LeBron James

I do about half of my leg exercises single-legged.  It undoubtedly looks strange since I’m usually the only one doing them at my gym (well, other than Lisa).  The obvious question that I’m sure a lot of people think but few have asked is, “Hey.  Why aren’t you using both legs?”

Well, hypothetical interrogator, I do them because I want to train my body in the manner that it is used in real life.  My Fitness Institute teachers pointed out to me what should have been obvious.  They said that walking is a single-legged movement.  I hadn’t thought of that before, but I wasn’t sure what it meant at first.  So, I kept doing two-legged exercise all of the time.

Then, my teachers went more in depth.  It turns out that we almost always use one leg at a time, and that holds true of everyone from great-grandma on her walker to basketball star LeBron James as he sprints down the court.  People use one leg at a time.

With that said, why do we need to train one leg at a time?  Because the Specific Adaptation to Imposed Demands (SAID) Principle states that the body will respond specifically to whatever task you ask it to do.  If you want to run better, then you should run.  If you want to bicycle better, then you should bike.  It’s really that simple.  Through the same reasoning, if you want to walk or run better, then you need to train a single leg at once because that’s what walking and running require.

Please don’t get me wrong.  I’m not demonizing two-legged exercises.  I’m simply stating that if we apply basic Exercise Physiology to the activity of human locomotion, then we have to train the body for how it is used.  Two-legged exercises have their place for building overall strength, but single-legged exercises have their place for building all of the supporting muscles and the coordination to use the leg strength you’ve built up with two-legged exercises.  After all, what good is having a 1000lb squat if you can’t even run to save your life?  Building strength is great, but building functional strength is even better.