Illustration of a Middle blocker attacking a 31

What is a 31?

A 31 (or a “Gap”) is a type of set in volleyball. When broken down (a 3-1), it’s a set to the 3 section of the net, at a 1 tempo. This is a set typically run by the middle blocker, but can also be run by outsides and, believe it or not, opposites.

Picture of a 31 set in Volleyball

When should I run a 31?

There are a few things to look for when running a 31. First of all, you’re going to want to make sure you’ve established your 1 ball; this is an incredibly important concept, so if you don’t know what establishing the middle is or why it’s important, go and read that first, then come back.

Essentially, a 31 is a force play on your opponent’s middle blocker. Much like the 1 ball (a 51), a 31 is a fast tempo set which forces the opponent’s middle blocker to follow and commit to blocking you (a.k.a moving the middle). If your opponent’s middle moves to block the 31, your setter will (ideally) set the opposite, who is now in a 1v1 matchup with a lot of space to attack angle — But let’s get back to the 31!

So, let’s think about running a 31 two ways:

  1. As an Attack (more common at beginner level)
  2. As a Bait (more common at advanced level)

31 as an Attack

A 31 requires the opponent’s middle blocker to watch/move with you. Now, why run a 31 as an attack set?

  • The opponent’s middle blocker is slow.
    If you’ve run some 1 balls and the opponent’s middle blocker has been late to commit to the block (but is still getting soft touches), they are likely trying to fix their block timing. A well-run 31 can throw off their calibration. You’d typically want to run a 31 before they correct their timing on the 1 ball. Running a 31 adds an attack to their mental while they attempt to find their timing.
  • The opponent’s middle blocker is shorter.
    Fast tempo attacks can lose the blocker with just speed alone. Add height (or lack thereof) into the mix and a 31 can be a free attack.
  • The opponent’s middle blocker has bad footwork when getting to the outside.
    This is similar to the first point: if the opponent’s middle blocker has bad blocking footwork, they’re going to be slower to move and block. Add a fast tempo set into the mix and you’ve got yourself an opportunity for a free kill.

Important note: more often than not, at advanced levels of volleyball, the 31 as an attack is rarely run. An offense is better off running a standard 4-1-3 attack because a 31 creates more blocking focus on the strong side of the court and you’d rather have all 3 blockers split into well-executed 1v1 matchups. But at intermediate and beginner levels of volleyball, a 31 can be a shock to the opponents defense.

31 as a Bait

31s, when executed well, create what’s called an isolated attack. The short version is that a 31 will pull the opponent’s middle blocker to their weak side of the court, creating a large gap for your opposite to hit through or for your setter to dump. A middle running a 31 should be selling it hard

How to call a 31?

Volleyball hand signals are regional, but for us, a 31 is: making a fist, and extending your thumb and middle fingers. Some regions extend index, middle, and ring fingers together and connect pinky and thumb over palm.

The easiest way is to just ask your setter, but just make sure your opponents can’t hear you.

Hitting Footwork for 31 Set

Approach footwork for hitting a 31

The 4-step approach is standard. It takes some practice because the steps are long and you’re facing away from your setter for a moment. But the benefit of the 4-step is that it does hide the fact that you’re running a 31 for a brief second, which is important.

The shuffle 3-step is a bit easier, but it’s a bit slower and is immediately noticeable by the opponent middle blocker. It’s semi-used at higher levels to create space for running a BIC. But, in general, you should just practice the 4-step and getting all the way to the 3 spot of the net.

For Setters: Running the 31

You should look to run the 31 as early into the game as passing allows, but only after you establish your core attacks. And, the first time you decide to run a 31, you should set it; this falls under the idea of establishing your sets.

However, after the first set, your set percentages generally will probably play out as follows:

  • 60% of the time: You set the Opposite, or Dump
  • 25% of the time: You set the Middle
  • 15% of the time: You set the Outside

“Why will the numbers work out this way?”
Well, your real job, besides putting up a hittable ball, is to create attacking opportunities, especially isolated ones. The 31, as mentioned above, is mainly used to create an isolation matchup between their outside and your opposite (or, if you’re front row, you). When the 31 “works”, you set the isolation/dump the ball. You’ll want to set the 31 when it’s advantageous, to keep the threat alive, but again, when it’s working (their middle keeps following your 31 attack), you’ll mostly be setting opposite.

However, at higher levels, these numbers will change; a specific backrow attack (BIC) is perfect to execute when running a 31, and overloading the strong side of the court can be fine because of the necessity of the opponent’s middle committing to blocking the 31. But generally, assuming an intermediate level, you’ll mostly be setting your opposite.

“Why is the outside percentage so low?”
It doesn’t make much sense to set the outside when you’ve moved the opponent’s middle blocker in their direction. By setting the outside, you’re just giving their middle blocker the opportunity to correct and get a (soft) block on the outside.

“So, when do I actually set the 31?”
When the opponent’s middle blocker is weaker (block strength or speed-to-block) or doesn’t bite on blocking the 31 (rare, but possible). Using your peripheral vision takes time and it should be a focus point of your training.

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