One of the thing that volleyball coaches seem to debate a lot is the value of blocked training as opposed to random training. During these arguments there is sometimes a confusion of terms. In this post I want to try to clear that up and provide definitions. I will do so based on how these terms are used in the academic research from which we get them.

Blocked training

Blocked training is doing the same thing repeatedly. For example, let’s say a coach wants a player to work on shuffling to pass a ball. They toss 10 balls to the player’s right such that they have to shuffle to the ball and pass. That is a blocked exercise.

The whole concept of blocked training in how many people apply it is to repeat one specific skill until the athlete develops mastery. Many people think of this sort of thing as how the athlete creates “muscle memory” (here’s a relatively short audio explaining this concept).

Serial training

The next step up from blocked training is serial training. This is where you have a group of skills you execute in the same sequence. For example, let’s say a player serves and then digs a ball, or digs a ball from 2 and then from 4, and that is one rep. They repeat that 5 times. This is serial training.

Random training

Finishing the progression, the basis of random training is that athlete should not be able to predict the sequence. I posted an example of this related to some interesting research into the value of the random vs. blocked training when it comes to hitting vs. a block. The random element was what type of block the hitter faced. Playing the game is inherently random in structure.

Constant vs. Variable

I’m going to mix in a couple of additional concepts the academics use. They are constant vs. variable. Constant is when you repeat the same thing each repetition. A player doing 10 of the same self-directed approach jumps is an example of this. Variable, on the other hand, is where you change things up in some way each repetition. Keeping with the approach jump example, variable would mean changing the angle of those approaches from repetition to repetition, or changing the timing.

So a drill could be blocked or serial in structure (performing the same skill(s)), but either constant or variable in composition. Random training, however, is inherently variable.

Here’s a good graphic from Rob Gray, author of How We Learn to Move, that explains the differences of all these concepts.

Game-like training

Training in a game-like fashion is a separate concept from blocked vs. random, though coaches often conflate them. As noted above, the blocked vs. random consideration has to do with how you distribute repetitions. The question of those reps being game-like or not relates to how specific they are to the way the skill gets used in the game.

There’s a really good discussion of specificity and making things game-like in an episode of Coach Your Brains Out featuring Steve Bain. Steve is the coach at Northwest University and a professor of orthopedics and sports medicine at Washington University. It’s a 2-part interview. The first part is the meatier one with respect to this topic. Steve has a very interesting observation in there about the dimensions of specificity.

Random is not the same thing as game-like

The thing I want to make clear here is that game-like and random (or variable) are not the same thing. The belief that they are causes problems, especially in some of the debates I see. An exercise can be highly random, but not game-like in the least.

Returning to our example of shuffling to pass from above, as I noted, mixing up whether the player must go left or right makes the drill random rather than blocked. There’s no way, though, you can call passing a tossed ball game-like.

Why does this matter? Because if the exercise is not game-like then the expected transfer to use in an actual game is low. Again, this isn’t something I want to go far with here. See the article I linked above.

Game-like tends to mean random, but not always

Now, while random doesn’t inherently mean game-like, game-like often does mean random. Why is that? Because game-like repetitions tend not to repeat the same thing over and over.

Continuing with our passing example, let’s say you start an exercise with a serve. Chances are you don’t have servers who can make exactly the same serve each time. That means even if the ball goes to just one passer each time, they are unlikely to pass the ball the same way each time. Sometimes they will move left or right, or forward or backward. Sometimes they won’t move, but will take the ball in different locations relative to their mid-line. Those are random repetitions.

Flipping things around, you can also have very blocked type repetitions in a game-like framework. Serving is the prime example. All it takes to be highly blocked (and constant) while still game-like for an individual athlete is a server attempting to repeatedly serve the same serve against a group of passers.


My point in all this is that you should be clear on your definitions with respect to these terms. They have different meanings, and those differences can be quite important. Know them and you’ll have a better handle on motor learning theory and practice.

You may also find my post on when blocked training makes sense of interest.

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John Forman
John Forman

John is currently the Talent Strategy Manager (oversees the national teams) and Indoor Performance Director for Volleyball England, as well as Global Director for Volleyball for Nation Academy. His volleyball coaching experience includes all three NCAA divisions, plus Junior College, in the US; university and club teams in the UK; professional coaching in Sweden; and both coaching and club management at the Juniors level. He's also been a visiting coach at national team, professional club, and juniors programs in several countries. Learn more on his bio page.

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