Many people like to go to the weight room and start performing the standard isolation exercises either using a machine weight system or even free weights.  Afterwards, they do a 20-30 minute cycle of cardio vascular exercise.  Then, after a normal day of picking up groceries in/out of the car and into the house and some moderate yard work, they find themselves injured.  Usually, this injury involves the lower back.

I have found after a few decades of training that the body really performs best when it is accustomed to movements not joint isolation exercises.   There are training programs out there that focus on Core Development yet really perform standard isolation exercises like crunches or sit-ups and some back extensions.

Now, do not get me wrong, isolation exercises have their place as they are safe, effective ways to train muscles that need rehabilitating.  They are also a great way to build a foundation of training that should inevitably lead to tougher movement exercises.

Now add in a squat to the exercise and a real life movement of picking up something off the floor and lifting it over your head is developing into MJDB#2: