The Effect of Changing the Contraction Mode During Resistance Training on mTORC1 Signaling and Muscle Protein Synthesis

In conclusion, changing the contraction mode to EC does not reinvigorate the blunted mTORC1 activation and MPS in response to RE during chronic RT. Introduction Resistance exercise is known to stimulate muscle protein synthesis (MPS), and chronic resistance exercise training induces muscle hypertrophy (Ogasawara et al., 2016). Muscle hypertrophy is believed to occur as increased MPS enables new myofibrils to be added to pre-existing muscle fibers (Glass, 2003). Although the detailed molecular mechanisms of the resistance exercise-induced increase in MPS remain unclear, recent research revealed that the both rapamycin-sensitive and -insensitive mechanistic target of rapamycin complex (e.g., mTORC1 and/or mTORC2) plays a role in this event (Ogasawara et al., 2016; West et al., 2016; Ogasawara and Suginohara, 2018). Several studies have reported that acute resistance exercise induces mTORC1 activation, which is typically evaluated by measuring the phosphorylation of its downstream targets, such as p70S6K and 4E-BP1 (Burd et al., 2010a,b). The time course of muscle hypertrophy by resistance training has been well studied. In general, muscle hypertrophy is greater during the early phase of resistance training (e.g., up to 2–3 months) than during the later phase (Woolstenhulme et al., 2006; Ogasawara et al., 2013b; Brook et al., 2015). Similarly, recent studies have reported that both mTORC1 activation and the MPS response are greater during the early phase of resis...
Source: Frontiers in Physiology - Category: Physiology Source Type: research