I commute by bike because I love it. It is alone time, it is invigorating and it is physically conditioning. I'm smarter, stronger and happier because of it.
Sucking air, working muscles and pumping blood around the body is already known to do that. God bless endorphins!

I do get that commuting may be a necessity for some people - job changers, for example. I know plenty of people in that situation - the old job gave out and their new one is further from home than before.
But, if I had to make a long commute by auto, I would do a multi-modal. I'd carry my bike on a rack, park the car somewhere 10-12 miles from work, and ride my bike to and from my car.

I'm thinking the study recognizes something I could have told them for a lot less time and money.