Window split from upstairs neighbour jumping around

[UpstairsDownstairsAndInBetween]

Is this even possible? The windows have cracked in the ground floor flat and the ceiling also now has a large crack. The tenants that live there are suggesting its because my tenants in the first floor flat have been jumping around doing exercise. I can understand that this may have caused the ceiling to crack, but the windows? Is this likely?

No. It sounds more like the lintel above the window has gone.

the agents didn't say anything about the lintel. I'll ask them to check.
God knows what my tenants thought they were doing though, it's an old building and just stomping across the sitting room makes the windows rattle and would be really noisy for anyone downstairs.

Joe Wicks exercise?

Sounds like a potential structural problem? Windows shouldn’t crack in a house because someone jumps up and down.