Movement Mechanics - Chapter 4 Flashcards
What is biomechanis
the study and analysis of human movement
Why is biomechanics so important in exercise theory?
Helps us to evaluate the effectiveness and safety of our programs and activities
What are the three types of muscle action?
- concentric
- eccentric
- isometric
What is concentric muscle action?
Action which causes the muscle to contract or shorten. The contractual force is greater than the force of resistance
What is eccentric muscle action?
Action which causes the muscle to lengthen or extend. The external force is greater than the concentrical force. In eccentric muscle action, the muscle is actually controlling the descent of resistance. The muscle’s origin and insertion point move further apart
What is isometric muscle action?
Action which engages the muscle but which does not require it to contract or to lengthen. The muscle becomes tense but length stays the same. Laying over a boca ball and staying flat - your spine and all your back and abdominal muscles are isometric - they are tense but not longer or shorter. Planking is a good example.
What are the 4 roles a muscle can assume? (also called movement roles)
- agonist
- antagonist
- stabilizer
- synergist
What is the agonist role of a muscle?
The agonist is the prime mover. It is the muscle that is doing the majority of the work.
Are agonist muscles responsible for doing most or least amount of initiation of movement?
Most
What is the antagonist role of muscle movement?
The antagonist role is the muscle working to stop the movement. It is also the muscle that assists with joint stability and protection.
What role of muscle movement assists with joint protection and stability?
Antagonist role
Muscle movement often happens in pairs - agonist and _______
antagonist
Muscle movement is often paired together - concentric and ______
eccentric
In a bicep curl, the agonist is the bicep and the antagonist muscle is the ______
tricept
In muscle movement theory - in a bicep curl, the bicep is moving ________ and the triceps is moving ________________
concentric
eccentric
What is the synergist role of muscle movement?
The synergistic muscle assists the prime mover. It provides added joint stability.
The synergist muscle is often engaged when we add weight to an exercise
What is the stabilizer role of muscle movement?
The stabilizer muscle is responsible for security of a joint or other body movement while another movement takes place. Ie the shoulder muscles functions as stabilizer to bicep curl. The shoulders are isometric in a bicep curl.
Key Movements in Exercise.
What muscles and movements are involved in an Abdominal Crunch?
Joint = spine
movement = flexion
against gravity
Action - concentric
muscle used - rectus abdominus
Key Movements in Exercise.
What muscles and movements are involved in Push Ups when arms are fully extended and body is lifted - Elbow joint?
Joint = elbow
movement = extension
against gravity
action - concentric
muscle used - triceps brachii
Key Movements in Exercise.
What muscles and movements are involved in push ups when arms are fully extended and body is lifted - from the shoulder joint perspective?
joint = shoulder
movement = horizontal adduction
against gravity
action - concentric
muscle - pectorales major
Key Movements in Exercise. What muscles and movements are involved in squats - when legs are in bent position and moving up to standing position - from the hip perspective?
joint= hip
movement =extension
against gravity
action = concentric
muscle - glutes and hamstrings
Key Movements in Exercise. What muscles and movements are involved in squats - when legs are in bent position and body is moving upwards to standing - from the knee perspective?
joint = knee
movement = extension
against gravity
action = concentric
muscle = quads
Key Movements in Exercise. What muscles and movements are involved in squats - viewed from front leg bent moring upwards to standing- hip joint?
joint = hip
movement = extension
against gravity
action = concentric
muscle = glutes and hamstrings
Key Movements in Exercise. What muscles and movements are involved in squats - viewed from front leg bent moving to standing position - knee joint?
Joint = knee
movement = extension
against gravity
action = concentric
muscle = quads
What is balance?
anticipating and reacting to outside forces
What 5 factors can affect balance and stability?
- Base of Support
- Center of Mass
- Line of Gravity
- Friction
- Inertia
What is Base of Support?
How much the body is in contact with the supporting surface.
The ______ the base of support, the greater the balance and stability.
wider
What is the Center of Mass?
An imaginary point where all the weight of the body is centered.
Where is the center of mass in most people?
near their belly button/pelvis area
What is an easy way to improve the center of mass and increase stability?
bend to a lower position. Move the center closer to the base.
What is the Line of Gravity?
An imaginary vertical line straight down through the center of the body.
Standing on 1 foot and holding a heavy suitcase in the opposite hand would be an imbalanced line of gravity.
What is friction?
the amount of resistance encountered when one surface meets another.
The _____________ the friction, the more effort is required.
Greater
True or false - there is more friction required to walk on ice than to walk on carpet?
False - ice has less friction.
What is Inertia?
Newton’s Law - those objects in motion will stay in motion; objects at rest will stay at rest unless a force acts upon them.
What is an easy way to use inertia principle to make an exercise more challenging?
Reduce the speed in which the exercise is done…….
The Human Lever System has 3 parts - name them.
- Lever - long bones
- Fulcrum - joints
- effort - muscles
What 4 factors can change the force of an exercise?
- increase resistance by adding weight
- changing the speed of an exercise - slower and more controlled movements are more challenging
- change the length of the lever - difference between push ups on knees vs on toes
- change the angle of the pull - the wider the angle, the harder the exercise is.
Using 5 factors, modify a lunge exercise to affect stability and balance.
- Change the base of support - lunge onto a boco ball as a base.
- change the center of mass - do the lunge with arms raised high above the head to increase the center of mass.
- change the line of gravity - lunge with left foot while holding a weight in right hand.
- change friction - lunge on a slider to decrease friction and make exercise more challenging
- inertia - place a bar bell with weights on the shoulders of the participant to increase inertia and make the lunge more difficult.
Modify a squat using the 4 factors to change the force of the exercise.
- add weight - a bar bell with weights on the shoulders of participant
- decrease the speed of the exercise to make it more challenging
- change the length of the level - make the squat deeper, challenging the participant to lower their behind as far down towards the floor as they can.
- Change the angle of the pull - do squats with hands above the head to change the center of mass and angle of the squat
