce physiological strain?
Research shows the most effective heat adaptations occur over repeated exposure of at least 7 consecutive sessions with the greatest acclimation at 10-14 sessions 2 weeks prior to and event. However, for professional tennis players, travel between tournaments, managing time spent with media and dealing with jet lag are unavoidable barriers that make this heat protocol challenging to practically implement. It is also important that this heat training doesn’t induce pre – competition fatigue that will become heightened when match play begins and the tournament progresses.
A structured heat acclimation block prior to travel will be an effective approach to achieve meaningful physiological adaptation before competition. This could involve approximately 10 heat exposure sessions across a two-week period prior to tournament/ match, with the aim of elevating core body temperature to above 38.5°C. Early sessions may consist of low-intensity exercise such as cycling or running to gradually elevate core temperature, while later sessions could incorporate shorter, higher-intensity efforts designed to replicate match demands more closely while still maintaining the thermal stimulus. To ensure players arrive in a fully recovered and competition-ready state, a taper period of 3–5 days will allow sufficient time for recovery, minimising residual fatigue. A pre match warm up session can take place the day prior, to ensure they are technically and cognitively prepared whilst replicating the environment they will be in on match day.
Following an initial heat acclimation phase, periodic maintenance sessions throughout the competitive season e.g., post-training sauna exposure, can be useful for retaining some adaptations whilst helping to reduce cumulative fatigue as the re – acclimation process pre-tournament can be shorter and less taxing.
In cases where a full acclimation block is not possible due to travel or other commitments, a combined strategy addressing both circadian disruption and environmental stress may be more appropriate. This would involve early arrival, low-intensity heat exposure sessions focused primarily on maintaining thermal stimulus and reducing training load. The player would expose themselves to shorter burst of heat within the days prior to match day but really reduce duration of each session. The focus here is heat exposure with a technical focus rather than heavy/ intense training sessions. After the first few days of exposure, and time to recover, short 30–45-minute higher intensity sessions in heat can provide a match specific environment without having the cumulative load build up.
Other appropriate forms of training may be passive heat training using sauna sessions. Sauna sessions are a really easy way of inducing thermal strain and forcing adaptation in a way that is more easily managed with training load. They can be particularly good for athletes new to heat training or those who cannot tolerate the additional training stress from the combined effects of training in the heat. However, a limitation of passive heat exposure techniques could be the athlete is not fully prepared for the sensations or physiological responses to the heat (Pryor et al., 2018). This is particularly important before high intensities reached in competitions. So, combining small bursts of active heat training (replicating a match environment) followed by a sauna session can ensure Tc > 38.5°C, without overloading stress pre- competition.
Practical Takeaway
Heat training is more common with runners and cyclists with less focus on the importance for tennis players despite its brutal conditions. Exposure to heat prior to matches/ tournaments massively improves on court safety and performance outcomes. Therefore, heat should be treated as a key training component for performance that can provide a competitive edge, rather than an external barrier beyond their control.
Conclusion
Heat is an increasingly important factor in professional tennis leading to serious heat-related illness and a significant limitation on performance. While governing bodies have introduced policies to help protect players when conditions become extreme to provide safer environments, these measures have not been applied to all tournaments in the professional calendar year and are not sufficient to maintain performance quality and comfort when temperatures are hot (>28°C).
Ultimately, heat acclimation provides a practical and effective solution to hot environments. Players will find they can cope better under thermal stress while maintaining high levels of performance.
References
Bergeron, M.F. (2014). Hydration and Thermal Strain during Tennis in the heat: Table 1. British Journal of Sports Medicine, 48(Suppl 1), pp.i12–i17. doi:https://doi.org/10.1136/bjsports-2013-093256.
Doherty, R., Madigan, S.M., Nevill, A.M., Warrington, G.D. and Ellis, J. (2023). The impact of long haul travel on the sleep of elite athletes. Neurobiology of Sleep and Circadian Rhythms, 15, pp.100102–100102. doi:https://doi.org/10.1016/j.nbscr.2023.100102.
Gescheit, D.T., Duffield, R., Skein, M., Brydon, N., Cormack, S.J. and Reid, M. (2016). Effects of consecutive days of match play on technical performance in tennis. Journal of Sports Sciences, 35(20), pp.1988–1994. doi:https://doi.org/10.1080/02640414.2016.1244352.
Gibson, O.R., Watt, P.W. and Maxwell, N.S. (2015). Prescribing workload administration to optimise isothermic heat acclimation. Extreme Physiology & Medicine, 4(S1). doi:https://doi.org/10.1186/2046-7648-4-s1-a83.
Hopkinsmedicine.org. (2024). Heat-Related Illnesses (Heat Cramps, Heat Exhaustion, Heat Stroke). [online] Available at: https://www.hopkinsmedicine.org/health/conditions-and-diseases/heatrelated-illnesses-heat-cramps-heat-exhaustion-heat-stroke?__cf_chl_tk=0FGC_mDIi1kkVIkQoEivYjJJsq.Swky.qtIsLJ98j24-1777641757-1.0.1.1-fduvetxjV559rw4HO9arYZsaBTMfaCEBUmj.EPIU4AI [Accessed 13 May 2026].
Moore, J.P., Harper Smith, A.D., Di Felice, U. and Walsh, N.P. (2013). Three nights of sleep deprivation does not alter thermal strain during exercise in the heat. European Journal of Applied Physiology, 113(9), pp.2353–2360. doi:https://doi.org/10.1007/s00421-013-2671-2.
Nichols, A.W. (2014). Heat-related Illness in Sports and Exercise. Current Reviews in Musculoskeletal Medicine, [online] 7(4), pp.355–365. doi:https://doi.org/10.1007/s12178-014-9240-0.
Périard, J.D. and Bergeron, M.F. (2014). Competitive match-play Tennis under Heat stress: a Challenge for All Players. British Journal of Sports Medicine, [online] 48(Suppl 1), pp.i1–i3. doi:https://doi.org/10.1136/bjsports-2014-093496.
Périard, J.D., Racinais, S., Knez, W.L., Herrera, C.P., Christian, R.J. and Girard, O. (2014). Thermal, physiological and perceptual strain mediate alterations in match-play tennis under heat stress. British Journal of Sports Medicine, 48(Suppl 1), pp.i32–i38. doi:https://doi.org/10.1136/bjsports-2013-093063.