The term “functional training” has been defined as everything from performing exercises that mimic real life activities to any exercise that incorporates 3 planes of motion. Some don’t consider an exercise functional unless it involves the use of balls, suspension straps, or wobble boards. When something means so many things to so many people the term itself loses value. We believe all exercises have value assuming client’s goals, limitations, and current tolerance levels areconsidered, but understand that there are risks and benefits to every choice we make and the benefits should ALWAYS outweigh the risks.
In the case of exercises that are often labeled “less functional” such as a leg extension, bicep curl, calf raise, etc. fewer muscles have to work together to create motion and provide stability and, therefore, there is likely a DECREASED chance/incidence of compensation. If you have more planes of motion, it stands to reason that you have more muscles contributing to motion in the multiple planes. Considering that the body will get from point A to point B in the way that requires the least amount of effort possible, when performing exercises considered “functional” such as squats, deadlifts, pullups, dips, etc. you have more opportunities to compensate, and chances are the body will do so in order to keep going resulting in an increased chance of injury. This is basic physics and defeats the idea that machines pose a greater risk than the many variations of lunges and TRX exercises commonly prescribed by misguided articles and social media posts.
Bottom Line: If your take away from this is that exercises that integrate multiple joints are dangerous or bad then you’ve missed the point. The point is there is no functional vs. nonfunctional exercise or good vs. bad exercise. There are only appropriate and inappropriate choices, which are determined by the individual.