Distinct muscle growth and strength adaptations after preacher and incline biceps curls.
Level 2 - randomized trial
Individual randomized controlled trial
PubMed 39809454 · doi:10.1055/a-2517-0509
What was done
Sixty-three young women were randomized to perform either preacher biceps curls (n = 30) or incline biceps curls (n = 33) twice weekly for 8 weeks. Investigators measured elbow flexor muscle thickness at proximal, middle, and distal sites and assessed muscle strength using three-repetition maximum (3RM) tests for both exercises.
What was found
The incline curl group had a greater increase in proximal elbow flexor thickness than the preacher curl group (mean difference: 0.08 cm [95% CI: 0.02, 0.13 cm]). Conversely, the preacher curl group had a greater increase in distal elbow flexor thickness compared to the incline curl group (mean difference: 0.10 cm [95% CI: 0.04, 0.15 cm]). Data for the middle site were not reported in the abstract. Strength adaptations were exercise-specific: preacher curls produced greater gains in preacher curl 3RM (mean difference: 1.88 kg [95% CI: 1.14, 2.62 kg]), and incline curls produced greater gains in incline curl 3RM (mean difference: 0.86 kg [95% CI: 0.10, 1.62 kg]).
Why it matters
This trial provides direct evidence that exercise selection and joint angle alter regional muscle hypertrophy within the elbow flexors, confirming that regional muscle growth and strength adaptations follow training specificity.
Limits
The study included only young women, so findings may not generalize to men, older populations, or well-trained lifters. The duration was relatively short (8 weeks), middle-site hypertrophy numbers were omitted from the abstract, and baseline training status and nutritional control were not detailed in the record.
Cited by
- supports Performing bicep curls on an incline places the anterior shoulder and biceps into a greater stretch over an extended range of motion, leading to increased initial muscle soreness.