Some could argue that the mental attributes required for endurance sports carry over to the workplace, but I would prefer to see those attributes woven into actual work experience and results on your resume.

One of my employers in Bermuda said he wouldn't hire anyone who promoted themselves as a "triathlete" , particularly an "Ironman" or an obsessed runner, on a resume. He said you only have so much energy in a day and the ones he knew spent most of theirs training, recovering from training, racing or thinking about their next race. He had an employee who did Ironman and said he was just too wrapped up in his sport that he had no time or energy for work.

I think it's best to focus on what you can provide an employer that will help his business. He probably couldn't care less what you do outside of work.