A week doesn't go by without a new fad diet or exercise routine popping up on social media. Plenty of Instagrammers and TikTokers have been blasted for posting photos of "unnecessarily elaborate" workouts to get views because oftentimes, the old-school basics are what get people into the best shape, as long as they stick to a consistent routine. \n\nBut that doesn't mean all "web workouts" are bad, and there are definitely some useful exercise tips to be gleaned from some routines, such as these TikTok ab challenges.It's important to note that not all TikTok challenges are created equally.For example: the TikTok weight-loss dance has actually been decried by fitness professionals who say that the maneuver, which involves greatly straining one's abdomen for prolonged periods of time, is actually harmful. \n\nThanks to the widespread criticism that this now-deleted video has been receiving, more people are learning about the "myth" of targeted weight-loss: it just doesn't exist.For example, a hundred sit-ups a day won't target fat-loss in a specific area. Sure, you might grow muscle mass in that area and it will become stronger, but doing a bunch of crunches and going out for a two-mile run every single day isn't really going to give you defined abs if your diet isn't on point and you're not doing other work to decrease your body fat percentage.So as a general rule, don't trust any "fitness guru" who tells you that doing ab movements alone will give you a sweet six-pack; it's not going to happen. \n\nThat being said, there are some legitimately great ab challenges on TikTok that are helpful if you incorporate them into a well-rounded exercise routine. This one, uploaded by a YouTube user, consists of four sets of four different moves.The video above shows an absolutely brutal ab routine. Here it is: \n\n- Four sets of 30 Ab Crunches (as demonstrated in the above video.)\n- Four sets of 30 Bicycles\n- Four sets of 30 Criss-cross flutter kicks\n- Four sets of 30-second PlanksAnd if you're wondering what the effects of some of these ab challenges are, YouTuber Carina actually posted a great video documenting all of her progress after doing different TikTok ab workouts for two weeks, paired with a one-mile run.She mentioned that there really wasn't much of a visible difference, but did notice slightly more definition in her abs. That's pretty darn good for two weeks, and it's not difficult to imagine that the results would be way more dramatic if she stuck to the routine for a few months.This TikTok ab challenge workout from chiropractor Alan Mandell is also getting rave reviews.Popsugar writer Maggie Ryan says she tried out Dr. Alan Mandell's three-move exercise and it left her core "shaking": \n\n- Seated arm raise: Hold it for one to two minutes.\n- Seated arm raise and leg lift: Holding your arms out, alternating moving one thigh up then switching to the other. Do 20 total (10 for each side).\n- Seated forward lean: Sit on the very edge of your chair, extend your arms out in front of you with your back straight, lean forward from your waist while tightening your core, and then sit up. Sit back down and repeat 20 times total.Dr. Mandell also has some other exercise videos. But if you are looking for something that's a little more O.G., you can follow the most no-nonsense fitness influencer in the game: Ross Enamait.