January 30, 2017

Concussions: Physics, anatomy, warning signs, and return to physical activity.


Before we explain what the protocol for return to physical activity is, we need to understand what a concussion actually is and how it happens. We all know that a concussion happens after an impact of a force (usually to the head) which causes an injury to the brain. Newton’s second law of physics states: “The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.” In this case, if we get hit in the head, the brain will move inside of the skull, which can cause a jarring of the brain against inside of the skull, leading to nervous tissue (brain or nerves) and even possibly blood vessel injury (bleeding into the brain = NOT GOOD!).




However, there are several factors that decide whether a concussion will occur or not:

  1. The brain itself is a factor, how big is it and how much wiggle room is inside of the skull.

  2. The structures inside of the skull, are they smooth or sharp, will be another determining factor.

  3. Neck strength and mobility play an important role when trying of decelerate the head (and the brain) after an impact, which can decrease the risk of a concussion (Gilchrist et al., 2015). If the neck is strong enough to resist movement upon contact, the head nor the brain will move. However, more research has to be done in this area to prove it significant.

  4. Protective equipment, there is a reason why people should be wearing helmets when playing contact sports or during recreational activities such as riding a bike. Helmets (regardless of activity) are designed to cushion the impact by the ground or other outside force.

  5. And the last and arguably the most important factor, the impact force itself. How great is the force itself? Forces between 70g (70-times its gravitational weight) and 75g have been linked to the onset of concussions. Wait… don’t jet pilots experience forces of up to 10g and sometimes pass out? Yes, but their entire body is moving (accelerating and decelerating) at the same rate, which is not the case in concussions. You might be asking: “Can’t we just develop a device that would measure the impact on the head and put in inside of a helmet?” Yes, we have, but we also wish it was that simple. Is the force only going to move our head backward, forward, sideways, or is it going to cause a rotation movement of the head (and the brain)? Due to the movement of the brain (and the factors mentioned above), concussions may occur at forces much smaller or greater, that is why the accelerometers in helmets are not 100% accurate, but still better than not knowing how great the force is. What is the smallest force to the head that can cause death? There are too many unknowns that play a role in this (see the factors above).

If and when a concussion does occur on the athletic field, there are symptoms we can diagnose a concussion by. These include:

  1. Confusion

  2. Disorientation (blank look, “where am I?”)

  3. Amnesia (loss of memory)

  4. Unconsciousness

  5. Dizziness

  6. Headache with possible tinnitus

  7. Loss of balance

More elaborate diagnostic tests include:

  1. Strength test

  2. Sensation test

  3. Reflex test

  4. Memory

  5. Eye test (sensitivity to light)

  6. MRI, CAT scan, other imaging test



What happens after the concussion? Well, you will have a splitting headache (your brain just bounced around your skull like a ping-pong ball in a glass jar), very stiff neck, sensitivity to light, confusion, and possible loss of memory about the accident. None of those are good, but it could have been a lot worse (being carried out on a stretcher, loss of consciousness).


What is the treatment for a concussion? Well, medication is not as effective as we would like it to be, in fact, there is not a “magic pill” that will make your concussion go away (Moser et al., 2012). If you do have a concussion and the splitting headache it comes with, DO NOT TAKE IBUPROFEN OR ADVIL BY ANY MEANS! Both have blood-thinning/anti-clotting effect and could cause further bleeding into the brain. TAKE TYLENOL INSTEAD (No, I am not promoting a product, I am trying to get you back on the field).


Since most concussions happen in sports, rest is prescribed right away and based on the concussion grade and recovery, an athlete might be able to return in one week, if lucky. The best way to treat a concussion is to not get another one. Athletic trainers or physicians will usually prescribe rest. And by rest they mean adequate sleep, decrease of cognitive activities, and an impact free environment.

  1. Rest = no sports, weightlifting, cardiovascular training, or leisure time physical activity. If an athlete has no concussion symptoms for 24 hours, they may be cleared to perform light aerobic activity or 5 to 10 minutes the next day, preferably on a stationary bike to prevent head shocks and no weightlifting or strain. 48 hours after the concussion, some jogging, light running, and light weightlifting may be done. 72 hours after, more intense aerobic and resistance activity may be done. After this point, the athlete needs to be slowly eased into team/contact drills with protective gear. In the milder cases of concussions, the athlete may return to competition one week after the injury.

  2. Decreased cognitive activity = time off from school/work, no homework, no reading, no visually stimulating activities (computers, videogames, television, cell phone, etc.), and no loud noises. Sounds like a vacation, you say? Nope, your brain wants to escape from your skull.

  3. No impact environment = once again, the best way to treat a concussion is to not get another one.

What can we do to prevent concussions from happening altogether? Do not participate in physical activities that could cause one. If that is not an option, make sure to wear proper protective gear (helmets, padding, seatbelts), learn how to tackle properly (do not tackle with your head), and learn how to break a fall (tuck and roll).



Woodpeckers experience forces of 1,000g (46-times the “human limit”) when pecking. How are they still alive? Their beaks are separated from their skull, allowing the force to be transferred into the neck muscles and attaching ligaments which will absorb the force. Moreover, their brains are surrounded by trabeculae (cancellous bone), which is very shock-absorbent. Their eyes are protected by a third eyelid, preventing the eyes from pooping out of the skull while pecking.




  1. Gilchrist, I., Storr, M., Chapman, E., & Pelland, L. (2015). Neck muscle strength training in the risk management of concussion in contact sports: critical appraisal of application to practice. Journal of Athletic Enhancement, 4 (2): 1-19.

  2. Guskiewicz, K.M., Mihalik, J.P., Shankar, V., Marshall, S.W., Crowell, D.H., Oliaro, S.M., Ciocca, M.F., & Hooker, D.N. (2007). Measurement of head impacts in collegiate football players: relationship between head impact biomechanics and acute clinical outcome after concussion. Neurosurgery, 61 (6): 1244-1252.

  3. Johnson, V.E., Stewart, W., & Smith, D.H. (2013). Axonal pathology in traumatic brain injury. Experimental Neurology. 246: 35-43.

  4. Ling, H., Hardy, J., & Zetterberg, H. (2015). Neurological consequences of traumatic brain injuries in sports. Molecular and Cellular Neuroscience. 66(B): 114-122.

  5. May, P.R.A., Fuster, J.M., Newman, P., & Hirschman, A. (1976). Woodpeckers and head injury. Lancet, 1: 454–455.

  6. Moser, R.S., Glatts, C., & Schatz, P. (2012). Efficacy of immediate and delayed cognitive and physical rest for treatment of sports-related concussion. The Journal of Pediatrics. 161 (1): 922-926.

  7. Shaw, N.A. (2002). The neurophysiology of concussion. Progress in Neurobiology, 67 (4): 281–344.

  8. Sivák, Š., Kurča, E., Jančovič, D., Petriščák, Š., & Kučera, P. (2005). Náčrt súačsného pohľadu na problematiku ľahkých poranení mozgu so zameraním na dospelú populáciu. Časopis Lékařů Českých, 144 (7): 445–450.

  9. Wang, L.Z., Zhang, H.Q., & Fan, Y.B. (2011). Comparative study of the mechanical properties, micro-structure, and composition of the cranial and beak bones of the great spotted woodpecker and the lark bird. Science China Life Sciences, 54 (1): 1036–1041.





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