When you watch a hockey game, you'll notice that players seem to follow a "code" when they change lines. They all change after a similar amount of time and only during certain moments in the play. 

But how do they know when to change lines? Why do they only change at particular times? And what constitutes a "bad" line change? In this helpful guide, we'll investigate everything you need to know about line changes.

How do you know when to change lines in hockey?

In hockey, players can change lines during stoppages in play or "on the fly" – during game action. In the NHL, today's players take approximately 45-second shifts to maximize their effort in short periods. 

Recreational players usually take 1 to 2-minute shifts. Players should change when the puck is in the opponent's defensive zone when changing on the fly. It is considered a bad change to change lines while on the backcheck or in your own defensive zone (if you're not in control of the puck).

How do NHL players know when to line change?

Players are mindful to keep their shifts within a 45-second range in the NHL. However, line changes should only happen during certain moments of play. Doing so outside these times could get you into hot water with your coach or, even worse, cost your team a goal. What are they? Let's go over them.

The simplest line change is after a whistle. Players can freely change lines when play is stopped or during an intermission. There are certain rules against this in the NHL and other professional hockey leagues, such as not being allowed to change after an icing. However, in most cases, you can change lines after a whistle.

Changing while the play is going on, more commonly known as "on the fly," is more complicated because you don't want to make a bad line change. 

Safe line changes can occur when the puck is in your opponent's defensive zone. Sometimes players dump the puck into the offensive zone to guarantee a safe line change.

Similarly, goalies can strategically freeze the puck in the defensive zone to get their tired teammates a line change.

A line change while the puck is in the neutral zone can be risky, especially for defensemen. Still, it can be accomplished if an exhausted player finds the right moment to change.

Defensemen wait for the play to shift to the offensive zone before changing lines.

For the most part, the golden rule when it comes to changing on the fly is not doing so when your team is in a vulnerable position. Take, for instance, when the other team is rushing down the ice into your defending zone. Changing at this point in time would leave your team temporarily short-handed.

The second instance would be changing when the puck is in your defensive zone. This would also result in your team being temporarily short-handed. Either of these changes would give the opposing team a high-quality scoring chance.

Why do hockey teams change lines so often?

Hockey is a very intense sport when it comes to endurance and stamina. Because of this, NHL players have often expelled all their energy in a 45-second timespan. If you have never played the sport, it may seem like a 45-second shift is extremely short. 

However, with the game's intensity, a shift of this length can completely drain your gas tank and require you to rest for a few minutes before returning.

Some players have higher endurance, stamina, and natural conditioning to take longer shifts in the NHL. However, most still don't. The difference between a top-tier player and a fourth-line player in the NHL is often not the length of their shift but the frequency of shifts. 

For example, a top-line player may take 30-35 shifts that are 45 seconds long for 23-25 minutes of ice time a game. A fourth-line forward, on the other hand, may only take 10-15 of these 45-second shifts in a game, resulting in less overall ice time.

How do NHL coaches call line changes?

NHL coaches will typically assign players to pre-determined lines before the game starts. From there, he will deploy those lines when he sees fit. On the fly, he will typically announce on the bench or tap the players on the shoulder to let them know they are the next line to go out. 

At a whistle, he will do much the same, but the players exiting the bench and onto the ice surface give the signal to the players currently on the ice to switch lines.

Depending on the situation, player changes can be outside of normal line situations. For example, in the defensive zone, a coach may put two centermen out, one to take the draw and the other to line up as the left or right wing. They will do this in case their centerman gets kicked out of the faceoff circle. If this happens, the other centerman can take the draw.

Why are there different lines in hockey?

Because hockey is played with 5 players and a goaltender on the ice in an even-strength situation, this is typically divided into 3 forwards and 2 defensemen. The lineups are constructed so that there is structure and order for those going on the ice at specific times. 

It also allows players to build chemistry with each other and develop predictable playing patterns to increase offence and defence.

Lines typically have different roles as well. For example, the top two lines on an NHL team are typically reserved for offensive production. The third line, often labelled the checking line for most teams, is more reserved for defensive play, and head coaches may match this line against the other team's top competition.

The fourth line, on the other hand, is typically a high-energy line that aims to wear down the opponent, make minimal defensive mistakes, and contribute offensively when it can during limited minutes. A four-line structure of an NHL team allows the team to rest its top-tier players while the third and fourth lines are on the ice.

The NHL has, at least recently, drifted away from a checking/high-energy role for its third and fourth lines, although it still does exist. In today's NHL, you will typically need at least 3 lines to score to be considered one of the top-tier teams. Three scoring lines and a single checking line, with the elimination of the high energy/low minute fourth line is a strategy a lot of teams have started deploying.

How many line changes are there in a hockey game?

Let's consider that the average shift length is about 30-45 seconds, with the higher quality NHL players taking longer and more frequent shifts. We can expect upwards of 26 line changes in a single period and over 75 in a single game.

This is highly dependent on a number of factors, however. Team structure, coaching strategy, special teams like the power play or penalty kill can all impact the amount of total line changes in a hockey game.

Who gets the last line change in hockey?

The last line change in hockey will be awarded to the home team, except in some rare circumstances. For example, the home team will not be awarded the last chance during a whistle if they iced the puck the play prior. Instead, the opposing team can change their lines while the offending team must keep the same players on the ice.

How does last change work in hockey?

The last change system is quite simple. When the away team puts their players on the ice, the home team can make substitutions before the puck is dropped.

The last line change can allow a coach to deploy strategic matchups throughout a game. For example, suppose a visiting team puts out their top-line players. In that case, the coach may then substitute his players out for his checking line, the line he wishes to match against the team's top line, to reduce the chances of getting a goal scored on them.

As mentioned above, there are rare circumstances where a home team cannot execute its last-change advantage. One of them is if they ice the puck and are now allowed to substitute players.

Shift length in recreational hockey

NHLers take shifts that average around 40-45 seconds. As the game progresses, this number can decrease to around 25-30 seconds. Players are very familiar with the feel of how long they've been on the ice, plus they get tired.

For recreational players, shifts of around 1 to 2 minutes are standard.

Rec players are, of course, trying their hardest. Still, their effort level will likely be lower than professional hockey's. This can allow for shifts to run longer than 45 seconds.

If players are playing on lines (on forward) or pairs (on defence), they should try to change at a similar time with their line/pair.

Be careful not to take shifts that are too long. Pay attention to the shift lengths of your linemates and teammates to avoid getting a reputation as a selfish player.

Shifts should generally not exceed two minutes unless trapped in your defensive zone.

It is also more than okay to take short shifts. For example, you may tire out faster than other players.

Your teammates will never complain about extra ice time if you take short shifts.

Defenseman versus forward shift lengths

It is not uncommon to see defensemen take slightly longer shifts than forwards. Forwards are required to work harder because their position involves more skating.

It is also more difficult for defensemen to find the proper moment to change lines, as they must wait for the puck to be safely in the opponent's zone or for a stoppage in play to change.

Should you jump over the boards to change lines?

If your main hockey knowledge is from watching the NHL, you'll often see players enter the ice by going over the bench rather than through its gate. Players coming off the ice usually return to the bench through the gate.

In recreational hockey, it is standard for players entering and exiting the bench to go through the gate. The player exiting the bench should always precede the player entering it.

Defensemen go through the gate closest to their team's net, while forwards go through the gate closest to the opponent's net.

If the goalie's change ends at the start of each period, the forwards and defensemen will switch ends on the bench.

Changing lines becomes more difficult when your goalie is in the far net because this makes your team's bench further from your defensive zone.

Strategic line changes are a critical yet subtle part of hockey. Keeping your shifts within a reasonable range maximizes the effort you can make while on the ice. 

A line change will then allow refreshed skaters to take over for you. But you should avoid bad line changes, especially when the puck is in your defensive zone or when you should be backchecking. Changing lines when the puck is in the offensive zone or after a whistle are the safest times to swap yourself out.