Allow me to summarize the study for you: There’s little to no hard science recommending core work for athletes. Now, before you get all up in arms and start screaming about instability leading to injury and how the researchers probably did ab work thinking it was “core work”, etc., I’d like to make my position clear:
The study isn’t saying, “Don’t do core work with athletes - ever.” In fact, the study is pretty clear that in rehabilitation, core strengthening shows marked effectiveness. It’s saying that in the non-injured athlete, improvements in core stability and strength don’t translate to improved performance.
Mostly what the study addresses is the issue of time. Whether you’re an elite-level baseball player with a multi-million dollar contract or a weekend warrior with a 3.0 NRTP tennis rating, you’re limited by the constraint of time (of course, if you’re a professional athlete, you’ll have more time to train than if you’re a recreational athlete, but that doesn’t change the fact that training time is finite). You only have so much time to develop fluency in all aspects of the game (conditioning, strength, skill, timing, etc. ); even less so if you factor in recovery.
If you’ve only a limited time to work on your game, why waste your time on things that don’t improve performance? Particularly if you’re a pro and your time is so valuable?
Of course, this applies to you even if you look upon exercise with as much delight as you do cleaning the toilet. Engage in activities that give you the biggest bang for your buck. Perform exercise that will actively improve your quality of life (and, perhaps, your longevity as well). Translated: Don’t waste your time in that Core Fusion class. Go pick up something heavy.