Head Acceleration Event Probabilities During Standardised Contact Drills in Academy Men's Rugby League.

This study investigated head acceleration event (HAE) probabilities between common contact-drills in rugby league. Fifteen professional male academy players participated in three training sessions, completing standardised contact-drills while wearing custom-fitted iMGs, all sessions were filmed. HAE data (peak linear acceleration and peak angular acceleration) were captured, synchronised, and processed alongside video data. Binomial logistic regression and ordinal mixed-effect regression models were used to calculate overall and exceedance probabilities. Data included 1402 (93 ± 50 per player) contact-drill observations, of which 133 had HAEs ≥ 5 g (9 ± 8 per player). Substantial variability in probability for HAEs ≥ 5 g (1.3%-41.3%) was observed across drills. Standing wrestle had the highest HAE ≥ 5 g probability (41.3%; CI: 31.0%-52.3%), while tackle shield hits at 1 m had the lowest (1.3%; CI: 0.5%-3.4%). HAE probability was greater for tacklers than ball-carriers. Overall, probability of a HAE ≥ 25 g was < 1.1%. Standardised contact-drills varied in HAE probabilities, but chances of higher magnitude HAEs was low for all drills. Overall, the probability of a HAE during standardised contact-drills was low, although practitioners should consider the differences (i.e., the variability) in HAE probabilities when managing HAE training exposure.