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Newton’s Laws, G-forces and the impact on the brain

Australasian Journal of Neuroscience Volume 30 Number 1 May 2020
When thinking about head injury, one needs
to first understand forces and the way they
impact the body. Gravitational force, or G-
force, is the force of gravity on a particular
body a measurement (in Gs) of accelera-
tion that causes the perception of weight. It
has significant applications in scientific & en-
gineering fields especially regarding racing
cars, fighter jets, large engines and roller-
It is interesting to note (see table below) that
the force of gravity whilst just standing on the
earth, increases markedly with a slap on the
back. Then further when in a car or a roller-
coaster and even more if having sustained a
In todays modern age, Sir Isaac Newtons
theories and laws are still included in the cur-
riculum taught to students at school. From his
theories of optics and calculus, to his ground-
breaking work on the laws of motion and
gravity, which formed the basis for modern
physics, he dominates the fields of science,
astronomy, physics and the natural world,
proving invaluable to centuries of mathemati-
cians, engineers and scientists.
In health, the Valsalva manoeuver is a tech-
nique of force used to equalise pressure
(Pstras et al, 2016). People perform the
Valsalva manoeuver regularly without know-
ing it. For example, it is used to increase co-
lonic pressure to induce a bowel movement
and it may also be beneficial when used in-
tentionally to try to regulate heart rhythms. It
is also used when experiencing a change in
altitude to help equalise the ears by forcing
them to pop’, such as when scuba diving or
in aeroplanes. The main side effect of per-
forming the Valsalva manoeuver is hypoten-
sion and resultant forces impacting intra-
ocular, intra-abdominal and intra-cerebral
The thrill to go fast and push boundaries is something that many seek. From John Stapps rocket
sled at Edwards Air Force Base in the late 1950’s to todaysFormula 1 drivers, the need for speed
is broadcast across TV screens weekly. So too are the horror stories of crashes, many at over
300km/hr. Yet need for speed continues. It appears that the higher and faster the rollercoaster,
the better. This leads to several questions. How does the brain stand up to speed and G-forces? Do
Newtons Laws still have reference in todays world?
There has been much attention in the general press on the possibility that high G-force roller-
coasters are inducing brain injury in riders. However, research does not wholeheartedly support this
notion, but rather the risk of brain injury from a rollercoaster is not in the rides, but in the rider
caused by previously undetected brain or neck conditions. That said there is some truth that high G
-forces do affect the brain at a chemical and structural level.
This paper will discuss the mechanism of head injury at speed and generally what Newtons Law
means in a neurological setting in todaysworld. Formula 1 racing and rollercoaster rides will be
evaluated within a neuroscience context.
Key Words
Concussion, head injury, Newtons laws, Formula 1, roller-coasters
Questions or comments about this article should be
directed to Vicki Evans
Email address:
DOI: 10.21307/ajon-2020-003
Copyright © 2020ANNA
Newtons Laws, G-forces and the impact on the brain
Vicki Evans 1.
1Royal North Shore Hospital ,Sydney.
Australasian Journal of Neuroscience Volume 30 Number 1 May 2020
These forces are also produced in the acts of
vomiting, coughing and sneezing. As neuro-
science nurses, the knowledge regarding the
impact of these forces is known to be trouble-
some in relation to the consequences of
these forces on intra-cerebral pressure and
the homeostasis of the brain. It should be
kept in mind that the involuntary act of sneez-
ing has ramifications from a G-force perspec-
tive. The act of sneezing with an open mouth
has a force of 2.9Gs. Yet holding in a sneeze
internally redirects the force and this can re-
sult in eye injury, ruptured ear drum, herniat-
ed nucleus pulposis (herniated disc) and
throat injury (Yang et al 2018).
Table 1: How Many Gs?
Adapted from Slade (2009)
Newtons First Law: (Inertia). An object will
remain at rest, and an object will remain in
motion, unless acted upon by an unbalanced
force. For example, a fast car hits a brick
wall. The car stopsbut the person does not.
Since an object at rest stays at rest, roller-
coasters have to be pushed or pulled along
the track. In this way, potential energy is
stored for the entire ride. At the top, the
rollercoaster is put into motion and will not
stop until the brakes are applied at the end of
the ride.
The worlds fastest rollercoaster is the For-
mula Rossa rollercoaster in Ferrari World,
Abu Dhabi, United Arab Emirates. It is 53m
high and has a maximum speed of 240km/h
via a hydraulic slingshot launch. In this way,
acceleration is 0 to 240km/h in 4seconds.
The G-force is 4.8G, requiring the rider to
wear goggles for eye protection.
Newtons Second Law: (Force = mass x
acceleration). This law explains how the ve-
locity of an object changes when it is subject-
ed to an external force. This is felt when go-
ing down hills. The coaster cars and your
body have mass. The gravity provides accel-
eration, which causes force. The rider feels
the force as it moves the cars along the track.
The track directs the force and the cars. In
positive Gs, the body feels heavier at the
bottom of the hills, turns and loops. For ex-
ample, a 70kg person at 2Gs would have the
perception of 140kg and at 3Gs it would feel
like 280kg. Whereas with negative Gs, the
body feels weightless – at the top of the hills.
Newtons Third Law: (Action/reaction). For
every action (force), there is an equal and
opposite reaction. For example, as your body
is pushed down into the seat of the roller-
coaster, the seat pushes back.
Newtons Laws permiate throughout engi-
neering and science fields and are still cur-
rent in todays practice. It was Dr John
Stapp, a United States Air Force Colonel,
flight surgeon, physician, biophysicist, and
pioneer in studying the effects of acceleration
and deceleration forces on humans, who put
Newtons Laws to the test on the human
At New Mexicos Air Force Base, December
10, 1954, John Stapp was strapped into the
Sonic Wind rocket sled. His arms and legs
were secured. There was no windscreen, so
he wore goggles, a mouthguard and a hel-
met. The sled was powered by nine solid fuel
rockets and it fired and propelled him more
than 3,000 feet in a few seconds. He came to
an abrupt stop and experienced a force
equivalent to 46.2 G. Not without injury, he
walked away with the world land speed rec-
ord, 632 miles/hour, which he still holds to-
day, giving him the title of "the Fastest Man
on Earth" (Atwell, 2017). However, the blood
vessels in his eyes had burst, rendering him
temporarily blind. He also sustained bilateral
wrist and rib fractures.
The outcome of these experiments allowed
for the development of improved pilot har-
nesses and aircraft seats, modern crash-test
dummies, the ejection seat and high-altitude
pilot suits. Stapps research improved aircraft
safety and also led to the development of the
shoulder seat belt. In September 1966, Presi-
dent Johnson, with John Stapp present,
signed the Highway Safety Act, in which it
was required that all new cars, as of 1968,
sold in the USA, be fitted with seat belts
(Ryan, 2015).
When thinking of acceleration, the picture
that formulates is usually of a sports car do-
ing 0 to 60 in six seconds. However, acceler-
ation is any change in the velocity of an ob-
ject – going faster, slowing down or changing
direction. Therefore, on a rollercoaster, the G
-forces are felt when rounding tight bends
and thrown against the side of the seat (a
Standing on the Earth 1G
Rollercoasters 3.5-6.3G
A slap on the back 4.1G
Formula 1 racing car 5G
The luge at Whistler 5.2G
Ploppinginto a chair 10.1G
Sneezing (open mouth) 2.9G
Concussion 80-100G
Australasian Journal of Neuroscience Volume 30 Number 1 May 2020
change in direction) just as much as when
falling from height (accelerate) or screeching
to a stop (decelerate). The thrill is felt, but
there is no fainting, because the rollercoaster
was designed to be within the G-force toler-
ance of the average person. However, the
amount of tolerable G-forces differs by indi-
vidual and it also depends on several factors:
the direction in which the G-forces are felt,
the amount of G's involved, and how long
those G's last (Evans, 2002).
At sea level, or 1 G, humans require 22 milli-
meters of mercury blood pressure to pump
sufficient blood from the heart to the brain. In
2 G's, twice that pressure is needed, in 3 G's,
three times, and so on. Even with a G-force
of 4 or 5, the heart struggles to summon the
necessary pressure. Blood pools in the lower
extremities and the brain fails to be ade-
quately oxygenated. Most people then faint.
Fighter pilots can handle greater head-to-toe
G forces—up to 8 or 9 G's—and for longer
periods by wearing anti-G suits. These spe-
cialised suits use air bladders to constrict the
legs and abdomen during high G's to keep
blood in the upper body. Fighter pilots can
further increase their G-tolerance by training
in centrifuges, which create artificial G's, and
by learning specialised breathing and muscle
-tensing techniques. Magnitude and duration
of the forces are as critical as direction.
Whilst John Stapp showed that people can
withstand much higher G-forces than had
long been thought, there is a limit to what
most people can tolerate.
Princess Diana was a catastrophic example
of how G-forces affect the human body. It
was estimated that the G-forces on her chest
were around 70 G's and 100 G's on her
head. The acceleration caused a fatal tear in
her pulmonary artery. If Princess Diana had
been wearing a seatbelt, the G-forces would
have been less and she may have lived.
(Operation Paget Report, 2009).
While Formula 1 (F1) racing drivers may feel
around 5-Gs, under heavy braking, they can
experience over 100-Gs if a crash causes
them to decelerate quickly over a short dis-
The weekend of May 1st 1994, during the San
Marino Grand Prix, was Formula 1’s worst
race weekend in history. That weekend of
racing in Imola, Italy, saw the death of Austri-
an, Roland Ratzenberger in practice and that
of Brazillian, Ayrton Senna the following race
Niki Lauda spoke these words in 1994 after
Ratzenberger crashed at over 306kph during
qualifying and 24hrs later, Senna died when
his car slammed into a concrete wall at
220kph. Both died as a result of catastrophic
head injuries. Following these deaths, F1
underwent many changes from car design to
fuel and tyres. There hadnt been any deaths
on the F1 circuit since 1994, but that came to
an end in 2015 during the Japanese Grand
Prix, when 25yr old driver Jules Bianchi
crashed at 258kph and sustained severe
head injuries. He succumbed to these injuries
a few months later. The G-force sensor locat-
ed in his earplugs recorded a 92-G impact
(Bednall, 2014), much greater than the hu-
man body is designed to withstand.
G-forces act on blood and blood vessels.
Just as they push the body into the seat, they
also push the blood back away from the brain
and toward the feet. Therefore, astronauts
wear a pressurised G-suit that prevents
blood pooling in the extremities. This is simi-
lar to anti-thrombotic stockings that can be
worn for long-haul flights. If G-forces are
brief, the effects on the body will be less. It is
when G-forces linger, or are sustained, that
causes concern. Hence, during launches of
the space shuttle, controllers keep the shut-
tlesacceleration low—no greater than 3-G's,
so as not to unduly stress the astronauts.
The eyes are especially susceptible to G-
forces and some of the first signs of problems
in the cockpit arise from partial loss of vision.
Pilots know it as greyout greying of vision
due to reduced blood flow to the eyes. This
can serve as a warning of the decreased
blood flow to the head. Consciousness is
maintained but blood flow to the eyes is com-
promised. However in some studies, half the
pilots experienced unconsciousness at the
same time as the loss of vision, therefore a
There is a limit to what humans can take.
Tragically, Princess Diana proved that.
God has had His hand over Formula 1
for a long time.
This weekend, He took it away”.
Niki Lauda – Reuters, 1994.
Australasian Journal of Neuroscience Volume 30 Number 1 May 2020
pilot cannot rely on visual disturbances to
warn them of unconsciousness.
Blackoutor loss of consciousness occurs
when cerebral blood flow is reduced. In many
centrifuge studies, the pilots were amnesic to
the events of losing and gaining conscious-
ness. Symptoms may include convulsive
movements and slumping in the seat. This
could be dangerous if falling against the con-
trols. However, it is an individual experience
whether or not consciousness is maintained.
Tolerance is related to the rate of onset of
acceleration and to the duration of exposure.
Individual tolerance depends on factors such
as the height of the person, age, elasticity of
the blood vessels, training, the responses of
the heart and blood vessels, and general
health. G-forces can also detach a retina.
What do some animals have that humans
Drake et al (2016) describe that the bighorn
sheep, as a part of fighting and mating, rou-
tinely experience violent impacts to the head
without negative consequences to their
brains or horns. Their horns consist of a bony
material and a trabecular mesh-like structure
which absorbs the impact that occurs during
ramming. The woodpecker too has significant
internal structures that absorb the impact of
pecking a tree at over twenty times per sec-
ond. Their secured hyoid bone, uneven beak
and tight cranial cavity absorb the shock. It is
from studying these two animals in particular,
that the researchers have developed im-
proved mouthguards, helmets and flight data
recorder cases. The European Organisation
for Civil Aviation Equipment Committee, an
international body on which the Australian
Transport Safety Board (ATSB) was repre-
sented, revised the standards of flight data
recorders in 2003. Today, these flight data
recorders are able to withstand an accelera-
tion of 3,400 Gs (3,400 times the force of
gravity) (ATSB, 2014).
So where does the literature stand with
regard to brain injury and rollercoasters?
In 2002 Smith & Meaney suggested that the
human body can withstand very large G-
forces when they occur over very short peri-
ods of time, which is the current thought to-
day. They suggested that the loss of con-
sciousness is from restriction of blood flow
rather than mechanical injury to the
brain. Their studies illustrated that to injure
the brain, there needs to be greater linear
force (Gs) as well as rotational force. They
went on to say that neck or back injuries
would be far more likely than brain injuries
from rollercoasters.
Again, the thought in 2003 was that the risk
of brain injury from a rollercoaster is not in
the rides, but in the rider caused by previ-
ously undetected brain conditions or spine
injuries from the force in the turns. (Brain In-
jury Institute of America, 2003)
Yamakami et al (2005) and Roldan-Valadez
et al (2006) described anecdotal case reports
of potential causal relationships of patients
suffering brain bleeding around the time of
riding a rollercoaster. This is now not sup-
ported by epidemiological or scientific data.
Although Roldan-Valadez et al (2006) pre-
sented a paediatric patient with a subdural
haematoma, fourteen days after having rid-
den a rollercoaster, the causative element
cannot be correlated entirely to the roller-
coaster. The results are also limited as there
was only one individual in this study.
Pfister, et. al., (2009) also agreed that its not
the ride, but the rider and said that there was
an extremely low risk of TBI due to head mo-
tions induced by roller coaster rides. Similar-
ly, Kuo et al (2017) suggested that roller-
coaster rides do not present an immediate
risk of acute brain injury. However, head mo-
tion and brain deformation during rollercoast-
er rides are highly sensitive to individual sub-
jects - who already are predisposed to brain
However, in 2018 there was a growing con-
cern about the G-force that is exerted on
people as they ride these faster rollercoast-
ers, as the desire to go faster is ever-present.
In October 2018, New Jersey, USA became
the first state to limit G-forces on theme park
The American Association of Neurological
Surgeons has assembled a national commit-
tee of neurosurgeons, NASA scientists and
engineers that are now looking at how the
stress of G-forces from rollercoasters might
affect the brain, specifically how the brain is
bounced around inside the skull on these
rides. The committee has not yet reached
any conclusions (ABC news, July 2018).
Zhu et al (2014) describes the studying ani-
mals such as the barbary sheep and wood-
peckers have given insight into how these
animals cope with extreme force impacts.
Inspired by the woodpeckers head, re-
searchers have developed a casing for air-
craft flight recorders that can withstand a G-
force of up to 60,000-Gs (previously 3,400
Australasian Journal of Neuroscience Volume 30 Number 1 May 2020
Being wrapped in cottonwool is not an option.
Sport and fun are synonymous. The desire to
go fast is thrilling and it seems that the faster
the rollercoaster, the better! Keeping a child
safe is a parents obligation and companies
have that same obligation of safety. As
demonstrated by Stapp in the 1950’s, hu-
mans can be subjected to high G-forces and
survive, as long as it is for a short duration.
Magnitude and duration are as critical as di-
rection, when it comes to forces. Safety is
paramount in industries where G-forces are
found engineering, space travel, F1 racing
and theme parks. With this in mind and
knowing the mechanism of injury, F1 re-
sponded with changes to car design and
changes to rules and procedures following
driver injury.
Rollercoasters that generate G-forces for the
pursuit of fun-filled terror must be conscious
of the pressure that is placed on the human
body during these rides. Safety mechanisms
and short duration of twists, turns and speed,
must be taken into account and adapted for
the safety of all.
With this knowledge of G-forces, people are
better placed to judge whether or not to put
their bodies through these forces. It must al-
so be clear that if a person knows or sus-
pects they might have a brain or neck injury,
then obviously it is unwise to participate in an
activity that could compromise their health.
Warnings at each ride are placed for a rea-
son, informed knowledge and decision-
making as well as coverage for litigation pur-
poses. These must be taken seriously, as it is
a fine line between being well and unwell.
Neuroscience nurses play a role in teaching
the public through seminars, school educa-
tional sessions and governments and compa-
nies have an obligation for public safety. Alt-
hough life is becoming a minefield of Safe
Operating Practicesand every product has a
warning attached, fun activities are encour-
aged, just within reason. The brain, within its
hardened case, is protected but also vulnera-
ble to changes in pressure and force. Pre-
existing conditions of the brain or neck,
whether known or not, plays a role in injury
from rollercoasters and theme park rides.
Some obligation must rest with the individual.
That is, the issue remains with the rider -
their health and informed decision on wheth-
er or not to ride.
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... To understand the military air force TBI, firstly it is essential to have a brief idea of the underlying causative factors. When it comes to brain injury, it is convenient to understand forces and the impact of forces on the intra-cerebral pressure and homeostasis of the brain [8]. The repercussions of pushing the body against the natural forces to fly high and battle can be dire in extreme cases. ...
Full-text available
Traumatic brain injury (TBI) is currently a rising player in the cause of disability and neurological dysfunction worldwide. TBI is a common occurrence in the military and extreme activities, sports arena and accidents. Severe TBI can be fatal but mild TBI persists and progressively deteriorates brain homeostasis and physiology. Apart from the physical disabilities, psychological complexities arise in people with mild TBI. Despite the seriousness of this hazard, treatments for TBI are not adequate, mostly due to the brain being involved. Nanoparticle (NP) therapy seems to be an effective alternative to combat TBI. This review outlines the state of TBI and describes the probable medical support that nanomedicine can provide.
Full-text available
Spontaneous perforation of the pharynx is an unusual condition. Due to its non-specific presentation and general lack of awareness, diagnosis and intervention may be delayed resulting in potential complications. This case reports a rare spontaneous perforation of the pyriform sinus after a forceful sneeze, leading to cervical subcutaneous emphysema and pneumomediastinum.
Full-text available
With 300 million riders annually, roller coasters are a popular recreational activity. Although the number of roller coaster injuries is relatively low, the precise effect of roller coaster rides on our brain remains unknown. Here we present the quantitative characterization of brain displacements and deformations during roller coaster rides. For two healthy adult male subjects, we recorded head accelerations during three representative rides, and, for comparison, during running and soccer headers. From the recordings, we simulated brain displacements and deformations using rigid body dynamics and finite element analyses. Our findings show that despite having lower linear accelerations than sports head impacts, roller coasters may lead to brain displacements and strains comparable to mild soccer headers. The peak change in angular velocity on the rides was 9.9rad/s, which was higher than the 5.6rad/s in soccer headers with ball velocities reaching 7m/s. Maximum brain surface displacements of 4.0mm and maximum principal strains of 7.6% were higher than in running and similar to soccer headers, but below the reported average concussion strain. Brain strain rates during roller coasters were similar as those in running, and lower than those in soccer header. Strikingly, on the same ride and at a similar position, the two subjects experienced significantly different head kinematics and brain deformation. These results indicate head motion and brain deformation during roller coaster rides are highly sensitive to individual subjects. While our study suggests that roller coaster rides do not present an immediate risk of acute brain injury, their long-term effects require further longitudinal study.
The Valsalva manoeuvre, a forced expiratory effort against a closed airway, has a wide range of applications in several medical disciplines, including diagnosing heart problems or autonomic nervous system deficiencies. The changes of the intrathoracic and intra-abdominal pressure associated with the manoeuvre result in a complex cardiovascular response with a concomitant action of several regulatory mechanisms. Since the main aim of the reflex mechanisms is to control the arterial blood pressure, their action is based primarily on signals from baroreceptors, although they also reflect the activity of pulmonary stretch receptors and, to a lower degree, chemoreceptors, with different mechanisms acting either in synergism or in antagonism depending on the phase of the manoeuvre. A variety of abnormal responses to the Valsalva manoeuvre can be seen in patients with different conditions. Based on the arterial blood pressure and heart rate changes during and after the manoeuvre several dysfunctions can be hence diagnosed or confirmed. The nature of the cardiovascular response to the manoeuvre depends, however, not only on the shape of cardiovascular system and the autonomic function of the given patient, but also on a number of technical factors related to the execution of the manoeuvre including the duration and level of strain, the body position or breathing pattern. This review of the literature provides a comprehensive analysis of the physiology and pathophysiology of the Valsalva manoeuvre and an overview of its applications. A number of clinical examples of normal and abnormal haemodynamic response to the manoeuvre have been also provided. This article is protected by copyright. All rights reserved.
To investigate the mechanism of brain protection of woodpecker, we built a finite element model of a whole woodpecker using computed topography scanning technique and geometry modeling. Dynamic analyses reveal: (i) 99.7% of the impact energy is converted into strain energy in the bulk of body and 0.3% is converted into strain energy in the head after three successive peckings, indicating the majority of the impact energy is stored in the bulk of body; (ii) the strain energy in brain is mainly converted into the dissipated energy, alleviating the mechanical injury to brain; (iii) the deformation and the effective energy dissipation of the beaks facilitate the decrease of the stress and impact energy transferred to the brain; (iv) the skull and dura mater not only provide the physical protection for the brain, but also diminish the strain energy in the brain by energy dissipation; (v) the binding of skull with the hyoid bone enhances the anti-shock ability of head. The whole body of the woodpecker gets involved in the energy conversion and forms an efficient anti-shock protection system for brain.
There has been enormous attention in the general press on the possibility that high G force roller coasters are inducing brain injury in riders. Armed with a handful of anecdotal case reports of brain injuries, the U.S. Congress has recently proposed legislation to regulate the level of G forces of roller coasters. However, high G forces are well tolerated during many activities and, therefore, are a poor measure for the risk of brain injury. Rather, accelerations of the head that can be caused by G forces are the key to producing injury. To determine the extent of head accelerations during roller coaster rides, we acquired G force data from three popular high G roller coasters. We used the highest recorded G forces in a simple mathematical model of head rotational acceleration, with the head rigidly pivoting from the base of the skull at a radius representing typical men and women. With this model, we calculated peak head rotational accelerations in three directions. Even for a conservative worst-case scenario, we found that the highest estimated peak head accelerations induced by roller coasters were far below conventional levels that are predicted for head injuries. Accordingly, our findings do not support the contention that current roller coaster rides produce high enough forces to mechanically deform and injure the brain.
Reports about neurological injury related to roller-coaster rides mostly involve adults; we present a case of subdural hematoma in a pediatric patient presented 14 days after a roller-coaster ride. These rides show extreme up-and-down, to-and-fro, and rotatory acceleration/deceleration forces that could produce tensile and shearing stresses with tearing of bridging cerebral veins resulting in subdural hemorrhage. Pediatricians should consider roller-coaster riding a modern cause of subdural hematoma, as well as a possible cause of unexplained neurologic events in otherwise healthy adolescents.
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  • S Donohue
Drake, A., Haut Donahue, T., Stansloski, M., Fox, K., Whealtey, B. and Donohue S. (2016). Horn and horn core trabecular bone of bighorn sheep rams absorbs impact energy and reduces brain cavity accelerations during high impact ramming of the skull. Acta Biomater Oct 15 (44) 41-50.