Bike fitness?

1 mile biking is equivalent to a 1/4 mile running

You can bike and lose almost no “fitness”. For a base fitness standpoint, aerobic strength, biking will keep you from losing fitness for weeks of not months. What you will lose is running specific skills/speed... how long it takes you to get back to normal depends on how long you were off (a week-three weeks, not much time at all assuming the injury is fixed). It also depends how long you have been training, a runner who has been running for years will bounce back pretty quickly, new runners will bounce back quickly because they were likely undertrained already, runners who are kinda experienced but not longtime runners will likely take the longest. Lastly it’s kinda individual, some people can take 4-5 weeks off and just bike and swim and PR or get very close to peak performances after a week or so of specific training.

Upshot is biking is great to keep base fitness, you can use the same efforts like long run, easy, tempo ect. As long as you aren’t missing more than a month don’t worry about anything crazy just go out and spend time biking if you ran for 7 hours per week maybe bike for 5-10 depending how you feel.

John A wrote:

HS senior guy. I had a minor achilles/ankle injury that's kept me out for a week (I'll hopefully be easing back into running this week). I started biking a few days ago, my question is how much fitness can I keep by biking? Is there a good running equivalent? For example, I did a 90min ride @ 14x bpm or roughly the same as easy run effort. How would that compare to me doing a run (let's say, 45min) at the same effort?

First of all, a week off running isn't a huge deal. It'll have an effect but you're not going to lose too much fitness in that time one way or the other and you'll be able to jump back into it pretty quickly (if it's really just a week).

Typically I find that I have to roughly double the time on the bike to get the same feeling as running (eg a 90 minute ride feels like a 45 minute run), but a lot of that time is coasting on downhills. Things are totally different when you're just starting to bike though, so go by feel and listen to your body.

For me there are a few things that happen when I bike: I get more quad muscle, which helps hill running and speed; I get more cardiovascularly fit; but there's something running-specific that slowly disappears, maybe it's the capillaries in my legs. When I come back from a long break from running (after many months) I find that I have trouble doing repeat intervals. Like I can do a couple of intervals at close to my previous pace, but my legs don't recover from anaerobic efforts and I just die really quickly after the first couple of repeats.

Good luck!

John A wrote:

HS senior guy. I had a minor achilles/ankle injury that's kept me out for a week (I'll hopefully be easing back into running this week). I started biking a few days ago, my question is how much fitness can I keep by biking? Is there a good running equivalent? For example, I did a 90min ride @ 14x bpm or roughly the same as easy run effort. How would that compare to me doing a run (let's say, 45min) at the same effort?

Too many variables when you’re on the road. If you had a trainer it would be an easier comparison. But not worth that for a single injury.

For a reference point your max HR on a bike will be lower than running. For me it’s about 8bpm, so factor that in when you’re trying to do your easy rides.

I’ll typically do a 60 min easy run in the am and a 90 min easy ride in the evening and but I wouldn’t say either are equivalent to one another despite the average calories burned being about the same.