To investigate neuromuscular activation strategies during simulated Rugby Union tackles, which are known to be a common injury event.
A 50 kg punch bag translated towards the tackler through a pulley system simulated the ball carrier under 3 conditions (see Figure 2). 15 male players (23 ± 5 years, 1.82 ± 0.06 m, 96.6 ± 12.9 kg) were tested and 8 wireless EMG electrodes (Delsys Trigno, Delsys Inc, USA) were attached bilaterally to the upper trapezius (UT), middle trapezius (MT), erector spinae (ES), Gluteus Maximum (GM).
Muscle activity in each condition was characterised by pre-activation of all 8 muscles prior to impact (Fig. 1), with the GM activated initially. The impact side trapezius muscles of the tackler always presented higher activation compared with the other side, while impact-side ES and GM were less active than in the contralateral side (producing a ‘criss-cross’ recruitment pattern, Fig. 2).
Pre-activations and ‘criss-cross’ recruitment pattern, which were more evident in dominant side tackles, can functionally lead to an increase in cervical and lumbar spine stiffness, and orientations of the body segments in the proper way, which may better prepare players to resist high impact loads.