The phrase "several marathons" means participating in multiple long-distance running races called marathons.
Sentences with «several marathons»
I played several marathon sessions of lasting more than 12 hours before going on to save my friends. (mcvuk.com)
Whether you have run several marathons in the past or none, there is always nervousness, anticipation and fear of screwing up prior to the race. (fitbodyhq.com)
She has completed several marathons including Boston, and holds the NYS record in bench press for her age and weight. (rochestercommunityanimalclinic.com)