Muscle Adaptation

Question 1

What are the 4 ways of expressing strength measures?

Answer 1

-absolute
-per kg BM
-per kg FFM
-per unit CAS

Question 2

Does cross-sectional area effect absolute or relative force, or both?

Answer 2

It effects absolute force
-greater CSA = greater force production

Question 3

How does body mass affect absolute strength and per Kg BM strength

Answer 3

-greater body mass causes an increase in absolute strength but a decrease in per kg BM strength due to the square-cube law

Question 4

What are the mechanisms behind the decrease in strength with older age

Answer 4

REDUCTION IN MUSCLE FIBER SIZE
-smaller CSA
REDUCTION IN # OF MOTONEURONS
-axonal degeneration causing reinnervation
LOSS OF MUSCLE FIBERS
-decrease in type I and type II
-greater decrease in type II
INCREASE IN MOTOR UNIT SIZE
-reinnervation of fibers by other units to preserve strength

Question 5

What are the sex differences across the various ways to express strength measures

Answer 5

Female have:
LOWER ABSOLUTE STRENGTH
-smaller CSA
LESS STRENGTH/BM
-greater body fat %
LESS STRENGTH/LBM
-less muscle mass per lean body mass
BIGGER DIFFERENCE IN UPPER BODY STRENGTH
-lower upper body: lower body muscle ratio
SMALL DIFFERENCE IN STRENGTH/CSA
-fiber type effect

Question 6

Why does strength training produce diminishing returns

Answer 6

-ceiling effect of hypertrophy
-fast newbie gains followed by reduction in hypertrophy rate

Question 7

How does results of strength training differ in females compared to males

Answer 7

same relative increase
males have a greater absolute increase

Question 8

How does hypertrophy work

Answer 8

-no increase in fibers
-increase in # of myofibrils
-increase in number of myofilaments
-no change in size of myofilaments

Question 9

Overshoot recovery hypothesis

Question 10

How does fiber length affect force if CSA is equivilent

Answer 10

-increase in range of motion
-increase in absolute range of the length-tension curve
-longer fibers= greater force at given velocity

Question 11

How does difference CSA affect force when fiber length is equivalent

Answer 11

-length tension relationship shifts higher but shape remains the same

Question 12

How does casting in a short position change the muscle

Answer 12

-decrease in number of sarcomeres
-muscle will produce max tetanic tension close to this length
-resting length resets to this length
-recover to normal length occurs when it is no longer casted

Question 13

How does casting in a long position change the muscle

Answer 13

-increase the number of sarcomeres
-muscle will produce max tetanic tension close to this length
-resting length resets to this length
-recover to normal length occurs when it is no longer casted

Question 14

Chronic training

Answer 14

training will adjust sarcomere length to optimize trained activity

Question 15

Why is there a large increase in type II fibers seen in spinal cord injury patients and sedentary individuals?

Question 16

What causes a shift to type I dominated muscles

Answer 16

low intensity, high volume, low velocity

Question 17

what causes a shift to type II dominated muscles

Answer 17

high intensity, low volume, high load, high velocity

Question 18

If a spinal cord injury patient were to miraculously gain function again, what type of fiber type changes would you expect to see, what type of muscle length variation would you expect

Answer 18

-increased type II muscle fibers
-muscle length adjusted to the length that the individual often kept there limbs in

Question 19

In a male who is over weight, would there be a strength/BM variation still observed between them and women?

Answer 19

yes because there is still less muscle mass per lean body mass and difference in fiber type ratios

Question 20

For sports requiring absolute strength, what type of individual would dominate this sport

Answer 20

large people