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Old 11-10-2013, 09:26 AM
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Join Date: Nov 2013
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Default Conflicting reports on MPS refractory period

Hey Guys,

After reading Layne Norton's article on protein meal size and frequency I drastically changed my nutritional plan by having larger protein doses with BCAA's in the middle. (

Several studies have shown that the duration of protein synthesis in
response to an oral leucine dose or an essential amino acid infusion is approximately two hours long (4,5).

However, these are purified amino acid solutions and are likely to be digested
rapidly and in the case of an infusion, no digestion is required at all. So it is possible that a whole food meal will have a different impact on the duration of protein synthesis than pure amino acids.

Our lab has recently shown that the duration of protein synthesis in response
to a complete meal containing protein, carbohydrates, and fats is approximately 3 hours long.
So it seems MPS becomes refractory for 2-3 hours after the ingestion of the protein. In the following article ( Norton seems to suggest this is because muscle ATP levels (which are required for MPS) seem to become depleted and have to be replenished with either a carbohydrate meal or a dose of BCAA's.

I was recently researching a bit more into this and found this paper ( They have termed this refractory period to be "muscle-full" but the pertinent extract of this article relevant to my question is this

There has been considerable work undertaken to determine the optimal timing of nutritional intake in order to maximise post-exercise MPS and ensuing adaptations to training (Cribb & Hayes, 2006; Hoffman et al. 2009). In general, we believe that it is largely irrelevant whether the feed is given pre-, during or post-exercise. This is because the delaying of the muscle-full response appears to last at least 24 h (Burd et al. 2011) after a single bout of exercise, which may help explain chronic adaptations such as hypertrophy/remodelling of muscle over time, independent of proximity-dependent feeding patterns (see Fig. 2).
They seem to suggest that there is a delay in the refractory period for upto 24 hours after training. This would imply that there is no need to dose with BCAAs during the first 24 hours to re-initiate MPS.

3 hours of MPS vs. 24 hours of MPS are both conflicting and vastly different values. There must be something I'm missing, can anyone shed any light on why this might be?
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