The Deep Cervical Flexors and Neck Pain

The muscles nobody can see

Longus colli and longus capitis run along the front of the cervical vertebral bodies, underneath the trachea, the great vessels, and everything else the eye or a tape measure can reach. They are postural stabilisers rather than movers — their job is holding cervical segments in a stable relationship to each other while other muscles produce motion.

Three consequences follow, and together they explain why this page exists.

They contribute essentially nothing to neck circumference. No amount of measuring tells you anything about them. A neck can look impressive and control itself poorly. See neck size and measurement.

They are the muscles most consistently implicated in neck pain. Reduced deep cervical flexor endurance is among the more reliable findings in the cervical literature.

They do not respond to the training the rest of this site describes. Loading a harness heavily trains the muscles that are already dominant in the people who have this problem. This is the one area of neck training where more load is usually the wrong answer, and saying so plainly matters more here than anywhere else on this site — because the publisher sells load.

The distinction this page exists to make

There are two different things called “neck exercise” and they are routinely conflated.

Strength training. Progressive loading to increase force production. Its evidence base is strong: a 2024 systematic review of 26 studies found a pooled effect of SMD 0.85 (95% CI 0.57 to 1.13) for resistance training on isometric neck strength, rated high quality.

Motor control and endurance training. Low-load, long-duration work — most characteristically craniocervical flexion, the chin tuck — performed at intensities deliberately kept low. Its purpose is not force production. It is recruitment: getting the deep cervical flexors to do their job rather than being substituted for by the sternocleidomastoid.

These are different interventions, aimed at different outcomes, with different evidence behind them. A programme that builds a strong neck is not automatically a programme that helps a painful one.

Why intensity is kept deliberately low

This is the part that surprises people coming from a strength-training background.

The deep cervical flexors — longus colli and longus capitis — are recruited preferentially at low contraction intensities. As effort rises, the larger superficial flexors take over, principally the sternocleidomastoid.

In people with chronic neck pain, that substitution pattern is a consistent finding: the superficial muscles dominate and the deep ones underperform. Which means that performing the corrective exercise at high effort reproduces the exact fault it is intended to correct.

So the instruction is genuinely counterintuitive: do it gently, hold it longer, and stop if the sternocleidomastoid engages. Two fingers resting on the SCM is the standard self-check — if it bulges, the effort is too high.

Full technique detail is on protraction and retraction.

The craniocervical flexion test

The clinical assessment for this is the craniocervical flexion test, and it is worth understanding even if you will never have it done, because it shows what the target actually is.

The patient lies supine with an inflatable pressure sensor — a pressure biofeedback unit — behind the neck, inflated to a baseline of 20 mmHg. They perform a gentle nodding motion, craniocervical flexion, aiming to raise the pressure by 2 mmHg at a time through five stages to 30 mmHg, holding each stage while the clinician watches for superficial muscle substitution and for whether the pressure can be held steady.

Two things about that protocol are the whole point.

The increments are tiny. Ten millimetres of mercury separates the easiest stage from the hardest. This is not a strength test in any sense a lifter would recognise — the entire useful range sits at an effort most people would describe as almost nothing.

What is being measured is control, not force. Failure looks like the pressure overshooting, wavering, or being achieved by the wrong muscles. Someone can be strong, fail this, and have that failure be the clinically relevant finding.

That is why a bigger neck and a better-controlled neck are different projects, and why this page does not end with equipment.

What the evidence supports, and how firmly

Deep cervical flexor endurance deficits are associated with chronic neck pain. This is one of the more consistent findings in the cervical literature. Whether the deficit causes the pain, results from it, or both, is not settled.

Exercise is a component of most evidence-based approaches to persistent neck pain. It is generally combined with other elements — manual therapy, education, activity modification — rather than delivered alone.

Prolonged rest and rigid collars are no longer standard for most non-specific neck pain or whiplash. Early gentle movement within comfort is generally preferred.

Reassurance appears to be an active ingredient. Being told that the neck is not damaged and that recovery is expected is part of good care, and the opposite message can be unhelpful.

What is not well established: which specific exercise protocol is optimal, for whom, and for how long. The clinical literature on neck pain is large, heterogeneous, and full of small studies with different populations, different outcome measures, and different definitions of the condition being treated.

Why this site does not publish rehabilitation protocols

Three reasons, stated plainly.

The right protocol depends on the diagnosis. Facet joint irritation, disc involvement with nerve root symptoms, muscular strain, and cervicogenic headache have different management, and some respond badly to loading.

Craniocervical flexion done wrong reinforces the fault. It is not a movement people reliably teach themselves from a written description — the failure mode is subtle and the self-check requires knowing what you are checking for.

The publisher sells neck training equipment. A company in that position writing rehabilitation protocols for anonymous readers with undiagnosed neck pain is exactly the conflict the disclosure page exists to name. The evidence does not support “buy equipment and train” as an answer to neck pain, and this site will not construct a page that implies it.

Where strength training does fit

As prevention rather than treatment. The strongest case is in people who do not currently have neck pain. Given prevalence figures reaching 65% in office populations and evidence that untrained control groups measurably lose cervical strength over periods as short as six weeks, building capacity before there is a problem is defensible.

After assessment, alongside clinical guidance. Strength work has a place in cervical rehabilitation, generally later in a progression, and generally once the cause is understood.

For load tolerance in sport. Athletes returning to collision or combat sport need capacity that a rehabilitation protocol alone does not build.

The honest summary

If your neck hurts, the useful question is not “how do I strengthen it” but “why does it hurt.” Answer that with someone who can examine you, and the exercise question usually answers itself — often with an intervention that looks nothing like training.

If your neck does not hurt, training it is a reasonable thing to do for reasons that do not depend on this literature at all. Those reasons are on the strength and hypertrophy page.

Gaps in this section

This page is thinner than the rest of the research library, and that reflects a deliberate limit rather than an absence of material. The cervical rehabilitation literature is large, and summarising it responsibly for a general audience — without sliding into prescription — is genuinely difficult for a publisher with a commercial interest in the answer.

What this section will not become is a set of protocols. What it may become, with more work, is a better map of what the evidence supports at the level of principle.