"In this model, mice lived in specially designed cages where food was accessed through a hinged, weighted lid. To eat, the mice had to lift the lid while wearing a small shoulder collar, causing a squat-like movement that engaged the muscle contractions people use during resistance exercise. The load was gradually increased over several days, mimicking progressive strength training."

So the study doesn't really show that weighlifting per se is beneficial, but putting food behind weighted hatches is?

"Voluntary wheel running (EEX) was conducted as previously described in single-housed mice with access to voluntary running wheels and food and water ad-libitum,"

And the runners could each as much as they liked?

Sounds like bunk.