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Activator vs. Diversified Adjustments: What’s the Difference?

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By Dr. Dave Bourgouin, DC · Chiro858, Solana Beach

Both are chiropractic adjustments. The difference is how the force gets delivered. Diversified is the classic hands-on adjustment: a quick, controlled push by hand, often with the familiar “pop.” The Activator Method uses a small handheld instrument to deliver a fast, light impulse, with no twisting and no pop.

In small head-to-head studies, the two have mostly performed about the same. The largest trial found the hands-on approach helped low back pain faster in the first month, and the gap closed after that. Here’s what each one involves and how we decide which to use.

Diversified: the hands-on adjustment

Diversified is a high-velocity, low-amplitude technique, usually shortened to HVLA. StatPearls describes it as a rapid force over a short distance that stays within the joint’s normal range of motion. The movement itself is small, roughly an eighth of an inch.

It’s the most widely used adjusting method in chiropractic. In a 2003 survey reported by the National Board of Chiropractic Examiners (NBCE), 96 percent of chiropractors said they used Diversified. More recently, in NBCE’s 2024 survey of more than 4,000 chiropractors, over 90 percent said they do hands-on adjustments every day.

About that pop

The sound comes from cavitation, which is a gas bubble forming in the joint space when the joint is moved quickly. A 2015 study that filmed knuckle joints with MRI found the crack happens when that cavity forms, not when a bubble collapses.

Do you need the pop for the adjustment to work? The research says no. In a study of 70 people with low back pain, 84 percent had a pop during treatment, and it wasn’t linked to better results. A study of 78 people with neck pain found no relationship between the number of pops and meaningful improvement.

Activator: the instrument adjustment

The Activator is a handheld instrument that delivers a quick, targeted force to a specific vertebra or joint. Earlier models were spring-loaded. The newest model, according to the manufacturer, is cordless and electronic. Researchers describe it as delivering a thrust without causing cavitation, which is why there’s no pop.

The method was developed by two chiropractors, Dr. Warren Lee and Dr. Arlan Fuhr. The company dates it to 1967. Its protocol uses leg-length checks and a series of isolation tests to decide where to adjust and when not to. Research on that leg-length analysis is limited. One review by the method’s developers found good reliability for the basic leg-length check but only one study of the full analysis.

It’s widely used, too. NBCE data from 2005 showed about 51 percent of American chiropractors reported using the Activator instrument.

What happens when they’re compared

The biggest head-to-head trial was published in Spine in 2015. It included 107 adults with recent (acute or subacute) low back pain. They were randomly assigned to hands-on adjustments, Activator adjustments, or usual medical care.

  • At 4 weeks, the hands-on group had improved more than the Activator group on both disability and pain. 76 percent of the hands-on group improved their disability score by at least 30 percent, compared with 50 percent of the Activator group.
  • At 3 and 6 months, there were no significant differences between any of the groups.
  • No adverse events were reported.

The authors pointed out their limits: a single clinic and a modest number of patients.

The smaller trials mostly found a tie:

  • Sacroiliac (SI) joint pain. A 2005 trial of 60 patients found neither method more effective. Pain scores dropped by roughly half in both groups.
  • Neck pain. A 2001 pilot trial of 30 patients found no significant difference. A 2010 trial of 47 patients, stopped early because of slow enrollment, also found none. In that trial, 7 of 16 Activator patients reported minor side effects compared with 4 of 16 in the manipulation group, and all of them cleared up within 1 to 3 days.

A 2012 review of 8 Activator trials concluded the instrument offered “comparable clinically meaningful benefits” to hands-on adjusting. It also listed real weaknesses in that research: small samples, short follow-up, and no sham or control groups.

Our read: both are reasonable options. For low back pain, hands-on adjusting may bring relief a little sooner. Over the longer term, the results look about the same.

What guidelines say about adjustments in general

Neither of the major low back pain guidelines separates instrument from hands-on adjusting.

The American College of Physicians (2017) recommends starting acute and subacute low back pain care with non-drug options, which include superficial heat, massage, acupuncture, or spinal manipulation. It rates the evidence for manipulation as low quality.

The UK’s NICE guideline says to consider manual therapy such as spinal manipulation “only as part of a treatment package that includes exercise.” That’s why corrective exercises are usually part of the plan we build.

Side effects and safety

The National Center for Complementary and Integrative Health (NCCIH) says the most common side effects of spinal manipulation are temporary: a bit more pain or discomfort, stiffness, or a headache. Most go away within 24 hours. Serious complications are very rare.

Neck adjustments come with one more topic worth knowing about. There’s an ongoing debate over whether neck manipulation can cause a tear in an artery in the neck (cervical artery dissection). NCCIH notes that experts disagree on whether manipulation can actually cause it, and the American Heart Association says patients should be informed. A large 2008 Canadian study found no evidence of excess stroke risk with chiropractic care compared with visits to a primary care doctor. The AHA’s definition of neck manipulation includes both high- and low-amplitude thrusts, so the discussion covers lower-force neck techniques too.

Some health conditions make a gentler approach the better choice. World Health Organization guidance on chiropractic lists significant bone thinning, such as osteoporosis, as a relative contraindication to manipulation. In those cases, it says low-force and soft tissue techniques are preferred. The Activator is one low-force option, but your exam decides whether any adjustment is appropriate.

When to see a doctor instead

Skip the adjustment and get medical care if back pain comes with any of these:

  • numbness, tingling, or weakness in both legs
  • loss of feeling around your genitals or bottom
  • changes in bladder or bowel control
  • pain that started after a serious accident

For any of those, call 911 or go to the ER. If you’re losing weight without trying, have pain that’s worse at night, or notice a lump or swelling in your back, see your doctor.

How we choose at Chiro858

We offer both Diversified and the Activator Method. Your first visit starts with a health history and an exam of your posture, movement patterns, and spinal alignment. We assess the patient as a whole.

Your preference counts. Some people like the hands-on adjustment and the release they feel with it. Others would rather skip the twisting and the pop. Your exam findings and your health history matter just as much, and we’ll explain our recommendation either way. You can read more about how chiropractic adjustments work at our office.

Call us at (858) 481-2481 or request an appointment. We’re at 320 S Cedros Ave, Suite 320, in Solana Beach.

This article is general information and not a substitute for an in-person exam. If you have pain or a symptom that concerns you, talk with your doctor or call our office. For any of the emergency signs above, call 911.

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