The key to protein synthesis

[KingProtein]

We've been told that protein synthesis is elevated for up to 36-48 hours post workout. We've also been told that there is a postworkout 'window of opportunity' where much of what we eat is going towards muscle growth.

My question is, are we confusing the high glycogen restoration rates postworkout with actual protein synthesis? Is there really any major muscle growth going on at this time?

Studies I have found are contradictory;

In;
Mixed muscle protein synthesis and breakdown after resistance exercise in humans. (Phillips SM, Tipton KD, Aarsland A, Wolf SE, Wolfe RR.)

"Exercise resulted in significant increases above rest in muscle FSR at all times: 3 h = 112%, 24 h = 65%, 48 h = 34% (P < 0.01)."


But in;
The time course for elevated muscle protein synthesis following heavy resistance exercise. (MacDougall JD, Gibala MJ, Tarnopolsky MA, MacDonald JR, Interisano SA, Yarasheski KE.)

"It has been shown that muscle protein synthetic rate (MPS) is elevated in humans by 50% at 4 hrs following a bout of heavy resistance training, and by 109% at 24 hrs following training."
and
"It is concluded that following a bout of heavy resistance training, MPS increases rapidly, is more than double at 24 hrs, and thereafter declines rapidly so that at 36 hrs it has almost returned to baseline."

Anyone have any enlightening words that can help explain this situation?

 

[Brian Withers]

Probably depends on the how the exercise was done (relative load, the volume done, etc) and the condition of the muscle (how deconditioned or not was the muscle). So both were true, but other variable changed.

 

[KingProtein]

Just to add a note about the exercise scheme for each;

In the first study;
"Six healthy young men performed 12 sets of 6- to 12-RM elbow flexion exercises with one arm while the opposite arm served as a control."

While in the second;
"Exercise was eight sets of eight concentric or eccentric repetitions at 80% of each subject's concentric 1 repetition maximum."
The researchers noted that there was no significant difference between contraction types for either FSR, FBR, or net balance (FSR minus FBR).
FSR=fractional synthesis rate
FBR=fractional breakdown rate

While exercise differences can conceivably change the timeframe for protein synthesis, I have a hard time believing it could account for the drastic differences seen in these studies. It's true that a lot of variables are at work here, but under 'normal' conditions, (say, using the HST program with adequate nutrition), can we conclude anything? Perhaps not.

My main point was to question whether or not this postworkout 'window of opportunity' is indeed supported by research, or if it's just another dogma. From what I have read, it seems to me that the main point of pre-post workout nutrition is not so much muscle growth, but instead recovery. Additionally, if that second study is closer to real world conditions than the first, maybe we ought to concentrate our calories more at about the 24hr mark after a workout, rather than concentrated during the postworkout period.

 

[Aaron_F]

Quote[/b] ]My main point was to question whether or not this postworkout 'window of opportunity' is indeed supported by research, or if it's just another dogma. From what I have read, it seems to me that the main point of pre-post workout nutrition is not so much muscle growth, but instead recovery. Additionally, if that second study is closer to real world conditions than the first, maybe we ought to concentrate our calories more at about the 24hr mark after a workout, rather than concentrated during the postworkout period.

yes it is. Glycogen synthesis after a single session like HST isnt as important as the total carb intake over 24hr or so post workout. having protein/carbs before and/or after training will increase protien synthesis above that than just done by training alone. But, the amount is very small, and hypertrophy is more the combined tiny increases over a long period.

 

[imported_edziu]

KingP -- there are many ways to measure anything, and one of the studies is measuring "synthesis and breakdown." You have to make sure they're counting the same fruits before you compare apples to oranges.

Bryan went by mRNA levels, which are a strong indicator of actual synthesis, and based his recommendation on their time curve.

 

[Aaron_F]

Most of tiptons work follows the same measure, (and tarnoploisky) fractional synthesis rate and fractional breakdown. Giving a measure of balance. Still not perfect as the overall changes is extremely small (especially since they are measuring it over 1 day, and you dont grow over one day)

While exercise differences can conceivably change the timeframe for protein synthesis, I have a hard time believing it could account for the drastic differences seen in these studies. It's true that a lot of variables are at work here, but under 'normal' conditions, (say, using the HST program with adequate nutrition), can we conclude anything? Perhaps not.
[/quoe]Exercise differences will cover basically all the differences. The group that protien synthesis remained higher was trained using a much higher volume.
mRna levels can be useful, but you have to decide which rna to track, adn tehre is a pleasant multitude of different ones to choose and unless those mRna are transcribed into actual protein, they dont mean a whole heap...