Would Mountain Biking help your fighting cardio?
Yes, but interval training is better.
I can't speak as someone who trains to fight all year round, but for me mountain biking shoots my cardio throught the roof durning the summer. Its a great option for someone like me who hates running.
yeah, it's easier on the joints as well, I mean you could easily mountain-bike for three hours straight, if you ran for that long you'd feel like an old man (at least me)
I love to mountain bike in the good weather - which reminds me that I need to put some air in the tires and get out there!!! Realistically, you can also interval train on a mountain bike too...
intervals is best.
just find a real hilly trail and hit it hard!