Arlan Fuhr

01 / Redwood Falls to Phoenix

Arlan Fuhr trained in a light-force method that wore out the hands practicing it

Arlan W. Fuhr was born on September 2, 1939, and grew up in Redwood Falls, Minnesota. He graduated from Logan Basic College of Chiropractic in September 1961. After two years of naval service he opened his first private practice in Redwood Falls. Fuhr is chairman of Activator Methods International, and he lives in Chandler, Arizona.

Logan Basic prescribed sustained contacts, and the thumbs paid for them

The method Fuhr learned was Logan Basic, built by Hugh B. Logan around light contacts held for long periods. The double thumb toggle produced real segmental specificity and a real physical cost. Fuhr and Warren Lee reported extreme fatigue, muscle strain, and elbow injuries from their elbows striking each other during rapid thrusts. The patent the two men filed in 1977 names those same problems in its own text. Vinton F. Logan, the founder's son and the college president, had urged students to develop what he called a push-button Basic. Fuhr took the assignment literally.

Warren C. Lee brought a paper trail that reaches back to Hugh Logan

Warren C. Lee was born on December 8, 1914, in Villard, Minnesota, and graduated from Northwestern College of Chiropractic in 1941. The Activator textbook reproduces a contract to study Logan's Basic Technique signed by Lee and Hugh B. Logan on January 26, 1942. Lee retired from practice in 1980. He and Fuhr worked together from the middle 1960s, and the two are the named co-inventors on the instrument patent.

02 / Two dental instruments

The first working Activator instrument was a surgical mallet for splitting wisdom teeth

In 1970 a Minnesota dentist named Stava supplied Fuhr with a surgical impact mallet used to split impacted wisdom teeth. Fuhr and Lee replaced the scalpel rivet with a brake shoe rivet and fitted a small rubber doorstop to the end. That device worked on patients. Union Broach of New Jersey manufactured it until 1976.

The 1967 dental impactor did not work

Three years earlier Dr. Steve Inglis had suggested a dental impactor, the tool that packs amalgam into a cavity. Fuhr ground a doorstop onto the end of it. The impactor never generated enough force to move anything, and Fuhr set it aside. A center punch needed too much preload. An instrument built by Frederick G. Proehl, a former Logan basic science instructor, went the same way. Only the 1970 mallet cleared the bar, and the Activator instrument descends from that one.

Fuhr formed his own company in 1976, and the patent issued in 1978

Fuhr left the Union Broach arrangement in 1976 and formed the company that became Activator Methods International. Freddy Hunziker, a Cleveland Chiropractic College student who worked nights in the Western Airlines machine shop, designed the hammer-and-anvil mechanism that made the instrument durable, and sold those rights to Fuhr in 1976. US Patent 4,116,235, naming Arlan W. Fuhr and Warren C. Lee, was filed on June 20, 1977, and granted on September 26, 1978. Its text describes delivering force at a very rapid speed in a precise and specific line of drive. Internal springs still failed after three months until Clark Bumgarner told Fuhr in 1978 that a 29-cent Parker ballpoint pen spring outlasted them.

03 / Speed as the design variable

Fuhr's instrument banks its energy in advance, so none of the doctor's body mass enters the thrust

Arlan Fuhr designed the Activator instrument to separate loading the energy from delivering it. Two springs inside the barrel compress when the doctor turns the adjustment knob. Squeezing the handle releases a hammer onto an anvil, which drives a rubber-tipped stylus into the contact point. The impulse leaves in about a millisecond, roughly a hundredth of the duration of a manual thrust. Nothing pops, because the instrument never takes a joint through the range that produces cavitation. Brodeur reported in 1995 that the audible sound of a manipulation does not indicate that any reflex was stimulated, so the missing crack costs the method nothing.

The first federal grant for chiropractic research put the output at 0.3 joules

Fuhr received $50,000 from the National Institutes of Health Small Business Innovative Research program in 1985. That is the earliest known federal grant awarded to chiropractic scientific research. The funded work measured the instrument's output at a maximum of 0.3 joules of kinetic energy. Fuhr's first peer-reviewed publication on the instrument followed in 1986 in the Journal of Manipulative and Physiological Therapeutics, reporting displacement accuracy within about ten percent of the expansion-control knob settings. Every later measurement of the Activator rests on that instrumentation.

The instrument delivers nearly the same force in a novice's hand as in an expert's

Two experts and two novices fired four instruments and also thrust by hand in a force-variability comparison reported in Fuhr's textbook. At maximum setting the Activator IV produced mean peak forces of 169.8, 177.6, 177.3, and 174.3 N across the four operators, with standard deviations between 4.6 and 8.6 N. Thrust durations ran from 1.098 to 1.324 milliseconds. The same design applied to manual thrusts gave means from 157.4 to 387.4 N, standard deviations from 24.6 to 61.5 N, and durations from 66.9 to 250.9 milliseconds. The instrument's spread across operators is a few percent. The manual spread is more than twofold between the lightest and heaviest operator. That reproducibility is why so much laboratory work on spinal manipulation is done with an Activator in the operator's hand.

04 / The Activator leg check

Fuhr built an analysis that asks the legs a question and rereads the answer after every input

Every Activator Methods visit opens with the patient prone while the doctor reads apparent leg length. Arlan Fuhr made that reading the center of the whole analysis. Fuhr and Lee held that faulty biomechanical behavior at a joint shows up as a difference in leg length, and traced the functional short leg most proximally to pelvic rotation. The reading is retaken after every intervention, which makes it a running signal rather than a one-time finding. The scan then works twenty stations from the feet to the occiput, clearing caudal segments before rostral ones are evaluated. Fuhr inherited that ordering from Logan Basic.

Isolation, pressure, and stress tests each ask a different question

An isolation test starts from balanced legs and asks the patient to perform one specific movement. If the short leg reappears, that segment is involved. A pressure test starts from uneven legs while the doctor applies gentle force in the direction of correction, to see whether the legs balance. A stress test starts from balanced legs and applies force in the direction of the suspected subluxation. Three questions, one signal, and no radiograph required to ask any of them.

Youngquist, Fuhr and Osterbauer tested the cervical isolation maneuver in 1989

Seventy-two subjects were evaluated by two examiners on separate occasions for the presence of a C1 subluxation. Agreement beyond chance reached kappa 0.52 and 0.55 across the two sessions. Ten years later two advanced proficiency rated Activator practitioners examined 34 patients in random order with findings recorded silently. They agreed on the prone extended leg-length reading 85 percent of the time, kappa 0.66. The last author on that 1999 paper was Joseph C. Keating Jr., the historian who sat on the board of the research institute Fuhr had founded.

De Witt and colleagues measured the leg signal optoelectrically in 1994

Eight patients with chronic spinal complaints and eight healthy controls lay prone with optoelectric markers fixed to the heels and occiput, sampled at 100 Hz. Cervical flexion and extension produced heel displacements under one millimeter, which the system resolved. Patients showed more asymmetrical heel movement than controls during the head-up trials, at t = 8.743 and p < .01. Range of motion and net displacement did not separate the two groups. Fuhr ran that study through a university biomechanics laboratory rather than in-house.

05 / The research program

Fuhr answered questions about his own technique by funding laboratories to test it

Fuhr founded the National Institute of Chiropractic Research in Minnesota in 1987 and has served as its president since. Joseph C. Keating Jr. joined the board in 1988. The institute reports granting more than $678,000 for research and scholarly prizes, and supporting work that produced 93 peer-reviewed papers, ten book chapters, four books, and 101 conference presentations. Arlan Fuhr's own indexed record runs from 1986 to 2005. Most of it is co-authored with engineers and university researchers.

Smith, Fuhr and Davis measured relative bone movement in 1989

Piezoelectric accelerometers attached to bone in an anesthetized dog recorded movements of the L2 and L3 vertebrae while instrument thrusts were delivered three vertebrae above and five below the joint interface. Relative translations of about 1 mm and rotations of half a degree occurred within the first 19 milliseconds. Skin translations averaged 77 percent of bone translations, with a standard deviation of 2 percent. The finding that mattered most for the method is that vertebrae which received no contact moved anyway.

Keller, Colloca and Fuhr took the instrument into engineering measurement

A 1999 validation study fitted the instrument with a load cell and an accelerometer, then fired it at a steel beam with a static stiffness similar to the human thoracolumbar spine. The impulse resolved into an initial pulse of 116 to 140 N lasting under 0.1 milliseconds, followed by several lower impulses of 30 to 100 N over 1 to 5 milliseconds. Peak energy arrived at 20 Hz. Peak forces varied by less than 8 percent. The following year the same three authors measured twenty asymptomatic people and found the thoracolumbar spine least stiff between 30 and 50 Hz. Their published conclusion is that procedures aimed at the resonant frequency of the spine require less force application.

Colloca, Fuhr and colleagues recorded from a nerve root during an adjustment in 2000

A 62-year-old man undergoing an L4 to L5 laminectomy received instrument thrusts of about 150 N to the lumbosacral spine while mixed nerve root action potentials were recorded directly. Anterior-superior and anterior-inferior lines of drive raised the responses by as much as three times over a straight anterior vector. Surface recordings the same year found a detectable reflex response after 68 percent of Activator thrusts in nine asymptomatic volunteers, rising to 94 percent at the sacroiliac joints and 83 percent in the lumbar spine. Those two results are the measured case for prescribing a line of drive at every segment.

Fuhr also put the instrument into clinical and practice-based studies

A 1993 case series followed ten patients selected from 153 consecutive new patients for chronic sacroiliac joint syndrome. Over six weeks of instrument adjusting, pain scores fell from a mean of 25 to 12 and Oswestry disability scores from 28 to 13 percent. In 2000 Fuhr joined Cheryl Hawk and the Palmer Center for Chiropractic Research on a practice-based study of 805 patients aged 55 and older. The data came from 96 practices across 32 states and two Canadian provinces. The report ran in the Journal of the American Geriatrics Society.

06 / Clearances, uptake, and the textbook

The Activator instrument is 510(k) cleared, and no chiropractic adjusting instrument has ever been FDA approved

Activator Methods has taken four premarket notifications through the Food and Drug Administration under product code LXM. Activator II cleared as K973506 in 1998. FS Activator III cleared as K003185 in 2001. The Activator V cleared as K072519 in 2007, and the Activator V-E as K112606 in 2012. A 510(k) clearance is a finding of substantial equivalence to a legally marketed predicate device. It is a marketing pathway. Approval is a separate and higher standard, and no chiropractic adjusting instrument has ever been through it.

What the published surveys record about how far the technique traveled

Reported use of the Activator Method by United States chiropractors rose from 51.2 percent in 1991 to 62.8 percent in 1998. By the 2005 status report Fuhr wrote with James Menke, roughly 45,000 chiropractors worldwide used some or all of the technique and about 75,000 instruments had been sold since 1967. That review counted more than 100 published studies on the instrument and the analysis, and listed 17 chiropractic colleges carrying the technique in required courses, electives, relicensure offerings, or student clubs. Activator Methods states that more than 150 peer-reviewed papers concern its instrument. The company's own count of clinical trials runs from 23 to more than 30 across its publications.

Fuhr wrote the reference text for instrument adjusting

Fuhr published the second edition of The Activator Method with Mosby in 2008. It carries the scan, the named tests, the force settings, and the laboratory data in one volume, and it remains the standard reference for instrument adjusting. Fuhr also holds 13 domestic patents and, by the company's account, 47 worldwide trademarks and more than 100 copyrighted works.

07 / Institutions

Fuhr opened a Veterans Affairs chiropractic clinic and paid for a university science building

Arlan Fuhr was the first chiropractic physician at the Carl T. Hayden Veterans' Affairs Medical Center in Phoenix, and was instrumental in setting up its chiropractic clinic between 2006 and 2010. He testified before Congress on chiropractic questions, worked on Arizona legislation, and volunteered at the Neighborhood Christian Clinic in Phoenix. Veterans were the population he chose when the profession finally had a door into federal medicine.

Fuhr's honors run from 1991 to 2015

Fuhr sat on Logan's board of trustees from 1981 to 1991. He was named a Fellow of the Palmer West Academy in 1991. In 1993 he received the Daniel David Palmer Chiropractic Scientific Award and was named Arizona Chiropractor of the Year. He became a select member of the International Society for the Study of the Lumbar Spine in 2000, which is a rare admission for a chiropractor. The American Chiropractic Association gave him its President's Award in 2005, Dynamic Chiropractic named him Person of the Year in 2006, and Parker Seminars gave him its Humanitarian Award in 2015. The World Federation of Chiropractic awarded him its Honor Award and selected him in 2012 as its delegate to the World Health Organization.

The Fuhr Science Center opened at Logan University in 2024

Arlan and Judi Fuhr gave Logan University a lead gift of $1 million in 2021. It let the school begin a 33,426 square foot renovation and a 14,400 square foot expansion housing anatomy labs, a simulated imaging center, and technique labs. The building was dedicated with a ribbon cutting on September 26, 2024, forty-six years to the day after the Activator patent issued. Fuhr spoke at the ceremony.

08 / The record

Ten dated facts about Arlan Fuhr, with the source for each

September 2, 1939. Fuhr was born in Minnesota. He grew up in Redwood Falls and now lives in Chandler, Arizona.

September 1961. Fuhr graduated from Logan Basic College of Chiropractic, the school Hugh B. Logan founded.

1970. A surgical impact mallet supplied by Dr. Stava of Marshall, Minnesota became the first Activator instrument that worked on patients. Union Broach manufactured it.

1976. Fuhr ended the Union Broach arrangement, formed his own company, and bought Freddy Hunziker's hammer-and-anvil patent rights.

September 26, 1978. US Patent 4,116,235 issued to Arlan W. Fuhr and Warren C. Lee for a chiropractic adjusting instrument, on an application filed June 20, 1977.

1985. Fuhr received $50,000 from the National Institutes of Health Small Business Innovative Research program, the earliest known federal grant for chiropractic scientific research.

1986. The first peer-reviewed publication on the instrument appeared under Fuhr's name in the Journal of Manipulative and Physiological Therapeutics, volume 9, pages 15 to 21.

1987. Fuhr founded the National Institute of Chiropractic Research in Minnesota. Joseph C. Keating Jr. joined its board the following year.

February 2005. Fuhr and James Menke published the status report on the technique in the same journal, volume 28, at e1 to e20.

September 26, 2024. Logan University dedicated the Fuhr Science Center. Fuhr spoke at the ribbon cutting.

09 / The tone through-line

Fuhr showed that speed turns force into a signal, and the Unified Model of Tone names what the signal carries

Arlan Fuhr's contribution to the understanding of tone is a measured one. An impulse delivered faster than the body can brace against needs almost no amplitude to do its work. His instrument fires in about a millisecond where a manual thrust runs 66 to 251 milliseconds, and it competes at 174 N against hand thrusts reaching 387 N. Under the Unified Model of Tone the smaller number is the whole point, because magnitude sits on a different axis from correspondence.

Force that outruns the guarding reflex arrives as information

Muscle tension dampens a mechanical input and strips frequency content out of it before the input reaches the mechanoreceptors. A patient who braces receives less of what was delivered. An impulse that ends before guarding begins loses none of it. Fuhr taught one click per contact for exactly that reason, since after the first the body has already started to guard. The model reads an adjustment as information delivered to the nervous system, and the carrying capacity of that information is set by how well the input matches the pattern the body is holding. What the body does with the signal depends on how well the body senses itself in the first place.

Fuhr's own frequency data is the measured face of correspondence

Keller, Colloca and Fuhr found the thoracolumbar spine least stiff between 30 and 50 Hz. They also found the instrument delivering its peak energy at 20 Hz, with a preload control frame widening the useful band. Their conclusion was that a thrust aimed near the spine's resonant frequency needs less force to produce the same motion. That is the model's claim about correspondence, stated in hertz. Tone is organized oscillation, and an input tuned to a system's own rhythm changes that system with less.

The Activator leg check is a reading that changes what it reads

The Activator analysis retakes the leg-length reading after every input. The model holds that the body's tension network is its own registration of where it is, so any contact alters the account the body keeps of itself. Assessment and treatment become one motion. Richard Van Rumpt built the same loop into the challenge of Directional Non-Force Technique. His rapid thumb thrust and his leg reflex were both folded into the early Activator method, so the resemblance is a matter of descent. Tone is the variable both men were reading without a name for it.

There is no single lynchpin, which is why the scan can start at the feet

Activator clears the pelvis and the caudal segments before it evaluates anything above them. Other traditions place the foundation at the sacral apex or at the atlas. The Unified Model of Tone holds that no single lynchpin exists, and that many sites can reach the whole system when the input corresponds to what is held there. Fuhr's own instrumented data show the mechanism plainly. Thrusts delivered at T11 through L2 moved L3 and L4, segments that received no contact at all.

Where Arlan Fuhr's line runs, backward and forward

Logan Basic is the documented parent. The 1942 contract, the feet-first ordering, and Vinton Logan's push-button challenge all lead straight to the Activator instrument.

Directional Non-Force Technique supplied the challenge logic and the thumb thrust the early Activator method used, and Van Rumpt built a spring-in-a-tube instrument of his own.

Clay Thompson solved the same guarding problem with a different machine. The drop piece of the Thompson Terminal Drop Point table and the Activator spring both use speed to beat the reflex.

The Activator Method page carries the twenty-station scan, the named tests, the force settings, the five instrument generations, and the clearances in full detail.

The thirty-three techniques are where instrument adjusting sits beside every other way of delivering an input to the same variable.