> The team, which also included researchers from Niigata University and Nishi Kyushu University in Japan and Brazil’s Londrina State University, had groups of people perform three different types of dumbbell curl exercise and measured the results.

First of all, I've been lifting for many years and I haven't done dumbbell curls in a decade. And to be honest, you probably shouldn't be doing isolation exercises unless you don't mind risking injury and joint inflammation in the long-term. For those who don't do bodybuilding but real training (that's going to be squat, press and deadlift, pullups and variations of these), this is sort of junk science. No one serious uses a "leg press" - another injury-prone nightmare (do you value your lower back and are you something other than a football player?). He mentions (overhead / strict) press and perhaps there's something to try there with negatives, if one is extremely conservative and not an olympic weightlifter. Negative pullups are a thing, that's been known by the calisthenics community for ages, but only as a variation.

>It found those who only lowered a weight saw the same improvements as those who raised and lowered weights — despite only performing half the number of repetitions.

No shit. That's because eccentric exercises are far more fatiguing for the muscles. It's not something you can do all the time without burning yourself out and damaging your training progress long-term ("long-term" not being a key feature of this junk science study).