Heating Up: How to Use the Sun to Your Advantage
- Rajit Garg
- May 27, 2025
- 5 min read
With the 1st round of Roland Garros having come to an exciting close, it's safe to say that the summer season is in full swing! Things are sure to get hot and spicy over in Paris in a few days, with little to no cloud cover + temperatures in the 80's (Fahrenheit) / high 20's (Celsius). Some players' games are well-suited to this atmosphere -- the first to come to mind being Rafa. In the 2012 final, even for Novak, it became discouraging after hours of sliding side to side on the hot, slow clay, trying to defend against Rafa's endless barrage of high RPM groundstrokes. This was actually the longest Grand Slam final in history, despite lasting only 4 sets. Do you remember how many hours of punishment Novak had to endure?:
How long did the 2012 Roland Garros final last?
8 hours
6 hours
5 hours
Answer can be found at the bottom of this post, after the citations.
In the spirit of summer, let's go over a couple topics relating to hitting in hot weather: first, how heat can actually influence the game via changes in the court; and second, the science of how to most effectively counteract dehydration.
Hot Plate
The manner in which elevated temperatures impacts play varies greatly, depending on the surface:
Hard 🔷. In direct sun, hard courts can reach between 120-140 degrees Fahrenheit (50-60 Celsius) -- side note: make sure you avoid sitting / resting on the court, as you could risk 3rd-degree burns within seconds. Hard courts are made of asphalt and concrete, which have high thermal conductivity. In other words, it is very easy for these materials to absorb heat, and this is primarily due to their high density (lots of mass per given unit of space to efficiently transfer the heat) and lack of insulation (no pores for cool air to enter).
These 2 materials sit beneath a layer of acrylic (used to make the court smooth and shiny), which has awful conductivity. It is very HARD for acrylic to DISSIPATE heat, due to the electrons being bound tightly to the atoms, resulting in a lack of energy transfer.
Put together, this implies that once heat gets into the lower layer, it takes a long time for it to get out of there. Heat causes molecules to expand, and the molecules in the court are no exception. As the court expands, it deforms and softens ever so slightly, causing the ball to have an incremental spring (less energy is transferred to the court, more is kept in the ball). The court won't turn into clay, but it could be prudent to stand back a step or two to adjust to the distorted trajectory.
Heat also expands the molecules in the air, lowering density and improving aerodynamics. So, the ball will be faster in addition to bouncier.
Clay 🟤. Clay is not as hard to deal with, given a couple of factors. First, clay is porous, which enables air and moisture to more easily enter and cool the surface. Second, you may have noticed, but sometimes at tournaments like Roland Garros, between sets, the staff water the courts to reintroduce moisture -- keeping the surface more consistent to play on.
Perhaps the biggest controversy that is most unique to clay is match timing. Rafa famously prefers playing during a particular time, and I bet you can guess when it is!:
"I don't like to play on clay during the night because humidity is higher, the ball is slower and there can be very heavy conditions especially when it's cold."
- May 22, 2022
I guess you could say that the timing of his draws during peak sun made a night and day difference on his opponents' fatigue levels!
Grass 🟩. Luckily, grass requires the least adjustment of the 3! Grass retains moisture even better than clay, as it stores water well in its blades and roots. If you're diving for a ball in the heat, it's not a problem, as the ground may barely even feel warmer than usual. The bigger worry may be trying to get the grass strain out of your whites!
No Sweat
The human body is complicated, and there are many physiological mechanisms involved in coping with extended match-play in the heat.
Your heart may pump up to 10-20 bpm's faster -- the energy directly required for your heart to beat at a faster pace is minimal, but let's examine the indirect impact. Instead of your heart sending blood to your muscles for aerobic glycolysis, it's getting directed to the skin, forcing anaerobic glycolysis, which is about 16x less efficient in terms of ATP (adenosine triphosphate) yield. This causes pros to burn at least 50-80 EXTRA calories per hour (equivalent to 2-3 gels or sports drinks), which adds up, especially if they're playing a 3 hour-long match. That's on top of the ~1,000 they're already burning.. I'm getting hungry just writing about this!
Here's another fun fact: in hot temperatures, reaction time can worsen by up to 25-50 milliseconds. When your reaction time needs to be 250-400 ms to return a serve, the 5-25% margin of safety matters.
You might be wondering -- what are some things I might be forgetting to do to keep hydrated during my match? Everyone remembers replenishing fluids in the heat of the moment.. but here are 3 other things you can do pre- and post-game time to keep the ball rolling (hopefully over the net):
3-4 hours BEFOREHAND, you should drink a 1/2 liter of water with a serving of your favorite electrolytes. It will take about 2-3 hours for this ingested fluid to work its way through the small intestine and distribute through the extracellular space, expanding plasma volume. This will ultimately improve overall thermoregulation.
1 hour BEFOREHAND, you should drink another 1/4 liter of water with a similar amount of electrolytes -- a little sour treat! This fluid will begin to circulate within 20-30 minutes, providing a little top-off to the earlier routine.
1-2 hours AFTERWARD, you should drink 1.5x the amount of fluid you lost. This could be up to 2-3 liters per hour of play depending on how much you sweat, so potentially get ready for an absolute chug-fest. The reason this final step is especially important is, the body is most effective at absorbing fluid right after exercise (due primarily to activation of aldosterone and ADH + increased insulin sensitivity in muscle cells -- all improving water uptake). If you're playing a match or training the next day, your future self will thank you.
One last very special tip before I sign off -- if you want to be extra prepared, the night BEFORE the match, you can also drink a 1/4 liter of water with a tablespoon of salt. The morning of, while you're drinking the remaining 3/4 liters, you can munch on some watermelon with.. you guessed it -- more salt! The sodium will actually have the added benefit of making the watermelon taster sweeter and juicier, through blocking the bitter taste receptors on your tongue and attracting water to the surface of the flesh.
Have fun, be safe, and enjoy the sun! ☀️
Links
Trivia Answer: 6 hours!
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