CSCS chapter 2: Biomechanics of resistance exercise

what are fleshy muscle attachments

commonly found at the proximal ends of muscle, the fibers are fixed to the bone over a wide area to distubute force

what are fibrous muscle attachments

tendon attachments where muscle sheath continues into connective tissue extending into the bone

what is the agonist

the prime mover of a motion

what is the antagonist

a muscle that can slow down or stop the movement

what does the antagonist do during motion

stabilizers or slows the motion down to protect a joint

what is a synergist

a muscle that indirectly assists a movement

when are synergists required

when the agonist muscle crosses two joints

what is a first class lever

The fulcrum (joint) lies between the applied force and the resistance force (opposed force)

what is the moment arm

the perpendicular distance from the line of action to the fulcrum

what is a second class lever

The resistance is in the middle, the axis is on one end and the force on the other (like a wheelbarrow).

what is an example of a second class lever

the foot during plantar flexion; the calf is the muscle force the leg is the resistant force and the fulcrum is the ball of the foot

what is a third class lever

A lever with the effort in the middle of the fulcrum and resistance

what is an example of a third class lever

bicep curl; the elbow is the fulcrum, the muscle force is in the middle from the bicep, and the weight in on the end as the resistance

what is strength

the ability to exert force

what is work

the product of force and displacement or the change of mechanical energy

what is mechanical energy

the sum of potential energy and kinetic energy

what is power

how quickly work is performed

what are scalar quantities

only provide magnitude

what are vector quanitites

have magnitude and direction

what is rate coding

the rate at which motor units are fired

what is a pennate muscle

fibers align obliquely with the tendon making a feather like appearance

what is the angle of pennation

the angle between muscle fibers and an imaginary line between the muscles origin and insertion

what occurs to the angle of pennation as a muscle contracts

it increases

what is the benefit of muscles with greater pennation

they have more sarcomeres in parallel and less in series making them able to generate more force but at a lower velocity

what are the benefits of muscles with low pennation

they can produce higher velocity forces due to having more sarcomeres in series

at what muscle length can muscles generate their greatest force

at resting length due to the actin and myosin filaments being aligned alongside each other allowing for the maximal amount of crossbridges

what is titin and what does it do

it is a muscle filaments that tightens during an eccentric muscle action beyond resting length to help align myosin filaments to increase their crossbridge sites

what occurs in muscle as velocity of contraction increases

force decreases

what is the bracketing technique

an athlete performs a sport movement with less than normal and more than normal resistance to improve acceleration

how is friction calculated

resistive force= k x normal force

what is surface drag

the friction of fluid passing along the surface of an object

what is form drag

resistance from the way fluid presses against the front or rear of an object passing through it

what do fluid resisted machines provide

they provide resistance that increases with velocity and force the agonist to work concentrically performing the motion and the antagonist to work concentrically returning to the start

what is impulse

change in momentum