The phrase "a marathon for the" is grammatically correct and can be used in written English.
It can be used in contexts where you are describing an event or activity that is extensive or requires significant effort, often in a metaphorical sense.
Example: "This project is turning into a marathon for the entire team, requiring long hours and dedication to meet the deadline."
Alternatives: "an endurance test for the" or "a long journey for the".
"I still have to manage as if it's a marathon for the team," he answered.
Coincidentally, each had run a marathon for the first time in the 1999 Marine Corps Marathon in Washington.
"It goes from being a marathon for the first 63 holes to a sprint for the last nine holes.
He lost a marathon for the first time in the spring of 1983, in Rotterdam, after pulling a muscle in his groin.
A few years earlier, in 1987, he broke three hours in a marathon for the first time, 2 58 45 in Philadelphia, and he wanted to know his chances of doing so again.
He was already an excellent sportsman – excelling in swimming, gymnastics and ice-sledge hockey, a sport he represented Great Britain in during the Winter Paralympics in Turin in 2006 – but he really found his calling when, in 2004, he entered a marathon for the first time.
The worst thing about running a marathon for me is the feeling of anticlimax after the race, when the certainty, focus and direction of the past few months disappears.
"Can I ask you to run a marathon for us in the last four days?" a young staff member in jeans earnestly beseeched a white-haired volunteer as he stepped into the Forest Park office.
I'd wanted to run a marathon for ages and watching the Paralympics finally gave me the nudge to sign up.
28, 29 The duration of labour equals a marathon for many women, hence the importance of careful administration of fluids.
Pakistan Technical Advisory Group Meeting 4-5 June 2015 - Comments by UNICEF Regional Director for South Asia Ms Karin Hulshof Islamabad, 04 June 2015: "Pakistan has run a marathon for polio eradication, and now the finishing line is in sight.
