The study I will be
looking at is the biomechanical principles within running.


The biomechanical principles that are influenced in running are;

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–       Friction

–       Forces pushing or pulling

–       Centre of mass


The Five
Laws of Friction:

1.    When the
body is moving, the friction is directly proportional to normal force and
frictional force direction is perpendicular to the normal force.

2.    Friction
doesn’t depend on the area of contact so long as there is an area of contact.

3.    The coefficient of
static friction is slightly higher the value than the coefficient of kinetic

4.    Kinetic
friction is independent of the velocity of the body.

5.    Friction
depends on the type of the surfaces in contact.


can be defined as the resistance to motion of two moving objects or surfaces
that touch. Friction plays a very important role in many sports, such
as running. Frictional
force is encountered within each movement the runner makes on the track. When
we try to run our foot is pressed to the earth in backward


direction and by third law of Newton (action
reaction) there will be a reaction for every action in opposite direction. Forces can affect your running greatly and can slow
you down and speed you up.  When you are
running the most important force that you should understand is friction. There is both Static Friction and Kinetic Friction. Static
friction is the friction before an object starts to slide, while Kinetic
friction is the friction when the object is actually moving or sliding. The
formula for both is the same, except they have different coefficient of
friction values.

Friction is a force
that opposes movement between two objects, (fisher 2015) but for runner’s
friction can make you faster.  Friction gives you a better and more
efficient way to use your energy into speed. Having the correct equipment such
as shoes appropriate to the type of race and track type can give you more
friction or another term for it is grip. Having more grip on the ground enables
you to move faster with every step. The second biggest force that you deal with
is air resistance or fluid friction. Air resistance is a force that slows an
object down while moving through the air. When you are running in to the wind,
air resistance makes it feel like you hit a wall and can’t move forward. Factors
such as incorrect footwear and track type and temperature can greatly affect
the frictional force on the runner and can decrease their speed. You can see
from the diagram below the force gravity pushes on the body as the propulsion
goes one way, friction goes the other fighting against each other making more
air resistance and acceleration.





Forces pushing or pulling












Centre of mass


The centre
of mass is an imaginary point at which the total body mass
is concentrated, and it is a general descriptor of whole body mass

The position
of your torso/head during running significantly influences kinematics,
mechanical work and metabolic energy expenditure whereby heel
strike running and forefoot strike running involves different
centre of mass positions. Heel strike runners have a more posterior (backward)
centre of mass position –the runner’s torso is kept upright (i.e. no leaning)
during running; whereas forefoot runners have a more anterior (forward
leaning) centre of mass position. Leaning
forward is actually better because it increases forward
momentum and encourages a foot strike position close to or under the centre of
mass. In runners the diagonal elastic support mechanism is utilised. This is
produced by a constant diagonal stretch and release that is enabled by the
body’s counter rotation. The force continually flows up and down these force
pathways alternately. The pattern of force distribution prevents force being
concentrated in one area, but allows wide distribution of force throughout the
body. Elphinstone (2013)