Heavy or light weights: which builds muscle?
About the same, as long as the sets are hard. What builds muscle is how close each set gets to failure, and heavy weights still win for strength.
By Anthony Topalides, who lifts and makes Two Plates. Checked against the sources below on 27 October 2026.
What the research found
In 2017, Brad Schoenfeld's team pooled 21 studies that compared heavy loads with light ones, with the sets taken to failure. Muscle growth came out about even.
Strength didn't. The heavy groups gained clearly more on their one-rep max, because you get strongest at the weights you train.
Hard is the part that matters
The weight only changes how many reps it takes to get close to failure. A 2024 review in Sports Medicine, led by Zac Robinson, found that muscle growth improved the closer sets ended to failure. Strength gains stayed about the same across a wide range.
So a light set only does its job when it ends near the rep you couldn't get. Stopping at 15 with ten more in the tank is the common miss.
Next session
On your last set, ask yourself how many more reps you had in you. If it's more than about five, push it harder next time.
About the app
I make Two Plates, so I'm biased. It logs how many reps you had left, or your RPE, beside the reps in one tap, so you can see whether your light sets are really hard. What @8 means.
Where this comes from
- Schoenfeld, Grgic, Ogborn and Krieger, Strength and hypertrophy adaptations between low- vs. high-load resistance training, Journal of Strength and Conditioning Research 31(12), 2017
- Robinson and others, Exploring the dose-response relationship between estimated resistance training proximity to failure, strength gain, and muscle hypertrophy, Sports Medicine 54(9), 2024