What is the fastest way to improve fitness?

StealthyJen

I had a knee injury (torn meniscus) this year that, while waiting for surgery and then during recovery, kept me on the couch for a good six months. Now, even though I get about 8-10K steps a day for my job, I feel winded still. Mind you, I’m 47 and overweight, but I’ve never felt like this and I want to feel like I can walk up a hill easily without feeling like I’m dying of breathlessness. I know losing weight will help, but I want a quicker improvement of cardio respiratory endurance. I can pretty much only do the stationary bike or walking and some weights. I don’t have a gym membership, but I have the bike, dumbbells of different sizes, stretch bands and of course YouTube.

Any recommendations for getting this *kitten* done?

spiriteagle99

Walking and the bike can both help your cardiovascular system. While most of your walks and rides should be moderate intensity (so you don't injure yourself by doing too much too soon) you can include some (5-10) short 30 second burst of higher intensity. That is short enough that you should avoid injury, but it will improve your heart and lung capacity. Your aerobic capacity will improve more quickly than you expect (unless you're dealing with long term covid issues).

MsCzar

I've gotten great results from rebounding. It's super gentle on the joints and the workout can be as easy or intense as suits you. Plus it burns mad calories!

https://blog.myfitnesspal.com/nasa-the-trampoline-and-you/

AnnPT77

If you want CV improvement, you want CV exercise. For best results, it may not be objectively quick, though you should see steady progress, and if you formerly had good CV fitness (relatively recent) it may be a bit faster. Sounds like the bike is your best bet, of what you have available. Make sure it's correctly adjusted for your size.

Warning: I'm conservative, especially in recovery situations. At my age (67), and maybe even yours, re-injury and detraining comes at a high cost. That said:

I would think re-building CV fitness is about the same as building it: Start with longer relatively easy sessions (can talk in whole sentences while doing it, maybe sing a little) to tolerance, stopping short of being so exhausted you drag through the rest of your day. These will increase your endurance, which you'll need as a base for further progress.

Do that for a period of time, maybe starting with 2-3 days a week (separated by a recovery day). Gradually increase duration or frequency, still staying short of persistent exhaustion. If your bike has resistance, that's another variable you can use to increase the challenge (but take care with your knee . . . speaking as myself someone with a torn meniscus, though mine has not had surgery yet).

After a period of time (weeks to months, at least one month, probably), start including one day a week that is a shorter session, more intense intervals. Warm up for 5 minutes or so, go hard for 1-3 minutes (to the "only short phrases talking" level), then back off to easy for 3-5 minutes, or something along those lines. Repeat the intervals 3-5 times, paying attention to how you feel - trying to just push current capability, not get exhausted. Then cool down for 5-10 minutes.

Work up from there (in repeats within a workout, or relative duration of hard/easy), but 1-3 intense or interval sessions per week is fine. All high intensity all the time is not how elites train for best outcomes, so there's absolutely no reason us regular duffers should do it.

There are lots of online stationary bike fitness plans. Most are more aggressive than the above. What's above is what I'd suggest based on my coaching education in a different CV sport, on-water rowing (which also uses machine rowing for conditioning). I bike some, trails and stationary, because I do better if I alternate days vs. row every day. (That might not be true if I were younger: I need to focus more on recovery now than I did 20 years ago.)

When I suggest CV exercise, because of your main goal, I'm not saying "do no strength exercise". That would be bad advice. For general fitness, you want at least a couple of days a week of strength exercise. If it were me, and my priority was CV, and I was using the bike, I'd stick with just CV for a couple of weeks until I saw how it was going. Then I'd add strength exercise as tolerated while allowing good overall recovery. Your biking will be leg intensive, especially quads (hamstrings too if clipped in), assuming your bike is fixed handlebars. It could make sense to start strength with upper body and core strength in parallel with the biking, to use different muscle groups. You can move on from there if/as tolerated.

At the same time, if you like, you can be working on slow weight loss via calorie deficit (whether you count calories or just cut portions, etc.). I'd not encourage aggressive weight loss in parallel with aggressive exercise: That's a lot of cumulative physical stress. I'm speculating you're not so overweight that your weight in itself is an acute health risk. If I'm wrong, then talk with your doctor, and maybe prioritize calorie reduction over fitness improvement. Burnout is the enemy of progress. Overdoing cumulative stress leads to burnout.

Just one li'l ol' lady's opinion, though.

Best wishes!