Bonjour! I'm plan to do plenty of trail running in French speaking areas in the future, so I simply must learn some French.
English is not always enough, and it might help you finish a race.
Like last summer, when I was running on the Alps in the middle of the night and required some help, a fellow competitor replied: "Sorry, but I'm too tired to speak English!"
Also after this years UTMB, I observed some complaints by English-speaking runners. They seemed to think that the organizers didn't do a good job communicating about the course changes during the race. I wasn't there, but I believe everyone did their best in a difficult situation. It occurred to me that it couldn't hurt to learn some French, if you are going to race in France (or Western Switzerland).
I believe a little French can go a long way to start a friendly conversation. You can always switch to English if your French fails.
It can be funny when a Frenchman tries to speak English, and vice versa. The two languages are quite different, so this will be a huge challenge, but I'll refuse to quit.
It seems one of the best ways for me to learn is to listen to Podcasts like Coffee Break French while training, commuting and shopping.
I've also started to follow some blogs by French trail runners, you can find them on the right margin of this page.
À plus tard!