I'm in the 130s and I can't run either-even with fancy running shoes (bought from a specialty shop). My knees just can't take it-and I've never had knee injuries/they don't hurt at all any other time, so odd lol. I've tried it a few times but have just come to terms that running isn't good for my body and I walk every day instead-so much gentler on my body and it's still good exercise