A Neck Strengthening Protocol in Adolescent Males and Females for Athletic Injury Prevention

Abstract

Objectives: Sport plays a major role in the physical activity, wellbeing and socialisation of children and adults. However, a growing prevalence of concussions in sports persists, furthermore, that subconcussive forces are responsible for neurodegenerative conditions. Current approaches towards concussion prevention are dependent upon coaching strategies and enforcement by referees, or only attempt to reduce further injury, not prevent initial injury occurring. A growing body of research has shown that strengthening the muscles of the neck might serve to reduce head acceleration, change in velocity and dissipate kinetic energy from concussive and subconcussive forces. Design: Following ethical approval and parental consent a single arm, pilot study recruited 13 male and 13 female high school stu dents to undertake 8 weeks of neck strengthening exercises 2 d.wk-1. Method: A low-volume, time-efficient approach considered progressive strength training for neck extension, flexion, and right- and left-lateral flexion exercises for a single set to muscular failure. Results: Strength outcome data was analysed using paired samples t-tests comparing predicted 1-repetition maximum for week 1 and week 8 revealing significant strength improvements for both males and females for all exercises; p < 0.001. Effect sizes were very large (2.3-4.3) for all exercises for both males and females. Conclusions: Participants showed very large increases in neck strength suggesting previous detrained condition and the potential to significantly improve strength using a simple, low volume, resistance training protocol. Athletic training should prioritise health of participants and longevity of career and as such the authors present a neck strengthening protocol with a view to reducing injury risks.

Full text

Short Communication
A Neck Strengthening Protocol in Adolescent Males and
Females for Athletic Injury Prevention
James P. Fisher, Mark Asanovich, Ralph Cornwell, James Steele
Objectives: Sport plays a major role in the physical activity, wellbeing and socialisation of children and adults. However, a grow-
ing prevalence of concussions in sports persists, furthermore, that subconcussive forces are responsible for neurodegenerative
conditions. Current approaches towards concussion prevention are dependent upon coaching strategies and enforcement by ref-
erees, or only attempt to reduce further injury, not prevent initial injury occurring. A growing body of research has shown that
strengthening the muscles of the neck might serve to reduce head acceleration, change in velocity and dissipate kinetic energy
from concussive and subconcussive forces.
Design: Following ethical approval and parental consent a single arm, pilot study recruited 13 male and 13 female high school stu-
dents to undertake 8 weeks of neck strengthening exercises 2 d.wk-1.
Method: A low-volume, time-efficient approach considered progressive strength training for neck extension, flexion, and right-
and left-lateral flexion exercises for a single set to muscular failure.
Results: Strength outcome data was analysed using paired samples t-tests comparing predicted 1-repetition maximum for week 1
and week 8 revealing significant strength improvements for both males and females for all exercises; p < 0.001. Effect sizes
were very large (2.3-4.3) for all exercises for both males and females.
Conclusions: Participants showed very large increases in neck strength suggesting previous detrained condition and the potential
to significantly improve strength using a simple, low volume, resistance training protocol. Athletic training should prioritise
health of participants and longevity of career and as such the authors present a neck strengthening protocol with a view to
reducing injury risks.
(Journal of Trainology 2016;5:13-17)
Key words: chronic traumatic encephalopathy  concussion  sub-concussive forces  strength training  adolescent
INTRODUCTION
Advances in physical and physiological training methods for
athletes have led to progressive improvements in sports perfor-
mance. Athletes are now bigger, faster and stronger than ever.
However, this increased performance has created an ever
growing gap between the physical ability to tackle and the
body’s physiological capacity to receive impact and trauma in
certain orthopaedic structures – notably the head and neck.
This has led to an increase in emergency department visits for
concussions and other traumatic brain injuries notably in
young children (aged 8-13 years) and adolescents (aged 14-19
years) who by 2005 were suffering sports related concussions
at a rate of ~4 in 1000 and ~6 in 1000 persons, respectively.1
Part of this increase might have arisen from improved aware-
ness of concussion resulting in greater reporting of head inju-
ries. However, in a society where we encourage activity in
children and where sports plays a role in both physical activity
and socialisation we must ensure the health and well-being of
these participants.
Governing bodies of sports have developed rule changes in
attempt to reduce these risks (e.g. outlawing head to head col-
lision in American football, etc.) and by withdrawing players
from the game if they have suspected concussion (e.g. the ‘if
in doubt; sit them out’ protocol2-4). However, in context rule
changes must be implemented by coaching strategies and
enforced by referees. Furthermore, protocols for suspected
concussions only attempt to reduce further injury, not prevent
the initial injury from occurring. Worryingly, there is a grow-
ing body of research to show that repeated sub-concussive
forces (e.g. those that do not cause an immediate concussion)
to the head and neck can also cause significant medical condi-
tions such as chronic traumatic encephalopathy (CTE) in later
life.5-7 This raises concern beyond more obvious contact sports
such as American football, ice hockey, and rugby and suggests
that perhaps soccer players, who are subjected to lower impact
forces by heading the ball, as well as other athletes, are at con-
siderable risk. A primary purpose of strength and conditioning
of all athletes should be the health and wellbeing of the partici-
pant and the longevity of their career, with performance
improvements being of secondary importance.
Neck Strength
In review, Benson et al.9 suggested that there was no evi-
dence to support that neck strength increases were related to a
decrease in concussion prevalence, however more recently a
review of 51 schools and 6,704 high school athletes reported
significant associations between smaller neck circumference
and weaker overall neck strength9. They continue, reporting:
13
Received February 26, 2016, accepted April 18, 2016
From the Southampton Solent University, East Park Terrace, Southampton, UK (J.P.F., J.S.), Minnetonka High School, Minnetonka, MN, USA (M.A.),
and Head, Neck and Spine Institute, Blacksburg Virginia, USA (R.C.)
Communicated by Takashi Abe, PhD
Correspondence to James P. Fisher, Southampton Solent University, East Park Terrace, Southampton, UK, SO14 0YN. Email: james.fisher@solent.ac.uk
Journal of Trainology 2016;5:13-17 ©2012 The Active Aging Research Center http://trainology.org/

Journal of Trainology 2016;5:13-1714
“Overall neck strength (p<0.001), gender (p<0.001) and
sport (p=0.007) were significant predictors of concussion
in unadjusted models. After adjusting for gender and
sport, overall neck strength remained a significant pre-
dictor of concussion (p=0.004). For every one pound
increase in neck strength, odds of concussion decreased
by 5% (OR = 0.95, 95% CI 0.92-0.98).”
Furthermore, studies dating back to 2007 have used models
to support that stronger necks reduce head acceleration,
change in velocity and displacement, which ultimately might
reduce concussion risks.10 Notably female soccer players have
been shown to have higher head acceleration values compared
to males likely as a result of the lower neck strength and mus-
cle mass.11,12 In addition, data suggests a far greater prevalence
of whiplash associated disorders (WAD) in females which, it
has been hypothesised, is linked to the weaker neck strength
compared to males (32% weaker in flexion, and 20% weaker
in extension; p < 0.001).13 Fundamentally it appears that as
strength in the head and neck muscles increase, kinetic energy
from concussive and sub-concussive forces can be better dissi-
pated. Though no data currently exists to show unequivocally
that prospective strengthening of the neck musculature reduces
concussion we should consider that, since there are no known
risks to strengthening the neck musculature, this is a training
intervention that is essential for all athletes. In fact since the
benefits likely extend to include reduced risk of whiplash inju-
ries in automobile accidents13 and improved posture14; neck
strengthening activities appear vital for all persons irrespective
of their sporting/exercise habits.
Regardless of the above, the consensus statement derived
from the 4th International Conference on Concussion15 stated:
“Given that a multi-factorial approach is needed for con-
cussion prevention, well-designed and sport-specific pro-
spective analytical studies of sufficient power are war-
ranted for mouthguards, headgear/helmets, facial protec-
tion and neck strength.”
Concluding: “no evidence was provided to suggest an asso-
ciation between neck strength increases and concussion risk
reduction”. However, we feel that delaying neck training until
sufficient evidence has demonstrated a reduction in prevalence
of concussions and other head and neck related injuries,
including CTE, is somewhat irresponsible. Consider that
strength and conditioning methods improve physiological
markers of performance (e.g. agility, power, strength, speed,
vertical jump, etc.) but are not directly proven to enhance spe-
cific dynamic sports performance because of the number of
associated variables (e.g. changes to opposition, psychological
variables, environmental variables, tactical strategies, team
performance, etc.) However, we undertake these conditioning
techniques with a view to enhancing overall performance, irre-
spective of underpinning evidence. Since the neck muscles,
when trained, might serve to protect athletes from concussion
and head trauma, and since there exists no likely risks to
strengthening these muscles we propose all athletes, and more
likely all persons, should undertake a neck strengthening pro-
tocol. As such the authors present a single-arm pilot interven-
tion of adolescent males and females having undertaken 8
weeks of low-volume, neck strengthening exercises.
METHODS
Methodological design
A single arm, ‘proof of principle’ trial was considered where
all participants performed the training protocol. The study
design was approved by the relevant ethics committee.
Participants
Twenty-six recreationally active high school students (male;
n = 13, m = 16.9 ± 0.8years, female; n = 13, m = 17.6 ± 0.5years)
volunteered, and provided parental informed consent, to
undertake a neck strength training protocol 2 d.wk-1 for 8
weeks (see Table 1 for participant demographics). Participants
performed neck extension, neck flexion, and right- and left-lat-
eral flexion exercises using a plate loaded 4-way neck resis-
tance machine. A familiarisation session was performed prior
to any testing/training to establish initial training loads and
allow familiarisation of technique and repetition duration.
Throughout the training intervention each exercise was per-
formed for a single set to momentary muscular failure (MMF)
of 8-15 repetitions using a controlled repetition duration (3
seconds concentric: 5 seconds eccentric) to maintain muscular
tension throughout.16 This equated to a time under load of ~60-
120 seconds, and loads were increased for subsequent sessions
once participants could perform more than 15 repetitions. This
was deemed a safe and appropriate progression based on the
nature of the participants and the sensitivity of the muscles
being trained.
Statistical Analyses
Due to the inherent risks and potential for soreness associat-
ed with maximal testing17, data was recorded as load and repe-
titions and predicted 1-repetition maximum (1RM) using the
Brzycki equation18 was calculated for week 1 and week 8. This
predictive equation shows a high correlation to maximal
strength (r = 0.99), albeit in an adult population19. Data was
confirmed for normality of distribution using a Kolmogorov-
Smirnov test and analysed using paired samples t-test compar-
ing week 1 to week 8 of the intervention. Pre-testing values
were compared between males and females using independent
samples t-tests to identify if any differences occurred at base-
line. Effect sizes were calculated using Cohen’s d20 for each
outcome where an ES of 0.20-0.49 was considered as small,
0.50-0.79 as moderate and ≥ 0.80 as large.
Table 1 Participant demographics
Male Female
Age (y) 16.9± 0.8 17.6± 0.5
Stature (cm) 178.2± 4.9 169.7± 8.1
Body mass (kg) 74.5± 11.8 63.5± 13.0
BMI 23.4± 3.2 21.9± 3.8

Fisher et al. A Neck Strengthening Protocol in Adolescent Males and Females for Athletic Injury Prevention 15
RESULTS
Adherence data revealed that participants performed a mean
of 14.6 ± 3.2 and 12.6 ± 2.5 training sessions for males and
females, respectively, over the duration of the intervention.
Strength outcome analyses revealed the following significant
improvements; Males; neck extension from week 1 (mean =
30.2 ± 7.9kgs) to week 8 (mean = 56.7 ± 10.6 kgs); t(12) =
-12.402, p < 0.001, neck flexion from week 1 (mean = 23.3 ±
5.2 kgs) to week 8 (mean = 48.8 ± 9.4 kgs); t(12) = -8.226, p <
0.001, right lateral flexion from week 1 (mean = 25.5 ±
7.0kgs) to week 8 (mean = 48.2 ± 9.5kgs); t(12)= -8.422, p <
0.001, left lateral flexion from week 1 (mean = 24.9 ± 6.2kgs)
to week 8 (mean = 50.1 ± 10.1kgs); t(12)= -10.631, p < 0.001
(see figure 1). Females; neck extension from week 1 (mean =
15.5 ± 6.0kgs) to week 8 (mean = 36.8 ± 8.4kgs); t(12)=-
15.448 , p < 0.001, neck flexion from week 1 (mean = 11.3 ± ±
5.1kgs) to week 8 (mean = 31.1 ± 9.1kgs); t(12)= -11.189, p <
0.001, right lateral flexion from week 1 (mean =12.4 ± 3.9kgs)
to week 8 (mean = 30.4 ± 5.1kgs); t(12) = -14.337, p < 0.001,
left lateral flexion from week 1 (mean = 12.2 ± 4.1kgs) to
week 8 (mean = 29.6 ± 4.9kgs); t(12) = -13.852, p < 0.001 (see
figure 2). Table 2 shows all mean predicted 1RM values for
* Significant difference from week 1 (p < 0.05)
Figure 1 Mean Predicted 1RM (± SD) for Males
* Significant difference from week 1 (p < 0.05)
Figure 2 Mean Predicted 1RM (± SD) for Females

Journal of Trainology 2016;5:13-1716
pre and post intervention along with P values and effect sizes
(ES).
Independent samples t-tests performed on baseline predicted
1RM revealed the following significant differences between
males and females; neck extension (males: mean = 30.2 ±
7.9kgs, females: mean = 15.5 ± 6.0kgs); t(24) = 5.292, p <
0.001, neck flexion (males: mean = 23.3 ± 5.2kgs, females:
mean = 11.3 ± 5.1kgs); t(24) = 5.952, p < 0.001, right lateral
flexion (males: mean = 25.5 ± 7.0kgs, females: mean = 12.4 ±
3.9kgs); t(24) = 5.915, p < 0.001, and left lateral flexion
(males: mean = 24.9 ± 6.2kgs, females: mean = 12.2 ± 4.1kgs);
t(24) = 6.210, p < 0.001.
Relative changes were: males = 94 ± 39%, 121 ± 74%, 100
± 56%, 108 ± 47% and females = 151 ± 53%, 191 ± 82%, 158
± 59%, 156 ± 60% for neck extension, neck flexion, right lat-
eral flexion and left lateral flexion, respectively.
DISCUSSION
The present study provides empirical evidence supporting
the potential to increase the muscular strength of the neck
using an uncomplicated, low-volume, and time-efficient
strength training protocol (e.g. single set to MMF 2d.wk-1).
Whilst we should not be surprised by strength increases as a
result of training the neck musculature, the magnitude of
increase suggests a prior detrained condition, and supports the
simple protocol demonstrated herein. Previous publications
have reported lower values for female’s neck strength, com-
pared to males13, and that this muscular weakness has likely
resulted in higher head acceleration values in female soccer
players11,12. The data presented herein shows pre-intervention
neck strength in females to be significantly lower (p < 0.001
for all exercises tested) compared to males, supporting previ-
ous research. However, relative strength increases were greater
in females than males suggesting that the degree of disparity
can be reduced as a result of neck strengthening exercises.
Previous research has supported that stronger necks reduce
head acceleration, change in velocity and displacement which
might serve to reduce concussion risks.10 Furthermore, adjust-
ed models have shown that overall neck strength is a signifi-
cant predictor of concussion, where a 1lb (0.45Kgs) increase
in neck strength produced a 5% decrease in likelihood of con-
cussion9. This suggests that the considerable increases in
strength demonstrated as a result of this intervention would
likely produce meaningful decreases in likelihood of concus-
sion.
We appreciate the present study does not provide evidence
of a reduced prevalence of concussion, and only longitudinal
studies can show a reduction in occurrence of neurodegenera-
tive conditions. However, in the case of strengthening the mus-
cles of the head and neck; even without unequivocal evidence
to support that stronger neck muscles reduce risks of concus-
sion or other head trauma (e.g. CTE) if there is the possibility
that strengthening the muscles of the neck can reduce risks,
and there exist no known limitations to strengthening the neck,
then all strength and conditioning coaches should be encourag-
ing, and all athletes undertaking, a neck strengthening proto-
col. More so, it is likely the evidence will always be equivocal
due to the dynamic and unpredictable nature of sports; a per-
son having performed resistance training for their neck might
receive multiple concussions (irrespective of strength) due to
the impact velocities and types of impact. In contrast, a person
who had never engaged in neck strengthening exercises (irre-
spective of strength) might never receive a concussion due to
the incalculable events occurring in sports. We should also
consider the likelihood of disparity in starting neck strength, as
exists in other strength variables, due to a large heterogeneity
of the population. In addition, it would still require a longitudi-
nal study lasting for decades to determine the prevalence of
CTE in persons following a neck training intervention along
with a control group, both of which being subjected to repeat-
ed concussive and sub-concussive forces. With this in mind the
authors of the present piece propose that it is irresponsible, and
time might show - negligent, not to apply a neck strengthening
intervention to any athletes exposed to potential head trauma
in order to attempt to protect athletes and reduce the risk of
injury resulting from concussive and subconcussive forces. To
date this appears one of few publications considering a neck
strengthening protocol and the only study to consider training
this musculature in an adolescent group of participants.
CONCLUSION
There is a relative dearth of literature considering
neck strengthening protocols and as such the present piece
serves to highlight the benefits of training the muscles of the
head and neck, potentially with a view to both reducing risks
of concussion as well as medical and neurodegenerative condi-
tions arising from sub-concussive brain trauma. In addition the
presentation of a simple resistance training protocol which can
be performed using resistance machines, or using manually
applied resistance will hopefully enlighten strength training
practitioners to the simplicity and importance of this exercise
procedure. We encourage practitioners at all levels to investi-
Table 2 Mean (± SD) Pre and Post intervention Predicted 1RM values (Kg’s), P values and Effect sizes (ES) for males and
females for all exercises
Males Females
Pre Post PES Pre Post PES
Neck Extension 30.2 ± 7.9 56.7 ± 10.6 < 0.001 3.4 15.5 ± 6.0 36.8 ± 8.4 < 0.001 4.3
Neck Flexion 23.3 ± 5.2 48.8 ± 9.4 < 0.001 2.3 11.3 ± 5.1 31.1 ± 9.1 < 0.001 3.1
Right Lateral Flexion 25.5 ± 7.0 48.2 ± 9.5 < 0.001 2.3 12.4 ± 3.9 30.4 ± 5.1 < 0.001 4.0
Left Lateral Flexion 24.9 ± 6.2 50.1 ± 10.1 < 0.001 3.0 12.2 ± 4.1 29.6 ± 4.9 < 0.001 3.8

Fisher et al. A Neck Strengthening Protocol in Adolescent Males and Females for Athletic Injury Prevention 17
gate and apply information regarding strengthening the mus-
cles of the head and neck to attempt to reduce prevalence and
risk of concussion and head trauma.
ACKNOWLEDGEMENTS
The authors wish to acknowledge the work of Minnetonka
High School Vantage students involved in this project.
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