Effects of an 8-week unstable core training on trunk muscle strength and sprint performance among kayakers

Unstable core training (UCT), widely used in various sports to enhance trunk muscle strength and sprint performance, results in significantly greater gains in both outcomes compared to traditional core training (TCT). The study aimed to examine the impact of UCT performed on unstable surfaces (Both Side Up (BOSU) balls, Swiss balls and Wobble boards) versus TCT performed on stable surfaces (floor and bench) on trunk muscle strength and sprint performance among flatwater sprint kayakers.

A randomized controlled trial was conducted, recruiting 60 eligible kayakers aged 14-19 years from the Ganzhou training base, China. Participants were randomly assigned to the UTC group and the TCT group. Both groups completed an 8-week core training program consisting of 1-hour sessions, 3 times/week. The difference is that the core training exercises of the UTC group were performed on unstable surfaces, while the TCT group was performed on stable surfaces. Trunk stability strength was assessed using the abdomen, back, and side bridge tests, while trunk dynamic strength was measured using the 1-minute sit-up, 1-minute back extension, and 1-minute trunk rotation tests. Sprint performance was evaluated using the 200 m single flatwater sprint time test. Statistical analyses were conducted via Multivariate Analysis of Variance (MANOVA), with the significance level set at p < 0.05.

Both the UTC and TCT groups demonstrated significant improvements from pre- to post-intervention across all dependent variables. However, the analysis of between-group effects revealed statistically significant greater improvements in the UTC group compared with the TCT group at post-test. These differences included These differences included trunk stability strength in terms of abdomen (p < 0.001, η ² = 0.228), back (p < 0.001, η ² = 0.285), left side (p < 0.001, η ² = 0.280), and right side (p < 0.001, η ² = 0.291); trunk dynamic strength in terms of flexion (p < 0.001, η ² = 0.243), extension (p < 0.001, η ² = 0.212), left rotation (p < 0.001, η ² = 0.182), and right rotation (p < 0.001, η ² = 0.303); as well as sprint performance in terms of 200m single flatwater sprint time (p < 0.001, η ² = 0.739).

The findings suggest that UTC may lead to greater improvements in trunk muscle strength and sprint performance compared with TCT over an 8-week intervention among young male Chinese kayakers. However, given methodological limitations (field-based strength tests and manual timing), results should be interpreted cautiously and require confirmation with more precise measurement methods in future research.