Global DNA Methylation Status in Relation to Resistance Training with High vs Low Loads to Failure

Abstract

Objective:
Our objective was to determine how global DNA methylation status of skeletal muscle differs with resistance training (RT) to failure in trained participants using either 80% of their estimated one-repetition maximum (Est. 1-RM) (80FAIL) or 30% of their Est. 1-RM (30FAIL).

Hypotheses:
We hypothesize there will be a significant decrease in global DNA methylation with both RT conditions, but that 30FAIL RT will elicit a greater magnitude of hypomethylation than 80FAIL RT.

Methods:
Previously trained college-aged males (n= 11, age 23 ± 4 years, percent fat 11.4 ± 6.4%, training experience 4 ± 3 years, squat strength relative to body weight 1.7 ± 0.3) voluntarily underwent two bouts of RT. Participants completed both the 80FAIL and 30FAIL conditions (separated by one week). For each bout of RT, participants completed 4 sets of back squats and 4 sets leg extensions with either the 80FAIL or 30FAIL training conditions. Muscle biopsies were collected from the vastus lateralis before (PRE), 3 hours (3hPOST), and 6 hours (6hrPOST) after each RT bout. DNA was then batch-isolated from muscle tissue and submitted for analysis using the Illumina MethylationEPIC array.

Results:
Total number of repetitions performed were significantly higher for 30FAIL training vs 80FAIL training (p< .001), however total training volume (sets x reps x load) was not significantly different between conditions (p= 0.571). Global methylation changes between PRE, 3hPOST, and 6hPOST are presented herein. In addition, significant differences between conditions are emphasized for each post-exercise time point.

Conclusions:
With this study we expand our understanding of how the manipulation of RT variables affect epigenetic modifications in skeletal muscle.