Muscle Adaptation Flashcards
What are the 4 ways of expressing strength measures?
-absolute
-per kg BM
-per kg FFM
-per unit CAS
Does cross-sectional area effect absolute or relative force, or both?
It effects absolute force
-greater CSA = greater force production
How does body mass affect absolute strength and per Kg BM strength
-greater body mass causes an increase in absolute strength but a decrease in per kg BM strength due to the square-cube law
What are the mechanisms behind the decrease in strength with older age
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
What are the sex differences across the various ways to express strength measures
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
Why does strength training produce diminishing returns
-ceiling effect of hypertrophy
-fast newbie gains followed by reduction in hypertrophy rate
How does results of strength training differ in females compared to males
same relative increase
males have a greater absolute increase
How does hypertrophy work
-no increase in fibers
-increase in # of myofibrils
-increase in number of myofilaments
-no change in size of myofilaments
Overshoot recovery hypothesis
How does fiber length affect force if CSA is equivilent
-increase in range of motion
-increase in absolute range of the length-tension curve
-longer fibers= greater force at given velocity
How does difference CSA affect force when fiber length is equivalent
-length tension relationship shifts higher but shape remains the same
How does casting in a short position change the muscle
-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
How does casting in a long position change the muscle
-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
Chronic training
training will adjust sarcomere length to optimize trained activity
Why is there a large increase in type II fibers seen in spinal cord injury patients and sedentary individuals?
What causes a shift to type I dominated muscles
low intensity, high volume, low velocity
what causes a shift to type II dominated muscles
high intensity, low volume, high load, high velocity
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
-increased type II muscle fibers
-muscle length adjusted to the length that the individual often kept there limbs in
In a male who is over weight, would there be a strength/BM variation still observed between them and women?
yes because there is still less muscle mass per lean body mass and difference in fiber type ratios
For sports requiring absolute strength, what type of individual would dominate this sport
large people
