For biceps growth
For biceps growth, machine preacher curl rates well ahead on our research criteria: more stretch, easier to progress.
Both are good choices that train the biceps the same way, so they swap freely. Rotating between them every few weeks is an easy way to vary your training.
The research score comes from these, scored by hand from the studies. Lifter scores appear once an exercise has 10 ratings. How scores work
Dumbbell Curl. Simple and joint-friendly, though tension fades at the bottom of each rep.
Machine Preacher Curl. The preacher position loads the biceps at the bottom, and the machine keeps that tension steady and easy to progress.
For biceps growth, machine preacher curl rates well ahead on our research criteria: more stretch, easier to progress. Both are good choices that train the biceps the same way, so they swap freely. Rotating between them every few weeks is an easy way to vary your training.
About the same: both are easy to learn.
Dumbbell curl needs dumbbells, so a home gym covers it. Machine preacher curl needs a machine, so for most people it’s a gym exercise.
About the same: both rate Excellent for joint and recovery cost in our research rubric.