Frequency and Output Are Not the Same Specification
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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Frequency and output are two different numbers answering two different questions, and treating them as interchangeable is the most common mistake in facial device marketing.
This article keeps the two apart, such as:
- What output decides, and what frequency decides
- Why a high frequency proves nothing about reaching muscle
- Which of the two a device varies during a session
- Why varying amplitude would be the wrong design
- How to compare two devices without being misled
and many more!
By the end you will not confuse a kilohertz figure with a milliamp figure again.
Key Points:
Output is how much current arrives, and frequency is how often the signal repeats, so one is quantity and the other is pattern.
Whether a muscle contracts depends on the whole delivered waveform plus contact, placement and your own tissue, not on either number alone.
A device quoting kilohertz but no milliamps has told you about its pattern and nothing about its strength.
PDM varies frequency and deliberately leaves amplitude alone, so the strength you set is the strength you keep.
Compare devices field by field rather than merging both numbers into one impression of power.
Two numbers dominate facial device specifications, and they get swapped for each other constantly, usually in the direction that flatters whichever one a brand can quote.
Keeping them apart is most of what it takes to read this category accurately.
What each number answers
Output, measured in milliamps or microamps, is how much current the device can deliver.
Frequency, measured in hertz or kilohertz, is how often the signal repeats per second.
Output is quantity and frequency is pattern, so a device can be high in one and low in the other, and neither figure tells you what the other one is.
A useful way to hold it: output is how loud the music is, frequency is what the music is.
Why frequency alone proves nothing about muscle
The claim you will meet is that a high frequency means deeper reach or a muscle-level device.
Whether a facial muscle contracts depends on the complete delivered waveform, together with how much current arrives, how good your contact is, where the device sits and what your own tissue does with the current.
A review of kilohertz-frequency stimulation describes three separate thresholds in everyone, the point you feel the current, the point the muscle moves, and the point it hurts (Ward 2009), and crossing the second one is a function of the whole delivery rather than of a frequency label.
So a device advertising kilohertz operation while publishing no output figure has told you about its pattern and left out its strength, which is the half you needed.
Why output alone is not the whole story either
The reverse mistake is just as common, since a device can have plenty of output and still deliver a session that fades.
Send a muscle the same fixed signal for ten minutes and it gets used to that signal, your nerves get used to it too, and the session quietly drops away even though the output has not changed.
That is a pattern problem rather than a power problem, and turning the dial up is the wrong fix for it.
Both numbers matter, and neither substitutes for the other.
Which one a device should vary
PDM, the delivery architecture inside every PureLift, moves the signal across 361 frequency points between 1,370 and 1,730 Hz so it does not repeat.
Frequency is the only thing being varied, since PDM does not change amplitude and does not change pulse duration.
That is a deliberate choice in both directions. Varying frequency addresses the accommodation problem, and leaving amplitude alone means the strength of your session stays exactly where you set it rather than drifting while you work.
A device that quietly moved your amplitude around would be harder to control, harder to keep comfortable, and harder to compare from one session to the next.
The research points the same way, since the work behind this approach found frequency variation more effective than pulse-duration variation at changing how quickly fatigue sets in, and found that benefit independent of amplitude.
What the evidence supports
Pooling 22 studies, researchers found that stimulation which keeps changing produced more evoked force with less fatigue than a fixed pattern (Cavalcante 2026), and a randomised crossover trial found that varying the frequency reduced how quickly people habituated to it (Avendano-Coy 2019).
Not every study agrees, and one found variable trains tired muscle as much as constant ones (Papaiordanidou 2014).
So the claim stays narrow: varying frequency is designed to reduce accommodation, and it cannot make accommodation impossible or guarantee a cosmetic result.
No randomised trial has compared a PureLift against any fixed-frequency device.
Comparing two devices without being misled
Put the numbers in separate columns and refuse to merge them.
Output, with its unit and its measurement conditions, since 680 microamps and 7 milliamps look similar and differ by about ten times, and a figure with no stated conditions is claiming more than it can support.
Frequency, and specifically whether it holds at one value or changes during the session, because a published range printed without explanation is not the same as a moving signal.
Then the fields that are neither, including session length, whether a proprietary gel is required, and whether there is a clearance record number you can look up.
If a brand has not published a value, record it as undisclosed rather than inferring it from price, packaging or how strong the device feels.
Where PureLift sits on both numbers
All five models run nanocurrent at level 1, microcurrent at level 2, EMS from level 3 to 10, and Infuse as a second pass, and all five carry PDM across the same 361 frequency points between 1,370 and 1,730 Hz.
Face at $499 and Pro at $699 reach up to 7 milliamps, Pro Edition at $799 reaches up to 7.7, and Pro Plus + at $899 and GLOW at $999 reach up to 9, all measured at 500 ohms and always written as up to.
The frequency architecture is identical across the range, so what differs between models is the output column alone.
The session is three minutes on each side of the face, about ten minutes including the Infuse pass.
GLOW alone adds light, red at 634 nm cleared for the treatment of wrinkles, blue at 465 nm cleared for mild-to-moderate inflammatory acne, and purple, which is red and blue running together.
Every model is cleared through the FDA 510(k) pathway, under records K190269 for Face, K230506 for Pro and Pro Edition, K221443 for Pro Plus + and K243587 for GLOW.
All five are made in Japan in an ISO 13485 facility.
Anyone with a pacemaker or another implanted electronic device, anyone pregnant, and anyone with epilepsy or a seizure disorder should not use the device at all.
For reading a full specification, see the spec sheet guide, and for why more output stops helping, read controlled power.
Model figures verified on 9 September 2026 against the PureLift LAB store and FDA records K190269, K230506, K221443 and K243587. Every model runs nanocurrent, microcurrent, EMS and Infuse; consumer copy always says up to.
Two related questions come up often alongside this one, and we have answered both in full: every output figure the market publishes, and which device is actually the strongest.