Free Weights vs. Machines: Which Is Better for Muscle and Strength?

When it comes to resistance training, there’s a long-standing debate: free weights or machines—which is better?

If you’ve spent any time in fitness circles, you’ve likely heard passionate arguments from both sides. Free weights are often hailed as "functional" and essential for building "real-world" strength. Machines, on the other hand, are praised for their ability to target muscles and offer a more controlled movement.

But what does the science actually say?

A recent systematic review and meta-analysis took a deep dive into this exact question—analyzing data from 16 studies that compared free weights and machines across outcomes like muscle growth, strength, and power.

What the Research Found:

👉 Muscle Growth
No meaningful differences. Both free weights and machines were equally effective for building muscle.

👉 Strength
It depends. If you want to get stronger on a specific exercise (say, a barbell squat), you need to train that exact movement. The same goes for machine-based lifts. Strength gains are specific to the exercise performed.

👉 Power
Again—no significant differences between modalities.

So... Which Should You Choose?

If your goal is overall muscle growth or general strength, you can use either machines or free weights—or a combination of both. What matters most is that you train with good technique, sufficient intensity (close to failure), and adequate volume.

If your goal is to improve performance on a particular lift (like a bench press or hack squat), specificity matters. You need to practice the exact lift to get the best results.

Debunking Common Myths:

• “Machines are useless because they don’t train stabilizers.”
  False. Machines offer targeted work and can be incredibly effective for hypertrophy when used appropriately.

• “Free weights are superior because they release more muscle-building hormones.”
  Not supported by evidence. Acute hormonal spikes don’t translate to better long-term hypertrophy.

• “Only compound barbell lifts build real strength.”
  Also false. Strength is specific. Machines can absolutely build strength and power when programmed correctly.

How to Apply This:

Best practice? Use a mix of both free weights and machines.

For example:

• Use free weights for foundational movements like squats, deadlifts, and presses—especially if you value skill development and total-body coordination.

• Use machines to isolate certain muscle groups, manage fatigue, and add training volume without the technical demands of free weights.

Bottom line: The best training plan is the one you’ll stick to and can progress consistently. If you love free weights—great. If you love machines—also great. Both can help you get strong, powerful, and muscular.

So next time someone says “barbells are the only way to build real muscle”—you can confidently smile and carry on with whatever tools YOU enjoy using.

References: 

Zabaleta-Korta A, Fernández-Peña E, Torres-Unda J, Garbisu-Hualde A, Santos-Concejero J. The role of exercise selection in regional Muscle Hypertrophy: A randomized controlled trial. J Sports Sci. 2021 Oct;39(20):2298-2304. doi: 10.1080/02640414.2021.1929736. Epub 2021 Jul 10. PMID: 34743671.

Schwanbeck SR, Cornish SM, Barss T, Chilibeck PD. Effects of Training With Free Weights Versus Machines on Muscle Mass, Strength, Free Testosterone, and Free Cortisol Levels. J Strength Cond Res. 2020 Jul;34(7):1851-1859. doi: 10.1519/JSC.0000000000003349. PMID: 32358310.

Mattocks KT, Buckner SL, Jessee MB, Dankel SJ, Mouser JG, Loenneke JP. Practicing the Test Produces Strength Equivalent to Higher Volume Training. Med Sci Sports Exerc. 2017 Sep;49(9):1945-1954. doi: 10.1249/MSS.0000000000001300. PMID: 28463902.