general prescription these days for Hypertrophy is 10 sets per muscle group per week 0-3 RIR.
And on a slightly more technical note, recovering from higher volume becomes harder as you age, so focusing on a smaller number (5ish) of reps at higher weight gives you adaptation without quite as much stress.
But I should be clear, when I said real lifting, I don't mean to exclude any form of well calibrated progressive overload, whether that's strength focused or hypertrophy focused. I do mean to exclude the "go to the gym and lift a 10 lb weight the same number of reps each time" BS
The title says they are focused on improving body composition which is boosting lean mass, lowering of fat mass which kinda seems achieved best by focusing on Hypertrophy and fat loss?
But it is very wrong otherwise, joints for example will suffer if not moved. Blood will only flow into all the areas of the joints if they are moved. And if you don't move, your muscles will be gone and without muscles to hold your joints, loss of stability, great risk of injury, etc.
According to google: "typical range for total heartbeats is 86,400 to 115,200 beats per day"
I run every day which would add a lot of beats, but my resting HR is 36 (pushed down by exercise i presume) with a daily average of 50 BPM. So in total a trained person may spend less of their heart beats.
I don't believe the limited heartbeats theory, but it does support the idea of exercise.
If people work out, or play sports, without knowing proper form, without using protection or precautions, they'll get injured and then worse off than before. Realistically, manual laborers should be in real good shape, but often their jobs are so low-wage, and they're so interchangeable, that safety precautions are ignored and must be regulated/enforced.
I took up roller skating and was rewarded with a broken leg. I took up gym exercise and was repaid with a hernia. Both required surgery. No regrets! Only wished I could've better understood how to exercise safely!
I once encountered a FB group that was for people to discuss "sports injuries sustained while we were in bed" and I could totally relate, having done weird stuff to my shoulder overnight, rather than pitching a baseball game...