Relation between Isometric Neck Strength and White Matter Organization in Collegiate Athletes.

Nicola L De Souza,Allison M Brown,Carrie Esopenko,Elisabeth A Wilde,Sasha Singh,Emily L Dennis,Jennifer F Buckman

doi:10.1089/neur.2020.0025

Nicola L De Souza, Allison M Brown + Show 5 more

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https://doi.org/10.1089/neur.2020.0025

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Abstract

Soccer athletes frequently experience repetitive head impacts (RHI) during games and practices, which may affect neural integrity over time and lead to altered brain structure. Neck strength is hypothesized to limit the transfer of force to the brain and decrease the effect of RHI on brain structure. The goal of our work was to examine whether greater neck strength is associated with more intact white matter organization (WMO) in collegiate athletes exposed to RHI. Collegiate soccer (n = 17) and limited/non-contact sport (n = 39) athletes were assessed prior to their athletic seasons. Participants completed neck strength assessments using handheld dynamometry in six test positions and diffusion tensor imaging. Fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD) were calculated for 20 white matter (WM) regions. A multi-variate approach was used to examine the relationship between neck strength and diffusion measures in soccer and limited/non-contact athletes. Neck strength was positively associated with FA and negatively associated with RD across several WM regions in soccer players only. Neck strength was not significantly associated with MD or AD in either group. Greater neck strength was related to more intact WMO in athletes with high exposure to RHI, particularly in regions prone to damage from brain trauma such as the basal ganglia, superior longitudinal fasciculus, and frontoparietal WM. Future studies should examine neck strength as a factor to moderate neural outcomes in athletes with exposure to RHI.

Highlights

Subconcussive impacts occur when force from an impact is transferred to the head, resulting in the brain moving within the skull.[1,2] there are no observable clinical symptoms or a concussion diagnosis at the time of impact, neuronal integrity can be compromised.[1,2] Further, there is growing concern that repetitive head impacts (RHI) that occur during contact sports may lead to the accumulation of neural damage, contributing to acute alterations in structural integrity[3,4,5] and reduced cognitive performance.[6,7]Soccer is a unique contact sport as players routinely use their head to control and direct the ball
The Partial least squares (PLS) analysis examining the relation between Fractional anisotropy (FA) and neck strength in soccer players and limited/noncontact athletes indicated one significant latent variables (LVs) ( p = 0.045, 70.9% of cross-block variance)
Greater neck strength across all positions tested was associated with lower radial diffusivity (RD) in the left anterior corona radiata, bilateral anterior limb of the internal capsule, bilateral external capsule, bilateral uncinate fasciculus, right retrolenticular part of the internal capsule, bilateral superior corona radiata, left superior longitudinal fasciculus, and left sagittal stratum in soccer players only (Fig. 1B)

Summary

Introduction

Subconcussive impacts occur when force from an impact is transferred to the head, resulting in the brain moving within the skull.[1,2] there are no observable clinical symptoms or a concussion diagnosis at the time of impact, neuronal integrity can be compromised.[1,2] Further, there is growing concern that repetitive head impacts (RHI) that occur during contact sports may lead to the accumulation of neural damage, contributing to acute alterations in structural integrity[3,4,5] and reduced cognitive performance.[6,7]Soccer is a unique contact sport as players routinely use their head to control and direct the ball. Subconcussive impacts occur when force from an impact is transferred to the head, resulting in the brain moving within the skull.[1,2] there are no observable clinical symptoms or a concussion diagnosis at the time of impact, neuronal integrity can be compromised.[1,2] Further, there is growing concern that repetitive head impacts (RHI) that occur during contact sports may lead to the accumulation of neural damage, contributing to acute alterations in structural integrity[3,4,5] and reduced cognitive performance.[6,7]. Players head the ball roughly 5–10 times per practice or game,[8,9] accumulating over 600 impacts per season.[10,11] Head impacts result from intentional contact with other players and unintentional impacts with the goal posts or ground.[11] These impacts appear to contribute to microstructural changes in the brain revealed by advanced neuroimaging techniques

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