Audience: Anyone who goes to the gym By Jose M Batista.
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Transcript of Audience: Anyone who goes to the gym By Jose M Batista.
Audience: Anyone who goes to the gym
By Jose M Batista
Lever Systems
Click icon to add picture
Levers consist of
• Fulcrum (Axis, joints)
• Force (muscle pulling from
tendon
• Lever ( Long bone)
• Resistance
What is it?
• Less force is needed
• Disadvantage in speed
and ROM
• Not as Far
Advantage in Force Production
• Further and faster
• Disadvantage in force
• Harder to lift
• Human movement
Advantage in motion and
speed
Torque (moment)=force x
moment arm
With this equation we can
calculate how much force
do we need to move
objects around.
Calculations
There are three types of levers
• First Class Levers
• Second Class Levers
• Third Class Levers
Breaking it Down
• Axis is in the middle
• Examples are see-saw and cutters
• Advantage in force production
• In the body (cervical extension)
First Class Levers
Example First Class Levers
• Force arm is longer than the resistance arm
• Examples are wheelbarrow and nut cracker
• In the body (plantar flexion)
Second Class Levers
Example Second Class Levers
• Resistance arm is always longer than force
arm
• These are most used in the body
Third Class Lever
Example Third Class Levers
Body must create torque while objects create
an opposite torque
Weight of ball creates torque
Resistance*moment or resistance arm
Weight of ball*distance ball is from axis
Length of Lever and Effect
When lifting weights is it more advantages to have longer arms and legs or would it be a disadvantage and why?
Longer arms means the resistance arm is going to create more force/torque.
Would you expect 100 meter sprinters to be taller or shorter and why?
Its advantageous for a longer stride but it’s a disadvantage as well because you need more force to move that leg.
Why do you think kids going through puberty seem to run awkwardly?
Their resistance arms are growing and its difficult for them to move each limb.
Practical Questions
Objects held in longer limbs travel a greater distance in a given time period and so can move with higher velocities and speeds.
Tennis players can hit a tennis ball with more speed with a straight-arm drive than with a bent elbow because the lever is longer.
Examples
• Baseball pitchers, golf, football punter, etc.
• Kids leg lengths in running.
• Running speed (cycling rate)
While they will need more force to move limb, they have a “mechanical advantage in speed and ROM”.
Objects of Different Lengths
What affect does choking up on the bat do and how does it affect hitting the ball? Talk about mechanics and why?
Moving the axis will either make the lever longer or shorter letting you hit the ball further.
Can a skilled lacrosse player shoot a ball faster with a defensive pole(72in.) or an attackers pole(42in.)?
An attackers pole is easier to hit the ball because its moment arm is shorter.
What affect does hitting a tennis serve have when you hit the ball at its highest point vs. at a lower point?
When you hit the ball at its highest point it would be easier to cover more ground.
Practical Questions
• We use levers for everything
• Our muscles and bones act together to form a lever
• We use levers to move things more efficiently
• Levers can be used to increase movement
How is it used in general?
• Strength advantage
• Movement advantage
• But not both
• Able to pick up things
• Move efficiently
• Obtain better ROM
Why is it important?
Recap
• Clinicians
• Physical Education Teachers
• Curriculum Developers
• Athletic Trainers
• Exercise Physiologists
• Sport Psychologists Careers
Careers using Lever Systems