Protein metabolism and exercise

Question 1

ex increases MPS and MPB

Answer 1

response of MPB is less and stays elevated for less time than MPS

still increases above that at rest

Question 2

muscle protein balance elevated for up to 48h following REx in UT

Answer 2

less neg than at rest - elevated but still neg

Question 3

response of MPS to diff dose of ex

Answer 3

increasing intensity led to an increase in MPS when conditions were work matched

different story if you work to failure

recruit both types of fibres

Question 4

MPS appears to be dose dependant

Answer 4

trained vs untrained

MPS ↑ 43% following 8x10 @80% REx before training

MPS ↔ following 8x10 @ same absolute intensity following training (~55-60%
1RM)

Question 5

absolute intensity

Answer 5

watts, speed etc

aim for same VO2

actual intensity same pre –> post

Question 6

relative intensity

Answer 6

% of max

Question 7

MPS dose dependant and specific

Answer 7

Trained swimmers

MPS↔ in rear deltoid following Rex

MPS ↑ 40% following 1h swim workout

MPS ↑ 80% following 1h swim workout and REx

have to stress body in right way and at high enough intensity - reg try and test yourself to know need to continually stress yourself

Question 8

intense ex reduces MPS in rats

Answer 8

2h treadmill running at 80% VO2 max - FSR lower with ex

equivalent to marathon pace for 24h

NO evidence in humans

probably not able to measure it!

Question 9

apparent paradox

Answer 9

both endurance and resistance exercise stimulate MPS yet the phenotypic adaptations to each are very different!

Question 10

muscle proteins

Answer 10

diff centrifuge speeds determine which proteins you get out

Question 11

diff muscle proteins and type of ex (UT)

Answer 11

REx increases myofibrillar protein synthesis

EE and REx increase mitochondrial protein synthesis

Question 12

diff muscle proteins and type of ex (T)

Answer 12

higher myofibrillar protein synthesis at rest and post REx
in REx leg

higher mitochondrial protein synthesis post EE

response more specific

Question 13

changes in muscle with 28D bed rest

Answer 13

leg lean mass -300
leg fat mass +370
muscle CSA - 1004
1 RM leg strength -18

Question 14

what happens after 1 week bed rest?

Answer 14

lose muscle, strength and lean body mass

Question 15

elderly muscle

Answer 15

muscle mass is lost with aging.

the effect of aging on elderly muscle is somewhat controversial.

decreased protein synthesis?

basal?

response to feeding?
inactivity?

increased protein breakdown?

Question 16

how much muscle is lots per decade with age?

Answer 16

6%

Question 17

muscle loss due to changes in basal levels of MPS with age

Answer 17

if this decrease is responsible for muscle loss, it would be catastrophic and physiologically impossible.

= muscle loss of ~60%/y

changes in basal muscle protein synthesis must be very small (undetectable) if they account entirely for loss of muscle with age.

Question 18

success of high-intensity resistance training in nonagenarians (90+)

Answer 18

mid thigh muscle +9%

leg strength +174%

walking gait speed +48%

Question 19

REx alone doesn’t result in pos net muscle protein balance

Answer 19

resistance exercise of sufficient intensity stimulates mixed muscle protein synthesis and breakdown

protein synthesis is stimulated more than breakdown

net muscle protein balance is improved

Question 20

MPS response to ex and nutrition

Answer 20

exercise stimulates MPS

amino acids stimulate MPS

exercise and amino acids have a synergistic effect on stimulation of MPS

Question 21

net muscle protein balance in response to ex and nutrition

Answer 21

exercise improves net balance but without amino acids positive values not reached

exercise and amino acids increase muscle protein balance and results in a positive protein balance

Question 22

nutrient intake and muscle protein balance

Answer 22

balance changes throughout day

areas of pos and neg balance cancel each other out

Question 23

interaction of ex and nutrient intake on muscle protein balance

Answer 23

ex makes balance less neg

respond better to food = more pos balance

respond better to every meal after - 48h after ex

Question 24

muscle protein accretion

Answer 24

pos > neg

nutrient consumption following exercise stimulates muscle protein synthesis and inhibits the exercise-induced rise in protein breakdown

this way muscle mass is gradually increased