What Does a Lock Do in Rugby Union?
Rugby IQ · 7 September 2026 · 5 min read
With Kieran Read · Number 8
The lock wears 4 or 5 in rugby union and is also called the second row. Locks win lineout ball, push in the middle of the scrum, clear rucks and carry off the scrum-half. They are the tallest players on the field, and the lineout is their set piece. The two shirts sit behind the front row in the pack — see where they fall among all fifteen rugby positions.
A note on the byline. Kieran Read played 127 Tests for New Zealand, 118 of them at number 8, packing directly behind the second row and pushing through it in every scrum. Elite Rugby App’s roster has no specialist lock, so this page is written from the loose forward’s view of the job rather than the jumper’s — and it says so rather than implying otherwise.
What are the lock’s four jobs?
Four things, and a side judges its second row on all four. Call them the Lock’s Four Jobs.
- Win lineout ball. Be the target, be lifted on time, and take it cleanly on somebody else’s call.
- Drive the scrum. Transmit the pack’s push through the front row instead of losing it in the middle.
- Clear the ruck. Arrive, get low, and remove the first threat over the ball.
- Carry off 9. One-out, over the gain line, so the attack starts moving forward again.
Why is the lock called the second row?
Because that is literally where the two of them bind. A scrum is three rows: the front row of prop, hooker, prop; then the two locks with their shoulders into those three sets of hips and their heads between them; then the back row behind. The pair in the middle row are the second row, and either player in it is a lock.
Both names are current; which you hear depends on who is talking: commentary and team sheets say lock, coaches call the player a second rower, forwards packs say second row, and everyone shortens it to the 2nd row. The rugby union second row is the same unit under every label.
What physical attributes does a lock need?
Five qualities, and where each one actually lives in a training week.
| Attribute | Why the lock needs it | How it is trained |
|---|---|---|
| Overhead reach and shoulder stability | The lineout is won above the head, and the ball is caught with the arms locked out | Overhead pressing and stability work, plus shoulder mobility |
| Vertical jump from a standing start | A lineout jump has no run-up and has to be timed to a call | Countermovement and static-start jumps, low volume, high quality |
| Scrum drive through a long lever | The lock pushes through the front row, and length makes that harder to hold | Heavy hinge work and braced pushing at a body angle, not upright |
| Neck and shoulder robustness | The second row binds into the front row and takes scrum load through the shoulders | Progressive neck work in all four directions, plus upper-back strength |
| Work rate around the field | The tallest player in the side still has to make the tackle count and hit the next ruck | Repeat-effort conditioning with contact, not steady running |
Locks are the tallest unit on a rugby field, and the second row is the one place height cannot be coached or substituted — the sourced bands, per unit not shirt, are on rugby positions body types.
4 or 5: is there a difference between the two lock shirts?
Less than the difference between 1 and 3, or between 6 and 7, and in some sides none at all. Where a split exists it is usually about the lineout: one lock is the front jumper, taken early and low for fast ball at the front; the other is the middle-and-tail option, taken higher and later, and more often the player calling it.
Sides load the rest on top — the caller organises, the other carries more. But both scrummage in the same row, both are lifted, and a coach who calls 4 and 5 separate positions is describing his own team, not the laws.
How does a lock train?
A lock trains for one moment in the air and eighty minutes on the ground, and the mistake is training only the first. Four qualities carry the week.
| Quality | Why the lock needs it | What a session looks like |
|---|---|---|
| Overhead strength | Every lineout take and every lift finishes with load above the head | Overhead pressing and carries, with shoulder mobility work in the warm-up rather than at the end |
| Jump quality | A lineout jump is one attempt, from standing, on somebody else's call | Low-volume jumping done fresh, quality judged on height and timing rather than on the count |
| Scrum drive | The second row is where the pack's push is either transmitted or lost | Heavy hinge and squat work, then the same drive rehearsed at the angle the scrum actually holds |
| Repeat-effort work rate | The lineout is a handful of moments; the other seventy minutes are tackles and rucks | Repeat-effort conditioning that finishes in contact, not steady-state running |
Those four sit inside a plan rather than beside one. The four-week workout plan by position sets out the split, and the per-position workout PDF is the version you can take to the gym. If you would rather it was written for you and progressed week to week, ERA’s gym programs are built per position by the internationals who play them.
What does a lock do at the lineout?
Three jobs, and only one of them is jumping. He is the target: in the right pod, moving on the call and not before it, hands early. He is lifted, so the take belongs to three players and the timing is rehearsed rather than improvised. And he is often the caller, reading the opposition pods and choosing the throw before the hooker moves.
The defensive half is the same job in reverse: work out which pod the throw is going to, and get there first.
How is the lock different in rugby league?
In rugby league this differs because the number 13 is called the lock and plays at the back of the scrum, so the word means a different shirt doing a different job — league’s equivalent of the union second row is its second-rowers, at 11 and 12.
Where to find out more
The second row and the front row are the tight five together: prop rugby covers the two shirts you push through. The hub, rugby positions, covers all fifteen numbers, and rugby positions by body type runs the question the other way, from your frame to the shirt it suits. To train it rather than read about it, the gym programs are written per position.
Frequently asked questions
What is a lock in rugby?
A lock in rugby union is one of the two second-row forwards, wearing 4 or 5, who win lineout ball and drive the scrum. Locks are the side's main targets in the air, the middle of the push at every scrum, and the forwards who clear ruck after ruck in between.
What is second row in rugby?
The second row in rugby union is the pair of locks who pack in the row behind the front row, wearing 4 and 5. The name describes where they bind: shoulders into the hips of the props and the hooker, heads between them, driving the whole front row forward.
What does a lock forward do in rugby?
A lock forward in rugby union jumps at the lineout, pushes in the middle of the scrum, clears rucks and carries off the scrum-half. He is lifted rather than jumping alone, and the timing of that jump is rehearsed against a call rather than improvised.
What does a second row do in rugby union?
A second row in rugby union does the same job as a lock: lineout ball, scrum drive, ruck clearing and short carries. In practice the two shirts split the work, one taking most of the lineout ball and the other calling it and covering the tail.
What does the position lock do in rugby?
The lock position in rugby union is the side's main lineout target and the engine in the middle of the scrum. It is also the position that does the least visible work: restarts, mauls, ruck clearouts and the tackles nobody replays, for eighty minutes.
Train it, don’t just read it
Every session in this guide is built, periodised and coached inside Elite Rugby App, from the strength staff behind international and Super Rugby teams.
Start for freeWeighing it up? Read how Elite Rugby App compares with other rugby training apps.