As a runner, not being able to run because of peroneal tendonitis is a huge pain. is it advisable to use a stationary bike instead? while i heal?

Peroneal Tendinitis: Stationary bike is excellent low impact option. Swimming & elliptical also good choices.

Perhaps: The key is that you shouldn't have any pain during the activity. Usually a non impact activity (like biking) should be less stress on your ankle than running.

Athletes: What is your aim when if you continue to workout? If its for fitness or to keep heart rate up, swimming could also produce the same results but less strain on your peroneal tendons. Stationary biking may also produce those results but if caution to use the recumbent bicycles. Hope this helps.