Interesting study. Thanks for posting it.
However, in the bigger scheme of things it probably doesn't matter too much.
Here's what I've learned in the last 40 years of reading/studying/doing resistance exercise:
Geo's Secrets to resistance exercise (learned the hard way)
1. Besides there being no real secrets, the MOST important way and ONLY way to gain strength is to use a progressive resistance type of exercise. It doesn't matter whether you lift weights, pull on rubber bands, use hydrolics, lift rocks or tree trunks, swing a big hammer or axe, use barbells/dumbbells/kettlebells/machines/bodyweight or just push against an immovable object. As long as the exercise is progressive, you WILL gain strength and subsiquently add muscle. Thats it. Doesnt matter what weight/resistance level you start at or even how heavy you lift. Doesn't matter what set/rep scheme you use. Doesn't matter how much rest you take between sets or any other of those little details. Give it 15-30 mins a day of work, 2-3 times a week to start.
All that matters is simply to progressively overload your muscles, in any way you desire on a continueing basis, day after day, week after week, month after month, year after year, for the rest of your life.
2. Feed your body properly, day in and day out, I recommend this program
3. Rest adequately between workouts. Resting is when your strength/muscles grow. Exercise is the stimulous, rest is the growth/over compensation phase. Usually 48-96 hours works well between workouts for most. Some may recover quicker, some slower. You only will know once you've been doing it for awhile.
4.The most important variable to get stronger the fastest (i.e., efficiently and effectively) is intensity. The more intense the exercise, the faster you get stronger, but also the more rest you may need. The harder the work effort, the greater/quicker the gains. But never forget the next tip! The harder you work the more important the next tip becomes!
5. Finally, be safe!!! Learn how to lift properly and what exercises are safe. Never lift dynamically. Smooth, slower movements, without using momentum, is the only way to go with weights for proper safety.
And my final tip, just get off your lazy ass and do it. If you follow the above and work hard every workout, then in 3 to 5 years (yeah, not that long), you will probably reach 90-95% of your genetic potential, not too mention look great, feel great and live a longer, higher quality of life.
Its simple...as long as you dont give up...just like this woe and everything else good in life