Is there an expression you would prefer rather than "Marathon is tiring"? Can I say it is "tiring" at all?
Thanks a lot!
Yes, a 42-km running race.
Informally, in BrE, "Running a marathon is knackering!"
For me, "Running a marathon" is more natural. It's not actually the marathon that's tiring - it's taking part in it.
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.
'Knackering' = 'tiring' – not 'running'.