Protein metabolism and exercise Flashcards
ex increases MPS and MPB
response of MPB is less and stays elevated for less time than MPS
still increases above that at rest
muscle protein balance elevated for up to 48h following REx in UT
less neg than at rest - elevated but still neg
response of MPS to diff dose of ex
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
MPS appears to be dose dependant
trained vs untrained
MPS ↑ 43% following 8x10 @80% REx before training
MPS ↔ following 8x10 @ same absolute intensity following training (~55-60%
1RM)
absolute intensity
watts, speed etc
aim for same VO2
actual intensity same pre –> post
relative intensity
% of max
MPS dose dependant and specific
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
intense ex reduces MPS in rats
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!
apparent paradox
both endurance and resistance exercise stimulate MPS yet the phenotypic adaptations to each are very different!
muscle proteins
diff centrifuge speeds determine which proteins you get out
diff muscle proteins and type of ex (UT)
REx increases myofibrillar protein synthesis
EE and REx increase mitochondrial protein synthesis
diff muscle proteins and type of ex (T)
higher myofibrillar protein synthesis at rest and post REx
in REx leg
higher mitochondrial protein synthesis post EE
response more specific
changes in muscle with 28D bed rest
leg lean mass -300
leg fat mass +370
muscle CSA - 1004
1 RM leg strength -18
what happens after 1 week bed rest?
lose muscle, strength and lean body mass
elderly muscle
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?
how much muscle is lots per decade with age?
6%
muscle loss due to changes in basal levels of MPS with age
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.
success of high-intensity resistance training in nonagenarians (90+)
mid thigh muscle +9%
leg strength +174%
walking gait speed +48%
REx alone doesn’t result in pos net muscle protein balance
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
MPS response to ex and nutrition
exercise stimulates MPS
amino acids stimulate MPS
exercise and amino acids have a synergistic effect on stimulation of MPS
net muscle protein balance in response to ex and nutrition
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
nutrient intake and muscle protein balance
balance changes throughout day
areas of pos and neg balance cancel each other out
interaction of ex and nutrient intake on muscle protein balance
ex makes balance less neg
respond better to food = more pos balance
respond better to every meal after - 48h after ex
muscle protein accretion
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
