Tour is usually held annually.
After playing a game, it will take a year before the players can return to the past venue. During the offseason, the event will trim, maintain and maintain the venue, which will cause slight differences in the stadium every year.
For example, the ongoing US Open , many players complain that the stadium this year has become faster than last year. It means that when the ball is swinging at the same speed, the players feel that the speed of the tennis ball rebounds is faster than last year.
On Wednesday, after Rude lost to Tsitsipas in the second round of men's singles, he said that the speed of the US tennis courts has obviously faster this year. "I have never played on a faster court in my life than this year's US Open."
also holds the same view as Rude Beretini . The Italian player who has entered the top 16 of this year's US Open said that the US Open's courts are "very fast".
2019 US Open men's singles runner-up Medvedev further pointed out that the driving range for players to train is the fastest. "I train on the driving range. The speed of the court is very fast, and I feel that every time I hit the ball is late. Compared with the official competition, the speed of the earth is slightly slower than the driving range, but it is still faster than last year."
Muguruza 's view and plum Dwedeff is somewhat similar, "I always think the US Open is a fast stadium. The speed of the venue this year is indeed a bit faster than last year, but it is not so fast that it is incredible. In addition, it depends on which stadium you play. According to my experience, stadium 17 is faster than any stadium here, and Arthur Ashe stadium also seems to be faster than Armstrong stadium."
However, some players expressed different opinions. Sabalenka said: "Before the start of the main game, I had trained at the Grand Billiards. I think the stadium is a bit slow. Maybe it's because it has no roof, so there's more air."
Regarding the players' response, the American Tennis Association, the organizer of the US Open, said that in 2018, more players reported that the stadium was too fast, so they appropriately lowered the stadium's speed in 2019, and the stadium's speed has remained unchanged since then. In other words, the speed of the US Open venue this year is the same as in 2019 and 2020.
Players are based on their own subjective feelings about the speed of the field. So, are there any measurable objective data to evaluate the speed of the ball on the court?
The answer is yes.
As early as 2016, TennisTV began to release the "Court Pace Index (CPI)" to measure and compare the stadium speeds of the nine-stop ATP1000 Masters.
Court speed index is calculated based on the friction coefficient of the tennis ball and the field and the recovery coefficient of the tennis ball after touching the ground.
The calculation formula is: CPI=100(1-μ)+150(0.81-e), where μ is the friction coefficient and e is the recovery coefficient. It should be noted that when we talk about the ball speed of the court, we refer to the ball speed of the tennis ball rebounding after the touchdown, because the speed of the tennis ball before leaving the racket and reaching the touchdown depends mainly on the hitter's swing speed and how the ball hits. The friction coefficient in the formula
is mainly related to the surface roughness of the court, while the recovery coefficient is mainly related to the material of the court. There are obvious differences in the friction coefficient and recovery coefficient of grassland, hard ground and red clay.
Even for the same tour, it is difficult for the competition party to use when renovating the stadium every year to achieve the same materials and construction technology, so there are subtle differences in the friction coefficient and recovery coefficient, which leads to changes in the stadium speed index. This is the real reason why the players feel that the speed of the court this year is different from last year.
The following figure is the stadium speed index (CPI) of the 2017 Four Grand Slams and Nine Masters venues released by a professional institution.
From the above figure, it can be seen that Australian Open is the fastest among the four Grand Slams, it is even faster than Wimbledon , and French Open is the slowest; Shanghai Masters 's ball speed is the fastest among the nine Masters, and it is also the fastest among the 13 venues included in the comparison.
Overall, the speed of the clay competitions in Monte Carlo, Madrid, Rome and the French Open is the slowest, which also meets the expectations of most people. Surprisingly, the ball speeds of Indian Wells and Miami are significantly slower, and their stadium speed index is only about 70% of that of Shanghai.
In addition, the ball speed of the court is also related to the frequency of use. The topcoat of the hard ground will be mixed with fine quartz sand , with the purpose of adding rough texture to the field and preventing players from slipping while running.
The brand new tennis court is always in the roughest state. As the use time accumulates, the player's shoes will grind off the quartz sand on the surface of the court, making the surface of the court smoother and smoother, which leads to a decrease in the friction coefficient, and therefore the ball speed will become faster.
This is exactly why Medvedev said that the ball speed of the driving range is faster than that of the official playing field - the driving range is used more frequently, so the surface is smoother, so the ball speed will naturally accelerate. (Source: Tennis Home Author: Yun Juan Yun Shu)
