When you lift weights, your muscles temporarily stop building protein, but right after you finish, they kick into high gear to repair and grow—this happens because key signaling molecules in your muscles get activated during recovery.

In healthy adult humans, muscle protein synthesis rates are measured via stable isotope labeling before, during, and at 1-hour and 2-hour intervals after a standardized resistance exercise session, while concurrent muscle biopsies assess phosphorylation levels of Akt, mTOR, and S6K1; comparator is pre-exercise baseline.

In healthy adult humans, muscle protein synthesis and phosphorylation of Akt, mTOR, and S6K1 are measured at multiple time points (0, 30, 60, 90, 120 min) after resistance exercise to establish the precise temporal relationship between molecular signaling and protein synthesis kinetics.

In healthy adult humans, inhibition of mTOR or Akt signaling during recovery from resistance exercise blocks the post-exercise increase in muscle protein synthesis, confirming the mechanistic role of these kinases.

In mice with muscle-specific knockout of mTOR or Akt, resistance exercise fails to stimulate post-exercise muscle protein synthesis, confirming the necessity of these pathways.

In human skeletal muscle myotubes, mechanical stretch or simulated resistance exercise induces phosphorylation of Akt, mTOR, and S6K1, followed by increased protein synthesis, replicating the in vivo sequence.