David Sinclair explores what parkrun’s age data tells us about physical activity, ageing and volunteering. I run parkrun. Badly, and inconsistently – but I enjoy it. I’ve done 356 of them, mostly at Bognor Regis, over more than a decade. I’ve watched my times get slower and slower, then – more recently – start to come back. I’ve wanted to understand the relationship between age and participation for a long time. AI has allowed me to do a bit of analysis that in the past it would have been beyond me.