The big free-weight lifts are the best exercises for muscle and strength, right? Well, it’s more nuanced than that. Here’s the new science.
You must focus on the big basic lifts to build muscle and strength, right? Well, not so fast. The newest research shows isolation exercises are just as good, and machines are fine.
Before you rage-post in the comments section, take a look at the latest research on exercise selection and gains.
Single-joint exercises are just as effective as multi-joint exercises for hypertrophy. For years, experts claimed that the big basic lifts are superior to more targeted, single-joint exercises to maximize muscle growth. But this is inaccurate.
Muscle growth is stimulated just as effectively from a single-joint approach (isolation lifts) as from a multi-joint approach (compound lifts), provided the exercises properly load the muscles and cover the whole body.
A recent review found no difference between single-joint, multi-joint, or a combination of both on overall muscle hypertrophy. Furthermore, researchers found indications that single-joint exercises could potentially be superior for eliciting growth in some muscle subdivisions (1).
Think about it. The main benefit of multi-joint exercises is that they allow you to provide some growth stimulus to many muscles simultaneously. But none of these muscles receive maximal individual muscle tension and stimulus because the workload is spread out.
Also, complex exercises require more coordination and are less stable, so the nervous system has a harder time recruiting the high-threshold motor units (the growth-prone fast-twitch fibers).
Recruiting these fibers requires a stronger signal from the nervous system. If a lot of resources are used to coordinate complex movements or stabilize the body, you have fewer resources available to send that strong activation signal. You won’t grow as much if you have a harder time recruiting high-threshold fibers.
If your goal is simply to maximize muscle growth, a program based on properly selected single-joint exercises CAN work just as well as a plan focused on the big free-weight lifts.
Surely someone who trains using mostly big lifts (thus handling bigger weights) will be stronger than someone whose workouts are mostly single-joint exercises?
Well, you must first understand the difference between having strong muscles and being good at demonstrating strength in a few specific exercises. Demonstrating strength in an exercise requires both a physical capacity (strength) and a movement skill.
In a sense, it’s no different than being able to hit a baseball a mile. You can have very strong and powerful muscles individually without being able to apply that to a powerful home run swing.
Most powerlifters are stronger and more powerful than the best homerun hitters, but they can’t usually apply their strength to the bat swing because they lack movement skill.
It’s the same with strength: just because all your individual muscles are strong doesn’t mean you have the skill to coordinate their strength together, much less demonstrate maximum strength on heavy lifts.
If a bodybuilder never squats or deadlifts, even if he has very strong muscles individually, his performance on those big lifts is perceived as poor. That’s not because his muscles are just inflated goo with no strength. It’s because he doesn’t have the motor skill to apply the individual potential of all of his muscles into one maximal effort on those complex lifts. You can have a subpar performance on the big lifts even when all the involved muscles are strong and developed.
If a big bodybuilder who built his physique mostly with single-joint exercises were to do a training phase focusing only on the big lifts, his performance would quickly be brought up to par. He’d get there simply by practicing applying maximal force on a set of movements. It wouldn’t take long; the strength is already there.
Researchers studied biceps strength and size gains from the curl versus a supinated lat pulldown, which activates the biceps just as much as a curl. The results? There was no difference in biceps strength or size gains between both groups (2).
Any exercise that can properly load a specific muscle – and with which you can gradually add more weight over time – will lead to similar gains in that individual muscle. In fact, some single-joint exercises might be superior for making a specific muscle stronger because you can better focus on maximizing tension.
That’s why Westside Barbell’s conjugate system uses up to 80% of its training volume in the form of assistance exercises (often single-joint) rather than the competition lifts. They use assistance exercises to build muscle and strength and practice their competition lifts to develop the skill to apply their strength.
Another shocker was discovered in a meta-analysis analyzing the differences between machine and free-weight exercises. The main findings:
- Hypertrophy was the same for free-weight versus machine training programs.
- More surprisingly, power output gains (explosiveness) were also the same between machine and free-weight exercises. Another study showed superior vertical jump gains from the leg press than back squats.
- As for strength, if the strength test was neutral (not one of the trained exercises), gains were the same between machine and free-weight work. They were only different when the test was done using free-weight exercises.
For instance, one group trained on the squat, the other group trained on the leg press, but both tested their strength gains on the squat. This proves the point above about muscle strength versus movement performance (3).
You can build strong, large, and powerful muscles with machines or free weights. How you train (loading schemes, how you perform reps, intent, intensity level, etc.) matters more than the tools you use, provided the tools you select properly load the muscles.
Here’s a common argument: “What about the stabilizer muscles? Aren’t free weight exercises better to develop those?”
First of all, there’s no such thing as “stabilizer” muscles. Stabilization and fixation are functions that muscles can carry out. No muscle is built only to stabilize. It depends on the movement.
But semantics aside, what people are often implying has more to do with greater core strengthening. And, lucky us, researchers also studied the activity of the various abdominal muscles between leg exercises with three different levels of stabilization needs:
- Leg Press
- Smith Machine Squat
- Free-Weight Squat
What did they find? The various ab muscles were less active in the leg press, but maybe surprisingly, they were the same for the Smith machine and free-weight squat. And that was measured during a 3RM effort, not a submaximal set (4).
So, some machine exercises may indeed involve less stabilization than their free-weight equivalent, but not all of them.
If you’re an athlete, it might be better to train “stabilization” with a separate movement and focus on more stable exercises for strength and size development. The same study found that in a 3RM effort, the subjects could use 5% more on the Smith machine than on the free-weight squats.
Again, it might be possible to recruit the high-threshold motor units more easily, and without causing as much central fatigue, with more stable movements.
Should we all stop doing free-weight squats in favor of a leg press, leg curl, or leg extension? Nope, that’s not what I’m saying or what you should take from these findings.
Here’s the bottom line: Free-weight, multi-joint exercises work. They build strength and size. But they’re not any better than other tools. What’s most important is how you use these tools.
Free-weight, multi-joint exercises do have benefits. For one, they’re time-efficient. You might need twice as many exercises to cover the whole body using single-joint or machine exercises.
Plus, you can’t forget about personal motivation and preferences. Getting strong on those big free-weight lifts is very important for many people. And when something is important to you, you train harder to improve on it.
If getting strong on the squat, bench, and deadlift is a primary goal, you’ll progress more by training hard on those movements rather than on their machine equivalents simply because you’re more motivated.
The take-home message? What matters the most is training hard and smart. The way you do your reps, the intent you have on each rep, the loads you’re using, the number of sets, etc., are all more influential on your progress than the type of exercise you choose.
You can get big, strong, and powerful with any form of progressive resistance training. Period.
Make any workout work better. Fuel it.
- Rosa A et al. Hypertrophic Effects of Single- Versus Multi-Joint Exercise of the Limb Muscles: A Systematic Review and Meta-analysis. Strength and Conditioning Journal. April 6, 2022.
- Gentil P et al. Single vs. Multi-Joint Resistance Exercises: Effects on Muscle Strength and Hypertrophy. Asian J Sports Med. 2015 Jun;6(2):e24057. PMC.
- Heidel KA et al. Machines and free weight exercises: a systematic review and meta-analysis comparing changes in muscle size, strength, and power. J Sports Med Phys Fitness. 2021 Oct 5. PubMed.
- Saeterbakken AH et al. Core Muscle Activation in Three Lower Extremity Exercises With Different Stability Requirements. J Strength Cond Res. 2022 Feb 1;36(2):304-309. PubMed.