What New Science Says About Bigger Arms (2025) – SET FOR SET

Plus 3 coaching purposes to maximise hypertrophy 

The search for the very best workouts to maximise muscle progress is endless. You possibly can simply discover articles titled “Prime 5 Workouts For (any muscle you need)”. However what if we have it fallacious? What if the easiest way to maximise muscle hypertrophy is not utilizing the very best train, however by utilizing a number of workouts? That is what new analysis revealed in Sport Sciences for Well being suggests, including to the rising stack of literature selling train variation over utilizing a single train.

The Research: Acute and persistent regional modifications in elbow flexor thickness after resistance coaching with dumbbell curl or dumbbell row workouts (2025)

A 2025 research in Sport Sciences for Well being (Leitão et al., 2025) wished to reply a few questions regarding bicep progress:

• Are there variations between acute and long-term muscle progress from resistance coaching?
• Do dumbbell curls or rows produce better muscle hypertrophy? 
• Does utilizing a number of workouts produce better muscle progress than a single train?

To do that, they in contrast single-joint dumbbell curls (DC) and multi-joint dumbbell rows (DR) to see how every train impacts muscle progress within the biceps.

How Did Researchers Examine Variations within the Biceps’ Muscle Progress? 

Because the researchers have been each persistent and acute results, they used two research. 

Every research used an identical protocol with a within-subject experimental design. Every participant carried out a dumbbell curl with one arm and a single-arm row with the opposite.

Muscle hypertrophy was measured at proximal (25%) and distal (75%) areas of the biceps.

Experiment 1 (Acute response): To find out acute response, 16 skilled males carried out a single session of dumbbell curls and single arm dumbbell rows utilizing a 4×8–12RM rep scheme. 

Ultrasound was used to measure muscle swelling instantly after coaching (a brief improve in thickness).

Experiment 2 (Persistent adaptation): To have a look at long-term progress, 9 untrained males skilled for 8 weeks, twice per week, performing curls with one arm and rows with the opposite. Muscle thickness was measured earlier than and after coaching at two factors alongside the biceps (proximal = close to the shoulder; distal = close to the elbow).

What’s The Distinction Between Acute And Persistent Muscle Progress?

Let’s contact on “acute” and “persistent” muscle hypertrophy and why that issues.

• Acute Results was the speedy swelling of the biceps measured proper after a exercise. This is casually known as “the pump,” attributable to blood circulation and water accumulation. 
• Persistent Results have been measured after eight weeks of coaching, reflecting true muscle hypertrophy from long-term adaptation. That is “precise progress” that can stick round.

The acute swelling can spotlight which areas of a muscle are most harassed throughout an train in actual time. Nonetheless, solely persistent measurements affirm whether or not that stress really interprets into lasting progress.

This distinction is essential in right this moment’s health club, the place many lifters are chasing the pump. They confuse their bigger muscle mass after an intense session with precise progress, however a number of days later, they discover out their muscle mass have “shrunk”.

Now, this does not imply the pump has no worth, as there is a relationship with muscle progress, and it might be anabolic. Nonetheless, it is essential to differentiate the distinction and that coaching for a pump does not mechanically translate into actual muscle progress.

What Did The Researchers Discover?

Alright, so what occurred? This is a rundown of the outcomes.

Acute (single session):

• Each curls and rows induced swelling alongside the biceps.
• Curls produced better swelling proximally (nearer the shoulder) than rows (19% vs 13%).
• Distal swelling (close to the elbow) was related between workouts.

Persistent (8 weeks of coaching):

• Dumbbell curls elevated muscle thickness each proximal (≈5%) and distal (≈11%).
• Dumbbell rows elevated solely proximal thickness (≈5%), with no vital distal progress (≈1%).
• Total, curls produced extra whole hypertrophy, particularly within the decrease (distal) biceps area.

Within the acute experiment, the dumbbell curls produced better progress in the complete biceps. Of curiosity, this progress was considerably better within the proximal area of the biceps (close to the shoulders).

Within the persistent experiment, the dumbbell curls once more produced better total progress. Of curiosity, each teams produced related will increase within the proximal area of the biceps. Nonetheless, within the distal area (close to the elbow), the row noticed minimal progress whereas the bicep curls produced an 11% improve in muscle.

Why May This Occur?

So, why would these two workouts trigger such variations? Effectively, there are 3 issues to contemplate.

1. Vary of movement: Vary of movement (ROM) performs a big half in muscle progress, with greater ROM generally being very best for progress. This is largely due to:

• The quantity of pressure positioned on the muscle 
• A extra even distribution of pressure all through the muscle stomach

Curls prepare the biceps by way of a bigger vary of movement, leading to better stretch and extra direct pressure alongside the size of the muscle.

2. Train mechanics: In rows, the biceps help the again and shoulder muscle mass quite than being the prime mover. This might restrict their hypertrophic stimulus and even focus.

When a person performs a curl, their focus is probably going directed extra to the biceps muscle. Theoretically, this might invoke the mind-muscle connection, which has been discovered to be a determinant in muscle progress (Calatayud et. al, 2017)

3. Regional variations: Proof now reveals {that a} muscle (just like the biceps or rectus femoris) can develop extra in particular areas relying on the train mechanics. 

Quite a few research have proven that when utilizing a single train, the working muscle will expertise totally different quantities of progress in areas that have extra stress (Antonio, 2000).

How This Compares To Different Analysis

The outcomes of this research align with different analysis, however they must be thought of in context.

1. The impact of muscle swelling and its relationship to long-term muscle progress is surprisingly largely understudied.

There was an fascinating research in 2022 revealed within the Journal of Energy and Conditioning Analysis that checked out the affiliation between the muscle swelling after the primary coaching session of a 6-week program and muscle progress on the finish. In contrast to this research, they did discover a direct relationship.

Whereas fascinating, that is mechanistic and should not have an effect on our coaching considerably.

2. By way of the non-uniform progress seen in a muscle, there was numerous analysis prior to now that traces up with these findings. A lot in order that we might say, to optimize progress, it is important to make use of train variation.

This opinion is echoed by Dr. Jose Antonio, who revealed a research within the Journal of Energy and Conditioning Analysis. He carried out a research researching the impact of a number of workouts on muscle activation and progress. As a result of non-uniform muscle progress from a single train, he concluded;

One other research from de Vasconcelos et. al (2021) revealed within the Worldwide Journal of Sports activities Drugs examined utilizing a single train to coach the biceps and quadriceps or a spread (3 workouts).  In it, each the biceps and quadriceps noticed fuller muscle progress throughout the complete muscle in comparison with utilizing a single train.

We now have written about this before in a dedicated article, so be sure you verify that out!

What Does This Imply For Your Coaching?

When the takeaways, it is essential to notice that the muscle swelling is mechanistic in nature, whereas utilizing train variation is immediately relevant to our coaching. 

So, whereas in search of the connection between acute swelling and long-term progress is unquestionably fascinating, “chasing the pump” in all probability is not the very best take-away.

Reasonably, this research reveals the essential roles that train choice and train variation alternative can play in our total coaching technique.

Now, since just one isolation and one compound train have been examined, we clearly cannot apply this to all actions. For instance, chin-ups and close-grip lat pulldowns are wonderful bicep workouts.

Probably the most sensible conclusion is that variation of workouts that combine compounds and isolations is probably going wanted to optimize muscle progress. 

With that stated, be sure you embrace train variation in your coaching following these 3 pointers.

1. Do not use workouts with related biomechanics in the identical session. This can turn out to be redundant because the muscle mass are being labored in the identical means.

• Do not Use: Bench press and push-ups
• Use: Incline bench press, dips, chest flies

2. In case you prepare the identical muscle twice per week, use totally different workouts. This can differ relying on the person and coaching objectives, however here is an instance of the way it would possibly look.

• Session 1: Incline barbell bench press, chest flies 
• Session 2: Dumbbell flat bench, dips

3. Alter workouts in a scientific method. You continue to want to focus on making use of progressive overload, which requires utilizing the identical workouts. The timeframe can differ drastically relying in your coaching age, however listed here are some basic suggestions;

• Massive workouts: Swap each 6-12 weeks
• Accent workouts: Swap each 2-4 weeks
• Isolations: You possibly can alter each session or two if you’d like

Consider these are basic pointers, and specifics depend upon the particular person. Regardless, bear in mind to all the time prepare smarter, not tougher!

References

1. Antonio, J. (2000). Nonuniform response of skeletal muscle to heavy resistance coaching: Can bodybuilders induce regional muscle hypertrophy? Journal of Energy and Conditioning Analysis, 14(1), 102–113. https://doi.org/10.1519/00124278-200002000-00017
2. Calatayud, J., Vinstrup, J., Jakobsen, M. D., Sundstrup, E., Brandt, M., Jay, Ok., … Andersen, L. L. (2017). Thoughts–muscle connection coaching precept: Affect of muscle power and coaching expertise throughout a pushing motion. European Journal of Utilized Physiology, 117(7), 1445–1452. https://doi.org/10.1007/s00421-017-3637-6
3. de Vasconcelos Costa, B. D., Kassiano, W., Nunes, J. P., Kunevaliki, G., Castro-E-Souza, P., Rodacki, A., Cyrino, L. T., Cyrino, E. S., & de Sousa Fortes, L. (2021). Does performing totally different resistance workouts for a similar muscle group induce non-homogeneous hypertrophy? Worldwide Journal of Sports activities Drugs, 42(9), 803–811. https://doi.org/10.1055/a-1308-3674
4. Hirono, T., et al. (2022). Relationship between muscle swelling and hypertrophy induced by resistance coaching. Journal of Energy and Conditioning Analysis, 36(2), 359-364. https://doi.org/10.1519/JSC.0000000000003478 
5. Leitão B. F. M., Albarello J. C. S., Halmenschlager G. H., Mannarino P., Nunes J. P., De Salles B. F., & Matta T. T. (2025). Acute and persistent regional modifications in elbow flexor thickness after resistance coaching with dumbbell curl or dumbbell row workouts. Sport Sciences for Well being. https://doi.org/10.1007/s11332-025-01530-7