Particularly damning is that the research participants were all female. Anyone who's set foot in a gym knows that women do cardio disproportionately, and that the cardio they do increases thigh musculature...
I have to disagree. Sure women do more cardio, but the cardio increasing thigh musculature? Not a chance. Squatting increases thigh musculature. Doing the elliptical for an hour a day does not. Running slowly or at a medium speed does not. Nor do either lead to any gain in strength anywhere.
Have you seen the thighs and calves of people who bike? Of course lifting will cause more hypertrophy, but arguing that cardio doesn't lead to some gains in musculature is just wrong.
Huh? Running certainly increases the strength of your leg muscles. The only possible exception to this would be if you were jogging very very slowly. But if you go from not running at all to running faster than, say, 6mph, your legs will certainly get stronger.