The first week of the 2017 tennis season saw the debut of many of the world’s best players. One of the players that tennis fans will be expecting the most from is the recently knighted Sir Andy Murray. Not just because of the knighthood but because of last year’s miraculous season that propelled that honour and saw Murray do the impossible: take the World No. 1 ranking from Novak Djokovic.
It took a confluence of events for Murray to dethrone Djokovic. But, if you asked most commentators and players, they would likely say that the work Murray puts into the game in competition and in training was a huge factor.
Work is a term that gets a lot of discussion in tennis, and the sport has a lot of beliefs about which players are the hardest workers and which players try to minimize effort. Yet the sport doesn’t have a statistic for work or a way to measure effort reliably across players. This makes it hard to do more than guess about the work performed by players and how it might contribute to their success.
To try to shed more light on work in tennis, the Game Insight Group at Tennis Australia has developed a work metric. Myself and the other scientists of GIG knew that work in a match is about more than the distance a player covers. It also about the speed of their movement, the direction of their movement, and the number and intensity of changes of direction. For example, moving the same distance and rate to the side requires more effort than moving forward. Changing direction after a 2 second sprint requires more energy than continuously running in the same period of time. All of these are factors that are a good measure of work should take into account.
Using tracking data of player movement during matches, we combine the speed, direction, and distance covered of athletes into a single number that encapsulates their total work during a rally in units of Joules. Figure 1 shows the average work per shot and average work per point (over all shots in a rally). Based on matches from the past 3 years at the Australian Open, Sir Andy Murray was found to have the highest work rate, expending an average of 350 Joules per shot. Because the World No. 1 also likes to rally, he had one of the three highest averages in the average work per point (which is influenced by the player’s work rate and how many shots they play in a typical rally), clustering with David Ferrer and Gilles Simon.
Hard-working Rafael Nadal is also in the top 10 workers among the men and Novak Djokovic and Roger Federer aren’t much further behind, though Djokovic had a higher average work per point among these three.
Who works the least per shot? A lot of the players toward the bottom of the list are players who heavily rely on their serve, such as Nicolas Almagro, Ivo Karlovic and John Isner. Interestingly, big-serving Milos Raonic has a relative high rate of work per shot compared to the other heavy-hitting servers. It will be interesting to see how that distinction in Raonic’s playing style could help the rising star.
Work rates for women are generally lower than for the men, largely due to their lower body weight. Some of the hardest working women at recent AOs include Caroline Wozniacki, Carla Suarez Navarro and Aga Radwanska. Simona Halep and Angelique Kerber are lower in the rankings based on work per shot, but both have high total work per point, with averages over 1200 Joules.
As with the men, we see some of the biggest hitters among the work minimizers, like Serena Williams and Petra Kvitova. As with the power of their groundstrokes, these players are likely to be more selective about when they use the power of their movement.
Their are some factors that contribute to work that we aren’t yet able to measure. Namely the upper body movement and energy exerted in the actual action of making impact. If we could, you might see player’s like Nadal move up the list. For now, we are able to capture foot movement and that gives us a starting place for thinking about player work on court in a more systematic way. It has already revealed interesting findings, like how, in terms of the work of foot movement, Sir Andy Murray sets himself a part from many other top players. We will get a chance to see that work ethic put to its toughest test so far for the season when Murray and Djokovic face off in the Qatar Open finals.