The Rules of Tennis
As we were exploring the four types of balls approved for sanctioned tennis competition last week, I stumbled across a YouTube video containing screen shots from the 2012 version of the “ITF Guide to Products and Test Methods.” One of the pages depicted in that video illustrated notional bounce paths for three of the four types of approved tennis balls. That image also contained a note that the Type 3 tennis ball is also permitted and recommended for play at High Altitude. It is a complete mystery why the ITF would make that recommendation.
As a quick history lesson, High Altitude balls were added to the ITF standard in 1979. The unimaginatively named Type 1 and Type 3 balls were codified in 2002. That update also designated the standard tennis ball used by the majority of players both before and after that change as Type 2.
At high altitude, a Type 2 ball bounces with a much higher rebound trajectory than the same ball at sea level. The reason for the differential is air pressure. A bag of potato chips purchased in the mountains will usually be puffed out like a pillow. The cause is the differential in air pressure between the altitude where the bag was sealed and the altitude where the chips were sold. The same thing happens to the pressurized interior of a tennis ball.
The necessity for high altitude balls was summed up nicely by Kurt Desautels on the USTA Colorado Website. “Here at 5,280 feet (give or take some elevation), those fuzzy yellow spheres bounce like they’re made of FLUBBER, not rubber!”
The specifications for the four types of tennis balls are provided in Appendix I, Table 1 of the ITF Rules of Tennis. The High Altitude ball is identical to the Type 2 ball with the exception that “rebound” which is essentially the bounce height requirement is lower. That is because all balls are tested by the ITF in the same facility and under identical conditions. Balls that might be regarded as “dead” at lower altitudes are better in the mountains.
There is a footnote attached to the specs for the Type 3 ball in Appendix I of the current ITF Rules of Tennis that repeats the assertion that Type 3 balls are good for high altitude play. It also provides additional detail on what constitutes high altitude.
This ball type [Type 3] is also recommended for high altitude play on any court surface type above 1,219 m (4,000 feet) above sea level.
ITF Rules of Tennis, Appendix I, Table 1, Footnote 2.
The rebound specification for the Type 3 ball are identical to the Type 2 ball and higher than what is specified for the High Altitude Ball. However, the Type 3 Ball is slightly larger, which may be the reason why the rebound height is depicted as higher in the 2012 “ITF Guide to Products and Test Methods.” That suggests that the Type 3 ball would bounce even higher at high altitude. That is exactly the opposite what is needed to compensate. Maybe that is one reason the Type 3 ball never caught on.
It is a mystery to me why the ITF would recommend a ball for high altitude that appears to be worse for playing in those conditions.
In true Fiend at Court spirit, I am not done with High Altitude balls yet. My research into this topic uncovered another curiosity regarding tennis balls and high altitude. It is another one of those cases where one rabbit trail leads to another. I simply can’t resist the temptation.
- Automated Testing of Tennis Balls – Mecmesin Force Measurement, YouTube Video, viewed 14 June 2021.
- The Right Ball for Altitude, Kurt Desautels, USTA Colorado Website, Undated. (Apparently originally published in the Fall 2013 issue of Colorado Tennis.)
- United States Tennis Association (2021), Friend at Court: Handbook of Rules and Regulations, White Plains, NY
