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Motion Analysis of Running

Ashley Buado and Taiah Gallisath

North Central College

Running
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Approximately 60 million people participated in running and jogging in the United States

in 2017. Whether it be for competition or recreation, the primary purpose of running is to get or

stay healthy by use of cardiovascular endurance and resistance training. Some individuals prefer

a longer duration, such as a marathon, while others prefer shorter sprints, such as 100 meters.

Whichever way an individual decides to run, it all follows a series of motions called the gait

cycle. The cycle begins when one foot comes in contact with the ground and ends when that

same foot cycles through to return contact with the ground. The gait cycle can be broken down

into two main phases; the stance phase and the swing phase. These phases can be further broken

down to heel strike, foot flat, midstance, heel off, toe off, and midswing (Figure 1). Walking

follows a similar gait cycle as running while having a couple key difference. The first being the

float phase of walking typically having at least one foot in contact with the ground at all times,

while in running both feet break contact. This can be otherwise termed that walking has a double

support phase compared to running having a double float phase.

Figure 1

Source: https://www.physio-pedia.com/Gait

Anatomical Analysis
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Running is a multi-joint exercise of the shoulder, elbow, hips, knees and ankles. This

exercise primarily uses the lower extremities, while movement in the upper extremities enhances

the skill. It is good to note that description of the skill is in relation to one leg.

Stance phase

The stance phase is the starting point of the gait cycle that comprises approximately 60%

of it. Muscles that are active in the stance phase are in the lower extremity including tibialis

anterior, the quadriceps (rectus femoris, vastus lateralis, vastus medialis, vastus intermedius), the

hamstrings (biceps femoris, semitendinosus, semimembranosus), the hip abductors, the gluteus

maximus, and the erector spinae. These muscles act to prevent buckling of the support limb

(DeLisa & Malanga). The stance phase begins with initial contact, then loading response, then

midstance and finally terminal stance. At initial contact, the hamstrings flex the hip anteriorly, at

approximately 30 degrees, with the knee fully extending. Knee extension is caused by the

quadriceps. The foot moves into a slightly dorsiflexed position, caused by the tibialis anterior, to

achieve a heel strike (Novacheck 1998). The tibialis anterior also contracts concentrically to

stabilize the ankle, while the gastrocnemius and soleus contract eccentrically to also stabilize the

ankle (Dugan and Bhat 2005). During the loading response the foot pronates when the midfoot

touches the ground. The knee also flexes approximately 5 degrees. Next is midstance, the hip

moves from flexion to extension and the knee reaches approximately to full flexion. This is now

beginning the swing phase.

Swing Phase
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The next point in the gait cycle is the swing phase. The swing phase can be divided into

initial swing, midswing and terminal swing. In initial swing the hip flexes, starting from the

extended position of midstance, to about 30 degrees. This is from contraction of the iliopsoas

muscle. The knee flexes from concentric contraction of the hamstrings (biceps femoris,

semimembranosus, semitendinosus). The ankle goes from plantar flexion to dorsiflexion.

Following the initial swing, in the midswing the accelerating limb is aligned with the stance

limb. The hip flexes to approximately 30 degrees due to hip adductors and the ankle flexes due to

contraction of the tibialis anterior. The knee flexes approximately 60 degrees and then extends

fully. Extension is caused by the quadriceps (vastus medialis, vastus lateralis, vastus intermedius,

rectus femoris). In terminal swing the decelerating leg adducts as it prepares for contact with the

floor (DeLisa & Malanga). The hip adductors concentrically bring the femur toward the midline

and stay active during this phase to stabilize the lower extremity (Dugan & Bhat 2005). The

ankle dorsiflexes to approximately 20 degrees to achieve heel strike restarting the gait cycle.

Upper Extremities

While the lower extremities significantly impact the motion of running, the upper

extremities assist in the efficiency. This can be achieved by the swinging motion of the arms and

the stabilization of the torso.

Once running is initiated, flexion of the shoulder starts from a neutral position of 0

degrees to a flexed position anteriorly of approximately 45 degrees. The reverse is true for

shoulder extension. Shoulder flexors include pectoralis major, deltoid, and biceps brachii.

Shoulder extensors include pectoralis major, deltoid, latissimus dorsi. The elbows are flexed

slightly by the biceps and biceps brachii. Elbow flexion stays constant throughout the exercise.

The rectus abdominis and oblique muscles help stabilize the torso for forward movement.
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Neuromuscular analysis:

Running is a series of acceleration and deceleration throughout the gait cycle. Force

production for running can come from different portions of the body. Joint angles from the legs,

i.e. stride length, or supination and pronation from the ankle influence the amount of force

produced. Proper impact absorption can come from joint motion, eccentric muscle contraction,

and articular cartilage compression (Dugan & Bhat 2005). In the stance phase of the gait cycle,

the first part of the the stance phase is concerned with force absorption and the second half is

concerned with force propulsion (Novacheck 2010). The body scales force production in running

with the connection between one's mass and the ground force being produced. It seems that if a

runner has more mass (sprinters) they have a higher ground force production than runners with

less mass (distance). Having a higher ground force production correlates to having more speed

whereas a lower production correlates with having more endurance. With sprinters having more

mass, although it generates more speed typically, their bodies will have to produce more force in

order to propel their body mass forward. By implementing more plyometrics, exercises that exert

maximum force in short intervals, a runner can anticipate increasing their ratio of body mass to

ground force production, thus increasing their speed.

The muscles involved in running are all very unique in the sense that they must work

both with and somewhat against one another. During running, agonist and antagonist muscles

work simultaneously to propel the body forward while also keeping it stabilized. An important

factor of this would be passive insufficiency, is the inability for two joints to reach full range of

motion within the same muscle. This is seen in running when the quadriceps contract causing the

hip to flex at the same time as the knee attempting to extend. Passive insufficiency does not

allow for the hip to be in full flexion at the same time the knee is in full extension.
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Proprioceptors are located throughout the entire body using stretch and pressure receptors

of the muscles, joints and skin to send impulses to the central nervous system about the physical

environment our body is enduring. In running, the majority of proprioceptors being utilized are

in the legs and feet. Proprioceptors in the feet are of the utmost importance while running. These

receptors reduce the risk of injury within this exercise by sending impulses to the central nervous

system in order to adjust to changes in ground surfaces, muscle tensions, and running postures

during all phases of the gait cycle. Proprioceptors are the main reason we are able to maintain

our balance while running especially in the swing phase where the body’s center of mass is

altered by primarily having only one foot in contact with the ground.

The body has the ability to respond to these changes subconsciously with its many types

of reflexes. Extensor thrust reflexes are stimulated by changes in pressure and stimulate the

pacinian corpuscles to initiate a reflex which leads to contraction of the extensor muscles of the

limb experiencing the pressure. Many runners often experience pain during their runs, the free

nerve endings of the flexor reflex reacts to the pain stimuli by withdrawing quickly from the

source of pain. When a runner feels off balance by turning for example, the crossed extensor

reflex is stimulated by the unweighting and responds with opposite extensors contracting for

support.

Some proprioceptive reflexes that occur during running are stretch and tendon reflexes. A

stretch reflex is a contraction of stretched muscle and synergists and relaxation of antagonists.

There are two types of responses to a stretch reflex, a phasic response and a tonic response.

Phasic responses are stimulated by high velocity (fast) stretches resulting in the annulospiral

endings of the muscle spindle sending a response to facilitate proportional contraction of the

stretched muscle. The tonic response is stimulated by slow sustained stretches resulting in the
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flower spray endings of muscle spindles to send a response for the gamma efferent system to

reset spindle tension using intrafusal fiber contraction or relaxation.

Finally, tendon reflexes that can occur during running are stimulated by high level

stretches, due to the muscle stretching or muscle contraction. The golgi tendon organ sends a

response to relax the stretched muscle and facilitate the antagonist. This reflex consists of a

feedback mechanism to control the tension that occurs. Tendon reflexes may affect a beginners

skills until the persons golgi tendon organ threshold develops.

The effects of running in shoes versus barefoot has been studied extensively. It is a

common ideology that running in shoes can ultimately hinder these proprioceptive reflexes. By

putting a thick sole between the foot and the ground forces, the foot is not receiving as much

stimulus from the external environment the body endures while running, which can in turn lessen

the strength and effectiveness of such reflexes. A study conducted in 2014 looked at 29

individuals with no previous experience with barefoot running over a 8 week training period to

look at the effects it has on muscle strength and proprioception. The researchers found that such

a short training period did not affect the strength or proprioception of the subjects, they

concluded that a much longer training period would be needed to assess the actual effects as well

has a heavier intensity. Since the subjects had no experience with barefoot running the

researchers had them running at low intensities to prevent an injuries from occurring (Mullen, et

al, 2014).

Kinetic and Kinematic Analysis

Running is a linear movement comprised of angular or rotary movements of the body

segments. The arm and leg segments are third class levels for the primary function of speed and
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range of motion. In order for the subject to perform the skill optimally, the body segments should

be manipulated, through kinetics and kinematics, that would favor speed and range of motion.

Newton’s Laws

For the gait cycle to begin an individual must overcome the moment of inertia at the

stance phase. The push off from the stance phase determines the forward momentum of an

individual (Zhong et. al. 2017). Further progression in the cycle increases or decreases velocity

depending on the individuals force production and mass. This can be determined by Newton’s

second law of acceleration. The position of the body can also change velocity. In walking, the

center of gravity shifts as the person moves, however when running, the body maintains a

forward lean. Newton’s law of reaction plays a significant role in the locomotion action of

running. This law states that for every action there is an equal and opposite reaction. For running,

the reaction is ground reaction force. The forward lean causes the ground reaction force and

friction to create a vector that allows forward acceleration (Novacheck 1998). Since the ground

and foot exert equal and opposite force on each other the type of landing of the foot can change

the amount of force produced and the amount of acceleration there is. The type of foot landing is

different for a specific kind of running: sprinting or endurance. The foot can contact the ground

by heel strike, midfoot, or forefoot. Generally, as speed increases, initial contact changes from

hindfoot to forefoot. Force production increases when following a heel strike foot pattern(OHS)

compared to a forefoot strike (FFS) as seen in figure 2 (Mercer & Horsch 2015). In the same

study, it was observed that stance phase decreases in the forefoot strike (Figure 3). Decreasing

stance phase achieves faster speeds.

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Figure 2

Figure 3

Impulse

Impulse is the product of force and the time it is applied. To achieve faster speeds for

running, an individual should decrease their time in the stance phase. By shortening time in the

stance phase, it reduces the time it takes to generate an impulse of the lower extremity (Tongen

& Wunderlich 2010). This causes force production to increase, but it can not be maximal. An

increased force production would be ineffective for longer durations, because it increases energy

expenditure. Another type of impulse that is affected in running is braking impulse. The braking

impulse happens when the foot lands on the ground and that force it produces when landing is

the impulse. This impulse can be manipulated by stride length. The further forward the foot lands

relative to the center of mass, the greater the magnitude of braking impulse that decelerates the
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body (Lieberman et. al. 2015). Foot landing at a farther distance increases the time the force is

applied, increasing impulse. By increasing braking impulse, it slows the runner down because

Torque

Torque is the turning effect of eccentric forces and can be manipulated by stride length,

which in turn can change the velocity of the runner. Stride length changes depending on the

range of motion of the hip. More hip flexion can cause a longer stride length. One should achieve

the optimal stride length, not too short, but not over-striding. Over-striding causes a smaller

moment arm from the hip to the ground, decreasing the torque. When the knee is overextended

there is less torque, reducing the power produced for the stance phase. “As speed is increased,

the lower extremity joints increase their range of motion to decrease the vertical shift in center of

gravity. Thus, faster runners require more flexibility and eccentric muscle strength than slower

runners” (Dugan, Bhat 2005). Running speed is determined by stride length and stride

frequency. Manipulating torque can manipulate angular momentum.

Potential and Kinetic Energy

Running is a bouncing gait in which the lower extremity; muscles, ligaments, tendons,

store elastic energy in the first half of the stance phase and recoil at the second half (Lieberman

et. al. 2015). Potential and kinetic energy changes throughout the different phases of running.

Potential energy is built up during the stance phase, when the foot leaves the ground and the hip

flexes. As the center of mass falls towards the ground during the swing phase, potential energy

decreases. As the foot touches the ground, kinetic energy decreases. The decrease of potential

and kinetic energy is converted to elastic potential energy in the muscles and tendons

(Novacheck 1998). As the center of mass accelerates upward during the float phase, potential

and kinetic energy increase.

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Mechanical Advantage of Arm Swing

Arm swing during the gait cycle has been seen to reduce angular momentum and energy

expenditure, and enhance gait stability (Brujin S, et al. 2010). Arm swing counterbalances the

swing of the leg. The swinging motion of the leg creates an angular momentum. Swinging the

arms creates an angular momentum as well. Typically in running the opposite arm and leg swing

in the same direction, example left arm swings forward while the right leg swings forward. This

creates a lateral stabilization and keeps the center of gravity in line. The center of gravity should

stay in line so the individual does not fall forward or backward, this is done by counterbalancing

the momentum on each side.

Conclusion

Running is an exercise that is used for cardiovascular fitness and can even be deemed a

resistance exercise. It follows a simple pattern of repetitive movements termed the gait cycle by

use of muscles of the upper and lower legs working to create a forward movement of the body

with the aid of muscles of the upper extremities. Each of the body’s reflex mechanisms can be

seen during running, the most important being that of proprioception keeping the balance of the

runner as well as reacting to changes in the environment. Optimizing the kinetics and kinematics

of joint angles and motions, such as torque, impulse, ground reaction force can improve running

speeds.Although running seems quite simple in itself, there are many components that influence

the action of running.

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References

Brujin, S., Meijer, O., Beek, P., vanDeen, J. The effects of arm swing on human gait stability

(2010). Journal of Experimental Biology. 213: 3945-3952.

Dugan, S., Bhat, K. Biomechanics and Analysis of running Gait (2005). Physical Medicine and

Rehabilitation Clinics of America. 603-621.

Lieberman, D., Warrener, A., Wang, J., Castillo, E., Effects of stride frequency and foot position

at landing on braking force, hip torque, impact peak force and the metabolic cost of
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running in humans (2015). Journal of Experimental Biology. 218: 3406-3414; doi:

10.1242/jeb.125500

Malanga, G., DeLisa, J. RRDS Gait Analysis in the Science of Rehabilitation: Clinical

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Mercer, J., Horsch, S. Heel-Toe running: A new look at the influence of foot strike pattern on

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