Studied by 2 people
Actin is what kind of filaments
Thin
Myosin is what kind of filaments
Thick
Force output is related to what?
The number of cross bridges occurring at the same time.
Force output is related to
active and passive components
Explain active component
voluntary activation-the number of cross bridges occurring at the same time
Explain passive component
no voluntary activation
Looking at the force length at a single fiber where is tension maximal?
At intermediate lengths and decreases at shorter and longer lengths
Looking at the force length at a whole muscle where is tension maximal?
At longer length because of the contribution of active and passive components
Looking at the force length at the joint where is the tension maximal?
At intermediate lengths and decreases at shorter and longer lengths, however does not correspond to the whole muscle relations, rather mimics the single fiber force-length relation
Because cross bridges slide past each other, is their reattachment slower or faster. Is it a mechanical separation?
Faster, therefore is a mechanical separation and no need for ATP
Looking at force-velocity for the whole muscle when does force output decrease?
shortening contractions
Why does force velocity decrease during shortening contractions?
Because the binding sites are missed as the thick and thin filaments slide past each other at a fast speed.
Looking at the joint where does force velocity decrease?
During shortening contractions the force output decreases with velocity.
During lengthening contractions where is force output with velocity.
it is constant
Is the force output influenced by the design of the muscle?
Yes, each muscle is different
When a muscle is arranged in series what is the ROM
Greater ROM
When muscles are arranged in parallel what is the ROM
less ROM but greater force generation
When muscles are arranged in pennation angle what does this mean
Maximize number of fibers in a given volume and thus max force capacity.
Although muscles produce linear forces motions at joints are all…
rotary
What is the rotary torque
Product of the linear force and the moment arm or the mechanical advantage of the muscle about the joints center of rotation.
What is the Torque equation
Force (N) x Lever arm (m)
Why do we have a patella?
It increases moment arm
Increases angle of pull on tibia
Some muscles have short tendons, Why?
Shorter moment arm will result in better involvement through ROM
Some muscles have long tendons, Why?
Longer MA will result in greater muscle torque generation
Many muscles cross 2 joints instead of one. Why?
Couple the movement of two joints, is better and more efficient for coordination
The shortening velocity of a two-joint muscle is less than that of its one-joint synergist
Redistribution of muscle torque, joint power, and mechanical energy throughout the limb
Explain concentric ROM
Muscle torque is greater than the load
Muscle shortens
Load is lifted, think the way up of a bicep curl
Explain Eccentric ROM
Muscle torque is less than load
Muscle lengthens
Load is lowered
Looking at an example recording of eccentric and concentric force output. What is the 2 y axis’s on the data chart
Left: SD of Acceleration
Right: AEMG
What happens to force output when we voluntarily shorten the muscle ?
Less Force
What happens to force output when we voluntarily lengthen the muscle?
Greater force
