IB SEHS- SL

Fundamentals of Biomechanics

Preparatory - Execution - Follow ThroughPhases of Motion

Why is it important to break motion down into phases?

So we can evaluate and correct in order to improve performance & prevent injury

In a ready position The movements that get the player ready for the force-producing movements

Preparatory Phase

performs the movements that produce force, impact or propulsion (kicking, hitting).

It is also at the point of contact or release of the movement

Execution Phase

movement slows down after impact and the player prepares for the next action.

Important in slowing the body parts down over a longer period of time.

Absorbing the forces produced and helping to prevent injuries.

Follow Through

Basketball - Bounce Pass

Preparation: • both hands on the ball• elbows in, wrist cocked, fingers spread (use finger pads)

Basketball bounce pass video clip.

Execution: • step forward with one foot• extend arms and snap wrists• bounce ball on floor approximately 2/3 of the distance between you and target (bounce pass)

Follow-Through: • finish with arms extended and palms facing out and thumbs pointing down

Video Clip. Cricket vs Baseball (6 min)

Additional questionWhich sport is it harder to hit the ball?

Observe the differences in the two swings.

clip of pitching phases of motion (5min)

Rigid structures hinged at one point (fulcrum) to which forces are applied to two other points (effort and load)

What is a lever?

Resistance arm- distance between load & fulcrum Effort arm- distance between effort & fulcrum

What parts of the body are used to create a lever?

Fulcrum

Effort

Load

Joints

Muscles

Resistance, gravity, weight

1. First Class Lever: The fulcrum lies between the effort and

load.

Levers

2. Second Class Lever: the fulcrum lies at one end with the effort at the other and the load in the middle. Ex. Standing heel raise

Levers

mechanical advantage is greater than 1, which means larger loads can be moved with less effort.

3. Third Class Levers: the effort lies between the load and the fulcrum.

Levers

Mechanical advantage is less than 1, which means more effort to move smaller loads.

Human body and LeversBiceps flexion & triceps extension are antagonistic muscle actions. Each can work as a lever. What type of levers are acting on each side of the humerus? Draw a picture of each lever.

Human body and Levers

What type of lever is at the neck when you flex and extend?

Human body and Levers

What type of lever is at the toes joints when you go up on your toes?

Types of Levers

Levers

How can the length of a limb change the how a lever functions?

Long levers result in greater speed at the end of a limb. This in beneficial for throwing or striking an object.

Short lever can be moved with less force and at a greater speed. This is beneficial for moving body parts quickly and applying strength for pushing, pulling and lifting.

In the human body, levers are made of joints (fulcrum) and the bones that connect them to the objects being moved.

Levers in the human body can be manipulated to improve speed & apply large forces at the same time

Can you think of any situation in the human body where this occurs? (hint: think about changing the length of a limb).

Running – lifting your foot and knee will create a shorter lever arm and increase speed.

Boxing- flexing elbow creates a shorter lever arm and increase speed of a punch.

Compare the throwing of a ball by hand and with the throwing of a ball with a jai alai basket, lax stick… Which is faster?

About 170mph Fastest shot 111mphAbout 95-100mph

Lincecum clip Jai Alai clip lacrosse shot clip

How can a 5’10” pitcher be such a powerful pitcher?

The normal stride length for a pitcher is 77% to 87% of his height. Lincecum's stride is 129%, some 7 1/2 feet

An excessively large stride increases the speed the arm can move as a 3rd class lever. See picture on next page.

Effort

Load

Fulcrum

Vocabulary

ScalarVectorForceSpeed

Velocity

AccelerationDistance

DisplacementMomentum

Impulse