Quick Overview

Researchers found EMS increased force production 20–40% in weeks, with strong neural activation seen in brain imaging. Even the untrained limb gained up to 60% of strength improvement (cross-education effect). EMS stimulates motor units in a different recruitment pattern than voluntary contraction. For trained individuals, this may mean accessing fibers not fully engaged during conventional lifting.

Introduction: Why ORIEMS FIT Research Digest Exists

At ORIEMS FIT Research Digest, we simplify real scientific research from universities and peer-reviewed journals into everyday language.

No hype.
No exaggerated claims.
No promises of cure.

Our goal is to help you make informed decisions about electrical muscle stimulation (EMS).

This article is educational only and does not provide medical advice, diagnosis, or treatment recommendations. Links to original studies will be always provided at the end of each article

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What Is This Study About?

Many people ask:

If I already train hard, can EMS activate muscle fibers that my normal workouts might not fully recruit?

This peer-reviewed research explored how electrical muscle stimulation (EMS) improves strength — and more importantly, how it does it.

Instead of focusing on muscle growth, the researchers examined neural adaptations — changes in how your brain and nervous system activate muscle.

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Who Conducted the Research?

• Authors: Tibor Hortobágyi & Nicola A. Maffiuletti

• Institutions: University of Groningen (Netherlands) & Schulthess Clinic (Zurich, Switzerland)

• Journal: European Journal of Applied Physiology

• DOI: https://doi.org/10.1007/s00421-011-2012-2

This was a peer-reviewed mini-review, meaning the authors analyzed multiple controlled studies on EMS strength training.

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What Type of Electrical Stimulation Was Studied?

The research focused on:

EMS (Electrical Muscle Stimulation)

Also called Electrical Stimulation Training (EST).

This is different from:

• TENS – mainly used for sensory nerve stimulation related to discomfort perception

• FES – used to restore functional movement in neurological rehabilitation

This study specifically examined muscle-strengthening EMS protocols, typically using:

• 30–75 Hz stimulation frequencies

• Repeated contraction cycles

• Multi-week training programs

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Who Was Studied?

Across the reviewed studies:

• Healthy adult men and women

• Trained and untrained participants

• Lower limb and upper limb muscles

The research did not focus on disease treatment.
It examined strength adaptation in healthy muscle.

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How Did They Study It?

Because this was a review paper, it examined multiple experimental designs, including:

• Randomized controlled trials

• Unilateral vs bilateral training

• EMS vs voluntary strength training comparisons

Common study features included:

• Duration: 3–6 weeks (short-term phase)

• Measurement: Maximal Voluntary Contraction (MVC)

• Neural drive testing (EMG, H-reflex, V-wave)

• Muscle fibre analysis

• Brain imaging (fMRI) in some studies

Importantly, many studies showed:

• Strength increased early

• Muscle size did not significantly increase during the first weeks

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What Did They Find?

1️⃣ Strength Increased Before Muscle Size Changed

Several studies showed measurable increases in maximal strength within weeks.

However:

• No significant muscle hypertrophy was observed in early phases.

• Muscle fiber size often remained unchanged initially.

This suggests something else was responsible.

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2️⃣ The Nervous System Adapted

The researchers concluded that early strength gains were:

Associated with neural adaptations.

These included:

• Increased neural drive to muscle

• Improved motor unit activation

• Changes in cortical (brain) activation

• Enhanced communication between brain and muscle

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3️⃣ EMS May Activate Muscle Differently Than Voluntary Training

The paper explains that EMS activates muscle through:

• Direct stimulation of motor axons under electrodes

• Strong sensory feedback sent back to the brain

This differs from voluntary contraction, where:

• The brain initiates movement internally

• Motor units are recruited in an orderly fashion

Because EMS activates nerves externally and non-selectively, it may stimulate motor units in patterns that differ from voluntary exercise.

That is where the idea comes from that EMS may recruit muscle fibers that normal training does not always fully activate.

However, the paper carefully avoids claiming that EMS replaces exercise.
Instead, it suggests EMS can provide a different neural stimulus.

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What Does This Mean If You’re Considering EMS?

Mechanism

EMS works by:

1. Electrically activating motor nerves

2. Producing muscle contractions

3. Sending strong sensory feedback to the brain

4. Modifying neural drive over time

Realistic Expectations

• Early strength improvements are likely neural

• Visible muscle growth may take longer

• EMS is a supplement to training, not a substitute

Safety

Most reviewed studies involved healthy adults and used controlled parameters.
However, individuals with medical conditions should consult a healthcare professional before use.

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What Does This Mean If You’re Already Using EMS?

If you noticed:

• Improved strength without visible muscle growth

• Better muscle activation

• Improved contraction “connection”

That aligns with what this research describes.

Consistency matters.
Proper electrode placement matters.
Intensity should be tolerable but progressive.

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EMS vs TENS – Clear Difference

This study relates specifically to EMS for strength training.

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Conclusion

This University of Groningen and Zurich review suggests:

Early strength gains from EMS are primarily driven by neural adaptations, not immediate muscle growth.

EMS appears to:

• Increase neural drive

• Influence motor cortex activity

• Potentially activate motor units differently than voluntary training

It does not claim to cure, treat, or replace training.

It explains how strength changes may occur.

For informed decisions, reviewing peer-reviewed evidence matters.

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🔵  SUMMARY TABLE

🔴 DISCLAIMER

This content is provided for educational purposes only.

It does not constitute medical advice.
It does not diagnose, treat, cure, or prevent any disease.

ORIEMS FIT does not make therapeutic claims.

Individual results may vary.
The research discussed may not apply to all individuals.

Readers should consult a qualified healthcare professional before using electrical stimulation devices, especially if they have medical conditions or implanted devices.

ORIEMS FIT is not affiliated with the University of Groningen, Schulthess Klinik, or Springer.

No endorsement of medical outcomes is expressed or implied.

ORIEMS FIT accepts no liability for misuse of products or misinterpretation of blog content.

This article complies with Australian TGA advertising standards.

All health decisions remain the responsibility of the reader.

ORIEMS FIT Research Digest makes complex research from top scientists and universities easy for anyone to understand—clear, simple, and never medical advice, just trustworthy science.

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