I recently had a client tell me that her physical therapist told her that she should probably avoid leg extension and leg curl as these exercises trained “muscles” but that they were not “functional.” This client is very well informed, so she knew exactly how off-base this advice was. The logical response to this physical therapist (and to all of those who espouse so-called “functional training”) is this: What causes function? The answer of course is MUSCLE and MUSCLE CONTRACTION. Here is the bottom line. The goal of strength training should be to improve the ability of a muscle to contact and produce force. Then and only then can functional ability (our ability to bend, run, swing, ski, jump, climb, live) actually improve.
Side note: To be precise, we can see improvements in performance by practicing a specific “closed-skill.” This simply means that if we practice a specific task or skill, we will get better at it. The limitation to this is that this improved performance does NOT transfer to other tasks or skills. This is a basic and long held tenet in the field of motor learning and control. Exercise should be all about changing our physiology, NOT about improving our skills.