Isolation Movements Waste Your Time

Hang around people in the fitness industry long enough, and you'll undoubtedly hear/read the term "muscle imbalance".  Muscles apply tension on joints, and that tension keeps joints operating like they're supposed to.  But some athletic pursuits strengthen the muscles that apply tension on one side of a joint more than their opposite counterparts.  That's an imbalance.

For example, long distance runners' hamstrings are often weaker than their quadriceps.  The difference in tension between the hamstrings and quads often results in knee injuries after years of running.

The conventional method of balancing the strength of muscle groups acting on opposite sides of a joint is to isolate the muscle groups and exercise them individually, often using machines.  Most physical therapists would advise a long distance runner with weak hamstrings to strengthen the quads and hamstrings separately with leg extensions and leg curls.

But that brings up a fairly obvious question.  Or, it should, anyway.  How does an athlete performing leg extensions and leg curls know if  his/her quads and hamstrings are balanced?  How does he/she know if they are operating as they are designed to?  Put simply, he/she can't know.  It's impossible.  Because the movements he/she is performing are movements his/her body is not designed to perform.  In fact, the human body can't perform those movements without the assistance of machines that were invented in the 1970s.

So, how can an athlete strengthen his/her quads and hamstrings evenly and help prevent knee injuries?

Simple.  Squat.

Unlike leg extensions and leg curls, the squat is a natural movement our bodies are designed to perform.  Because of that, when an athlete performs a squat correctly, all the muscles involved in the squat are automatically balanced.  The athlete doesn't need to think about which muscles to "fire" (I hate that term, by the way) because his/her nervous system does it instinctively.

You can find the following illustration on page 19 of the third edition of "Starting Strength".

Figure 2-11, page 19, Starting Strength Basic Barbell Training 3rd Edition

It demonstrates how the quads and hamstrings work together to help perform the squat.  As helpful as this illustration is, however, I recently ran across a video that I think makes this point much more effectively.



In the video clip above, CrossFit athlete Brooke Ence performs the squat with excellent technique, and you can watch the quads and hamstrings engage, contract and stretch in perfect concert with each other.  And it's not just her quads and hamstrings.  Her hip adductors, tensors, glutes, etc. work together to flex and extend her hips and keep her knees pointing over her toes.  Simultaneously, her abs and the muscles in her back maintain proper spine alignment and thus transfer force from the ground all the way to the bar.  And every muscle from the bar to her feet works to keep the weight balanced and centered over her feet.

That's why isolation movements waste your time.  It would take hours to train all those muscle groups by isolating each of them.  A 5x5 set of squats does it in minutes.  And even if you did manage to train all those muscle groups by isolating them, you'd never know if they were really in balance with each other.

Are there cases in which isolation movements are not a waste of time?  Sure.  Competitive body builders need isolation movements to compete in their sport.  Besides, they get judged on appearance, not performance.  Also, if an athlete is injured and can't perform compound movements like the squat, it's better to do something than nothing.

If, however, an athlete is not injured and wants to improve performance and prevent injury, compound movements - squats, deadlifts, presses, the Olympic lifts, etc. - are the way to go.  For such an athlete, isolation movements are an unnecessary, counterproductive waste of time.