Lecture #7

Question 1

• How do muscles work with the skeleton?

Answer 1

○ Muscles pull on the skeleton.

Question 2

• What are the benefits of the bundle of bundles muscle structure?

Answer 2

○ Similar design to a cable.
§ Increased strength when working together
○ Equal work/pull distribution
○ Stronger/more efficient muscle contraction
○ Less tissue damage

Question 3

• How do the protein filaments in the muscle cell interact with each other to cause force generation?

Answer 3

○ The myosin filaments attach to the actin filaments. And pull the muscle tissue closer together- so the muscle shortens.

Question 4

• What are the terms for these filaments?

Answer 4

○ Myosin-thin protein filament

○ Actin-thick protein filament

Question 5

• What is a motor unit and what determines the size of motor units?

Answer 5

○ A neuron and all of the muscle fibers in which it connects

○ The task of the motor unit determines the size

Question 6

• What is the all-or-none principle?

Answer 6

○ The nerve impulse is either a full strength impulse or the impulse does not occur
○ Result is either all of the muscle fibers connected to a nerve contract, or none.

Question 7

○ Slow twitch

Answer 7

is predominant in individuals which high endurance capabilities
			§ Contraction time: slow
			§ Resistance to fatigue: high
			§ Force production: low
			§ Aerobic
			§ High mitochondrial density
			§ High capillary density
			§ Fuel storage: triglycerides (fat)
Color: dark red

Question 8

○ Fast twitch type iia

Answer 8

is predominant in individuals successful in power/anaerobic activities.
			§ Type iia
				§ Contraction time: fast
				§ Resistance to fatigue: intermediate
				§ Force production: high
				§ Long term anaerobic
				§ High mitochondrial density
				§ intermediate capillary density
				§ Fuel storage: CP glycogen 
Color: red

Question 9

○ Fast twitch type iix

Answer 9

§ Type iix
				§ Contraction time: very fast
				§ Resistance to fatigue: low
				§ Force production: very high
				§ Short term anaerobic
				§ low mitochondrial density
				§ Low capillary density
				§ Fuel storage: CP glycogen 
Color: white

Question 10

• Why can’t fiber type change from fast to slow twitch and vice versa?

Answer 10

○ In order to change the type, the wiring in the body must be changed. The neuron sets the fiber type by firing at a certain electrical frequency. Every time it fires it sends out the same electric frequency. Since we can’t change the wiring we can’t change the fiber type.

Question 11

• What are the 3 types of resistance training that are most commonly associated with a wt. training program?

Answer 11

○ Isometric
○ Isotonic
○ Isokinetic

Question 12

• How does a muscle “contract” and yet have no length change?

Answer 12

○ The actin and myosin engage and produce force, but they don’t change the muscle length

Question 13

• How does demonstration of strength in an isometrically trained muscle differ from a muscle which moves through a full range of motion?

Answer 13

○ An isometrically trained muscle is very angle dependent. In other words, the muscle is built at the angle in which the muscle is worked out in.
○ Athletically, isometric training also has much more limited applications as well.

Question 14

• Why might isometric exercise/contraction be detrimental to your health?

Answer 14

○ The contraction of the muscles lead to a contraction of the blood vessels.
○ Blood pressure will go up if you block it, and circulation doesn’t occur as much.
○ Harmful to cardiovascular system because of this

Question 15

• What are concentric and eccentric contractions? When are these used?

Answer 15

○ Concentric - shortening phase of the muscle cell
○ Eccentric - lengthening phase of the muscle cell
§ Eccentric is typically not focused on as much, but should be
§ Most strength gains are from eccentric

Question 16

• What are variable and constant resistant exercises? When are these used?

Answer 16

○ Variable resistance exercise is when a variable load is placed throughout the range of motion of the exercise.
§ Adjusts load to match your strength curve. Your effort stays constant.
○ Constant weight, constant resistance

Question 17

• What is isokinetic wt. training and how is it generally used?

Answer 17

○ Muscle activity performed at constant angular velocity
○ Torque and tension remain constant as muscles shorten
○ Most frequently used in rehabilitation setting