The individual hypertrophic responses to resistance training (RT) is highly variable and could be one of the main reasons why some RT protocols do not result in positive muscle adaptations in all individuals. Our group successfully investigated (FAPESP funded, #2012/24499-1, #2014/19594-0 and #2013/21218-4) the relation between acute integrated myofibrillar protein synthesis (MyoPS) and chronic hypertrophy in different RT phases. In this project we aim to determine the individual MyoPS responses to RT protocols manipulating variables (e.g., load, number of sets, type of contraction, rest between sets) vs. a control RT protocol, when all are performed up to muscle fatigue. Using an unilateral design in trained men we want to evaluate a currently unanswered question: is there any importance of manipulating RT variables when applying RT up to muscle fatigue, or is fatigue really enough to maximize MyoPS independent of other RT modulations? We propose to analyse the MyoPS responses in 20 previously trained men following an acute RT session in which one leg performed a control RT protocol (RT-CON) - leg 1 (n=20) and the contralateral leg performed RT with either load variation, sets, contraction type or rest interval (RT-VAR) - leg 2 (n=5 per condition). For MyoPS measurements, subjects ingested deuterated water two days before the acute protocols, saliva samples were collected daily and bilateral muscle biopsies were conducted before and 24h and 48h after the protocols. Our hypothesis is that the inter-individuals variability of the MyoPS response will be high, and performing distinct RT protocols can promote slight differences in intra-individual MyoPS response. However, since all RT protocols proposed herein are all are performed to fatigue resulting in moderate to high training volumes, maybe the slight changes in MyoPS will not be enough to show significant differences in the intra-individual MyoPS response among RT protocols.
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