With such a small threshold of effect (able to do 30 minutes of lifting per week / not doing anything), are they able to distinguish correlation from causation here?
30 minutes per week might be a easy as 5 minute warmup followed by three sets of 3 max weight bench presses then 5 minute rest, twice a week. This alone is huge and you will see effects in the mirror in 1-2 months. The key is max weight, not aerobic exercises.
This is what I always wonder about these studies. How do you differential people who do regular exercise with those who eat healthy? Clearly there is correlation between those.