Small/sporty pram for big child

[AndWhat]

I have an uppababy vista which I love but have taken up running following c25k. I am very slow and it is low impact around a park. The vista is not really suitable as it’s too heavy

Sorry, posted too soon! I don’t think a proper running pram is needed as I will only use it for roughly 3 hours a week.
My son looks like he’s following his brother and is already 90th centile height and weight so it can’t be too flimsy any suggestions?