Acute and chronic resistance training downregulates select LINE-1 retrotransposon activity markers in human skeletal muscle

Herein, we examined if acute or chronic resistance exercise affected markers of skeletal muscle LINE-1 retrotransposon activity. In study 1, 10 resistance-trained college-aged males performed three consecutive daily back squat sessions, and vastus lateralis biopsies were taken prior to (Pre), 2 h following session 1 (Post1), and 3 days following session 3 (Post2). In study 2, 13 untrained college-aged males performed a full-body resistance training program (3 d/wk), and vastus lateralis biopsies were taken prior to (week 0) and ~72 h following training cessation (week 12). In study 1, LINE-1 mRNA decreased 42-48% at Post1&2 (p<0.05), and reverse transcriptase (RT) activity trended downward at Post2 (-37%, p=0.067). In study 2, LINE-1 mRNA trended downward at week 12 (-17%, p=0.056) while LINE-1 promoter methylation increased (+142%, p=0.041). ORF2p protein expression (-24%, p=0.059) and RT activity (-26%, p=0.063) also trended downward by week 12. Additionally, changes in RT activity versus satellite cell...