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What Does 120 MPH Really Mean?

by USPTA Master Professional Alan Cutler and USPTA Elite Professional Jose Pastrello

As tennis players watch matches on TV, most commentators tell us how fast balls are hit -- serves going 120 mph, backhands going 100 mph. We can even see the ball speed display on TV and use it to judge the quality of the hit. But is speed the only good way of describing a shot, or is the duration of time between shots that the ball is in the air a more useful piece of information? Everyone talks about how fast a tennis ball is moving and 120 mph sounds fast. But what does that mean to the average player and how do we explain that importance to our students?

Even our least skilled students talk about how fast the pros hit and make it their goal to hit hard and fast. Speed is only part of the story and sometimes we miss the opportunity to continue with an explanation. Most mph numbers are just that -- a descriptive number, but what does it really relate to? As coaches, it is our job to find different ways to communicate information that may be more practical for our students.

Our lower level students, our serious recreational, and even the high-performance tennis athletes all want to hit the ball hard like the pros, but have we, as coaches, explored and explained to them the reasons why we ought to pay attention to speed?

With the new racket designs being developed to allow players to hit the ball harder & faster and strings are becoming better designed to match power, more recreational players are now able to hit the ball at substantially faster speeds than in past generations of players. We all have students who are 3.5 – 4.0 that can hit 100 mph on their serve. Consumers are demanding that racquets allow for more powerful and faster strokes, and it does not seem that this trend will change in the near future.

The following chart is ball speed; distance traveled over one second. This is assuming no extra factors that will be addressed later in this article. But just moving in the air without a bounce and assuming speed is constant.
So, what do all these numbers really mean? At 55 mph, the speed for a common recreational ground stroke, the ball travels 78 feet in just under one second. That simply means that from one contact to the next, the player has just under a second to get ready and hit the ball. If we look at a ball that is hit at 105 mph, the player has just over half a second to hit the ball. This time between the opposing player’s initial contact of the ball and the returning player’s contact with the ball, is what we refer to as duration.

There are many things that affect duration, and the following is just a short list:
  • Depth of shot, or where the ball bounces The farther from the baseline or service line the ball bounces, the more speed is lost and the duration increases.
  • Court surface The friction of the ball contacting the court surface affects how much speed is lost. Grass courts are the fastest; hard courts lose more speed; and clay really slows down the speed and increases duration.
  • Trajectory of shot The arc of the ball also can affect duration. High trajectory takes the longest; mid-trajectory is slightly less; low line drive is the quickest.
  • Spin A flat spin tends to have a flatter trajectory; topspin tends to arc taking slightly longer; and a slice can be hit at many trajectories.
  • Temperature and humidity Dry and hot conditions allow the ball to move faster in the air; high humidity might slow down the speed.
Reducing the distance can also affect the duration. This is probably the most overlooked way to affect duration. If your student moves off the baseline (78 feet) and hits near the service line (61 feet), this cuts the distance that ball needs to travel by 20 percent. Moving forward while the ball is coming to you shortens the duration quicker because of the combined effect. It takes time away from both players, but the double effect is controlled by the player hitting the ball. Forward movement combined with shortened distance is a killer.

Explain to your student that if they’re able to affect duration, shot selection can be altered. If a shot requires more footwork but the duration does not allow for it, this may cause issues. Taking a tenth of a second away from the player can cause all kinds of issues, including making it harder to properly prepare and making good contact with the ball.

Using the example of a 55-mph groundstroke having about one second to prepare, if you can take 2 tenths of a second (.20) off the duration that a player has, this is a huge advantage. This equates to a 20 percent reduction in time, meaning 20 percent less time for the player to react. If the goal is to make the opponent feel rushed or pressured, taking 20 percent off their prep time is a great way to do it. If one player is at the net, shortening the distance, the ability of the opponent to move quick enough is reduced by just short of 50 percent. Placement is all that it would take to terminate a point.

It is also important to explain how far a player can move in the amount of time given. A world class sprinter runs 100 meters in just under 10 seconds. Very few of our students will have that kind of speed. Most of our students are recreational players who will move at a lesser pace. How far can an average recreational player move in a half a second or even in one second? From my experience, not very far. In a second, maybe an average player can run five steps or less. In a half a second, less than three steps for sure. One of the things that most recreational players try to do is use a boundary such as the sideline or baseline as a target. When they understand duration, it becomes clear the baseline or sideline target do not have as much to do with the ball. Even if the opponent gets to the first ball, they are unlikely to get to a second one.

Another very important factor with regards to ball speed and duration is the time between shots. Assuming that a player has hit a tennis ball at 55 mph or higher, and the opponent returns the ball back at a similar speed, there will be very little time (only two seconds total) in between shots that a single player can hit. Coaches must explain to the players why recovery after a shot is important. With a maximum time of two seconds in between shots, the player must realize that time is not on their side, and every fraction of a second is important.

Whether playing singles or doubles, a player must understand how to recover after a shot to minimize the number of steps to be taken in the next shot. As previously mentioned, a player can take just a few steps in one second. If the player is off position when his opponent hits the ball because he was not able to return to the neutral position, now the player will be forced to run more steps which will effect his shot. Recovery is a huge part of tennis that has a direct relation with balance. In a club level, how a player uses the first second after he or she hits a ball becomes even more important because as bodies age, the response time of the feet become a little slower.

As coaches, we maybe need to look for clearer ways to explain mph, why it is useful and why it is important. It is our job to find ways to get people to understand tennis and being a good coach means being a good communicator. Looking at mph, explaining and relating that information to duration between shots is another way to communicate what the speed of the ball really translates to and how we can use that information. Most tennis athletes know that their performance declines when they are rushed. It’s always better when it is the opponent who feels rushed.


About Alan Cutler
Alan Cutler is the general manager for Playtennisforlife.info. He is one of the only dual master professionals (USPTA and RPT) that holds two specialist degrees in computer and competitive player. He taught tennis in municipalities, leased facilities, resorts, and HOA’s and has held many levels of positions from teaching professional to general manager.







About Jose Pastrello
Born and raised in Sao Paulo, Brazil, Jose Pastrello attended Florida Gulf Coast University, where he was part of the tennis team and graduated with a degree in Business Management. After college, Jose worked in the software business as a data analyst. A USPTA elite professional, he is the director of sports at Collier’s Reserve Country Club where he is responsible for tennis, fitness, pickleball, bocce, and aquatics.


 
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