Distinct muscle growth and strength adaptations after preacher and incline biceps curl.

We compared performing preacher and incline biceps curls on changes in elbow flexors muscle size and strength. This was a between-group repeated measures randomized trial. Sixty-three young women performed preacher biceps curl (PC, n = 30) or incline biceps curl (IC, n = 33) for 8 weeks, twice a week. We measured the muscle thickness of elbow flexors at the proximal, middle, and distal sites. We assessed muscle strength using three repetition maximum (3RM) tests in the preacher curl (3RM-PC) and incline curl (3RM-IC). We observed a greater increase in proximal elbow flexors thickness in the IC compared to the PC (meandiff = 0.08 cm [95% confidence interval (95% CI): 0.02, 0.13 cm]). We observed a greater increase in distal elbow flexor thickness in the PC compared to the IC (meandiff = 0.10 cm [95% CI: 0.04, 0.15 cm]). The PC showed a greater increase in 3RM-PC (meandiff = 1.88 kg [95% CI: 1.14, 2.62 kg]). The IC showed a greater in-crease in 3RM-IC (meandiff = 0.86 kg [95% CI: 0.10, 1.62 kg]). Our findings suggest regional dif-ferences in muscle growth induced by the preacher and incline biceps curls. Strength gains appear to follow the principle of specificity.