Lecture 9 Flashcards
What do differences in torque influence?
The direction and range of motion of the muscle motion.
Why are variable resistance strength machines beneficial?
Provide a constant load (force) but different torques requirements. This means the machine adjust strength depending on where the muscle is.
What is moment of inertia? When does it have a smaller value?
Resistance to Angular Motion. Smallest when object has a small mass and is able to rotate.
What happens to the moment of inertia if the mass is located closer to the axis of rotation?
It becomes smaller.
Name factors that affect the ability for muscles to generate force.
- Cross-sectional area
- Muscle fiber orientation
- Muscle length and velocity
- Prior activity (fatigue)
- Muscle fiber and motor unit composition.
Why do bigger muscles typically produce more force and therefore torque?
They have a bigger cross-sectional area and therefore have more muscle fibres and contract more and produce more force.
What is the difference between parallel and serial muscle fibres?
Serial means they are attached at different points and the more fibres there are, the muscles don’t get necessarily stronger. Fibres are attached to the same point and have a lot more resistance. The amount you can shorten and lengthen is always the same.
What is the difference between active and passive components of total force development.
Active: attachment of myosin cross bridges to actin filaments with a sarcomere.
Passive: stretching of connective tissue (sarcolemma, connective tissue).
In plantar flexion, what muscle does not change in length?
Soleus
Why do we still activate weaker muscles?
Because we can’t always activate muscles that their optimal length.
What do EMG do?
- Tell us which muscles are active and when.
- the amplitude increases as the intensity of the muscle contraction increases.
What type of concentric make the muscles stronger?
Slower contractions.
Can we activate all muscles to 100%
Depends, the will is somewhat more physiological than physical.
