When I was a teenager, I left my home and family to train at a tennis academy about 2 hours away. I grew up in a small city where there was only 1 outdoor tennis club and no indoor tennis at all - which is why I made the move. Growing up and playing at a small club, with no junior program, you tend to get friendly with older adult members. Most of my practice partners were over 35 with many above the age of 50. When I had told them I was leaving, they were adamant about one thing...something that stuck with me til this very day - “hopefully they build on the game you currently have, rather than changing all of your strokes at once”.

I didn’t really realize what that meant at the time, but I’ve started to figure it out. I’ve had many coaches over the years - some not even aware of their influence on me. But all of which have had some sort of impact on my development as a coach. Before I get into the meat and potatoes of this post, which is on skill acquisition/motor learning, I’d like to point out that I don’t believe I have what most coaches would say is “good” or “proper” technique. I have a western forehand grip and have difficulty flattening the ball out (although I don’t think it’s because of my grip as many tour level players have more extreme grips than me and can still flatten the ball). And while I’ve had well intentioned coaches over the years, each with their own strengths and weaknesses, I admit that many tried to change my technique by using a "model approach" (i.e. what looks like good technique). The results were often limited and short lived. The greatest progressions I had as a player were when training was oriented towards task/goal execution...but more on this later.

Technical training is obviously important. It’s one of the 4 quadrants that the ITF has identified as critical in the development of an elite tennis player. The other 3 being psychological, physical and tactical.

But how is technique developed? It’s an interesting topic and I don’t claim to be an expert, but I’ll share my personal beliefs based on over 20 years of playing the sport, 10 years of coaching and over a decade of research & study. If I had to sum it up best in one line, this is what I’d say:

Technique is a function of tactics.

Let me explain. Pick any player on tour and watch one of their matches. Specifically, watch that one player as they play. You will not find 2 strokes that are exactly identical to one another. They may look similar but there are always slight variations and these variations are based on the tactical situation of the moment. When referring to tactical we're not simply looking at the phase of play (defense, offense etc) but we’re also talking about where the player is positioned on court, the flight of the oncoming ball, the bounce of the ball, the position of their opponent and so on.

Let’s use an example to illustrate this point. Hitting an inside out forehand off of a deep but soft ball will require different movements versus hitting an inside out forehand off of a hard hit ball. If a player attempts to hit the exact same inside out forehand on every shot, regardless of what the oncoming ball looks like, where it bounces, how much speed is on it etc., they’ll likely make errors - or hit shots that aren't ideal.

Here's a look at Rafa hitting 2 inside out forehands. One of them where he's able to catch the ball at a higher impact and drive it into the diagonal corner while the other forces him to hit that Rafa style forehand where he finishes behind his head. If he attempted the same stroke on either of those shots, they probably wouldn't end the way they did. 

How does this affect stroke development?

Instead of hampering on tiny details - where the left arm should be during the preparation phase, what angle the wrist must be at impact etc. - it may be more effective to provide players with an external cue (or better yet, a constraint) and allow them to self-organize their movements based on these cues. This is a form of dynamical systems theory (DST). DST, a motor learning theory introduced by Bernstein (1967) is based on a constraints led approach to learning. What does that mean exactly? It means placing so called 'boundaries' on an athlete to facilitate a desired outcome.

Many coaches implement constraints without even knowing it. Let's say that you'd like your player to improve their ability to hit with more depth. You may implement a drill where if a ball lands inside the service line it’s a point for the opponent. This is where DST gets interesting. Using the concepts of DST, you should be reluctant to give the student solutions as to how to hit the ball past the service line, but rather allow them to figure it out on their own. They may miss the first few shots either short or long but this is part of the learning process. All of sudden, however, you notice they add height to their shots and hit several balls in a row past the service line. Fantastic! Now to get more height (and consequently, more depth), they had to have changed their mechanics in some way - but recall, we didn’t tell them ‘how’ to hit the ball deep, we only provided a constraint. In other words, we provided them with a problem (task) and they came up with the solution (movement). 

As the coach, you then realize that although using height to gain depth is a viable option, your player is using it on EVERY BALL. That becomes quite predictable and good players will likely have tactics to beat that game. So what can you do? You can create another constraint. For example, you tell your player they cannot hit the ball more than 2 times in a row above a certain height (a visual like a cord at a desired height above the net helps in this type of scenario). They must now find another way of achieving depth without using height (perhaps by increasing power). Again, you’re not telling them to hit the ball with more speed, or how to hit the ball with more speed, but rather providing the constraint and letting them solve the movement puzzle or their own.

The Constraints Led Approach - What Else Can We Manipulate?

The above examples would be classified as ‘task constraints’ but there are 2 other constraints that may be manipulated, according to DST - ‘environmental’ and ‘organism’ (or performer) constraints - see image below. An example of an environmental constraint would be to purposely ask a player to practice serves into the sun or schedule practices at different times of the day (middle of the day heat, nighttime darkness etc.). Or perhaps vary the surfaces for young developing players (practices on hard, clay, carpet etc) as all would require adjustments to mechanics to meet the new demands. Environmental constraints are less easily manipulated but can also play a role in how a player changes their technique to adapt (ball bounces higher on clay versus carpet, less time on fast surfaces to prepare for shots etc.).

Lastly, we have performer constraints. An example of this type of constraint would be to emphasize a certain starting or finishing position. Frans Bosch, a leader in the field of sport science, has examined this constraint in detail - and the following examples are based on his work. Here's an example. Your player is having trouble getting their racquet into an ideal cocking position on the serve - one that would create good acceleration towards impact. To break the skill down you may get them to begin their service motion in that position - I witness firsthand a top 100 WTA player do this for months, even during competitive tour matches, until it was mastered. Here's another serving example. Many coaches want young juniors to use more leg drive on their serve (this in itself is somewhat questionable...but more on this in another post). This may be difficult without sufficient leg strength/power but if that's not necessarily the problem, a good way to start is to ask the player to land on their front leg when completing their serve and to hold the landing for a few seconds. It’s virtually impossible not to use the legs to propel upwards with this as a constraint. You can get more specific and ask them to land on the front leg AND inside the court - which requires even more push-off and even facilitates a better toss. Again, to perform the intended task, they will organize their body in the most efficient way they know how at that moment. 

There are times when coaches can organize a drill with multiple constraints, combining task, performer and environmental aspects all at once. This becomes quite cognitively engaging for the player and differs significantly from merely hitting balls.

 
 

Research and Dynamical Systems Theory

How important is equipment/court scaling for young players?

There are less players hitting one-handed backhands these days than in years past (although 3 out of the 4 Aussie Open semi-finalists had one-handers...so perhaps we’ll see a revival?!). Why though, are we seeing less one-handers in the game today? Although there could be a number of factors - children imitating their favourite players, coaches encouraging to hit with 2 hands etc. -  it’s likely that when children first begin to play, they don’t have the necessary strength to hit with a one-handed backhand. According to Chow et al (2015) in Nonlinear Pedagogy in Skill Acquisition, to encourage developing players to explore the one-handed backhand, coaches should implement smaller racquets and lighter balls during practices. Most tennis federations (and subsequently coaches) have already adopted these suggestions but even a small racquet may still be too big for a youngster who has limited strength. An alternative approach would be to begin with no racquet at all and use a balloon to smack around emphasizing the use of the back of the hand. Progressions can be made to a beach ball and then the use of a racquet & balloon, beach ball, foam ball etc.

What about court scaling? A 2014 study by Timmerman et al - which included support from Tennis Australia's sport science research unit - attempted to answer that question. Nine year old boys played 30 min matches in 4 different conditions where court size and net height were scaled (from a regulation court/net all the way to an adapted court/net for children). The results showed that when the court and net were scaled (i.e. smaller court, shorter net), children hit more winners, committed more unforced errors, hit fewer balls behind the baseline and hit most shots between the knees and shoulders - which is generally a more ideal impact point. The authors concluded that this type of game-style is more aggressive/attacking and more representative of what the adult game looks like. What’s interesting to note is that the 2nd most favourable condition was a regular court size with an adapted net while the worst condition out of the 4 was the smaller court with a regular size net - this condition resulted in the most amount of unforced errors and based on a questionnaire, was the least comfortable for the children.

Nonlinear vs Linear Learning - Interesting Results

Another 2014 study by Lee et al, implemented a 4-week training intervention with 10-year old females to determine if differing learning outcomes would result from a nonlinear (NLP) versus a linear (LP) approach to coaching. The aim was to determine which approach would facilitate better learning of the forehand groundstroke. The nonlinear group was guided by the manipulation of task constraints - adjusting net height, court size, target areas, calling out targets etc. While the linear group can be best summarized by the authors:

“The LP condition in this study consisted of prescriptive tennis forehand groundstroke technique instructions and repetitive practice drills. The forehand cues provided were according to the different phases of a forehand stroke: 1) Preparation: ‘‘Shake hands with racquet’’, ‘‘Racquet in front, feet shoulder-width apart’’; 2) Pre-execution: ‘‘Turn shoulders to side and bring racquet back’’, ‘‘Move to ball and step’’; 3) Execution: ‘‘Moving racquet low to high, contact ball in front of forward foot’’; 4) Follow through: ‘‘Follow through and end swing above opposite shoulder’’

Here are a few of the key results from this study:

  1. Both groups, NLP and LP, improved their forehand accuracy scores significantly from pre to post.

  2. The LP group performed better than the NLP group when compared to a movement criterion (i.e. a model of what the forehand should look like).

  3. The NLP group had greater movement degeneracy (more ways to achieve the same task) than the LP group.

  4. The LP players who had the best movement criterion scores had the lowest accuracy scores suggesting they were too focused on what the stroke should look like, rather than the task at hand (hitting into the desired target area). Conversely, the best accuracy score was performed by a player from the NLP group.

  5. Following a retention test, the NLP group showed less variability in accuracy scores compared to the LP group, who had higher drop-offs in accuracy.

While the results of this study seem to favour a nonlinear approach, there are hints that some aspects of a linear approach may accelerate the learning process. In other words, providing key features of a forehand stroke from a model perspective may help individuals early on, but then quickly switching to a nonlinear teaching style could further help players find more options during task oriented situations (like hitting targets or playing competitive matches). But more on this in another post. 

To Conclude

This is still an area of study that requires further investigation, but one that is extremely interesting, especially when considering the development of a tennis player. Many real world examples exist where players adapt a technique or shot to the evolving demands of the game, without being taught in a traditional manner. For example, the evolution of the grip towards a more western one, hitting squash forehands on defense, the SABR etc. Facilitating a DST/nonlinear approach to the development of a tennis player may help them become better problem solvers while at the same time facilitating creative, never seen before, solutions. I mean how many times have we gazed in wonder at what Federer has done? Many of his remarkable shots have come because of his problem-solving abilities with the tactical context at hand. I hope we see more players in years to come with this ability...but how critical is the teaching approach? With time, I'm sure we'll learn more.

If this topic interests you, I suggest the following for further reading:

Nonlinear Pedagogy in Skill Acquisition: An Introduction, by Chow et al

Strength Training and Coordination: An Integrative Approach, by Bosch

7 Principles of Nonlinear Pedagogy, by Upton

The Effect of Equipment Scaling on Children’s Sport Performance: The Case for Tennis, by Timmerman et al

Nonlinear Pedagogy: An Effective Approach to Cater for Individual Differences in Learning a Sports Skill, by Lee et al

The Inner Game of Tennis, by Gallwey

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