Quick Overview

A 2016 randomized pilot study from Seoul National University examined whether adding electromyostimulation (EMS) to back extension training could enhance results.

Twenty healthy young men trained their back extensors for two weeks. 

Both groups improved strength and endurance, but the group receiving superimposed EMS showed moderately greater gains. The difference was not statistically significant due to the small sample size, but effect sizes suggested a meaningful additional stimulus.

Researchers proposed the benefit may come from enhanced neural activation. For sports enthusiasts, this suggests EMS may provide a small added edge when layered onto consistent strength training—not replacing it, but potentially supporting it.

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Today, we look at a 2016 study published in the Journal of Strength and Conditioning Research examining:

Does adding EMS on top of back strengthening exercise improve strength more than exercise alone?

Original study available here:
https://journals.lww.com/nsca-jscr/fulltext/2016/09000/effect_of_superimposed_electromyostimulation_on.14.aspx 

What Is This Study About?

This study explored whether superimposing electromyostimulation (EMS) on voluntary back extension exercises could improve strength and endurance of the lower back muscles.

Who conducted it?

Researchers from:

• Seoul National University

• Seoul National University Hospital

• Seoul National University Boramae Medical Center
  South Korea

What type of stimulation?

This study used:

EMS (Electromyostimulation)

Not TENS.
Not FES.

Let’s clarify:

This study used EMS designed to create muscle contraction for strengthening.

Who was studied?

• 20 healthy men

• Age 20–29

• No low back pain

• Non-athletes

This was a pilot randomized controlled trial.

How Did They Study It?

Study Design

• Single-blind randomized controlled trial

• 2 weeks duration

• 2 groups:

  • EMS group (maximally tolerable intensity)

  • Sham stimulation group (very low 5 mA intensity)

Number of Participants

• 10 in EMS group

• 10 in sham group

Exercise Protocol

All participants performed:

• Back extension on Swiss ball

• 10 repetitions per set

• 2 sets per day

• 5 days per week

• For 2 weeks

During each repetition:

• 1–2 seconds concentric contraction

• 8–9 seconds hold

• 10 seconds electrical stimulation

• 20 seconds rest

EMS Parameters

• Asymmetric biphasic pulse

• Pulse width: 300 microseconds

• Frequency: 100 Hz

• Mean stimulation intensity (EMS group): ~56.8 mA

• Sham group: 5 mA

Measurements Used

Primary Outcome:

Isokinetic peak torque of back extensors at:

• 60°/sec

• 180°/sec

Measured with Biodex dynamometer.

Secondary Outcome:

Back endurance via:

• Sorensen test (time holding trunk horizontal)

What Did They Find?

Within-Group Results (Both Groups)

After 2 weeks:

Both groups showed statistically significant improvement in:

• Peak torque strength

• Back endurance

This means simple back strengthening exercise worked.

Between-Group Comparison

The EMS group showed:

• Larger average strength increases

• Larger average endurance improvements

Effect size was medium (Cohen’s d ≈ 0.5–0.65)

However:

There was no statistically significant difference between groups.

What does that mean?

The EMS group improved slightly more,
but the study was too small to confirm this difference statistically.

Researchers calculated that:

• ~78 participants would be needed for proper statistical power.

Why Might EMS Help?

The authors suggest:

Short-term strength gains (2 weeks) are likely due to:

Neural adaptation

Not muscle growth.

EMS may:

• Increase neural drive

• Enhance motor unit recruitment

• Improve brain activation patterns

Previous imaging studies show EMS activates brain regions related to motor control.

But:

The exact mechanism is not fully understood.

What Does This Mean for Someone Considering EMS?

1️⃣ Safety

EMS is generally safe when:

• Used properly

• Avoided in pregnancy

• Avoided with pacemakers

• Avoided over infected or malignant tissue

• Skin monitored for irritation

Always consult a health professional if unsure.

2️⃣ Mechanism

EMS:

• Creates involuntary muscle contractions

• May enhance neural activation

• Does not automatically create muscle growth

• Works best when combined with voluntary effort

3️⃣ Realistic Expectations

This study shows:

• Exercise improves back strength.

• EMS may add moderate additional effect.

• 2 weeks is short.

• No dramatic transformation was observed.

4️⃣ Who It May Suit

• People wanting additional neural stimulation

• Early rehabilitation phases

• Individuals struggling with muscle activation

5️⃣ Who Should Seek Advice First

• Chronic back pain patients

• People with medical conditions

• Individuals with implanted devices

• Anyone unsure about safety

What Does This Mean for Someone Already Using EMS?

Consistency matters.

2 weeks showed measurable changes.

Longer duration may produce clearer results.

Proper intensity matters.

The EMS group used maximally tolerable intensity.

Very low intensity did not produce the same magnitude of change.

EMS is not TENS.

TENS targets pain pathways.

EMS targets muscle contraction.

EMS does not replace exercise.

In this study:

All participants exercised.

EMS was added on top.

Conclusion

This pilot randomized controlled trial suggests:

• Back strengthening exercise improves strength and endurance.

• Adding EMS may provide moderate additional benefit.

• Larger studies are needed.

• No exaggerated effects were observed.

The responsible conclusion:

EMS may support strength development when combined with exercise, particularly in short-term neural adaptation phases.

Read the full study here:
https://journals.lww.com/nsca-jscr/fulltext/2016/09000/effect_of_superimposed_electromyostimulation_on.14.aspx 

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🔴 LEGAL DISCLAIMER

This article is provided strictly for educational and informational purposes only.

It does not constitute medical advice.
It does not constitute diagnosis.
It does not constitute treatment recommendation.

No therapeutic claims are made.

ORIEMS FIT does not claim to cure, prevent, or treat any disease.

Results discussed are based on specific research conditions and populations.
They may not apply to all individuals.

Individual responses to EMS vary.

No guarantee of results is provided.

Readers are responsible for their own health decisions.

Always consult a qualified health professional before beginning any exercise or electrical stimulation program.

This content is not intended to replace professional medical care.

The research cited is not affiliated with ORIEMS FIT.

ORIEMS FIT does not endorse specific medical outcomes.

No liability is accepted for misuse of products.

No liability is accepted for interpretation of blog content.

This content complies with Australian TGA advertising requirements by avoiding therapeutic claims.

Not affiliated with the National Strength and Conditioning Association or Seoul National University.

No reproduction rights are granted without permission.