This is the first study to compare the effects of isometric vs. dynamic core training and characterize core-training adaptations using climbing-specific performance and core strength tests in elite climbers. The aim of the study was to compare the effects of attending a progressive core-training program on climbing performance. 19 advanced and elite climbers (7.3±5.6 years climbing experience, red point skill grade 19 IRCRA) were randomized into a dynamic (DCT) or isometric (ICT) core training group and trained twice weekly for ten weeks. The climbers were tested using two climbing-specific core tests (body lock-off and body-lift) and four non-specific core strength tests—one dynamic (superman) and three isometric (trunk flexion and trunk rotation left and right). Between group comparisons showed no differences between the groups at post-test (p = 0.328–0.824) and neither group demonstrated greater improvement compared with the other (p = 0.300–0.926). The ICT group demonstrated 10.8% and 29.6% improvement in trunk flexion and body-lift (p = 0.029–0.037 with no improvement in body lock-off and rotation (p = 0.101–0.343). The DCT group demonstrated 5.0–14.9% improvement in the core strength tests (p = 0.012–0.043), a non-significant 33.8% improvement in body-lift (p = 0.100) and no improvement in body lock-off (p = 0.943). In conclusion, none of the training groups demonstrated greater improvement than the other and both dynamic and isometric core training improved climbing-specific test performance. Dynamic training was slightly more favorable although not significantly superior to isometric core training in improving core strength.