The Influence of Cervical
Muscle Characteristics on Head Impact Biomechanics in Football

JD, Guskiewicz KM, Blackburn JT, Mihalik JP, Siegmund GP, and Marshall SW. Am J Sport Med. 42 (9). 2014.

Take Home Message: Football players with greater cervical
neck muscle strength and size were as likely to sustain larger head impacts as
their peers. Football players who had greater cervical stiffness and an ability
to decrease the displacement of their head following perturbation were less
likely to sustain a moderate and severe head impacts.

While many believe that strengthening cervical
muscles may reduce head acceleration after an impact, and thus reduce the risk
of concussions, there is very little evidence to verify this concept. If
athletes with stronger, larger, or stiffer cervical muscles are less likely to
suffer higher magnetic head impacts compared with their peers then this could
provide more justification for targeting cervical muscles in a concussion
prevention program. Therefore Schmidt and colleagues completed a prospective
cohort study to compare the risk of, “sustaining higher magnitude in-season
head impacts between athletes with higher and lower preseason performance on
cervical muscle characteristics.” Forty-nine football players (34 high school,
15 college) underwent a preseason cervical screening program. The researchers
assessed isometric strength in flexion, extension, right and left lateral
flexion. The study team also measured the cross-sectional area of the
sternocleidomastoid, upper trapezius, and semispinalis capitis muscles with
ultrasound. Finally, the researchers assessed cervical stiffness by applying unexpected
perturbations in cervical flexion and extension. All athletes were divided into
either a high performance (above the median split) or low performance (below
the median split) for each cervical characteristics (e.g., strength, stiffness).
Following preseason testing, head biomechanics at each game and practice were
measured by the Head Impact Telemetry (HIT) system. Researchers observed and recorded 19,775
(19,172 mild, 514 moderate, and 89 severe) head impacts. Only 1 impact (a mild
impact) resulted in a diagnosed concussion. Overall, muscle size and strength
were not factors in mitigating the severity of head impacts. Athletes with
greater cervical stiffness and less displacement following perturbations were
at lower risk for sustaining moderate or severe impacts.

While it is commonly believed that stronger
cervical muscles will decrease head displacement following impact, this is may
not be the whole story. Instead the activation of, and the ability to stiffen
cervical muscles may be the key to preventing severe head impacts. This may
suggest that clinicians should incorporate neuromuscular training into strength
and conditioning programs – to promote cervical muscle activation in
anticipation for an impact – because simply strengthening cervical muscles may
not be sufficient. Since the research team only followed 49 football players
over one season it will be important to find out if these findings are
applicable to other sports and specific positions in football. It’ll also be
helpful to see whether clinical trials will provide support for using cervical
neuromuscular training for reducing head impact severity and concussions. In
the meantime, clinicians could try implementing these types of programs with
their athletes since the risks of a properly supervised program is low.

for Discussion
: Have you implemented a cervical muscle strengthening program for you
athletes? If so, do you feel this has led to a decrease in concussions? Do you
think we will eventually use concussion prevention programs that include
neuromuscular training?

Written by: Kyle Harris
Reviewed by: Jeffrey

Related Posts:

Schmidt, J., Guskiewicz, K., Blackburn, J., Mihalik, J., Siegmund, G., & Marshall, S. (2014). The Influence of Cervical Muscle Characteristics on Head Impact Biomechanics in Football The American Journal of Sports Medicine, 42 (9), 2056-2066 DOI: 10.1177/0363546514536685