History of concussion is associated with higher head acceleration and reduced cervical muscle activity during simulated rugby tackle: An exploratory study

Abstract

Objectives: The objective of this study is to explore the effect of concussion history on head control during front on rugby tackles in non-professional male and female Rugby Union players.

Design: An observational cross-sectional design.

Setting: A laboratory-based study of simulated front on rugby tackles with a dynamic relatively-weighted (∼50% body-mass) tackle bag.

Participants: 27 club Rugby Union players were recruited; 10 (7female) with no-concussion history, 10 (3female) within 12-months of concussion and 7 (3female) with 24 + months since last concussion.

Main outcome measures: Linear and rotational head acceleration measured with a skin mounted CSx^® triaxial accelerometer. Normalized Surface EMG amplitude of the bilateral sternocleidomastoid (Scm), upper trapezius (Trap) and splenius capitis (Spl). All outcome measures were synchronised with moment of impact with the tackle bag.

Results: A mixed-model analysis showed that players with 12-Month concussion history had the highest head acceleration (females = 48.6g, males = 68.3g, p < 0.05) with lower Trap (6.9-11.7%, p < 0.05) and Spl (3-12%, p < 0.05) amplitudes compared to athletes with No-concussion.

Conclusions: These findings suggest probable disruption to neuromuscular control of the head in athletes with concussion history as a potential mechanism for recurrent concussion incidence.

Keywords: Concussion; EMG; Head acceleration; Impact sensor; Rugby tackle; Rugby union.