Is it better to isolate a muscle, or should you just stick to the tried-and-true compound lifts?
Theoretically, compound movements present more potential bottlenecks to reaching true muscular failure than isolation exercises. When it comes to targeting one muscle as well as possible, this is a downside. There are simply more muscle groups involved – and that means more chances for something else to give out first.
In the absence of a precise way to gauge how close a specific muscle gets to failure, this could make compound lifts slightly less effective for hypertrophy, all else being equal.
But, does the research actually support this? Have studies found that compound movements are worse than isolation movements for muscle growth?
Let’s look at the evidence.
Nice and al compared wide-grip lat pulldowns to dumbbell curls.
Despite being a compound versus isolation comparison, both resulted in similar elbow flexor hypertrophy – though only one site was measured.
Mannarino et al compared underhand dumbbell rows to dumbbell curls.
This time, the curls produced roughly double the growth in the elbow flexors compared to the rows.
BRANDÃO et al compared the bench press and the skullcrusher.
The skullcrusher led to more growth in the long and medial heads of the triceps, while the bench press favored the lateral head.
Burke et al compared the leg press to the leg extension.
The leg press produced more growth in the vastii muscles, while the leg extension favored the rectus femoris.
Two additional studies compared the squat and leg extension. The first, by Zabaleta-korta et alfound similar growth between the two for both the rectus femoris and vastus lateralis.
The other, by Earp et al, found slightly more overall growth from the leg extension.
Taken together, there’s no consistent trend suggesting compound lifts are better or worse than isolation exercises. If anything, they appear to be similarly effective most of the time.
Supporting this, we have a meta-analysis by Avery et al. Their review of seven studies found no statistically significant difference in hypertrophy outcomes between single- and multi-joint movements.
There’s one caveat, though: each of these studies only compares one isolation exercise to one compound. It’s very possible that other pairings would yield different results.
So, where does that leave us?
- The compound movements we’ve examined through research aren’t inherently worse for hypertrophy – and certainly not by any meaningful margin.
- Compounds are highly time-efficient, often training multiple muscles at once.
- Since compounds and isolations seem largely interchangeable for growth, most of your program can – and probably should – revolve around compound lifts.
- That said, not all compound or isolation movements are created equal. A squat might bring your quads, glutes, and adductors pretty close to failure. A barbell row, on the other hand, likely won’t take your forearms as close to failure as something like a wrist curl would.
