It is estimated that approximately 33 billion viewers watched the 1998 FIFA World Cup over the course of its 64 games (Kirkendall, Jordan & Garrett 2001). Fans from all nations have a thorough understanding of the rules of soccer, which if broken are often manifested by yellow or red cards. What fans, players and even coaches sometimes do not readily recognize are the behind-the-scene rules or laws that govern the game of soccer much more strictly than those enforced by the referees. These are the laws of physics. They govern how high a player can jump, how much the ball can spin as it travels across the field, and even how well a soccer player can take hits. This last area in particular has received growing clinical interest since injuries related to soccer are an ever increasing concern.
The past 50 years have seen rapid improvements in medicine, bioengineering and computers. It is the interdisciplinary collaboration of these three fields that has given birth to the field of biomechanics. While biomechanics has become diverse and broad, it basically uses mathematical differential equations to describe known physical phenomena within the human body as it reacts to external mechanical stimuli. Since the system of equations created is often impossible to solve by hand, computers integrate the system of equations and approximate solutions. To set up a robust and valid system of equations is not easy and requires practical experience as well as academic knowledge. Many assumptions have to be justifiably made, boundary conditions (values required to arrive at a solution of any differential equation) have to be established, and while no mathematical model will ever exactly predict “real life” behavior, its accuracy at times can be extremely helpful and insightful for clinical and scientific purposes.
The challenges encountered by biomechanical engineers are many. First of all, differential equations require known mechanical properties of biological tissues. These values, which are obtained empirically, are hard to capture by conventional engineering devices and techniques that traditionally only deal with more homogeneous materials. Several different measurement devices have been created to measure biological tissue mechanical properties (Bartsch et al 2012). Once these mechanical properties values are procured, then the math begins. These values are plugged into the differential equations as constants or functions. Once solved, these equations are validated through experiments to see if they are accurate. Once validated, the equations are used to study deformation and other desired variables.
Though ongoing research in the field of biomechanics for soccer head trauma will continue to generate further discoveries, current studies show that heading the ball may not be as much of a concern as physicians and parents thought (Broglio et al. 2004). More research is necessary to fully understand the repetitive nature of head shooting for those engaged in the sport through many years. Further development in the area of computing, mathematics, engineering and medicine will continue to provide more answers for parents and coaches.
Learn the technical biomechanics behind heading a ball.
By: Cristian Clavijo
Asken, M.J. and Schwartz, R.C. 1998. Heading the ball in soccer: What’s the risk of brain injury? The Physician and Sportsmedicine, 26, 11.
Bartsch, A., Benzel, E., Miele, V., Morr, D. and Prakash, V. 2012. Hybrid III anthropomorphic test device (ATD) response to head impacts and potential implications for athletic headgear testing. Accident Analysis and Prevention, 48, 285-291.
Broglio, S.P., Guskiewiez, K.M., Sell, T.C. and Lephart, S.M. 2004. No acute changes in postural control after soccer heading. British Journal of Sports Medicine, 38, 561-567.
Kirkendall, D.T., Jordan, S.E. and Garrett, W.E. 2001. Heading and head injuries in soccer. The American Journal of Sports Medicine, 31, 5:369-386.
Articles by Cristian Clavijo.