NMES Machine Hire NZ: How Neuromuscular Electrical Stimulation Works After Surgery
If your surgeon or physiotherapist has mentioned NMES as part of your recovery, you are probably wondering what it actually does, whether it is worth using, and where you can get hold of a machine in New Zealand. This post covers all of it.
What is an NMES machine?
NMES stands for neuromuscular electrical stimulation. It is a device that delivers low-level electrical impulses through electrode pads placed on the skin, directly over a target muscle group. Those impulses stimulate the motor nerves that control the muscle, causing it to contract — without you having to voluntarily activate it yourself.
This is different from TENS (transcutaneous electrical nerve stimulation), which primarily targets pain pathways. NMES targets the motor nerves responsible for muscle contraction. The distinction matters because the clinical applications are different. TENS manages pain. NMES maintains and rebuilds muscle function.
Why NMES matters after surgery
The core problem after most orthopaedic surgery — particularly knee surgery — is a phenomenon called arthrogenic muscle inhibition (AMI). When there is swelling and trauma around a joint, the nervous system responds by suppressing voluntary muscle activation in that area. This is a protective reflex, but it creates a significant problem for recovery: you cannot fire your quadriceps properly, even when you are trying to.
Within the first week of immobility following knee surgery, measurable muscle atrophy begins. Research has consistently shown that without intervention, patients can lose a substantial proportion of quadriceps muscle mass and strength in the first few weeks post-operatively. That lost muscle has to be rebuilt from scratch during rehabilitation, which extends the overall recovery timeline and affects long-term outcomes.
NMES bypasses the inhibition. Because the electrical impulse goes directly to the motor nerve rather than relying on a voluntary signal from the brain, the muscle contracts regardless of the inhibition signal. This keeps the muscle fibres active, slows atrophy, and maintains the neuromuscular pathway — the connection between the brain and the muscle — during the period when voluntary activation is compromised.
What the research says
The evidence base for NMES in post-surgical rehabilitation is well established and spans several decades.
A study published in the Journal of Orthopaedic and Sports Physical Therapy found that patients who used NMES following ACL reconstruction had significantly greater quadriceps strength at six weeks compared to those who completed standard rehabilitation alone. The NMES group also showed better functional outcomes at three months.
Research in total knee replacement populations shows similar findings. A 2019 systematic review in the Journal of Rehabilitation Medicine concluded that early NMES use post-TKR produced meaningful improvements in quadriceps strength and functional recovery compared to exercise-only rehabilitation, particularly in the first six weeks following surgery.
The mechanism is consistent across populations: keeping the muscle activated during early immobility preserves fibre integrity and neuromuscular signalling, giving patients more to work with when active rehabilitation begins.
Who benefits from using an NMES machine
NMES is most commonly used following:
ACL reconstruction — quadriceps inhibition is one of the primary barriers to early ACL rehab. NMES is frequently recommended by physiotherapists to maintain quad activation in the first two to four weeks post-surgery when swelling is at its peak.
Total knee replacement — the quad tends to switch off significantly following TKR due to the extent of surgical trauma. NMES is used to maintain activation and support the early mobilisation programme.
Patella tendon repair — extended immobilisation following patellar tendon surgery makes quad maintenance critical. NMES is one of the few interventions that can work during periods where active loading is not permitted.
Meniscus repair — depending on the extent of the repair and the rehabilitation protocol, NMES can support early muscle maintenance while weight bearing is restricted.
Hamstring and quad tendon injuries — where loading the repaired tissue is restricted, NMES offers a way to keep the surrounding musculature active.
Athletes returning from surgery also use NMES during strength phases to supplement resistance training, particularly for neuromuscular re-education when movement patterns have been disrupted by injury.
How to use an NMES machine at home
Modern clinical-grade NMES units are straightforward to use outside of a clinic setting. The Compex, which is the device we use at RecoveryTec, comes with pre-programmed settings for different applications — post-surgical recovery, muscle strengthening, active recovery, and pain management — and guides you through each session.
The general process is:
Place electrode pads over the target muscle. For quad work following knee surgery, this typically means two pads on the vastus medialis (the inner quad, just above the knee) and two pads higher on the rectus femoris or vastus lateralis.
Select the appropriate programme. For early post-operative use, the recovery or muscle stimulation setting at a low to moderate intensity is appropriate. Your physiotherapist should advise on the specific programme and intensity level.
Run the session for the prescribed duration. Standard sessions are typically 20 to 30 minutes. The muscle will contract and relax in a rhythmic pattern throughout.
Frequency varies by protocol, but two to three sessions per day is common in the early post-operative period.
It is important to follow the guidance of your physiotherapist on placement, intensity, and frequency. If you have metal implants near the electrode placement site, cardiac conditions, or are pregnant, check with your surgeon or physio before using NMES.
NMES vs EMS: what is the difference?
You will see both terms used, sometimes interchangeably, which creates confusion.
EMS (electrical muscle stimulation) is the broader category. It refers to any electrical stimulation that causes a muscle contraction, and includes both motor nerve stimulation and direct muscle fibre stimulation.
NMES is a specific type of EMS that targets the motor nerves — the nerves that carry movement signals from the brain to the muscle. Because it works through the nervous system rather than directly on the muscle fibre, it more closely replicates voluntary muscle contraction. This is why it is the preferred approach in rehabilitation settings.
In practice, devices marketed as EMS machines (including the Compex) use NMES technology. The Compex programmes relevant to post-surgical rehabilitation — the muscle stimulation, recovery, and strength programmes — all operate on NMES principles.
NMES machine hire in New Zealand
Clinical-grade NMES units are expensive to purchase outright. Hiring one for the duration of your rehabilitation is a far more practical option for most people, and gives you access to the same equipment used in physiotherapy clinics without the cost of ownership.
RecoveryTec hires the Compex muscle stimulator from our base in Christchurch. We deliver across Christchurch and Lincoln, and ship nationwide by courier.
Hire includes the unit, electrode pads, full instructions, and support. If you have questions about how to use the device during your hire period, we are available to help.
Hire pricing starts at $120 for the first week and $80 per additional week. Most post-surgical patients hire for two to four weeks, covering the early rehabilitation period where NMES is most beneficial.
If you are combining NMES with cold compression therapy — which is common following knee surgery — we also offer an ACL Recovery Package that bundles the CryoPush ice compression machine with the Compex at a combined rate.
What to ask your physiotherapist
If you are considering NMES as part of your recovery, these are the questions worth raising with your physio:
Is NMES appropriate for my specific surgery and recovery stage?
Which muscle groups should I target?
What programme and intensity level is right for me?
How many sessions per day and for how long?
Are there any contraindications I should be aware of given my medical history?
Most physiotherapists working in orthopaedic rehabilitation are familiar with NMES and will have specific recommendations based on your protocol.
Summary
NMES machines deliver electrical impulses directly to the motor nerves, causing the target muscle to contract without voluntary effort. Following surgery, this is clinically significant because swelling and trauma suppress the ability to voluntarily activate the muscle — a phenomenon that leads to rapid atrophy if left unaddressed.
The evidence consistently supports early NMES use following knee surgery in particular, with measurable benefits in quadriceps strength and functional outcomes at six weeks and three months compared to standard rehabilitation alone.
If you are recovering from ACL reconstruction, total knee replacement, or another orthopaedic procedure and want to discuss hiring a Compex NMES machine, visit recoverytec.co.nz or contact us directly.
RecoveryTec hires clinical-grade recovery equipment in Christchurch and across New Zealand. Our range includes CryoPush cold compression machines, Normatec compression boots, Compex muscle stimulators, and BFR cuffs.
