HIFEM (high-intensity focused electromagnetic energy)

What is HIFEM, and how does it work?

HIFEM is a way of exercising a muscle without the person moving. The applicator contains a coil that is switched on and off many times a second, producing a magnetic field that passes through clothing, skin and fat without heating them. Where that field crosses a motor nerve it induces a small electrical current, the nerve fires, and the muscle it supplies contracts. Because the stimulation arrives faster than the muscle can relax, the contractions stack into a sustained, supramaximal tension that voluntary exercise cannot reproduce.

The muscle responds the way it responds to any heavy load: fibres thicken with repeated loading. The MRI studies on the abdomen measured a thicker rectus abdominis and a narrower gap between the two halves of the muscle after a course. They also measured a thinner subcutaneous fat layer, which the authors attribute to the metabolic demand of the contractions rather than to any direct action on the fat, and a one-year follow-up found the muscle change persisting while the fat change was less durable.

The principle is magnetic induction, the same physics as transcranial magnetic stimulation in neurology. What makes HIFEM a body-contouring tool is the intensity of the field and the size of the applicator, which is built to cover a large, flat muscle group.

Which devices use HIFEM? Emsculpt, Emsculpt NEO, Emsella and EMFACE

HIFEM is a BTL trademark, so the devices that carry the name are BTL's. Other manufacturers sell electromagnetic muscle stimulators on the same principle under their own names; Z Sculpt, the device in Dr Sin Yong's practice, is one of these.

The distinction in the last row matters. EMFACE is often described as HIFEM for the face, but the facial device uses high-intensity facial electrical stimulation, an electrical rather than magnetic input, synchronised with radiofrequency heat. How that compares with Dr Sin Yong's radiofrequency facelift protocol is set out in EMFACE vs VF Lift – Vertical Facelift.

“A magnetic field that passes through skin and fat without heating them cannot be expected to change either. HIFEM is a muscle tool, and I use it when the examination says the muscle is the problem.”

Dr Sin YongOn HIFEM

Where HIFEM matters in a body plan

HIFEM answers one question: is the problem the muscle? A flat lower abdomen with little to pinch, a buttock that has lost shape without being loose, or a pelvic floor that has weakened after childbirth are muscle findings, and a muscle device is the relevant category. A soft roll you can pinch is subcutaneous fat; skin that stays tented after a pinch has lost recoil. Neither is a muscle finding, and a magnetic field that passes through them without heating them will not change them.

That is why Dr Sin Yong examines before naming a device. The pinch-and-recoil test on the sagging tummy, buttocks and arms guide sorts the three findings; the head-to-head of a muscle device against his radiofrequency protocol is in Emsculpt vs 4K Body Lift. Where two findings coexist, a plan can address the muscle with electromagnetic stimulation and the fat and skin with the 4K Body Lift, in an order decided at assessment.

What HIFEM is often confused with

• EMS (electrical muscle stimulation). Pads on the skin pass a current directly into the muscle. HIFEM induces the current magnetically from outside, which lets it reach deeper and contract the whole muscle group rather than the fibres under the pad.
• Radiofrequency. Monopolar and bipolar radiofrequency heat tissue. HIFEM does not; Emsculpt NEO is the exception because it bolts radiofrequency onto the same applicator.
• Fat freezing. Cryolipolysis cools a pinchable fat pocket. It has no effect on muscle, and HIFEM has no direct effect on a fat pocket.
• Exercise. HIFEM loads a muscle, but it does not train coordination, cardiovascular fitness or the muscles the applicator does not cover, and it is not a substitute for weight management.

When HIFEM is not the answer

It is not used over a pacemaker or other implanted electronic device, over metal implants in the field, in pregnancy, over an abdominal hernia, or soon after abdominal surgery. A thick fat layer between the applicator and the muscle weakens the field that reaches the muscle, so a person with a large deposit is usually treated for the fat first. Abdominal separation after pregnancy is checked before any stimulation of the wall is planned.

And it does not tighten skin. Marked excess skin after large weight loss is a surgical question, and Dr Sin Yong refers it to a plastic surgery specialist rather than offering any energy device. Where the skin has lost recoil with little fat beneath, the VF Lift – Vertical Figure Lift on Volnewmer monopolar radiofrequency is the body protocol he reaches for; where laxity and a thin fat layer coexist, Time Freeze Laser LCLR®.