Effect of a restrictive breathing mask on resistance exercise performance in resistance-trained males.
Andre, Thomas L., 1987-
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The purpose of this study was to define the impact a RBM has on performance variables, and genes potentially impacted by the stressful nature of the RBM. In a cross-over design, ten participants performed two separate testing sessions, RBM and No Mask, consisting of squat, leg press, and leg extension. Muscle samples were obtained at baseline, 3hr, 6hr, and 24hr post-exercise. Blood samples were obtained to examine cortisol at baseline, 30min, 3hr, 6hr, and 24hr post-exercise. From each muscle sample, glucocorticoid receptor-DNA (GR-DNA) binding and mRNA expression of Atrogin-1, Foxo1, MuRF1, MAFbx, Myostatin, and REDD1 was determined. Two-way repeated-measures analyses of variance (ANOVA) were performed (p ≤ 0.05) with condition and time as main effects. Paired-samples t test was utilized for session rating of perceived exertion (S-RPE). There was a significant decrease in total repetitions during the RBM session (p = .001). A majority of the decrease in repetitions to failure occurred in the squat (p = .030) and in the leg press (p = .001), while no difference was observed in leg extension (p <=.214). There was a significant increase in S-RPE during the RBM session (p = .004). There was a significant increase in pre-stress (p = .007) and post-stress (.010) in the RBM session. No significant difference between mean HR between exercise sessions (p = .083). There was a significant decrease in pulse oximetry during the RBM session (p = .002). No significant interactions between session and time for Atrogin-1, Foxo1, MuRF1, MAFbx, Myostatin, and REDD1. There was no main effect for session for serum cortisol. There was a significant interaction between session and time for GR- DNA binding. For the RBM session, compared to baseline GR-DNA binding was significantly elevated at 3-hr (p = .007), 6-hr (p > .001), and 24-hr (p = .002) post-exercise. The use of a RBM negatively impacted the amount of repetitions completed during an acute session of lower-body resistance training, but failed to affect serum cortisol or alter the expression of proteolytic genes.