How much does biking actually help keep you in shape?

Yes, elliptical and, especially, running in the pool are more effective “running” workouts, but they are a helluva lot more boring. Personally, I used running in the pool when injured, and, while it did not feel like it, it helped me maintain my fitness and translated back to land running within 3-4 weeks.

But, cycling is great and certainly not without benefit, especially when you do hill climbs and have to get out of the saddle. There are many triathletes and duathletes who limit their actual running mileage but are still incredibly fast at running.

Lastly, OP, look into taking vitamin K2. If you have doctors telling you you should take more calcium, run away as fast as you can. K2 (with D3) helps mobilize calcium away from where it’s not supposed to go (plaques in arteries) to where it’s supposed to go (bone). I once heard a doctor (MD), when asked if a patient with bone problems should take more calcium, answer with “why would you need to bring more sand to the beach?”

I arc'ed / biked for two months before last indoor season, where I ran 4:09 mile off of this cross training regimen and like two weeks of real running. I'm similar to you where my body can't handle high mileage.

I'd do 8-10 hours of arc training (main session) and biking (double) a week, with an average HR of 150-160, and workouts on the arc I'd get it up to 190. My HR tends to run on the higher end of things though so take those numbers with a grain of salt.

I also threw in some double threshold sessions on the arc 1-2x per week which I think really helped my fitness, and it also makes it less boring.

This was a week in my training log from mid November before running 4:09 in early January:

M: 60min arc
Tu: 60min arc workout: 6x5min, 10x60sec
W: AM 80min arc. PM 40min arc (avg HR 160)
Th: AM 45min elliptical (5x60/30). 35min arc (10x30sec)
F: AM 80min arc trainer: 20x60on/30off. PM 20min arc, 20min elliptical
Sa: 60min steady arc
Su: 40min bike 203 watt avg; 80min arc trainer, 6x6min hard (max HR 195)

I was prolly overtraining and too anal about getting in minutes, but I do think this helped my fitness a lot. Hope this helps and good luck!

I'm going through the same thing with a foot injury. I use the adaptive motion trainer (AMT) at the Y a lot. The level of effort compares very closely with running, yet there's no impact strain like running does. I can comfortably train at per mile pace very close to my running pace and heart rate tracks very closely as well. It's about the only non-running workout that feels like "real" running to me.

I ran an easy recovery effort Monday at 109 avg heart rate and my pace was 8:40/mile. That's not walking.

Yeah you are talking about quite a bit of training load, will no doubt keep you fit. Keep in mind though for your zones - your max cycling HR will be lower that your max running HR.

https://podcast.letsrun.com/episode/8d27222b/ncaas-ny-champ-abdi-nageeye-guest-jon-wejo-go-to-vegas-virtually-with-noah-lyles-hobbs-kessler-more

Listen to the interview with Abdi Nageeye (2024 NYU City Marathon winner)- he bikes for a month straight prior to his marathons.

Biking is a big big help

Spent a couple years on a bike going to school, my thighs got massive. But, that was about it.

I'd be reluctant to write off 2-3 months running because of a "possible" stress reaction, I would advise getting a definite diagnosis.

I ran mid 21, then high 19s my freshman and sophomore years. Didn't even run track sophomore year. Then that summer I started biking 20-30 miles most days, a heavy old 3-speed mostly on gravel roads but I was putting in a good effort every time. Junior xc year I showed up and was suddently running 18 flat off doing near zero running that summer. Finished the season in the 17:20s.

Aerobic training is aerobic training and less running-specific than many want to admit.

I ran in college and we got 300 inches of snow on average, hilly, nearly impossible to run in the winter. Most serious guys cross country skied. Instead of running 60-90 min a day, we skied 2-3 hours, which you could do with similar fatigue as there was no impact. First year I did that, I came into track in the spring a minute faster over 10k than I'd left off in the fall. Again, like zero running involved.

Similar experience, in highschool i was a swimmer and off no running, was faster than the previous season at during the first week. Just a ton of cardio After cross training a ton running seems easy. Same on the bike, now older I was training for 100mi ride with over 10K feet climbing so rode a lot, then went back to running, and it felt easy from a cardio perspective. Maybe needed a few weeks to get the speed back, but no loss in cardio which propably takes the longest to obtain.

i would favor cross training in the first half of the base work phase

you recruit slightly different muscles, and the wear and tear is reduced on specific running muscles. all the while widening the base. say 1/3 of the work is cross training, cycling, swimming, gym, running in water, etc.

in the second phase of the build up, i'd move to mostly running, and get specific to the task, after a month or so, specialization will take place, and surely after the speed, speed endurance phase.

In my youth i used to bike for 1 hour at 4 minute mile pace. Sometimes i would do 6 miles in 18 minutes. This is all flat road if you are wondering. Anyways this keeps you in great shape if you have the attitude and discipline to do it every day

so when i bike should i keep it at a high resistance or low resistance but pedal fast

You can get in better aerobic shape from cycling. It’s the musculoskeletal system that will suffer a bit from lack of impact.

I run d2, never broke 16 in highschool. I have had 4 fractures since starting college in 2 years. I started biking 10-12 hours a week doing structured workouts and really became a better cyclist than a runner. That being said I have run for a couple months between fractures and always able to get into 15:30 ish or 25 mid shape in a few weeks. I think it really builds the aerobic engine and is a great tool, but all of the speed I had to run low 4:2x in highschool is gone. Cross training (for me) seems to be primarily helpful for maintaining and building aerobic capacity. Be sure to continue including it as you begin running again too.

I second this. I have had stress reactions before (precursor to a fracture), and am actually getting over it now. I would not assume you need to take 2-3 months off.

6 weeks is probably all you need with a fracture. I would do all the things you are planning to do. Take 2 full weeks off of running, then work back in a few 2 mile easy runs. Expect to feel some discomfort. Ice your leg a couple times during the day after those runs. And stretch.

I'll bet you can get back to running much sooner than you think. But by all means, continue to work in the cross training.

Thank you, I’ve been incorporating some strength work for my calves and tibialis interior to keep them strong if that helps

Really appreciate your advice NErunner! I agree with that too, some aqua jogging can be great I just feel like I can’t get my HR over 110 bpm doing it. I’ll try to mix in some easier bike sessions

I feel the issue I’m running into is running everyday is going to be a hurdle getting over. I’ve only been healthy running 4-5 days a week. 6 at most. I’m not sure how I can do that staying FULLY healthy if you have any advice. But I try to treat the bike training like running would adding in a couple of harder interval sessions like a workout.

Is there anything else you recommend I implement into my training. Probably not gonna go over 12 hours a week of training just from the bike.