Regarding the gym, specifically lifting -- progressive overload ( thus muscle growth) can definitely be accomplished in a minimal amount of time. BUT, it requires a high to maximum amount of effort to be effective, so not sure if that counts.
This could depend a bit on what your goals are with respect to minimal dose training.
If your goals are just longevity and health, you do not actually have to train very close to failure to reap most benefits of strength training, up to a point of course. Training even to mild discomfort is enough for strength gains and modest hypertrophy for beginners. So effort can be moderate up to a point.
Additionally a trained lifter who is just looking to maintain on minimal doses can do so with what research has shown is as little as a staggering 1/9th of the volume they normally use, and they would likely be accustomed to hard training.
If your goal is continuing progress it's sort of an optimization problem when it comes to minimum effective dose.
I think it still counts because it makes sense as with any task. You must make the tradeoff that while you are minimizing time at the task, you must increase the effort to match if you still want to see gains past a basic level.
I think the science says you need <= 3 reps in reserve to build muscle. But yes, it is easier for beginners.
Also yes on the 1/9th of the volume but from what I've read you still need to obey the <= 3 reps in reserve. e.g. you can get by with one set per muscle group per week.
Progressive overload forces you into close to failure territory regardless of volume/time.
The other thing to be said is there are variations between people and something that works for one might need to be tweaked for another.
Its more like <= 2-3 reps to achieve roughly equivalent muscle growth - but the science here is still shaky since studies contradict each other all the time due to so much individual variance. Some studies show consistently going 2 reps from failure vs going to failure all the time result in roughly equivalent muscle gains, but from what I've read and watched the running hypothesis seems to be this is due to to volume being roughly equated. i.e. Going 2 reps from failure all the time means your rep count can stay still pretty high across sets, whereas going to failure typically results in the first set having more reps but higher dropoff per set leading to roughly equivalent volume overall.
But nonetheless it doesn't mean you have to go that far to get any gains at all, up to a point. It depends on whether your goal is maximal growth vs getting some growth at all and just looking for health benefits.
Regarding the lower volume to maintain, like I said before - anybody who got to a significant amount of muscle mass would likely have already been accustomed to frequent strain/hard training, but yes I agree.
And yeah a lot of this is hard to generalize since studies show so much individual variance to training that it makes it hard to generalize. But regardless, just train hard and you'll see benefits whether you do minimal sets or many sets lol.
Another thing is many beginners have no idea what real failure is, so while they may be able to not hit failure and see growth, its still recommended to take some sets all the way to failure. Beginners tend to underestimate how much more they really have since they have lower pain tolerance/adaptation to straining their muscles than others. They often are actually 5+ reps from failure when they would have estimated they were only 1 or 2.
It absolutely applies to lifting and progressive overload. A measure of progressive overload can be applied to amount of time spend lifting, also knows as time-under-tension, it can also apply inversely with shortened rest periods. Whether or not these methods align with your fitness goals, is a separate issue.
Effort, or what the fitness industry calls Rating of Perceived Exertion (RPE), is another lever to pull with progressive overload, and is necessary in programming for all experience levels. Beginners start their programs using minimal weights, slowly increasing the weight each week as their skill improves and through that process their strength and muscles grow.
A more advanced lifter, will need a higher minimum effective dose due to what is needed to trigger adaptation, will manipulate RPE throughout their programming to manage fatigue accrued throughout the program.
A great personal trainer is someone that will help their clients find their own personal mimimum dose of training that aligns with their fitness goals.
A full body 40 minute routine using supersets will work great for most people. x3 a week (might be too much if you're just starting so ease into it) is going to also be great for most.
I think the latest science favours full body workouts over splits. I find it easier and more enjoyable as well.
Absolutely agree and my intent was more that the majority of the proven routines can have you out of the gym pretty quickly. Full body, upper / lower split, PPL, etc.
Regarding the gym, specifically lifting -- progressive overload ( thus muscle growth) can definitely be accomplished in a minimal amount of time. BUT, it requires a high to maximum amount of effort to be effective, so not sure if that counts.