When you curl with your arms stretched out on a bench, your forearm muscle has to work harder than your biceps.
Scientific Claim
Elbow flexion performed in a stretched position (e.g., incline or preacher curl) increases relative activation of the brachioradialis by limiting biceps mechanical advantage.
Original Statement
“placing your arm on an incline bench or preacher curl puts your biceps at a disadvantage and forces your brachioradialis to work harder and experience more growth.”
Context Details
Domain
exercise
Population
human
Subject
elbow flexion in stretched position (preacher/incline)
Action
increases relative activation of
Target
the brachioradialis by limiting biceps mechanical advantage
Intervention Details
Evidence from Studies
Supporting (2)
When you bend your elbow all the way back (like in a preacher curl), your biceps can’t push as hard, so your forearm muscle (brachioradialis) has to work harder — and this study proved it by measuring muscle activity at different angles.
Muscular coordination of biceps brachii and brachioradialis in elbow flexion with respect to hand position
When your palm faces down during a bicep curl, your biceps can't pull as well, so your forearm muscle (brachioradialis) has to work harder — which is exactly what the study found.