What if you could get more out of every single rep you perform? More tension, more muscle fiber recruitment, and ultimately, more growth—without necessarily adding more weight to the bar.
For most of us, that sounds like the holy grail of training. We're always looking for an edge, a scientifically-backed method to optimize our time in the gym. A new meta-analysis published in 2025 suggests that one such tool, Neuromuscular Electrical Stimulation (NMES), might be a powerful amplifier for your resistance training.
Let's break down what the science says about strapping in and turning on the electricity during your lifts.
What is NMES, Anyway?
Neuromuscular Electrical Stimulation (NMES) isn't new. It's been a staple in physical therapy and rehabilitation for decades, used to activate muscles in patients who can't do so voluntarily. In simple terms, an NMES device sends controlled electrical impulses to your motor nerves through pads placed on your skin, causing a muscle contraction.
Think of it as an external signal that bypasses your central nervous system to make a muscle fire. While it's a go-to for preventing muscle atrophy after an injury, researchers and coaches have long wondered: what happens if a healthy, trained individual uses it while they are already lifting?
The Big Question: Can It Boost Gains for Lifters?
This is where it gets interesting for us. Does superimposing an involuntary, electrically-stimulated contraction on top of a voluntary, hard-earned contraction lead to better results? Or is it just an unnecessary complication?
To find a reliable answer, a team of researchers conducted a meta-analysis—a powerful type of study that pools the data from multiple previous experiments. They searched for all the randomized controlled trials that directly compared two groups:
- A control group performing conventional resistance training (RT) only.
- An experimental group performing the exact same resistance training but with NMES applied simultaneously (RT + NMES).
By combining the results of 13 different studies, they aimed to get a clear, high-level picture of the "additive effect" of NMES.
A quick note: This review is based on the study's abstract, as the full text was not publicly available at the time of writing.
The Evidence: More Strength and More Muscle
The results of this meta-analysis were clear and statistically significant, pointing to a favorable effect for the group that combined lifting with NMES.
More Strength
When the researchers pooled the data on strength gains, they found a clear advantage for the RT + NMES group. The effect size (measured as a Standardized Mean Difference, or SMD) was 0.31 in favor of the combined training method.
In statistical terms, this is considered a small-to-moderate effect. It's not a night-and-day difference, but it's a real, measurable advantage. It suggests that adding NMES helps you get stronger, faster than lifting alone.
More Muscle Mass
What about hypertrophy? The story is the same. The analysis revealed that the RT + NMES group also experienced greater gains in muscle mass. The effect size here was an SMD of 0.26.
Again, this is a small but significant effect. Over a training block, this small edge could compound into noticeable improvements in size. The data confirms that the combination provides a superior stimulus for muscle growth compared to traditional training in isolation.
What This Means For You: The Practical Takeaway
The conclusion from the researchers is direct: "Use of NMES during RT results in greater gains in strength and muscle mass compared to RT performed in isolation."
For lifters, athletes, and coaches, this is a compelling finding. It positions NMES not just as a rehab tool, but as a legitimate performance enhancement device. It acts as an amplifier, increasing the total stimulus on the muscle during a given workout.
Here’s how to think about applying it:
- It's an Additive, Not a Replacement: NMES doesn't replace hard work and heavy lifting. It works with it. The best results came from combining it with a solid resistance training program.
- Breaking Through Plateaus: For advanced lifters struggling to eke out new gains, the novel stimulus from NMES could be the key to unlocking further progress.
- Maximizing Lighter Loads: While the abstract doesn't specify the loads used, one could theorize that NMES could help maximize muscle recruitment during periods of deloading or when working around an injury that prevents you from using heavy weights.
Limitations and What's Next
As with any study, context is key. Since we only have the abstract, we don't know the specifics of the protocols used in the 13 studies. We're missing details on:
- Which exercises were performed (e.g., squats, leg extensions, bicep curls)?
- What were the exact NMES settings (intensity, frequency, duration)?
- Who were the participants (beginners, trained athletes)?
These details matter for precise application. However, the overall trend is undeniably positive.
The authors also suggest a path for future research: exploring whether this supercharged training method could have additive effects on metabolic and cardiovascular health. This could open up even more applications for NMES down the line.
The Bottom Line
This high-level evidence suggests that combining NMES with your lifts is a viable strategy for getting more out of your training. It provides a small but significant edge in both strength and muscle growth.
While it may have once been seen as a niche gadget for physical therapy, the science now supports its place in the serious lifter's toolkit. If you're looking for a new way to maximize your results, NMES is an evidence-based tool worth paying attention to.
Reference
Narvaez, G., Apaflo, J., Wagler, A., McAinch, A., & Bajpeyi, S. (2025). The additive effect of neuromuscular electrical stimulation and resistance training on muscle mass and strength. European journal of applied physiology. Advance online publication. https://pubmed.ncbi.nlm.nih.gov/39747583/