Doing some interval work on a stationary bike a couple of times a week, like a warm up, spin really hard until out of breath, recover, repeat several times, then cool down? I'm doing a lot of base miles, hoping to peak for 2 miles in May or June. This would just be something extra to add some variety. Good idea or bad? I was thinking it would strengthen my cardiovascular system but really don't know. Better to just run more?
I'm not sure if it is better to run more or not, but here's my anecdote: In college I had a weak base of 30-40mpw for a few months, but I somehow still had a stress fracture by the time indoor came around. I hit the bike and the pool hard, ran one workout per week, and raced on the weekends. I pr'd twice in the mile on this schedule!
Biking workouts:
1)5min up, 5min hard, 5 min easy, 15x(1min hard, 1min easy), 5min easy, 5 min hard, 5 min easy.
2) 10min up, 30min at tempo running hr + 5 bpm, 5min easy, 5min hard, 5min easy.
If you can run in the mornings and do each of these workouts twice per week, you will be fit.