The Effect of Sub-Concussive Impacts during a Rugby Tackling Drill on Brain Function

Abstract

Concussion is known to detrimentally affect brain health. Rugby tackles commonly occur with high collision force between tackler and ball carrier, and low impact head contact is not uncommon. Cognitive deficits following a bout of soccer ball heading has been attributed to the impact and termed sub-concussion. Although soccer ball heading studies provide evidence for acute effects of sub-concussion, it is unknown whether this phenomenon occurs following rugby tackles. This study investigates the acute effects of rugby tackles on brain function and balance in rugby players. Twenty-six volunteers were assigned to either the ball carrier (9), tackler (9) or control (8) group. Controls performed running without the tackle. Outcome measures included corticomotor function using transcranial magnetic brain stimulation (TMS) and balance was assessed by a series of tasks performed on a NeuroCom Balance Master before and immediately after a tackle training drill. Following the tackling bout, the cortical silent period (cSP) increased for the tacklers with no change for ball carrier and control groups, and no differences between groups for balance measures were observed. Lengthening of cSP observed in the tacklers following the bout has been reported in studies of concussion and may indicate long term detrimental effects.

The Reliability of Transcranial Magnetic Stimulation-Derived Corticomotor Inhibition as a Brain Health Evaluation Tool in Soccer Players

“…not exposed to impacts to the head). This is of interest in light of previous findings where excitatory and inhibitory mechanisms were found to be affected by concussive and subconcussive impacts [ 12 – 14 , 18 , 36 ]. That said, in the absence of data on long term reliability of TMS-evoked parameters in sports where players are routinely exposed to concussive/subconcussive impacts (e.g.…”

Dual-Task Gait Performance Following Head Impact Exposure in Male and Female Collegiate Rugby Players

“…A study examining acute postural control effects after a simulated match load of rugby impacts also suggested no changes following subconcussive impacts. 47 The learning effect is likely noticeable in this study as athletes completed the protocol multiple times in a season, and many participated in multiple seasons. Other studies compared concussed athletes to controls, 34,35,48 which reduces the overall number of times an athlete would complete the dual-task protocol.…”

Head Accelerations during a 1-on-1 Rugby Tackling Drill Performed by Experienced Rugby Union Players

“…The relationship between sub-concussive head impacts in rugby and the development of long-term neurological impairments remains underexplored. However, data from a study that was undertaken in tandem with the present investigation assessed cortical inhibition, using transcranial magnetic stimulation, and showed deficits immediately after the bout of tackling among the tacklers but not the ball carriers nor a third group of controls who ran through the drill without performing the tackle component [ 27 ]. While both the tackler and ball carrier are exposed to sub-concussive impacts during simulated tackling, it appears that the tacklers in this drill are more prone to these minor changes in cortical function than the ball carriers even though the difference in HrT was not statistically different [ 27 ].…”

“…However, data from a study that was undertaken in tandem with the present investigation assessed cortical inhibition, using transcranial magnetic stimulation, and showed deficits immediately after the bout of tackling among the tacklers but not the ball carriers nor a third group of controls who ran through the drill without performing the tackle component [ 27 ]. While both the tackler and ball carrier are exposed to sub-concussive impacts during simulated tackling, it appears that the tacklers in this drill are more prone to these minor changes in cortical function than the ball carriers even though the difference in HrT was not statistically different [ 27 ]. Other recent investigations in soccer ball heading and boxing sparring practice have found a similar acute disruption in cortical function, absent of any detectable changes, using standard sideline testing procedures that assess memory and balance [ 28 , 29 ].…”