Hits cardio, grip strength and unilateral stability stuff.
Exercise is not a panacea, and those who say it will fix everything and cure depression and make you perfect are quacks. But, it pains my contrarian ass to say, some light cardio every now and again is much closer to what our bodies are happy with than desk life, such has been my experience.
Of course, that's going to be different for everyone. It'll make some people worse. For me, though (and apparently for you, too), it is the right way to treat those issues.
For those with knees not tolerant of running, I've taken to also rucking around with a heavy backpack. It's fantastic for building torso strength, and "your body weight plus 30 pounds" is still far less impact than "your body weight, but running". Walk up some hills steep enough to make you pant and wonder if you can make it to the top and your body may thank you for it, the way mine thanks me.
BTW, doctors have a saying: "motion is lotion". Also, "when you stop moving, you die". We are not evolved to take root on a sofa. Our bodies are meant to move and jostle and bounce and twist. Absent specific reasons not to, it can make a huge difference in physical comfort.
But the dopamine boost I get from this is immense. It lasts 24-48h. I‘m in a general good mood for this period. Sometimes, a little more competitive than normal - that’s a downside.
Normal jogging or long walks don’t have this effect, at all.
I also do hill sprints. I try to do one [HIIT] workout a week and also some longer runs.
Hill sprints tend to be safer then sprinting on flat surfaces. Last time I did my HIIT sprinting on level ground my knee didn't really like that at all. A stationary bike (like the "assault bike") is even safer. Or you can just do burpies. People who don't run and haven't sprinted in a long time shouldn't just jump into sprinting.
The way to really maximize your potential is to do high intensity 30 mins 3x/wk and then intersperse it with a great deal of low intensity cardio. Like 4x more if you can, per the 80/20 rule.
It works because it's starting to approach the most exercise your body can handle. (Although some athletes definitely fit in more.)
30 minutes and you are gassed...
Nowadays I switched over to Pump It Up - I feel like the 5-step configuration lends itself towards larger body movements and less river dancing. :)
I don't want the fuss or expense of an Android or Apple watch. Garmin makes some nice models but they are still relatively expensive.
Specifically: MIE consisted of 90-min of continuous cycling at 90%–100% of the predetermined first lactate threshold, while SIE consisted of 6 sets of 30-s all-out cycling at a resistance of 0.075 kg·kg−1 body mass, with 4-min rests between the sets (Figure 1A).
The study's sample size was small and the period studied fairly short, but they did measure the levels of several thousand proteins.
EDIT: This book is maybe a bit old but covers a lot of ground on high intensity interval training vs. traditional training. I guess this study adds to the body of evidence that HIIT is effective. My take as a random person interested in this stuff is that ideally you are mixing both high intensity and longer duration workouts for their different benefits. But if you are limited in time it seems high intensity is a winner.
As an experiment, I switched to high-intensity interval type training for a couple months, which required about half the time to do. All of my cardiovascular metrics immediately changed in a strongly positive way. When I did the old endurance training, performance was much higher than it had been before the high-intensity training.
It is the strongest positive effect I have ever seen from any exercise/gym theory that has been widely promulgated. I never expected to see my cardiovascular metrics change as quickly or as much as they did.
For optimum gain you should mix moderate exercise with intense exercise, but the time you put in likely made your later success possible.
This is about health.
High volume of exercise is damaging via oxidative stress and other ways. Weekly training volume is the most reliable predictor for injuries.
If health and basic fitness is the goal, rather than bringing home the gold, you can add intensity to just a fairly small volume of moderate exercise, or perhaps even none at all, other than a warmup and cooldown.
Then once the base is built, to make any progress one needs stronger, more focused stimulus, so you introduce interval training at high aerobic (tempo and threshold paces) as well as anaerobic (400-800 "very hard" sustained and all-out sprints) training, combined with a few zone 2 long runs.
And then the cycle repeats: you have to let the body recover so deload, then start a new cycle.
Nicklas Rossner has fantastic resources; there's a video there that explains how to find your current bottleneck: https://m.youtube.com/@NicklasRossnerPT
There are plenty of online training program generators that are pretty good and will take you from zero to running 10k. I used an online program to run my first 10k somewhere circa 1990.
There a lot of more cutting edge science online (and I follow Nick as well) but if you're not a competitive athlete and are just trying to get in better shape then the answer is mostly just do it. Over some base of running you can throw in some interval training including HIIT.
To be clear, performance-maxxing was never the objective. I am in it for the health benefits and conditioning for grueling pursuits. Nonetheless, observable effects of different kinds of training on performance are still interesting to me and helps me optimize the time I spend on it.
It is also possible you were over-training in your "moderate" intensity or conversely not increasing the load/distance enough. Training over years should result in good improvement even without HIIT. You will need to put a lot more time in.
To be clear, I was objectively in good cardiovascular condition before adding HIIT. My resting heart rate has been in the 40s for years. The surprise was that there was so much easy margin left by adding HIIT to my regimen.