How much does biking actually help keep you in shape?

Nah fr. Ellipticals r terrible. Bike >

In my experience, biking on medium-to-big hills provides a workout that is analogous to running intervals. Now, there are lots of steep and long hills where I live, so this kind of workout is nearly de rigueur in these parts. Think about biking up steep hills. Depending on your type of bike and its weight, you may be giving back most of the rolling wheel efficiency compared to the pavement pounding of running steep hills. I bike on some hills that are steep enough to have me breathing deeply in my Granny gear. Then comes the downhills, where you get a recovery.

IMHO, riding at 80% + ability on big hills is a great aerobic workout that does no harm for certain types of injury.

Get a power meter, establish your FTP and build up to doing 2-3 sweetspot sessions a week + easy hours.

I was out for a month twice this year due to a knee injury, and I managed to run a treadmill 5K TT few seconds per km slower than my best time after doing just that + strength training.

Yeah I eventually started doing two double threshold days a week which I wouldn't advise but I was freaking out about losing fitness.

Morning sesh I'd shoot for ~25-30min of threshold work total, something like 6x5min w/ 60sec rest then in the PM session I'd shoot for ~20min of threshold with shorter reps and shorter rest like 20x60sec on/30sec off. I wasn't too specific with it, just switched it up to keep things interesting and not get bored.

What is better cadence or lower cadence higher watts I.e. indoor trainer on high hills?

This old cat (64) is busted up from 25 yrs of running (post-traumatic OA from an assortment of major injuries 😖).

I can run maybe one day week for old times sake (actually more of a walk/jog. Lol).

My main cardio training is full-throttle HIIT workouts 3×week on a spin bike. The gym I go to has an awesome spin room with state of the art spin bikes (aero bars, power meters, clipless pedals, etc). I'll do the Norwegian 4x4s & go all out - no sissy workouts. Feel like a million bucks when I'm done & no stress on my joints! 👍

I'm also hitting the weights hard trying to put some size back on. After playing a little college football back in the 80s, I competed in bodybuilding & powerlifting for about 12 yrs before transitioning to running - which was the activity that tore up my body the most. Go figure. Lol

i was in same situation as you in summer... stress reaction, no runnning for 10weeks...
outside biking is what kept like 95% of my fitness
i did about 10h/w on my racebike
Mo - off
Tu - 2h - 15minWU/CD; 90min Z3 effort in form of 5/1, 6/1, 8/1, 10/2, 15/3min ON/OFF (as many as i cpuld fit in 90min or my loop of the day)
Wed - 1h - steady Z2 or easy if legs are sh#t
Th - same as Tu
Fr - off
Sa - 2h - Z2 or easy with 95% effort out of saddle on every uphill on the route ~30s to 3min depending on lenght of the hill ( i live in onöy small hill area)
Su - 3-4h - 60min easy, 90-120min like on Tu, 60min easy, if legs are good some hard uphill efforts
Intervalls hepls to keep overall feeling not to hard especially if your muscles are not used to cycling inthe beginning (feels harder to keep hr up in comparison to runnning). After 4-6 weeks this will be gone and on your easy rides ypur hr will match that of an easy run.
every 2nd week i did some hard vo2 intervalls like 4x4min, 10x30/30s, 4x5min on Tu.
At last i could never do that amount of training indoor or on stationary trainer! Its incredibly boring and sucks big time. If you can go outside... racebike or mountainbike. You can hop in the lake, get icecream on the way or something. Bike is for discovering landscape
Good luck and do strenght training before you start rnning again and then work on running fast get your muscles used to running. then youll be back in no time

It’s better than nothing. I couldn’t run for 2 months due to hamstring tendon injury in left leg. I cycled for a minimum of 90 minutes everyday. I had one VO2 max day like 4 reps of 3-5 minutes at VO2 with equal recovery, one threshold day / one hour power like 3x15 minutes, and a long ride that was 2.5 or 3 hours. On a road bike hooked up to an indoor trainer indoors for consistent power.

I still felt winded and gasping for air the first 20 minute run back, but after 5 months I regained my fitness and felt equal strength on both legs, was even better 1 year later.