Tackle direction and preferred side affect upper body loads and movements in rugby union tackling.

Tackling in Rugby Union is associated with most match injuries. New tackle regulations have been explored to reduce injuries, but limited quantitative evidence is available to inform any law changes. Using a novel tackle simulator, we investigated upper body loading under different tackling conditions: direction of approach (0° - frontal, 45° and 90° to the ball carrier direction) and side of body (dominant vs. non-dominant). Peak impact force between tackler and simulator , and head and upper trunk segment motions were measured from 10 male players. Impact load averages were 17% higher at (0°) compared with (90°), across the two different tackling sides ( = 0.093), with the highest impact force measured during dominant-side shoulder tackles at 0° (5.63 ± 1.14 kN). Trunk resultant accelerations were higher (+19%,  = 0.010) at 0° compared with 90°, with the highest resultant acceleration measured in frontal tackles with the dominant shoulder (17.52 ± 3.97 g). We observed higher head lateral bending around the impact when tackling with the non-dominant shoulder at 45° ( = 0.024) and 90° ( = 0.047). Tackling from an offset angle from frontal may be safer. Deficiencies in tackling techniques on the non-dominant side should be reduced.