So, as an “expert” in your given field, it is always a good idea to try and stay up with the latest trends, right?  So why are most trainers showing their clients exercises and methods that have been around since the 70s?  Popular opinion has not changed on what is good exercise.  I feel (and I’m by no means alone) that that is just not right nor is it the way to do things.  For example, single joint exercise.  Single joint exercises are exercises that move only one joint at a time, like a bicep curl or a leg extension.  Therefore, since they only work one joint, they only work one major muscle group, while pretty much ignoring (or minimizing, at best) all the other stuff around it.  When was the last time that you had to isolate ONE system or muscle group in your body to do anything?  Truth is is that just about everything that we do is a combination of multiple groups and multiple systems all working together simultaneously to perform our task.  So when we workout, why would we not perform exercises that mimic THAT?  The why lies in history.  Think about when exercise in gyms became really popular.  It was about the mid-70s to early 80s.  Before that, the average person wasn’t in the gym at all, and had no idea what the hell was going on with their bodies.  Who WAS in the gym?  Bodybuilders.  So who became the first generation of personal trainers?  Bodybuilders.  And they taught what they knew…single joint, isolation based exercise.  And that became accepted and passed on to the next generations of trainers.  Remember, just because something is accepted, doesn’t mean that it’s right.  It was accepted that the Earth was flat and that not everyone was born equal, based on nothing but color of skin or mere gender.  Those accepted premises have been proven wrong over and again, and this one is, too.  Exercise should mirror life and daily function.  Use exercises that utilize many systems at the same time, like squats and deadlifts.  Walk around on all fours.  Bear Crawl, crab walk, etc.  Play like your kids.  They know what’s up.  The bottom line is that just like with anything else, knowledge has progressed.  So why hasn’t practice?