Background

Over the last 20 years, there has been a 200% increase in emergency room visits for sports-related concussions for youth ages 14-19 in the US.¹ A concussion is a brain injury due intense biomechanical forces acting upon the head and neck, as defined by Aaron Provance M.D. - Director of Sports Medicine at the Children’s Hospital Colorado.² According to the Utah Department of Health, in 2011, 6,228 Utahans were treated and released from the emergency department due to diagnosed concussions. Of these cases, nearly 45% of the concussions were due to sports-related incidents. Furthermore, of the 45%, 25.7% of sports-related concussions occurred in individuals between the ages of 15 and 19.³

At the forefront of these sports is football; arguably the most aggressive of all high school sports offered to teenage students in the state of Utah. Youth athletes are more vulnerable to concussion, are at higher risk for severe complications and prolonged recovery, and develop cumulative negative effects with multiple concussions. In Utah, there are approximately 8,100 high school football athletes with an estimated 2,400 sustaining one concussion and 243 players sustaining multiple concussions each season.⁴ In addition to the aggressive nature of the sport, many students are lacking proper education, preventative measures, and resources to treat traumatic brain injuries (TBI). Athletes also feel compelled to play through any injuries in which they sustain, which is viewed as being ‘tough’ or ‘showing passion for the game’. In fact, among Utah high school athletes in 2013, more than 35.9% of athletes manifested concussion-like symptoms and did not inform anyone (parents or coaches), including their school athletic trainers.³

Over the last couple of years, sports-related concussion rates across the United States have skyrocketed, making concussions a serious public health issue among athletic populations. Those who are most at risk to sustain a concussion are those who play high-contact sports such as football, hockey, boxing, etc.⁵ One study evaluated concussions reported by 425 athletic trainers throughout 100 different high school football programs in the United States. The results of the study showed an Incidence Density (ID) of 1.55 concussions per 1000 athlete-seasons.⁶ These injuries can lead to more severe and even catastrophic brain injuries such as hematomas, aneurisms, and edema.⁷ On average these type of brain injuries are seen across high schools in the United States seven times per year. This is a relatively low number considering that over one million individuals participated in high school football during the 2012 season.⁸ This incidence rate can be and should be reduced with proper training among coaches and trainers.  

Previously conducted studies suggest that increasing cervical strength and muscle mass in the neck can lower concussion rates in athletes. Athletes with weaker necks and smaller neck mass are more likely to experience forced extreme linear and rotational forces.⁹

The purpose of this study is to observe the effectiveness that regularly performed dynamic neck exercises may play in preventing concussions among high school football athletes. These exercises include flexion, extension, lateral bending and axial rotation exercises with resistance. The formal definition of a concussion is a clinical syndrome characterized by alteration in brain function, mental status and consciousness.

The human neck differs from many muscle groups, in the sense that necks do not move in one directional dimension. Movements of the head and neck occur in three dimensions about axes defined anatomically as flexion– extension, lateral bending, and axial rotation.¹⁰ A 2010 study evaluated neck flexion-extension, lateral movements and axial rotation.¹¹ The results showed that in flexion- extension movements of the neck, the sternocleidomastoid and the middle trapezius show the greatest range of flexion and extension respectively. The anterior scalene muscles and the sternocleidomastoid yielded the greatest range of lateral bending movement. The middle trapezius, sternocleidomastoid and semispinalis capitis muscles showed the greatest contralateral axial rotation, while the rectus capitis posterior major, obliquus capitis inferior and splenius capitis showed the greatest ipsilateral axial rotation. The great ranges of flexion and extension exhibited by the neck expose athletes in contact sports to potential TBI.

These bio-anatomical observations suggest the need and benefits to strengthening cervical muscles. By participating in dynamic neck exercises every one to three weeks, high school football players can increase cervical strength and potentially reduce the risk of sustaining a TBI(s).

Methods

The study design applied an incidence study approach to TBI occurrences among five high school football teams (designated as teams A – E) during the 2015 Utah High School Football season. In this study incidence conveys information about the risk of sustaining a concussion. The observed schools consisted of two teams who regularly performed dynamic neck exercises and three schools who did not perform these exercises regularly. Concussion incidence was accessed from records kept by coaches and/or athletic trainers. No medical records were reviewed or were any medical physicians contacted.

Five Utah high schools were included in the study with two different sample sizes being evaluated. One of the study populations being the total number of athletes and incidences of concussion reported by coaches and/or athletic trainers (total roster population N=505) at five Utah high schools. The study then compared the concussion rates among the same five teams during the 2015 football season of those athletes who were surveyed (survey population N₂=106).

A brief survey was orally administered to obtain medical and football history on enlisted subjects. Questions in the medical portion included: history of past concussions, history of neurological disease, migraine history, and a question which quantified the amount of students who exhibited concussion-like symptoms in the 2015 football season. The medical portion of the survey included a table of common concussion symptoms which was accessed from the Oregon Health and Sciences University website.¹² Due to the nature of high school football players and how frequently these injuries are not reported, if an athlete met four or more of the symptomatic criteria (from table), they were deemed as a ‘probable concussion’ and placed into a probable concussion category. Questions in the football section included: height, weight, position, equipment, etc. Interviews were conducted at the high school of interest in a private room/area at each location. Each interview was conducted by the same researcher to avoid an interviewer bias and each interview took no longer than five to six minutes. The total survey sample population (N₂=106) was stratified by team and furthermore on the basis of performing dynamic neck exercises versus those teams that did not perform the exercises.

Those who participated in the study must have played high school football in the 2015 Utah High School Football season. These athletes must have played at the school of interest in the 2015 season and completed either parental consent or athlete assent forms to be included in the study.

Data collected was analyzed using Excel MegaStat. In addition to basic descriptive statistics, an incidence risk ratio (risk ratio) with a 95% confidence interval was applied to determine statistical significant differences.  The risk ratio calculation was based on a relative risk calculation to quantify the risk-prevention of dynamic neck exercises using the 2015 concussion incidence numbers. A chi square test was applied to the qualitative data to detect significant differences with an alpha of <0.05. No outside sources of funding were used for this study.

Ethics Approval and Consent to Participate 

Participants either received an athlete assent form, for those individuals who were over 18 years of age, or a parental consent form for those who were still minors. The overview of this study was approved by an International Review Board at Westminster University before the initiation of this study.

Results

In the survey sample population (N₂=106), teams A and E both performed dynamic exercises. Both teams demonstrated insignificant chi square p-values (p=0.37, p=0.31) for those athletes who weighed over 200 pounds.  However, both teams demonstrated strongly significant chi squared p-values (p= 0.006, p= 0.01) for those athletes who weighed between 120 and 200 pounds (for concussions).

When observing the survey sample data for teams that did not perform dynamic neck exercises (schools B, C and D), Teams B, C and D demonstrated insignificant chi squared p-values (p=0.15, p=0.56, p=0.058) for those athletes who weighed more than 200 pounds. In assessing the chi squared values for athletes weighing between 120 and 200 pounds of teams B, C, and D, teams B and D demonstrated statistical significance at p=0.007 and p=0.004, respectively. Team C demonstrated a chi squared p-value of p=0.15 and did not demonstrate statistical significance. (The researcher recommends caution in the interpretation of team C’s result due to a small sample.) 

The survey sample data (N₂=106) was also stratified by the total number of athletes who performed the neck exercises (n=57) as compared to the total number of athletes who did not perform the neck exercises (n=49). In analyzing both chi-squared tests (those who performed the exercises and those who did not), the researchers observed nonsignificant chi squared p-values (p=0.19, p=0.08) for those athletes who weigh over 200 pounds However, when observing those athletes who weighed between 120 and 200 pounds, strong statistical significance (for concussions) was demonstrated in both groups; those who performed dynamic exercises (p= 0.0063) and those who did not (p=0.00004).

The total roster population (N=505) yielded a risk ratio of 5.03 (95% CI 1.53, 16.52). In addition to the risk ratio calculation, a chi squared test was also conducted on the total roster population. The chi squared test compared the teams who performed dynamic neck exercises to those who did not. The test demonstrated a highly significant p-value of 0.002.

Discussion

When analyzing the survey data, it was apparent that those athletes who weighed (>200 pounds) showed less significance to reject the null hypothesis. Although there was predominantly no statistical significance among these groups, those athletes who weighed (>200 pounds) and did not perform dynamic neck exercises, showed more statistical significance compared to those who performed the exercises. These chi squared p-values show that not only do dynamic neck exercises play a potentially preventative role in concussion onset, but body size may also be an indicator in concussion risk. Those athletes who weighed (120-200) pounds, demonstrated strong significance to reject the null hypothesis. These low chi squared p-values show a potentially protective measure between dynamic neck exercises and concussion risk, as do body size and concussion risk. While most of the athletes observed weighing between 120 and 200 pounds demonstrated a similar pattern of statistical significance, Team C did not demonstrate the same statistical significance. Team C consisted of a small survey population size (n=5) which may have skewed the data collected. Therefore, caution is recommended in the interpretation of this result.

These observations emphasize the critical role that dynamic neck exercises may play in preventing concussions for high school football athletes. The survey data also quantified the high percentage of athletes (32%) who are not reporting concussion-like symptoms to their coaches or trainers when experienced.

The chi squared test that was conducted on the total roster population (N=505), demonstrated a strong significant p-value (p=0.002). This p-value represented the stratified population and supports the hypothesis that dynamic neck exercises play a role in concussion prevention among high school football athletes. In addition to the chi squared test, a risk ratio was calculated representing the total roster population concussion incidence for 2015. The risk ratio calculation demonstrates that per our study, high school football players who do not perform dynamic neck-exercises, are 5.03 times more at risk to sustain a concussion than those players who perform dynamic neck exercises.

Another point of discussion is the lack of monitoring neural activity of high school football athletes. In Utah high school football, many football teams are limited to a single athletic trainer, and very few teams have a licensed physician on site throughout the course of the season. Many top tier college football programs and all National Football League franchises have licensed neurologists to closely monitor and assess neural activity and the mental health of their football players. The lack of these professionals in high school football places a heavy burden on the non-medical staff, coaches, and guardians of these athletes to consistently monitor their mental state and well-being. A valid question to be investigated is if these high school athletes are receiving adequate healthcare provisions and if the “return to play” protocols are as effective as possible.

Various limitations may have positively/negatively skewed collected data and/or interpretations of this data. One of said limitations may include the measurement of data. In the medical/athletic portions of the issued questionnaire, participant answers may have not been accurate or truthful. That being said, each questionnaire was administered by the same researcher and orally given in the same manner, so if any bias or error is present, it will be distributed equally among all participants.

One other limitation of this study was the time length of the cohort. The data collected in the study was based off the 2015 football season alone, giving the potential for statistical outliers. To account for the short term of data collection, future research should aim to follow-up on these same teams and compare their concussion rates in future athletic seasons.

Conclusion

This study demonstrated that high school football players who do not perform dynamic neck-exercises, are five times more at risk to sustain a concussion than those players who perform dynamic neck exercises. In high school football, most players exceeding 200 pounds in weight are offensive and defensive lineman. These positions endure short term and short-range contact compared to the remaining positions in football. This may explain why skill-position players (not offensive and defensive lineman) showed more significance in our testing. Skill positions usually involve contact at higher velocities and span a greater distance between player starting location and impact, therefore resulting in greater biomechanical forces applied to the head and neck. With these observations and conclusions, we recommend coaches and trainers alike to implement dynamic neck exercises into their workout regimens- with a close focus on those highly susceptible skill positions. By increasing cervical strength, an athlete may reduce the risk sustaining a concussion due to applied biomechanical forces. Further research is recommended to follow up this data in a prospective cohort design, looking at how concussion rates differ from year to year.

Practical Implications

• It is suggested that these exercises be implemented across all sports and age groups of sport participants.
• Dynamic neck exercises are useful in the sense that they are cost efficient, customizable and very quick. These exercises can be implemented into daily workout regimens easily.
• This study should serve as an impetus to exhaust effective methods of concussion prevention.

References

1. Schatz, P., Moser, R. S. Current Issues in Pediatric Sport Concussion. The Clin Neuropsychol. 2011;6:1042-57.
2. Provance, A., MD. Concussion- Epidemiology and Current Guidelines. 2014. http://www.ucdenver.edu/academics/colleges/medicine/sportsmed/cusm_events/2014-Extreme-Sports-Medicine-Congress/Documents/Presentations/Concussion%20Epidemiology%20Guidelines.pdf. Accessed 10 October 2016.
3. Utah Department of Health. Violence and Injury Prevention Program. http://www.health.utah.gov/vipp/teens/sports-concussions (2014). Accessed 10 June 2016.
4. Utah Department of Health. Sports and Recreation-Related Traumatic Brain Injuries in Utah. 2012. http://utah.ptfs.com/Data/Library2/publications/dc033483.pdf. Accessed 1 February 2017.
5. Mayo Clinic. Concussion. http://www.mayoclinic.org/diseases-conditions/concussion/basics/risk-factors/con-20019272 (2014). Accessed 10 June 2016.
6. Daneshvar, D. H., Nowinski, C. J., McKee, A., et al. The Epidemiology of Sport-Related Concussion. Clin Sports Med. 2011;1:1-17.
7. Boden, B. P., Tacchetti, R. L., Cantu, R. C., et al. Catastrophic Head Injuries in High School and College Football Players. Am J Sports Med. 2007;35:1075-81.
8. Jeffrey, T. P. Football Is Top Sport in U.S.: 1,088,158 High School Players. 2014. http://www.cnsnews.com/news/article/terence-p-jeffrey/football-top-sport-us-1088158-high-school-players. Accessed 10 June 2016.
9. Collins, C. L., Fletcher, E. N., Fields, S. K., et al. Neck Strength: A Protective Factor Reducing Risk for Concussion in High School Sports. J Prim Prev. 2014;5:309-19.
10. Vasavada, A. N., Li, S., Delp, S.L. Three-Dimensional Dynamic Strength of Neck Muscles in Humans. Spine. 2001;17:1904-09.
11. Ackland, D.C., Merritt, J.S., Pandy, M.G. Moment arms of the human neck muscles in flexion, bending and rotation. J Biomech. 2011;3:475-86
12. Oregon Health and Sciences University. Concussion. http://www.ohsu.edu/xd/health/services/ortho/getting-treatment/services/sports-medicine-clinic/treatment/concussion.cfm. Accessed 1 June 2016.

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Custom Major in Biomedical and Translational Research

West Jordan, Utah

I love to play sports, listen to and mix music, and hang with family and friends.

Personal idea, mentored by John Contreras.