Hello and sorry for the somewhat necro from mid last year, I just think I should add this in case the OP is still watching.
Some background first:
I am not a coach, professional player or even notable amateur. I am just very interested in table tennis mechanics and I can practice what I preach. So feel free to shoot me down because x coach said so, but do remember that there's many ways to skin a cat. The concepts discussed here are fairly "advanced" to most players in the west, but they are fundamentals IMO. It's not anything magical, and you can learn it too.
I play "Chinese style" with European rubber on both sides, focusing on third ball attack and performing long strokes from close, mid and long range, and performing shorter, more bent elbow strokes from just right at the table or when caught with a fast ball to my elbow. This is for forehand only.
Tip number 1: Make sure your drive is good.
The drive is the foundation of the modern loop, and it is the basis for the body mechanics in the loop. Truly under-appreciated.
While there is nothing wrong with learning the slow, high arc, spinny loops described here, in fact you must learn and perfect those, it is inherently not a very quality shot. Practiced and drilled players have no problems killing every shot like that unless it's a counterloop rally where they're performed due to the inherent safety of them, while trying to gain a better foothold for a better stroke.
The slow, spinny loop is essentially suicide if you throw one out when you could be performing the modern loopdrive
. (Unless, you're playing a lower player and they struggle with topspin. Go ahead and throw very spinny loops at them and watch them make unforced errors.)
Now, we've all heard about the loopdrive. What it essentially is, is a very dynamic and powerful loop, with a swing geometry closer to a drive than a loop. You sacrifice just a little consistency and spin for far better speed, placement and accuracy while not actually giving up too much spin. It should have a very visible arc compared to a drive of somewhat comparable pace but much less so than a loop of a comparable pace.
Many players, myself included, prefer to brush the ball than to drive the ball when looping. That is also what is taught in the west and what is considered correct. I would have to disagree.
The reason why most players' natural swing is a straight line, where you essentially chop into the ball upwards and your blade angle is close to or exact to your swing angle, is because it's easy and safe. You also do not have to involve the forearm when doing this, you can just pivot upwards from the elbow and you will produce a consistent shot of acceptable quality quite comfortably.
What you want to be doing is a swing geometry that starts more vertical and levels out more horizontal by the end of it. The best way to do this is to drive with the elbow starting close to the side of the body and finishing far and high from the body, with the blade angle closed, and your swing geometry more "closed" than your blade angle. You're hitting more than you're brushing along the side of the ball, while still producing considerable topspin due to the blade angle and the lifting motion.
The stroke mechanics when driving forwards is actually quite similar to traditional tennis. The forearm "lags" behind and on contact the elbow snaps violently across the body, to the left of your head, perhaps even nearly behind your head when looping very heavy backspin. Your arm will be quite extended just before contact and "loading up" for the snap. Of course, you will be relaxed when doing this.
Recovery is elliptical.
The main point is to drive with the elbow and control the placement with the elbow, and not to brush in a straight line across the ball. The reason you want to drive INTO the ball, while also performing the brushing motion upwards is because modern rubber responds better to sinking the ball into the sponge than skimming it across the topsheet. This is especially true for Chinese rubbers.
The stroke can be performed with European, Japanese, Chinese, whatever rubber. Chinese rubber just benefits a lot due to the technology. I play with non-top end European rubber, and the stroke has worked even with absolutely rubbish bats.
Take a look at Ma Long for the perfect example of straight arm looping with this technique, and also compare your drive motion to his drive motion, especially what your body is doing during the movement. most examples I have seen posted here have "worse" body mechanics for this stroke. I call it "lazy posture". Too straight knees, not enough leaning the torso over to shift weight, not enough driving with the hips. Lazy. (Take into account your physical state, of course. Young players can do this better and you might have to adapt your style. This is from the perspective of a young adult.)
When performing Ma Long's drive motion, you will most likely hit every ball into the net at first, unless you're using a very fast bat. In that case, get a slow wooden beginner's bat.
Once you begin to understand the timing for the hip and shoulder drive and the relation between body and arm mechanics, your regular drives will carry outstanding pace and quality, and you will probably outdo your current loop in everything expect pure topspin. Then once you're certain that your drive is good and you're not just "winging it" in terms of what feels right, you can start to incorporate it into your looping.
Of course, don't blindly copy x player's strokes, especially if their serves and equipment largely differ from yours. Do compare the mechanics between their stroke and your stroke. Even in the CNT there's a dozen ways to skin a cat. They all share the same fundamental aspects, though. https://www.youtube.com/watch?v=xsg4M6fOObIhttps://www.youtube.com/watch?v=K-b-n4dHT5U
Some tips for the end:
Place weight on your soles and lift your heels slightly.
Squat lower than you normally do. Far lower.
Learn further than you normally do. Not too much.
Have a wider stance than you normally do.
Have your rear leg further behind than you normally do. If out of position, prefer to push front leg than to pull rear leg. More balanced, less load transfer.
Strike the ball far more to the side, with your body at a 45 degree angle to the playing direction.
Lean forward through the entirety of the stroke.
Tense your core slightly, then fully tense it on impact and release.
You know you're doing it right when it feels like you're doing a crunch and squat at the same time.
Hope it helps and doesn't start a convex vs concave loop discussion.
I'd love to give more tips on looping, but the body mechanics are essentially the same for driving and can be learned from observing pro players with great mechanics, and using your head. I also do not have any credibility, so yeah.