Free Weights vs Machines: What's Better For Muscle Gains?

Not so many moons ago (July 2020), Schwanbeck S and colleagues investigated¹ the effects of training with free weights and machines on muscle and strength gains:

Here’s what they did:

These forty-six subjects (26 women; 20 men) were randomized into two groups:

The exercise program lasted for 8 weeks and consisted of 2 days on and one day off training cycle:

Progressive overload was applied throughout the whole study—repetitions were decreased and rest periods increased:

After eight weeks, there were no differences in lean mass between groups as bicep and quad muscle thickness increased similarly (now go and tell this to that big, hairy meathead in the gym who told you that you’re farting around in the gym using machines):

As for strength gains, there were no differences between groups either—both groups saw a significant increase in strength.

The principle of specificity (strength gains are specific to the type of training you perform) played a part—the machine-training group got stronger at machine exercises while the free weight group got stronger at free-weight exercises:

So there you go, both free weight and machine training are equally effective for increasing muscle and strength. Pitting free weights against machines is like pitting fruits against vegetables—eating both fruits and vegetables will make your diet healthier.

The same applies here—both training “styles” offer a unique benefit to the other misses, so it makes sense to do them both to get the best out of the two worlds. Free weights beat the living fuck out of machines by requiring you to stabilize and control not just the weight being lifted but also the path of the movement.

However, machines beat the living shit out of free weights by keeping constant mechanical tension on the muscles throughout the full range of motion.

And if you think I’m cherry-picking this study like low-carb & keto mindless muppets like to do, I gotta say:

“Uh, how about you don’t put me in the same sentence with keto zealots. Gottit? Good.”

There is a pile of research big enough to choke those zealots that free weight training and machine training produce equivalent increases in muscle mass and strength:

So how do you apply this to your training? Well, here’s how, my internet human friend:

Both free weights and machines build muscle and strength so there’s no reason to avoid machines if you have access to them.
As longs as you train with sufficient volume, intensity, and progressive overload, use the mix of both free-weight and machine exercises. Both have advantages so don’t let popular misconceptions blind you to using only free-weights because some fucknuckle said so.