1. BASIC TRACK & FIELD
BIOMECHANICS
Cameron T. Gary
• USA Track & Field - Level II Coach
• Jumps
• Sprints, Hurdles & Relays
• USA Weightlifting
• Level 1 Performance Coach
2. DEFINITION OF
BIOMECHANICS
Bio = Body (living)
Mechanics = The study of the mechanical
principles of living organisms, particularly
their movement and structure
3. PLANES OF THE BODY
Frontal: Front side,
Back Side
Sagittal: Left side, Right
Side
Transverse/Horizontal:
Upper, Lower
4. THE NATURE OF ENERGY
You can hear energy as sound
You can see energy as light
You can feel energy as wind
6. MASS
The amount of matter accumulated in an object
◼ Mass never changes, regardless of location
Center of Mass (COM)
◼ The point where the object is perfectly balanced
◼ Where the object’s center of acceleration is also located
8. WEIGHT
• The amount of gravitational pull on an object
• Gravity pulls at a constant rate of 9.81 mps²
– Weight changes relative to one’s location
– Moon is 1/7 the mass of the earth, so your weight would
be 1/7 that on earth...but your mass would be unchanged
9. FORCE
Strength of a force is defined by the
rate at which it can speed up one
kilogram of mass
“You can see movement, but you
cannot see force.”
◼ Dr. Gideon Ariel
10. KINEMATIC PARAMETERS
• Description of the appearance of
movement, particularly as it pertains to
the position of the human body
• Basic Kinematic Parameters
– Displacement/Velocity/Acceleration
– Momentum/Speed
11. DISPLACEMENT, VELOCITY &
ACCELERATION
Displacement
◼ The change in the position of an object
◼ Shortest distance between the starting and
ending point
Velocity
◼ Displacement of an object in a particular
direction
Acceleration
◼ The rate of change in displacement of an object
◼ For our purposes, there is a unit of time with
respect to a particular direction
12. MOMENTUM & SPEED
Momentum
◼ Is the product of mass and
velocity
◼ Has direction and
magnitude
◼ Transfer of Momentum
○ When the momentum of a
system is imparted to a part
of the system
○ This requires stopping a part
of the system
! Throwing an implement
13. MOMENTUM & SPEED (CONT.)
Elastic vs. Inelastic
Collisions
Speed
◼ The magnitude of velocity
◼ How fast something moves,
regardless of direction
◼ Generally a measurement of
length, divided by time (Kps,
Mph, etc.)
◼ Speed is not the same as
acceleration
◼ Speed is relative to the
object’s position
14. NEWTON’S 1ST LAW
Inertia
◼ Objects in motion/at rest tend to stay in motion/at rest, unless
acted upon by a net force
Example
◼ The mass of the car/occupant is moving at 60 mph
◼ The net force is the immovable concrete block
◼ Unless something restrains the occupant, the momentum will
transfer to him and he will continue to move after the car is
abruptly stopped
15. NEWTON’S 2ND LAW
F = Ma
◼ F = Force, M = Mass, a =
Acceleration
Net force causes an object
to accelerate
◼ The magnitude of
acceleration is directly
proportional to the force on
the object,
○ Larger forces are capable of
creating more acceleration
◼ and inversely proportional to
the mass of the object
○ It takes less force to accelerate a
smaller object than a larger one
16. NEWTON’S 3RD LAW
In every action,
there is an equal
and opposite
reaction.
◼ If an object A exerts
a force on another
object B, then
object B will exert a
force on object A
○ Equal in magnitude
○ Opposite in direction
◼ Newton’s Cradle
18. ANGULAR INTERPRETATIONS OF
NEWTON’S LAWS
All of the above apply
in a Rotating System
Rotating inertia is
called Angular Inertia
Rotation-producing
force is called a Torque
◼ Torque = Twist
A torque force always
produces rotation
about an axis
19. ANGULAR VS. CURVILINEAR
VELOCITY
Objects rotating about
an axis have the same
angular velocity
However, objects
further from the axis
have a higher
curvilinear velocity
◼ Can you find the axis?
◼ Where is the highest
curvilinear velocity?
20. SUMMATIONS OF FORCE
Proximal: Closer to the center of the body
◼ Proximal joints tend to be more heavily muscled
◼ Proximal muscles/joints tend to produce more
force
◼ Proximal muscles/joints tend to be slower moving
Distal: Away from the center of the body
◼ Distal joints tend to be less heavily muscled
◼ Distal muscles/joints tend to produce less force
◼ Distal muscles/joints tend to be faster moving
21. FIRING ORDERS
This is the sequence of
joint usage
Generally Proximal to
Distal
Not consecutive
◼ Tends to overlap
Slower/Stronger
muscles/joints tend to
move first
◼ VOLUNTARY movements
- Reflex reactions are
the exception
22. HINGED MOMENT
Combination of Linear and
Angular Momentum
◼ Requires a change of direction
from linear to angular
◼ Stoppage of momentum at one
end of the system
◼ This becomes the axis
◼ Resultant energy is transferred
toward the distal end
The energy does not go away
– is increased at “free” end
Running/Jumping is a series
of controlled “trips”
24. ACKNOWLEDGMENTS…
I would like to express my
gratitude to Coach Jim Kiefer of
Vista Murrieta High School for
allowing me to borrow (quite
liberally) from his “Essentials of
Biomechanics” presentation.
And Thank YOU all very much for
your kind attention to this
presentation. I hope you enjoyed
it!
25. CAMERON T. GARY
USATF CERTIFIED - LEVEL 2 COACH
JUMPS
SPRINTS, HURDLES & RELAYS
USA WEIGHTLIFTING – LEVEL 1 COACH
www.ctgdevelopment.net
619-895-4699
jumpmaster@ctgdevelopment.net
