Understanding Load and Capacity: What Causes Musculoskeletal Pain

by Dr. Christopher on May 2, 2011

Understand these two words and you have understood ALL musculoskeletal pain.

Load and Capacity.

Load: how much you ask your body to do.  (the sand)

Capacity: how much load your body can handle without damage.   (the bucket)

When load is LESS than your capacity, you are healthy. 

When load EXCEEDS your capacity, injury sets in.  Pain is the signal, letting you know, that you’re overflowing.


The Purpose of Exercise 

The purpose of exercise to fill the bucket with as much sand WITHOUT overflowing.  This creates maximal tissue damage and allows your body to patch the damaged muscle with more muscle as opposed to scar tissue. 

The healthy way to exercise.

Exercising in a healthy way will give you a bigger bucket (the ability to do more work) after every workout.

Say you have the capacity to do 20 squats.

You do 20 squats.  You recover.  The next time you do squats, you can do 22 squats. 

You’ve increased your capacity to do work, further preventing injury.

How might load EXCEED capacity?  In 2 ways:

1.  The Sedentary or People Who Don’t Exercise: This is the majority.  They don’t realize they’re putting sand in the bucket.

        a) Sitting on your butt for eight hours a day is putting a significant amount of sand in the low back and sciatic nerve bucket.  This is why sciatica is so common … you’re sitting right on your sciatic nerve (although you’re not contracting the nerve or your butt muscles, the PRESSURE of gravity pushing your butt into the chair causes decreased blood flow, decreased oxygen, local damage, free radical generation, soon followed by scar tissue generation)!

       b) Typing puts sand in your median nerve and forearm musculature bucket.  Carpal tunnel anyone?

       c) Sleeping on your side puts sand on the “down” shoulder bucket.  I’ve seen frozen shoulders in people who do zero activity.  And they ask how it happens.  This is how.

2.  Overachievers, Overtrainers, and Crossfitters: Most people don’t exercise too much.  But for those who use exercise as their drug to fulfill hormonal needs, overtraining is common in this population.

While I love Crossfit, people use it improperly in two ways:

       a) Bad form: Getting a shovel that is twice as big and putting sand in a bucket that is twice as small. 

       b) Working out too often: Working out on Day 1 or Day 2 before you’re fully recovered, so your bucket is already partially full.  You can compensate for some time.  But you’re rolling the dice.  Eventually, you will break).

The painful way to exercise.

So you have the capacity to do 20 squats. 

You fatigue at repetition 20.  You think “Screw it.  I ate some doughnuts last night or work is stressing me out.  I’m going to do more.”

In situation a) from above, the bad form begins.  Your knees start caving in putting excessive load on the medial meniscus and your lumbar spine begins to flex. Now, it’s only a matter of time before something breaks.

In situation b) you only do a few reps more after rep 20, but you feel good.

So you do squats the next day.  And the day after that.  And the day after that.  After each day, your form gets worse and worse.  Eventually your bucket is smaller even though you feel better (perhaps you only do 10 squats) or you break.

People Who Hate Exercise

If you don’t use it, you lose it.

A very necessary question to address.

My step-dad asked me “I’m not in pain.  Why do I need to exercise?”

I answered “Because your bucket is shrinking everyday.  Your bucket is going to shrink until the load of your activities of daily living (simply sitting or bending over to pick up the paper or washing the dishes) will exceed your capacity … creating significant injury…

Then it will be too late to give you a bigger bucket.”

Using the darn treadmill or elliptical machine is better than nothing.  Agreed.

But if you don’t maintain your capacity for a pain-free life …maintain your capacity to do a squat (and thus sit or use the toilet), your capacity to reach overhead (and lose the ability to reach above your head to get things out of cabinets like my Babci did), your capacity to do a push-up (and get yourself off of the ground if you fall down), you’ll lose it. 

There are 4 exercises, at minimum, that you should be doing.

That’s when older people need a cane, then a wheelchair, then someone to wipe their butt.

Exercise may not be fun for all.  But it keeps your bucket big so you can move well into your 70’s, 80’s, and 90’s. 

It gives you a long, healthy life. 

That’s a cool thing.

Here’s to keeping your bucket BIG!

Do you exercise and prepare to live the life that you imagine?

I owe my understanding of these concepts to Dr. William Brady, one of the best musculoskeletal specialists I’ve ever seen.

Dr. Christopher Stepien is a chiropractor, chronic pain specialist, and A.R.T. provider, and clinic director of the Barefoot Rehabilitation Clinic in Morristown, NJ.  He practices out of Crossfit Morristown.

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{ 4 comments… read them below or add one }

Kevin May 3, 2011 at 1:41 pm

Hi Chris,

I like this post. Your drawings are spectacular! I do squats and lunges to keep me hiking forever and pull ups and presses so I will always be able to climb trees better then my kids (when that time comes not yet). By the way dinner last night….toasted portabella mushroom, grass fed, free range, organic beef burger on top, guacamole, sauteed onions on that, topped with kale, cabbage, and purple kale. Results: tasted way better then expected, way messier then expected. Conclusion: next time bite size sliders of the same thing, wont be as messy if the entire thing is in my mouth (there is no escaping once in). Try it please.

Dr. Christopher May 3, 2011 at 4:22 pm

Haha Kevin.

I like the idea of being able to climb trees better than my kids. Next time I see you, we’ll have a swinging competition to see who is king of the jungle.

That dinner sounds delicious! I want it in my belly right now. We’ll cook together again when I see you.

Love, Chris

Kevin May 14, 2011 at 1:10 am

Ok…so, sliders were just as good but only slightly less messy and a little more work. The take away, either way is wonderful. King of the jungle sounds fun. Makes me remember when we climbed up the waterfall then climbed back down through all those hau bush vines and branches. I love that place.


Dr. Christopher May 15, 2011 at 1:08 pm

Yes, I was pretty upset with you for bringing me up there. But I did enjoy climbing down through those crazy trees. You are crazy Kevin.

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