We are a commune of inquiring, skeptical, politically centrist, capitalist, anglophile, traditionalist New England Yankee humans, humanoids, and animals with many interests beyond and above politics. Each of us has had a high-school education (or GED), but all had ADD so didn't pay attention very well, especially the dogs. Each one of us does "try my best to be just like I am," and none of us enjoys working for others, including for Maggie, from whom we receive neither a nickel nor a dime. Freedom from nags, cranks, government, do-gooders, control-freaks and idiots is all that we ask for.
I am not surprised about the testosterone and growth hormone results. Those are good products of extreme physical stress.
A few problems with the article: First, it only went on for 12 weeks. Second, and maybe most importantly, the study had them lifting four times/week. That makes no sense. A set of heavy deadlifts takes 4-6 days from which to recover properly. Next, you can light- deadlift 100 lbs four times a week with 25 reps if you want, but you will still not be able to lift that 200 lb. of rocks a prankster placed on your front porch. And your exercise will not be time-efficient. Part of heavy is the time-efficiency. 5 reps of heavy deads, benches, etc once a week is plenty for the average fellow to stay youthfully strong.
In any event, exercise of any sort to muscle failure is the only way to gain strength. BTW, I do do lighter-weight exercises almost weekly on off-days to failure. Squats, curls, overhead presses, etc. It's just to remind my body that it is not on vacation.
Diversify, diversify, diversify. Once a month after a heavy lift, do it again with half the weight to failure, then half of that to failure, then half of that. Once a month push a car around the block, starting from a dead stop every time it builds up momentum. Jump as far as you can. Jump as high as you can. Throw heavy rocks at the prankster. Lie on the floor and get up without using your arms and when you can do that well, do it without using your arms or your knees (I'm 60 and I can do it). Balance on one leg with your eyes closed.
And, all seriousness aside, try running from the cops with your pants undone and your shoes untied (this does not appear to work but this exercise is attempted often a lot in urban areas).
I remember watching Herschel Walker play football and seeing the pictures of his chiseled physique. At the time it was rumoured that he didn't lift weights. From the information I could find he didn't. He trained using massive reps and his own body weight. http://www.artofmanliness.com/2016/07/19/the-herschel-walker-workout/ I don't know about now but in the past boxers didn't lift weights, it was all body weight excercises. The good boxers were in excellent condition and quite muscular.
I am getting close to 58, I squat twice a week, lighter and more reps on Monday and a 3 x 5 heavier workout on Friday. With deadlifts and farmers carry in between.