Rugby tackle kinematics in adolescent players: effects of tackle height and shoulder side

Tackling is a major injury event in rugby, yet little is known about how adolescents adjust their body position when tackle height and shoulder side are manipulated. This cross-sectional study determined how tackle height and shoulder side influenced neck, trunk, hip, knee, and ankle positions, and centre-of-mass velocity in adolescent rugby players. Fifteen male amateur players (14.86 ± 0.77 years) completed tackles against a tackle bag under four conditions: regular-height dominant shoulder, low-height dominant shoulder, regular-height non-dominant shoulder, and low-height non-dominant shoulder. Two trials per condition were analysed using eight cameras and the Theia3D motion capture system. Linear mixed-effects models were used to test differences in joint angles and centre-of-mass velocity, with effect sizes reported. Tackle height and shoulder side altered joint positions. Low tackles increased trunk flexion by 16.4° and neck flexion by 7.1°, with the largest deviations when a low target was combined with the non-dominant shoulder, increasing trunk flexion by 29.1° and neck flexion by 10.2° versus regular-height dominant tackles. Hip flexion increased by about 20°, knee flexion changed less, and approach speed was similar between conditions. Coaches should emphasise lowering through the hips and knees, trunk control, head-up positioning, and regular tackle practice on both shoulders.