Does Practice Type Matter? An Intro to Blocked vs. Random Practice in Tennis
Many experts in the field of motor learning believe that the way a coach interacts with an athlete, bears a tremendous impact on the improvements that athlete makes. These same experts, however, would argue that the organization of a practice is perhaps even more important than what a coach says to his/her athlete. Let’s assume that to be true for a moment. As a coach, would that change the way you look at your practices? As a player, would it affect your perspective when attempting to improve serve accuracy, for example?
While I am by no means an expert on this topic, it’s one that interests me greatly. This interplay between how practices are organized and implemented versus what is said during that time period, can have a tremendous impact on learning. But I’d like to focus on the latter point - the organization of practices. To keep it simple, we'll explore two basic forms of practice, blocked and random. This post, therefore, will define both practice types, offer some examples as they relate to tennis and try to make sense as to which is more effective...a tall order to say the least.
Stabilization & Adaptation in Learning
Before we get into the details regarding blocked vs random practice, it’s important to note that the goal of practice in and of itself is to improve performance beyond the point at which we started. In beginners, the process generally happens at a faster and steeper rate. As a performer becomes more skilled, improvements are smaller and less noticeable. This concept is termed the ‘law of diminishing returns’ (figure below). The question we need to ask ourselves is, does learning stop at a certain point? Or can even the most elite tennis players, athletes, musicians and so on, continue making improvements throughout the course of their careers/lives?
Before this complex question can be answered, we must have some sense of how learning occurs. Here’s a brief rundown. Our bodies are constantly seeking homeostasis - in other words, equilibrium. We don’t like disruption; we rather stay at our current point. When it comes to learning complex motor skills, however, this disruption, is exactly what is necessary. When we are confronted with drills and tasks that are novel and difficult, this is the beginning of the adaptation to learning process. A review by Correa et al (2014) on this topic says it best:
“Adaptation occurs when changes in the environment perturb the system, challenging its stability and causing uncertainties”
The key concepts here being stabilization and adaptation. Let’s use a tennis example to illustrate the interplay between these 2 terms. Imagine you’re coaching a complete beginner how to serve. Perhaps one of the early steps is to have them simply make contact with the ball in an overhead position, regardless of technique, direction the ball travels etc. Even this can be challenging for some. Sometimes they make contact with the frame instead of the strings, sometimes they contact the strings but it's off-centre and other times they do hit the sweet-spot. Over time, as they are continuously exposed to this scenario, stabilization occurs. In other words, they are able to make clean contact with the ball, relatively consistently. This is achieved via the ‘negative feedback mechanism’ - meaning that internally, because the performer is aware of the desired outcome, they provide themselves with feedback - 'no that’s not good, it hit the frame’, ‘no that impact is too low’ or ‘no that’s not quite the sweet-spot’. Note that there are positive internal feedbacks as well, but because beginners make more mistakes than not, the negative mechanism is theorized to predominate. In any case, our actions have adapted and we are now capable of performing this task with consistency - it is ‘stable’, so to speak. But to gain increased skills and abilities, we must again perturb the system and create uncertainties by challenging the learner with ever-increasing demands.
So to come back to our earlier question, can we continue to learn, even at the most elite levels? I will answer this with another question - can we create tasks for elite players that are challenging them and causing instability in the system? I believe so. But look again at the law of diminishing returns graph - if only learning and performance looked so simple. It doesn't. There are times when certain skills outperform others. And other times when you need to revisit a certain skill entirely. All of this now leads us into the main topic of this article, practices. How we organize practices will determine how our players learn, re-learn, adapt and ultimately, how they will create stability to continuously achieve higher levels of performance.
Blocked Practice
Let us begin with blocked practice as this is probably the form of practice which is most common, especially in tennis settings. Blocked practice’s premise lies within consistency. The theory here being that to learn a skill, we must repeat that skill over and over until it looks and feels like the desired outcome. In blocked practice settings, the coach would instruct the learner to perform task A first, then task B, task C and so on.
In tennis, true blocked practice would be something like hitting a specific forehand, from a specific position on the court, towards a particular target and repeating this skill many times - usually until the student is showing signs of improvement or for a specified number of attempts. Once this task is complete, you would go on to a different type of forehand task, for example - perhaps hitting from a different location of the court, or with less spin, more direct and so on. Next you would move on to a backhand drill, finish that drill and move on again. While studies demonstrate that learners do quite well DURING practice time with a block schedule, most research looking into this form of practice suggests that it doesn’t hold much value in retention tests - i.e. longer-term learning (Schmidt and Wrisberg 2000). How many tennis practices have we either seen or carried out that follow this type of schedule? I know I’ve done them...and still do. But are they completely useless? We’ll explore this question below.
Random Practice
The other form of practice that has been extensively researched, is called random practice. It doesn’t mean you assign random drills, it simply means that instead of practicing one particular stroke over and over, a number of different skills are practiced in a mixed manner. This may mean, for example, that a coach feeds a variety of balls to a player, in random sequence (i.e. all over the court). In extreme scenarios none of these feeds are directed towards the same position more than once in a row. In other words, the balls are fed constantly in random order - one deep to the forehand, one wide to the backhand and then a short forehand, for example. While block could look like this: AAAAAA etc. BBBBBB etc. CCCCCC etc., random could look like this: AAA BBB CCC or ABC ABC ABC or like this ABC BAC CBA and so on.
Many studies confirm that random practice outperformers block practice when it comes to long-term learning, even though performance initially dips compared to block. The theory being that learners must reconstruct the action plan with each repetition, because we’re not seeing the same task consistently. It’s interesting to note that random practice has been seen to extend beyond what was performed during training (Schmidt and Wrisberg 2000). In other words, researchers theorize that when a thrower, for example, practices throwing a ball for a distance of 10m, 20m and 40m, they will also be able to throw with accuracy to the 5m mark, the 30m mark etc - even though they never practiced throwing to those distances. This contradicts the specificity of learning theory but does make practical sense. Tennis players cannot work on every single shot type - I mean, how many spots can the ball land on a tennis court, with varying degrees of spin, speed, height. I’m sure someone out there has done the math...and I’m guessing the possibilities are almost infinite. But elite performers still have the ability to adapt to these different shot types. Given this info, should we only structure practices that reflect a random schedule?
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What About Open Environments?
Before we debate the effectiveness and implementation of each practice type, let’s remember that tennis is primarily and open skill sport. And while I do believe closing skills off in practice has it’s place, for better transfer to the match court, practices should reflect the situations that a player we’ll encounter in competition.
That said, it’s easy to distinguish between blocked and random practice when feeding balls out of a basket - i.e. in closed-loop environments. But it becomes a bit trickier when players are in open-loop environments. Of course, playing points and competing would be considered a form of random practice - we don’t know exactly where the oncoming ball will end up, and our shot responses will vary. But what about a cross-court forehand drill? On the surface, it may seem like a blocked skill - and it very well could be - but it could also be classified as a random practice drill. Let me explain. Hitting cross-courts at low speeds, with little movement, virtually no variation in height or spin and towards the same target, would likely be considered under the blocked practice type.
On the other hand, if we’re hitting cross-courts with greater speeds, making the appropriate recovery movements, adjusting to the depth and spin of the oncoming ball by moving in multiple directions, and varying the targets (even if it’s just slightly) - in my opinion, would be considered random practice. In essence, no 2 shots would be EXACTLY identical. From my experiences, both forms of practice types hold value - even when working with players who are competing at the national or international stage.
Here’s where the debate begins. Why do I believe both forms of practice are important? Remember Ericsson’s theory on deliberate practice? His theory being that we should constantly be challenging our students by organizing tasks that take them out of their comfort zones. Well, if we are to take it as 100% fact, our athletes would be completely wiped out. It’s just not logical for someone to be uncomfortable all day long, on every task, over the course of time. This is something that coaches and researchers call ‘cognitive/emotional load’. Think of those times when you were in school studying for a big exam. And how you felt after writing that exam. If you were anything like me, you were completely drained. The same concept applies in sport. Which is why, in my opinion, simple, repetitive drills still have a place in the training of elite performers. In fact, repetitive tasks with low thought may provide parts of the brain breathing room to get creative - but that’s a whole other topic we’ll leave for another day.
Blocked vs Random - From Research to Practice
Let’s take a look at some of the research to help gain more perspective on this topic. In a landmark study by Shea and Morgan (1979), 2 groups of individuals were asked to perform a variety of arm and hand movement tasks. The aim of the task was to knock down a small barrier (located on an apparatus), as fast as possible, in response to a light stimulus. One group practiced the sequences in a block format while the other in a random format. During these practice settings, the block group outperformed the random group, but after 2 retention tests - one which was administered 10 minutes after practice and the other 10 days - the random group had superior results. The authors conclusion was that, while block practice is better at improving performance immediately, random practice produces better LEARNING.
Many studies have confirmed these results; even in tennis settings. Hernandez-Davo et al (2014) put the theory to the test using the serve. The block (consistency) group improved at a steep pace early on - and continued to improve even during the first retention test, which was carried out at the 2 month mark. The random group, on the other hand, experienced decrements in performance during practice, but had steady improvements at the 2 and 4 month marks (look at radial errors in figures below).
This is an interesting finding for 2 practical reasons. First, it’s ok (and normal in fact) to see performance drops early on when utilizing a random approach. A review article by Reid et al (2006) confirms this. These researchers argue that many coaches are only concerned with the observable. That if a student isn’t achieving a certain task in that particular moment, something must be wrong. Often times, the task is adjusted (usually by decreasing it’s difficulty) so that success is achieved right away. But many times, when practice outcomes look awful, the student is in the process of learning. During these periods of missing and not achieving, learners are constructing mental maps through constant evaluation and reevaluation.
That said, if block practice is so effective early on in practice schedules, shouldn’t we employ these tactics as well? I’d say yes. Not only does it tell the coach, and the player, that yes, they are in fact capable of performing this shot, thus providing confidence and belief, but it also sets the stage for more complex (random) drills later on. Here’s a quote from Correa et al (2015), that highlights this interplay:
“Consistency is necessary to achieve goals with reliability. Variability (on the other hand) is fundamental to cope with environmental instability.”
A mentor of mine once questioned me - if an athlete can’t master a fundamental closed chain skill, in a closed parameter, why would you introduce variability? If a player has difficulty hitting a serve target with some resemblance of consistency, is it logical to assign them to hit a variety of targets in random order? While researchers may disagree with me, I’d argue no. Remember the stability-adaptation theory from earlier? Many beginners must practice in this block type manner in order to create stability in the specific movement patterns necessary to execute tennis shots. And this type of practice allows beginners to concentrate, uninterruptedly, on one particular skill. But elite players can benefit too. Just because a player was able to hit a wide serve consistently 3 months ago, doesn’t mean they can do it today. We need to revisit certain skills and qualities many times during the course of a year and/or career. It’s just not realistic to think that a player can do everything well, all the time.
A Critical View of the Research and Final Comments
Now while I’m not discrediting random practice and it’s value (I actually believe it’s EXTREMELY valuable and EXTREMELY necessary) - but we must look at research with a critical eye. Yes, studies have seen better results following retention tests (tests conducted after some sort of delay, whether that be days, weeks, months etc), that random practice outperforms blocked practices. However, as with most research, these studies are short lived. What about longitudinal results? Like 6 months or 1 year later? Furthermore, each player is unique and may respond differently to each form of practice. I’ve been around the game long enough to know that some players need the extra repetition in a closed setting to gain confidence. While other players want to play points right off the bat. Some players need that repetition - and if it helps them ‘feel’ the ball, and improves their perception of that skill, can we argue against it?
In any case, what this tells us, in my opinion, is that both types of practice structures are necessary depending on a number of factors. Like what stage of development your athlete is in, or what time of year it is, or each individual's response to training and so on.
Lastly, researchers believe that “motor skills should be conceived of as hierarchically organized at a macroscopic and microscopic level”. Put another way, skills are placed into either one of 2 categories - macro or micro structures. It’s this macrostructure which is order-oriented (consistency focused) while this microstructure which is dis-order oriented (variability focused). Given this, both blocked (order) and random (dis-order), have a place, don’t you think? It’s up to us to determine when and to what extent we implement each form of practice type...echoing the words of my mentor, beyond theory and science, lies the art of coaching.