(OG) threatened weightlifting’s place at the 2024 OG. Despite this, analysing doping practices in weightlifting and an investigation of IOC re-test efficacy, across all summer OG sports, is outstanding. AAS induce human hypertrophy via increasing myonuclei, and mice data suggests myonuclei permanency causing a “memory” of exposure and long-term advantage. However, limited human data exists on past AAS users and there is no longitudinal data post AAS exposure. Furthermore, RNA-Seq has yet to be conducted on human samples exposed to AAS. Chapter 1 outlines an introduction and Chapter 2 methodologies. Chapter 3 provides results of analysing weightlifting doping practices from

2008-2019 and identified continental differences in detected substances. Chapter 4 analysed doping that impacted medal results for the 1968-2012 summer OG and showed most doping (74% of medals impacted by doping) was identified retrospectively, either from events prior to OG (17%) or IOC re-tests of 2004-2012 (57%). Chapter 5 describes the males recruited for cross-sectional observational research on AAS and myonuclear permanency and Chapter 6 their transcriptome data. Fifty-six men aged 20-42 years were recruited: Non–resistancetrained (C), resistance-trained (RT), RT currently using AAS (RT-AS), of which if AAS usage ceased for≥ 18 weeks resampled as Returning Participants (RP) or RT previously using