tennis player serena williams forehand grunting

Research: Grunting Provides a Competitive Advantage

The topic of grunting in tennis is both interesting and controversial.

Many spectators see grunting as disrespectful and ultimately annoying to listen to. I personally know a few die-hard tennis lovers who can only watch certain players with the volume down.

On the other hand, some see it as a means to an end. A performance-enhancing trait if you will. Grunting may add the finishing touches to a powerful shot down the line, or help return an awkward drop shot just out of reach.

So I read with interest, a recent study that looked at the effects of grunting during physical exertion. It isn't tennis-specific but I think their results make perfect sense intuitively, perhaps supporting the player's use of it in-game.

So let's take a look at what they found and what it means for the grunting debate.


Grunting in Tennis Debate

Before we do a deep dive into the study, let's provide a little grunting context.

Grunting became a topic of discussion thanks to Monica Seles back in 1992. Since then, certain players have become famous, or rather infamous for their low, guttural expressionism.

Andre Agassi, Serena Williams, Rafael Nadal, and Maria Sharapova, who's grunts have surpassed the 100-decibel mark - the equivalent of a motorcycle or jackhammer, are the most obvious.

Many have become more accepting of grunting in tennis over the last 30 years. However, there's still an undertone of distaste for those who may use it a little too liberally. Perhaps it goes against the grain of tennis tradition, particularly its fiercely protected "quiet please" culture.

Interestingly, the stigma around grunting in tennis doesn't seem to exist in other sports. Activities like martial arts and weight lifting not only accept grunting but actively endorse its use.

So in a lot of ways grunting is not a bad thing. It just may not be the best fit for tennis, it's culture and those who love to watch it.

With this in mind, let's shake hands at the net and begin.


Study Design

As mentioned before, it's important to note this American study was not tennis-specific. It instead looked at the impact of grunting on MMA performance. They conducted two separate experiments which explored the following:

  • Force production
  • Athlete distraction


Experiment One

The first experiment took 20 participants from a Hawaiian MMA academy and asked them to kick a 100-pound heavy bag as hard as possible. The participants performed two kicking sessions one week apart. Each session consisted of five kicks and 30 seconds rest in between.

The kicking sessions were conducted 15 minutes after a 60 minute MMA or Muay Thai class, with participants able to do their own preparation before the session began.

Force production was measured by an accelerometer attached to the back of the heavy bag. Importantly, each kick was paired with or without a grunt.

Overall, 18 participants were male and two were female. Their ages ranged from 20-35 years and each participant had at least one year of MMA/Muay Thai training.


Experiment Two

The second experiment looked at the potential for simulated grunting to affect reaction time and accuracy.

Twenty-two students from an Undergraduate Psychology course at the University of Hawaii took part.

Eleven participants were male and the remaining eleven females with ages ranging from 18 to 47 years.

No participant had previous martial arts experience, except for one who had previously completed a single kickboxing cardio class.

In this experiment, participants watched a video of a man performing a high or low kick. Some kicks were accompanied by the simulated grunt and the others were not. Their task was to respond as quickly and accurately as possible to the direction the kick was going.



Overall the study found some interesting relationships between grunting and performance.

The first experiment found a 9% increase in force production when grunting and kicking (p-value 0.003).

In the second experiment, simulated grunting accounted for a decrease in reaction time (p-value of 0.001) and accuracy of response (p-value 0.001) when assessing the characteristics of the kick.

Reaction time was reduced by approximately 56ms with 3% more errors made.

Interestingly, these results align with an older tennis-related study from 2010 which looked at the effects of grunting on an opponent's ability to concentrate.

Their results also suggest grunting may decrease reaction speed and accuracy when trying to determine which side a tennis shot was going.

So, it seems that grunting may provide a competitive advantage despite how unpopular it may be for spectators and administrators. Particularly when bringing this concept back around to tennis.

I mean, why wouldn't you grunt if it comes naturally and it provides the potential to increase how hard you hit the ball and decrease the chances of it coming back successfully.

Related: Since we're talking tennis, here's why we should think of Tennis Elbow as a neck-related injury.



I can certainly appreciate the potential for grunting to aid sports performance. As a Physical Therapist and avid gym-goer, I get how the sudden increase in intra-abdominal pressure associated with grunting could be performance-enhancing.

So when we insert the information from this study back into the grunting in tennis debate, the conversation shifts a little. If these results represent a real connection and can be applied beyond martial arts to tennis, then the debate becomes more about what's appropriate for the culture and aesthetics of the sport.

In this instance, those who staunchly oppose grunting in tennis because "it's not a good look" may need to soften their stance a little. After all, each athlete deserves to do their best to win, particularly if grunting comes naturally to them.

On the other hand, those that play the game of tennis also have some responsibility to uphold the values and culture of the sport. Those who go out of their way to grunt, or purposely overdo it for a competitive advantage, beyond what comes naturally, may need to reign it in a little. Clearly it's hard to police but that's the minor moral dilemma each athlete faces.



Before getting too carried away it's important to look for potential bias and the ability to generalize these results.

The obvious limitation here (and no fault of the study itself) is the fact this particular study looked at the effects of grunting on martial arts performance and not tennis. The results may apply to tennis or they may not.

Force production seems the most appropriate as it's more of a generic measurement. Whereas the ability of a grunt to decrease the speed and accuracy of an opponent's response sounds feasible, judging the characteristics of a kick may not translate smoothly to a tennis shot.

Like many studies, the pool of participants wasn't huge. In total, forty-two people participated across the two experiments. Furthermore, only 10% of the athletes used in the first experiment were female. Grunting may provide a real increase in force production, but we can't be as certain it applies to women of only 2 were represented by the study. This is important as some of the world's best grunters in tennis are female.

Similarly, each participant performed their own preparation in the 15 minutes between the 60-minute martial arts class and the experiment. Does this individualization also make it hard to generalize the first experiment's results beyond each participant?

Those in the first study were also relatively well-trained athletes, and so are those who play tennis professionally. But it becomes a little harder to know if these results speak of a real increase in force production for the untrained athlete.

Similarly, the opposite may apply to the second experiment. Each participant was a Psychology student with no prior martial arts experience. Would the same effect have been seen if each participant was an experienced martial artist? Does being a student of the mind via Psychology skew their results? Would this affect a professional tennis player more or less than someone who had no tennis experience?

Interestingly, the second experiment also used a simulated grunt rather than a human one. They did control for changes in "pitch, length, and amplitude" however it was still artificial. We don't know if participants would react the same to a real grunt, which is of most value to our conversation.

So as you can hopefully see, we always need to ask these types of questions just in case they challenge the validity of the study's results.

I've also written a piece on some issues I have with the current state of Evidence-Based Practice. It's a worthwhile companion piece to any study as I discuss some basic flaws in research and how we use it. It may help give a little more depth and context to this study.



We clearly need more tennis-specific research to flesh out the benefits of grunting in tennis. However, a study like this one at least gives us a moment to pause for thought.

As reported, grunting may help increase force production, while decreasing an opponent's reaction speed and accuracy in a select group of participants.

If you're a tennis player fighting tooth and nail for the win, perhaps grunting is not the worst use of your valuable energy.

However, considering the sport of tennis and its values, the debate around whether grunting is the right fit for the sport may persist long into the future.

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