The Claim

In adult male C57BL/6J mice, high-intensity muscle contraction induces greater phosphorylation of mTORC1 downstream targets S6K1 and rpS6 during the light phase compared to the dark phase, without resulting in time-of-day differences in contraction-induced protein synthesis rates.

Source: Time-of-day effect of high-intensity muscle contraction on mTOR signaling and protein synthesis in mice

What the research says

Supports is higher

Support is ahead, but a single strong opposing study can change this.

Supports
18score
Challenges
0score

These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.

How it works
1 study reviewed
In plain English

In adult male C57BL/6J mice, high-intensity muscle contraction leads to higher activation of mTORC1 signaling proteins during the light phase than during the dark phase, but the rate of muscle protein synthesis remains unchanged between these times.

See the scientific wording

In adult male C57BL/6J mice, high-intensity muscle contraction induces greater phosphorylation of mTORC1 downstream targets S6K1 and rpS6 during the light phase (sleep period) compared to the dark phase (active period), suggesting circadian regulation of mTOR signaling sensitivity in skeletal muscle, though this does not translate to time-of-day differences in contraction-induced protein synthesis rates.

Why this might work

During sleep, lower levels of a protein called REDD1 and higher phosphorylation of another protein called PRAS40 remove brakes on a growth signal pathway in muscle cells, making the pathway more active after exercise — but this increased signaling does not lead to more protein production because muscle cells use a different, unrelated pathway to make proteins after exercise.

Verified mechanismbased on 1 study

What the research says

1 study

  1. Study: Time-of-day effect of high-intensity muscle contraction on mTOR signaling and protein synthesis in mice

    In mice, when muscles are worked during sleep, the body’s growth signals turn on stronger than when worked during active hours — but the actual amount of new muscle made stays the same no matter the time. So, the signals change, but the outcome doesn’t.

Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies

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