Can verbal suggestions influence the short-term effects of spinal manipulation ?

Chronic non-specific low back pain (CNSLBP) is a huge driver of disability worldwide, and it’s increasingly showing up in younger adults. Even though spinal manipulation is commonly recommended, the size of benefit is often modest, and there’s ongoing debate about why it helps. One growing area of interest: the context around the treatment—especially what the clinician says before the technique.

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What this study tested (in plain language)

This randomized trial asked a simple question:

Does what you say before a lumbar spinal manipulation change what happens next?

Young adults (19–30 years) with CNSLBP who had never had spinal manipulation were randomized into three groups:

• Positive suggestion: “This is very effective and will significantly reduce your pain.”
• Negative suggestion: “This is not effective and may temporarily increase your pain.”
• Neutral suggestion: “Effectiveness hasn’t been verified for your pain.”

Everyone then received the same single session of lumbar manipulation.

Outcomes measured

They measured both:

• Patient-reported outcomes: pain, stress, disability, fear of movement, sleepiness, expectations
• “Mechanistic” outcomes: pressure pain threshold (PPT), tissue temperature, lumbar range of motion (AROM), and blood markers (cortisol, serotonin, oxytocin)

Measurements were taken:

• Before (t0)
• Immediately after (t1)
• 24 hours later (t2)

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Key results (what happened)

1) Pain improved in all groups—but language mattered

• Pain dropped in every group after manipulation.
• But the positive suggestion group improved much more than the negative group:
  • Immediately: positive had ~1.4 points lower pain than negative
  • At 24 hours: positive had ~2.2 points lower pain than negative
• Neutral generally sat in the middle, and by 24 hours neutral was also better than negative.

Clinical takeaway: Negative framing didn’t just “fail to help”—it reduced the benefit patients experienced.

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2) Stress followed a similar pattern

• Stress reduced in all groups immediately,
• But at 24 hours, the positive group reported noticeably lower stress than the negative group.

Clinical takeaway: Your pre-treatment message may influence not only pain, but the patient’s overall threat/stress response.

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3) The “objective” measures mostly didn’t change—except pain sensitivity

Most mechanistic markers (temperature, ROM, blood biomarkers) did not differ between groups.

But pressure pain threshold (PPT) did change in a clinically interesting way:

• Positive suggestion tended to increase PPT (less sensitivity)
• Negative suggestion tended to decrease PPT (more sensitivity)
• Between-group differences were clearest for PPT at certain lumbar levels.

Important nuance: PPT looks objective, but it’s still influenced by attention, expectation, and emotional state—so it sits on the border between physiology and perception.

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4) Disability and fear of movement didn’t shift much short-term

• Disability improved a little in positive and neutral groups (24h), but there were no clear between-group differences.
• Kinesiophobia and sleepiness did not meaningfully change.

Clinical takeaway: Expectation effects show up fastest in pain and stress, not necessarily in function within 24 hours.

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What it likely means (mechanism in therapist-friendly terms)

This study supports a practical model:

The words you use shape the “meaning” of the manipulation

Pre-treatment suggestions likely prime the brain to interpret what follows as:

• Safe + helpful → reduced threat → better pain modulation
• Risky + ineffective → increased threat → dampened response

So the manipulation may be the same, but the nervous system response can be different because the context changes the input.

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Practical takeaways for clinicians

What to do more of

• Use calm, confident, realistic reassurance (no hype, no guarantees).
• Frame treatment as a safe step toward movement and recovery.
• Align your message with the patient’s goals: function, confidence, returning to activity.

What to avoid

• “This might make you worse,” “Your spine is unstable,” “Your back is out,” or other threat-heavy messaging.
• Overly uncertain statements that leave the patient expecting failure.
• Negative suggestions—even if meant to be “honest”—may reduce therapeutic benefit.

A balanced script you can actually use

“This technique helps many people feel more comfortable and move easier. We’ll reassess right after, and again over the next day to see how your body responds.”

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Limitations (so we don’t overclaim)

• Only one session and only short-term follow-up (24 hours).
• Young adults only; may not generalize to older or more complex cases.
• “Mechanistic” markers were limited; no imaging here.

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Bottom line

The study provides experimental evidence that verbal suggestions act as a modifiable contextual factor capable of amplifying or attenuating short-term responses to spinal manipulation.

If you’re doing good manual therapy but your outcomes are inconsistent, it may not be your hands—it may be the story surrounding the hands.

https://www.sciencedirect.com/science/article/pii/S2468781225001791