Concussions are a result of the deceleration or acceleration of brain tissue within the skull. If a person is stationary, a direct blow to the head or body will most likely result in a certain acceleration of the head and therefore the brain. If a person is moving and suddenly met with an abrupt stop from a ball or person, the brain continues to travel inside the stopped skull until it impacts the internal wall of the skull. This quick deceleration of the brain tissue within the skull results in an impulse delivered to brain tissue.
A hit does not have to be delivered directly to the head to cause a concussion. A hit to the body, or even a fall, can also lead to a concussion provided that the incident results in a significant acceleration to the head.
Viano, et al. Neurosurgery V61,No 2, Aug 2007. and his colleagues examined impacts seen in professional football. They then modeled these impacts and played with the variables in an attempt to determine how the acceleration of one’s head can be decreased during and after impact. If we can decrease the acceleration of the head, we reduce the risk that the impact will cause a concussion. It was determined that the variable with the greatest influence on head acceleration was NECK STIFFNESS. Increasing neck stiffness effectively links the head with the torso.
At the fourth annual Youth Sports Safety Summit in early February, Dawn Comstock, associate professor of epidemiology at the Colorado School of Public Health, presented the relationship of pre-season measures to concussion incidence during the season. During the 2010-2011 and 2011-2012 academic years, athletic trainers collected measurements of head circumference, neck circumference, neck length, and four measurements of neck strength — extension, flexion, right lateral and left lateral — on 6,704 athletes nationwide across three sports; boys’ and girls’ soccer, lacrosse and basketball.
The results indicated that concussed athletes had smaller mean neck circumference, a smaller mean neck-circumference-to head-circumference ratio (a small neck, large head relationship), and smaller mean overall neck strength than athletes who did not suffer a concussion. After adjusting for gender and sport, overall neck strength remained a statistically significant predictor of concussion. For every one pound increase in neck strength, odds of concussion fell by 5%.
While these studies positively suggest neck strengthening exercises as a preventative measure for concussions, other studies have proved inconclusive. At the 4th International Conference on Concussion in Sport held in Zurich, November 2012, the consensus was that no acceptable evidence was provided to suggest an association between neck strength increases and concussion risk reduction. Such relationships require further research with larger randomized sample sizes.
In more recent studies, Dezman, et al, Sports Health: A Multidisciplinary Approach 2013; 20(10), demonstrated that balanced neck strength may reduce the acceleration of the head during the act of heading a soccer ball, thus reducing the risk of brain injury from such low grade hits. Strengthening neck muscles may be a way to reduce head injury risk from concussion and repetitive sub-concussive trauma
Studies have proven that mouth guards while reducing the risk of dental and fascial injuries do not reduce the risk of concussion. Barbic 2005, Benson 200g, Knapik 2007, Labella 2002, Mihalik 2007, Navarro 2011, Viano 2012, Wisniewski 2004
Results of soccer headgear studies have revealed mild protection from concussion from players colliding heads but not from heading the ball. Withnall, et a,. Effectiveness of headgear in football. Br J Sports Med. 2005: 39(suppl 1); i40-i48. Headgear seems to protect against soft-tissue injuries, such as lacerations, contusions, and abrasions, and is more likely to be worn by female soccer players. Withnall, et al and Delaney, et al. The effect of protective headgear on head injuries and concussions in adolescent football (soccer) players. Br J Sports Med. 2008;42(2):110–115
Prospective data is not currently sufficient to support recommending universal use of headgear in soccer. Heading the ball in soccer is felt to be safe, if performed properly. Avoiding heading does not prevent concussions. Koutures, Gregory. American Academy of Pediatrics, Council on Sports Medicine and Fitness. Injuries in youth soccer: a subject review. Pediatrics. 2010;125(2):410–414
What is clear from current research on concussion prevention is that most of the existing research is focused on examining the frequency, cause, diagnosis, and treatment of a concussion after the fact. The next step must be in the reduction of an initial concussion. Sample research has demonstrated that a stronger neck reduces the incidence of concussions, but this must be coupled with proper technique. Neck stiffness has been demonstrated to reduce the acceleration of the head in simulated models. A strong neck, however, does not mean a stiff neck upon impact. Technique and environmental recognition by the athlete must be trained to engage the muscles properly to create a stiff neck and couple the head to the torso. If technique is sound a strong neck will allow a more stiff neck upon impact.
Strength training of the neck is inconclusive in reducing the incidence of concussions, but no studies have suggested that strength training of the neck has a negative effect on injury rate or hazardous play. Promoting a neck strengthening program in athletes may reduce the risk of concussions with no demonstrated risk to increase injury.