yeah i think bike, elliptical, and aqua jogging all used together is the ultimate cross training program. but biking can certainly help out with running a lot. it's not that running specific but the aerobic benefits are good for running and also if you keep a high cadence on the bike it helps stride rate for running.
Originally I was mixing a lot of different things. Water running etc, elliptical etc... . But the HR is so much higher on the bike that I thought it must be the way to go. I could get basically get in LT type workouts on the bike, trying to keep cadence above 90. Really thought this was a good alternative, until I noticed the gain in quad size.
I wouldn't be overly concerned about the quad size. The big issue is to avoid a return of the stress fracture. As you gradually - you will return gradually, right? - return to running, your legs will change shape accordingly. You did not hurt your running performance by getting bigger quads. You hurt your running performance by, well, not running. But that was the right thing to do. Now you can move forward.
After 30 years of running, I've noticed that my leg muscles change depending on whether I'm doing trails (wider thighs), speedwork, hilly workouts, hill sprints, cycling, or plyometrics.
I have cut my running down about 40% but increased my overall exercise with mostly bikng but also weight lifting and some swimming.
My quads have gotten huge. I am slower but actually seem stronger on moderate distances 10k's versus 5K's. I can power up hills and have a slower turn over rate.
Overall I am slower but most think I'm faster just based on how I look.
Bekele has freaking huge quads for his height. Don't worry about it, just keep your flexibility around your hips and you will be ok.
Trying to return slowly. After being cleared went like 10, 20, 26 and hopefully 32-35. (was around 80 mpw before injury). Hamstrings are really tight. Wonder if thats from the added quad strength or lack of use.