Classes where the teacher can give grades based on what he feels like are pointless anyway.

But for male students, who continued to see higher grades with attractiveness even when student-teacher interaction was low, beauty seems to be a productivity-enhancing attribute.

Or maybe women were the only one enjoying an eye-candy premium in the first place? Could also be that there is no such premium and women simply stop trying as hard with no in-person attention received anymore.

There are exceptions

So we can't generalize, but let's generalize in the title for clickbait anyway.

Study after study indicates running rarely causes or exacerbates arthritis in most runners’ knees

Even if it is rare and thus only affects some runners, it's a bit disingenuous to essentially say "hey, only some people get cancer from smoking and smoking is actually strengthening your lungs".

recruited 82 middle-aged, first-time racers [..] most of their first scans showed signs of incipient joint injuries, including cartilage tears and bone-marrow lesions, any of which could be early steps toward arthritis.

The wisdom I know from health professionals is that running is fucking up your legs and that you should train by doing fast walks instead.

But this simmering damage had been partially reversed by training

Yeah, training is good, but running is doing damage. Do fast walks.