Why PureLift Uses 1.37 to 1.73 kHz for Facial EMS
Medically reviewed by
4 independent reviewers
Andrew Conrad Barile, PT, DPT
Doctor of Physical Therapy (DPT) | Licensed Physical Therapist (PT) | CEO and Founder, Xtreem Pulse LLC
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Dr. Andrew Conrad Barile is a Doctor of Physical Therapy and the CEO and Founder of Xtreem Pulse LLC, the engineering company behind PureLift. He earned his Doctorate in Physical Therapy from Daemen College and is a licensed physical therapist.
He brings over two decades of clinical and entrepreneurial experience across physical therapy, craniosacral therapy and medical device innovation, built on a working knowledge of human anatomy and muscle physiology.
For PureLift LAB he reviews how current is delivered across all ten levels, from sub-sensory nanocurrent and skin-level microcurrent to motor-level EMS, and how the Infuse pass fits into the same ten-minute routine.
Bertica M. Rubio, M.D.
Board-Certified Physician, Dartmouth Medical School | Medical Director, Antiaging Regenerative Medicine Clinic
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Dr. Bertica M. Rubio is a board-certified physician and Medical Director of the Antiaging Regenerative Medicine Clinic in Redlands, California. She earned her Doctor of Medicine from Dartmouth Medical School and completed her pediatrics residency at UC Irvine Medical Center.
With decades of clinical experience, she specialises in age management medicine, regenerative medicine, wound healing and growth factor therapies, and her practice integrates evidence-based medical science with advanced aesthetic treatment.
For PureLift LAB she reviews articles for medical accuracy across the whole dial, from the gentle nanocurrent and microcurrent settings through to muscle-level EMS and the Infuse pass.
Daniel Grinberg, MD, FACS
Board-Certified Otolaryngologist | Head and Neck Surgeon | Fellow, American College of Surgeons | Mount Sinai
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Daniel Grinberg, MD, FACS is a board-certified otolaryngologist and head and neck surgeon at ENT and Allergy Associates in West Nyack, New York. He earned his medical degree from Columbia University College of Physicians and Surgeons.
He completed his otolaryngology residency at New York University Medical Center, serves as Assistant Clinical Professor at Mount Sinai School of Medicine, and is a Fellow of both the American College of Surgeons and the American Academy of Otolaryngology.
For PureLift LAB he brings a wider clinical lens, connecting at-home facial stimulation from microcurrent to EMS to the anatomy underneath, with the same rigour we apply to every device specification.
Prof. Dr. med. Ivo Buschmann
Chair of Angiology, Medizinische Hochschule Brandenburg | Clinic Director, University Clinic for Angiology
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Prof. Dr. med. Ivo Buschmann is Chair of Angiology at the Medizinische Hochschule Brandenburg Theodor Fontane and Clinic Director of the University Clinic for Angiology at the Brandenburg University Hospital.
He trained at the University of Hamburg, was a Max Planck Society Fellow at the Max Planck Institute for Heart and Lung Research, and held senior consultant posts at the Charite Universitatsmedizin Berlin before his appointment as Chair in 2016.
One of Europe's leading authorities on arteriogenesis, with over 150 peer-reviewed publications and US and EU patents, he reviews for PureLift LAB how the evidence on electrical stimulation is read and where its limits lie.
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PureLift works between 1,370 and 1,730 Hz, which is the kilohertz range, and the choice of band is about comfort at the skin rather than power.
This article explains the reasoning, such as:
- Why skin resists low-frequency current more
- The three thresholds every person has
- What the band does not decide
- How this differs from microcurrent devices
and many more!
Frequency and intensity are two different dials, and confusing them is where most spec-sheet arguments go wrong.
Key Points:
Skin resists current less at kilohertz frequencies than at very low ones, so more of it passes with less surface discomfort.
Frequency governs how comfortably current crosses the skin; intensity governs whether a muscle contracts.
Everyone has three thresholds, sensory, motor and pain, and the gap between them varies by person and by area.
The band does not decide how deep the current goes or which tissue responds.
PDM moves the signal across 361 points inside that band so the pattern never repeats.
Why skin resists low frequencies more
Skin is not a simple conductor, and its opposition to current, its impedance, depends partly on the frequency of that current.
At very low frequencies the outer layer resists strongly, so a device has to work harder at the surface to get anything through, and the surface is where your sensory nerves are.
As frequency rises into the kilohertz range that resistance falls, so more current crosses for a given amount of surface sensation.
That is the whole reason for the band, comfort at the interface, and it is a smaller and more defensible claim than the ones usually attached to frequency figures.
The three thresholds
A review of kilohertz-frequency stimulation describes three thresholds present in everyone, the point you first feel the current, the point the muscle moves and the point it becomes painful (Ward 2009).
The useful setting is the second one, and the space between the second and the third is what a comfortable session lives in.
Working in the kilohertz range widens that space, which is why the same amount of muscle work can be delivered with less sting than a low-frequency device would produce.
The gap varies with skin thickness, hydration and area, which is why one setting can feel mild on the cheek and sharp along the jaw on the same face.
Frequency and intensity are different dials
Frequency describes how many times per second the signal cycles, and intensity describes how much current is delivered.
Whether a muscle contracts is a question of intensity crossing the motor threshold, and no frequency makes a sub-threshold current contract a muscle.
On a PureLift the band stays the same across the whole dial, and what changes as you move from level 1 to level 10 is the intensity, with nanocurrent at level 1, microcurrent at level 2 and EMS from level 3 upward.
Maximum intensity is 7 mA at 500 ohms on Face and Pro, 7.7 mA on Pro Edition and 9 mA on Pro Plus and GLOW, all inside the same frequency band.
What the band does not decide
It does not set a depth, and any claim that one frequency inside the band reaches the surface while another reaches muscle is describing something the physics does not support.
It does not select a tissue, since which tissue responds is a function of intensity relative to the motor threshold rather than of frequency.
It does not by itself make one device better than another, because two devices in the same band can sit on opposite sides of the motor threshold.
How this compares with microcurrent devices
Devices sold as microcurrent operate at much lower intensities, in millionths of an amp, and stay below the motor threshold across their whole range.
FOREO BEAR 2 publishes 680 microamps, Therabody TheraFace PRO 500, ZIIP Halo 309 and NuFACE Trinity+ between 170 and 200, with the last three taken from their FDA clearance documents since none prints the figure on its own site.
That is a difference of intensity rather than of frequency, and it is the difference that decides whether a device can contract a muscle at all.
Why the signal moves inside the band
Holding one frequency for ten minutes lets your nervous system learn the pattern, and once it can predict the signal the response falls away.
PDM, Pulsed Dynamic Modulation, moves the signal across 361 distinct points between 1,370 and 1,730 Hz so the pattern never repeats.
Pooling 22 studies, researchers found stimulation which keeps changing produced more evoked force with less fatigue than a fixed pattern (Cavalcante 2026), and a randomised crossover trial found varying frequency reduced how quickly people habituated (Avendano-Coy 2019).
One study disagrees (Papaiordanidou 2014), so PDM is designed to reduce accommodation and we never claim your muscles cannot adapt.
All of that work was done on limb muscle in laboratory conditions rather than on faces, so it supports the principle rather than testing this implementation.
Two related questions come up often alongside this one, and we have answered both in full: what frequency specific microcurrent means, and which muscles a session actually reaches.